Sign in

NSTX-U eXperimental Proposal (XP) Idea Form (Responses)

Share

File

Edit

View

Insert

Format

Data

Tools

Form

Add-ons

Help

Accessibility

$

%

123

Conditional formatting...

Conditional formatting...

SUM

AVERAGE

COUNT

MAX

MIN

More functions...

More

|

Still loading...

| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | S | W | X

1

Timestamp

Title of proposal

Proposer first name

Proposer last name

Proposer e-mail address

Co-authors on your proposal

Proposer home country

Proposer home institution

NSTX-U group assessing proposal

Contributions to milestones or ITPA

Machine time requested (run days)

Pre-lithium-wall-conditioning machine time requested (run days)

Minimum useful machine time (run days)

Goal, importance, and plan of proposal (2000 character Limit)

Special requirements (500 character limit)

Document Merge Status - Forum idea summary

Document Merge Status - Forum idea summary update

| | | | | | | | | | | | | | | | | |

2

2/2/2015 21:36:00

NSTX-U breakdown scenario development

Devon

Battaglia

[email-masked]

Dennis Mueller

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

None

1

0

0.5

The goal is to develop 2 or 3 breakdown scenarios at different OH precharge levels. This involves optimizing the PF3/5 and OH ramps, pre-fill level, GDC length and ECH pre-ionization to achieve reliable timing of breakdown, suitable Ip ramp and plasma growth until 20ms and acceptable OH/TF coil temperature differentials (ie OH preheating) while minimizing flux consumption, I2t heating and impurity generation. These activities will also provide an opportunity to examine the shot cycle limitations and the impact of a long bake and boronization on plasma breakdown by comparing to CD4. The results, combined with modeling and NSTX experience, should provide the "recipe" for breakdown at any OH pre-charge level. At a bare minimum, we need to achieve one working breakdown scenario. Work on the PCS gap and Ip control will be happening in parallel once we get a suitable target at 20ms.

XMP follows gas and magnetics calibrations in commissioning phase. Require plasma TV, magnetics, neutron diagnostics, filterscopes. Steve promised me EFIT, so I better have EFIT. RGA, bolometers, SXR, VB would be nice.

Doc Created @ Tue Feb 10 2015 17:31:28 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:31:28 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:31:33 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:22:52 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:22:52 GMT-0500 (EST)

3

2/4/2015 5:23:38

NSTX-U Automatic Shutdown

Stefan

Gerhardt

[email-masked]

devon battaglia, dennis mueller, keith erickson, dan boyer

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

none

1

0

0.5

DCPS is intolerant of up-down asymmetries in the plasma. These often occur during disruptions. Hence, we need some simple reliable thing to shut down the plasma upon detecting that a disruption is imminent.

Need the PCS code written and debugged offline (or in the background). Spec has been written, but it is still be iterated with software engineering.

Note that parts of this may be phased in over multiple days.

Doc Created @ Tue Feb 10 2015 17:31:37 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:31:37 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:31:43 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:23:02 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:23:03 GMT-0500 (EST)

4

2/4/2015 5:33:25

Maximizing the non-inductive current fraction in NSTX-U H-modes

Stefan

Gerhardt

[email-masked]

jon menard, dan boyer, devon battaglia, francesca poli, dennis mueller

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

R15-1, R15-2, R15-3

2

1

1

A primary justification for the upgrade is to operate with 100% non-inductive current drive. Papers by Menard and Gerhardt have indicated the likely non-inductive plasma currents for a range of Bt and confinement assumptions. This experiment will assess those predictions against the available TF operating space.

Note that these would have an ohmic current ramp, and go into H-mode either at SoFT or a bit before. Goal is to get high non-inductive fraction in the flat-top.

Would probably be good to try both before and after lithium conditioning, as Zeff and confinement will likely both be different. And obviously, the higher the TF, the better.

A few shots attempting this early in the run would also be good, since Vloop is already a good diagnostic for this.

Might need some vertical control optimizations, though we can hope that the low l_i of these discharges will be more forgiving.

Doc Created @ Tue Feb 10 2015 17:31:46 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:31:46 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:31:50 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:23:12 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:23:13 GMT-0500 (EST)

5

2/4/2015 18:11:05

MSE-CIF Calibration

Fred

Levinton

[email-masked]

Howard Yuh

United States

Nova Photonics

Cross-Cutting and Enabling (CC)

JRT-15, R(15-2)

1

0

1

MSE-CIF beam into gas calibration as per XMP-33, but with some
modification to higher TF and PF.

Source A @90 kV

Doc Created @ Tue Feb 10 2015 17:31:53 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:31:54 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:31:58 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:23:24 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:23:25 GMT-0500 (EST)

6

2/4/2015 11:18:29

Commissioning the MGI Valves

Roger

Raman

[email-masked]

S. Gerhardt, D. Mueller

United States

University of Washington

Cross-Cutting and Enabling (CC)

JRT-2016

1

0

1

NSTX-U will for the first time conduct MGI Research. Three MGI valves will be installed on NSTX-U. These need to undergo the following tests before they will be ready to support XPs.
1) Test each of the valves in the presence of a magnetic field. Initial tests will be conducted at BT=0.4-0.5T
2) 200 Torr.L of Neon will be injected and the vessel pressure increase will be compared to that from shots without a magnetic field. The fast micro ion gauges will be used to record the pressure increase.
3) Repeat the tests in the presence of plasma.

Most of the diagnostics will be turned off. For the plasma tests a limited set of diagnostics will be used.

Doc Created @ Tue Feb 10 2015 17:32:03 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:04 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:08 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:23:34 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:23:35 GMT-0500 (EST)

7

2/4/2015 11:20:52

MSE-LIF Calibration

Fred

Levinton

[email-masked]

Howard Yuh, Yancey Sechrest

United States

Nova Photonics

Cross-Cutting and Enabling (CC)

JRT-15, R(15-2)

1

0

1

Calibrate MSE-LIF sustem

DNB operation

Doc Created @ Tue Feb 10 2015 17:32:11 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:11 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:16 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:23:45 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:23:45 GMT-0500 (EST)

8

2/4/2015 11:28:17

Commissioning the CHI System

Roger

Raman

[email-masked]

D. Mueller, B.A. Nelson

United States

University of Washington

Cross-Cutting and Enabling (CC)

Contributes to full NI Opeartions

1

1

1

The CHI configuration on NSTX-U is different from that on NSTX. Specifically, the gap between the inner and outer vessel in both the injector and absorber regions is now much less. An initial test of the ability of the new system to be able to generate plasmas is necessary before the system can support experiments. This test is needed very early during the current run period to identify and correct any potential issues.
The work to be done involves:
1) Using only the PF1CL coil at 2, 4 and 8kA,
2) Inject 2 to 6 Torr.L of D2 using the Bay-K injector (at -13ms)
3) With the CHI capacitor bank configured for 10mF, and starting from 1kV, apply increasing levels of voltage to establish plasma break-down requirements and to successfully produce a CHI discharge in which the plasma is localized to the injector region.
4) The most important goal is to determine operating conditions that avoid the formation of absorber arcs, as this is essential before an XP can be written.

Plasma current Rogowskii, all magnetics, lower divertor spectroscopy, micro ion gauges are needed. Other diagnostics will be used if available.

Doc Created @ Tue Feb 10 2015 17:32:19 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:20 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:24 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:23:55 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:23:56 GMT-0500 (EST)

9

2/6/2015 21:28:17

MSE Measurement of NB Interference

Fred

Levinton

[email-masked]

Howard Yuh, Yancey Sechrest

United States

Nova Photonics

Cross-cutting and Enabling (CC)

JRT-15, R(15-2)

1

0

1

Assess interference effects of new NB sources on MSE.
The MSE-CIF sight lines cross the new neutral beam path.
In this XMP we propose to assess the effects of the emission from these beams on the MSE-CIF signal and determine if there is any interference
on the pitch angle measurements.

MSE-CIF, source A at 90 kV, New NB sources at ~90 kV.

Doc Created @ Tue Feb 10 2015 17:32:27 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:28 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:32 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:24:05 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:24:06 GMT-0500 (EST)

10

2/13/2015 18:42:37

Make contact with NSTX for n=1 tearing mode stability

Robert

La Haye

[email-masked]

John Ferron, Josh King, Carlos Paz-Soldan, Ted Strait, Jack Berkery, Dylan Brennan, Stefan Gerhardt, Clayton Myers, Jong-Kyu Park, Steve Sabbagh, Zhiuri Wang

United States

General Atomics

Macroscopic Stability (MS)

None

1

0

0.5

In NSTX at 0.9MA and 0.44T, a prescription was found for reproducible onset of m/n=2/1 tearing modes with self-stabilization at the "marginal" condition on NBI step-down. Stability was interpreted as close to marginal classical tearing with balance thus between stabilizing curvature DR term and neoclassical bootstrap destabilization term Dnc; the stabilizing curvature effect is weak at large aspect ratio as in DIII-D (R/a=2.7) for DR/Dnc ~-1.2*(a/R)**2 all else equal [1]. NSTX-U has somewhat larger aspect ratio than NSTX (R/a from 1.4 to 1.7) so that the relative stabilizing effect of curvature should be decreased by a third, opening up the difference between onset beta and marginal beta. This XP will investigate this and make NSTX-U n=1 tearing onset beta contact with NSTX at similar parameters.
Experiment would be carried out as for NSTX #134020 with reproducible n=1 tearing onset using modest Li evaporation, IP=1MA and BT=0.5T as close to NSTX parameters (NSTX-U startup parameters but half of eventual NSTX-U full parameters). On-axis NBI only for H-mode and a preprogramed step-down of NBI power aiming to lower beta after tearing onset, stay in ELMing H-mode, keep n=1 tearing mode rotating (no locking to the wall) and self-stabilization at the "marginal" condition.
[1] R.J. La Haye, R.J. Buttery, S.P. Gerhardt, S.A. Sabbagh, and D.P. Brennan, "Aspect ratio effects on neoclassical tearing modes from comparison between DIII-D and National Spherical Torus Experiment”, PHYSICS OF PLASMAS 19, 062506 (2012).

Could be done in reduced IP and BT startup plasmas? Later in weeks 5-8 or 9-12 OK but want similar IP and BT as in NSTX previously run.
Best is to be done after Li evaporation is made routine in order to achieve reproducible conditions.
Do not want off-axis NBI as want to match NSTX discharges previously run.

Doc Created @ Tue Feb 10 2015 17:32:35 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:35 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:40 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:24:15 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:24:16 GMT-0500 (EST)

11

2/4/2015 13:15:27

Magnetics Calibration

Clayton

Myers

[email-masked]

Stefan Gerhardt

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

None

1.5

0

1.5

Calibrate magnetics, including AC PF coil currents for assessing error fields from induced vessel currents.

None.

Doc Created @ Tue Feb 10 2015 17:32:43 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:44 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:47 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:24:26 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:24:26 GMT-0500 (EST)

12

2/4/2015 17:07:18

Commissioning the Thomson Scattering System

Ben

LeBlanc

[email-masked]

A. Diallo, M. Coury

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

none

0.35

0.35

0.35

The goal of this XMP is to commission the MPTS 42-channels. We will be requiring high density L-mode type discharges during which a radial motion (few cm) of the plasma is generated.

none.

Doc Created @ Tue Feb 10 2015 17:32:51 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:32:51 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:32:57 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:24:37 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:24:37 GMT-0500 (EST)

13

2/5/2015 10:58:00

HHFW antenna conditioning and performance evaluation

Rory

Perkins

[email-masked]

Joel Hosea, Gary Taylor, Nicola Bertelli

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

R(15-1)

3

2

2

Prior to each set of HHFW experiments, operate HHFW into plasma to check out system performance, to condition antenna to maximum voltage, and to evaluate antenna performance with regards to current machine conditions (especially wall conditioning). Power will be applied starting at a low level (~ 0.6 MW) and raised until either a hard voltage limit or 6 MW is reached. System performance includes verification of phase and amplitude control, arc control, and plasma current inhibit. Some arcing during the conditioning process is typical but is also expected to improve, increasing the maximum applicable HHFW power that can be applied. Evaluate plasma heating utilizing magnetics and Thomson scattering. Compare voltage limits and performance in multiple plasma configurations and over different wall conditions.

Additionally, for the first HHFW run in 2015, we must evaluate the heat load from the second neutral beam onto the HHFW antenna limiter under a range of conditions to determine the minimum allowable outer gap and also whether an upgrade is needed for the HHFW limiter. Also, a new electrical ground was added between the back of each antenna-strap box and the vessel, and we should evaluate the impact of this additional short early in the campaign, as this will guide future work on the test stand to identify further improvements.

Would like to condition after boronization but before any lithium has been applied.

Doc Created @ Tue Feb 10 2015 17:32:59 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:00 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:05 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:24:48 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:24:48 GMT-0500 (EST)

14

2/5/2015 16:35:27

Neutron diagnostic calibration plasmas (XMP)

Douglass

Darrow

[email-masked]

none

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

none

0.5

0.5

0.25

The goal is to establish, as accurately as possible, the ratio between counting efficiencies of the different fission chambers on NSTX-U. In addition, the goal is to transfer the absolute calibration to the fission chamber current mode signal in at least one detector. This is all required to assure NSTX-U is operating within its stated safety envelope for neutron production, plus assure that neutron rates for TRANSP comparison are as accurate as possible.

Low neutron rate plasmas needed with a single beam at ~45 kV injecting. Low plasma current (650 kA) may also be desired. Transition to He gas may be requested if initial neutron rates are too high. Goal is to obtain as many sec or msec of accumulated neutron emission under steady or slowly varying plasma conditions while maintaining the neutron rate such that the necessary cross-calibrations can be achieved.

Doc Created @ Tue Feb 10 2015 17:33:07 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:08 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:12 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:24:59 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:24:59 GMT-0500 (EST)

15

2/5/2015 17:57:32

Characterization of the Pedestal Structure as function Ip, BT, and Pnbi

Ahmed

Diallo

[email-masked]

R. Maingi, S. Smith, et al.

United States

Princeton Plasma Physics Laboratory

Pedestal Structure and Control (PS)

R15-1

1.5

1.5

1.5

The goal of this proposal is to provide a complete characterization of the pedestal on NSTX -U with increased engineering parameters (Ip, BT, NBI power). The leading model predicting the pedestal is EPED, which has two main hypotheses, peeling-balloning theory and the microinstability – KBM for limiting the pedestal gradient. To test the hypotheses of this model, the aim of this XP is to obtain data on the pedestal scaling with plasma current, magnetic field, beam tangency radii, and the plasma shape (triangularity). These various scaling will provide the necessary ingredients to understand the pedestal formation in H-Mode. The dependencies of these scalings as a function of wall coatings (Boron vs Li) will be investigated. In addition, this experiment will target the inter-ELM characterizations of the turbulence to test the KBM hypothesis limiting the pedestal gradient. Finally, this experiment is expected to provide sufficient data to generate a database to provide to edge codes for validating their models.
This experiment will be carried in 1.5 days for each wall conditioning (Boron and Li) and high triangularity plasmas
• Scan Ip [0.7, 1.0, 1.3] MA @ BT =0.5 with PNBi = 4 MW (use the adequate combinations of the two NBIs to be determined by XMP)
• At Ip= 1.0 MA, scan BT = [0.4 , 0.55, 0.65] T
o PNBI=[5, 6,7] MW
All the kinetic and turbulence diagnostics are required.

All kinetic, and edge turbulence diagnostics will be required.

Doc Created @ Tue Feb 10 2015 17:33:15 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:16 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:21 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:25:14 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:25:15 GMT-0500 (EST)

16

2/6/2015 9:30:01

6 SPA and Proportional RWM control Checkout

Stefan

Gerhardt

[email-masked]

Sabbagh, Myers,...

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

none

0.75

0.75

0.5

Qualify the RWM control system with Bp only and Bp+BR sensors.

Note that this also checks 6 sub-unit operation under physics control for the first time.

Need to verify that mode-ID is properly functioning before this can be done.

Also need to ISTP the HF/SPA system

Doc Created @ Tue Feb 10 2015 17:33:24 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:25 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:30 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:25:24 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:25:24 GMT-0500 (EST)

17

2/6/2015 9:47:30

Software Test fon n=0 Control

Stefan

Gerhardt

[email-masked]

Boyer, Mueller

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

none

0.5

0.5

0.5

Goal is to checkout the new voltage difference loops, and understand how to run the machine with different combinations of those loops.

Note that these were installed for 2011, but never used.

It is unclear if this needs a separate XMP, or if it will be folded into something else. I include it for completeness.

Doc Created @ Tue Feb 10 2015 17:33:33 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:33 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:37 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:25:33 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:25:34 GMT-0500 (EST)

18

2/6/2015 9:56:06

FIDA/ssNPA/sFLIP checkout

Deyong

Liu

[email-masked]

D. S. Darrow. W. W. Heidbrink, M. Podesta

China

University of California - Irvine

Cross-Cutting and Enabling (CC)

R15-2, JRT-15

1

1

1

The t-FIDA and ssNPA system are new and critical diagnostics to characterize the confinement of fast ions from the new off-axis NBI. The goal of this XMP is to check and optimize v-FIDA, t-FIDA, ssNPA and sFLIP fast ion diagnostics with quiescent L mode plasmas and beam blips to assure they are ready to support the main XPs. The FIDA system checkout will involve: (a) background signal check with modulated NBI, and (b) f-FIDA filter angle optimization with a few identical repeat shots. For the ssNPA system, modulated on-axis and off-axis NBI will be used to check each individual ssNPA subsystem and active/passive signals. Additionally, the sFLIP diagnostic will monitor fast ion losses during Ip and Bt scan or current ramp-up/ramp-down phase with beam blips.

Require relatively clean machine (low oxygen) to avoid impurity contamination in FIDA spectra. Also require on-axis and new off-axis NBI systems with relatively low voltage and low power, plus a few beam modulation patterns. Need magnetics, plasma profile diagnostics (Thomson scattering, CHERS), MSE, and fast ion diagnostics (neutrons, vertical-FIDA, tangential FIDA, ssNPA and sFLIP).

Doc Created @ Tue Feb 10 2015 17:33:40 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:41 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:45 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:25:43 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:25:44 GMT-0500 (EST)

19

2/6/2015 10:06:05

CHERS XMP

Mario

Podesta

[email-masked]

R. Bell

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

all of the above...

2

0

1

This XMP will assess schemes for interpretation of CHERS data when the 2nd NB line is operating.

Requires 2 run days, separated by 2-4 weeks.
Day#1 can be run early, as long as plasmas (L- and H-mode) have flat-top phase of ~0.5sec.
Requires MPTS, EFIT.
Requires NB power of 4MW or more, NB modulation for both NB line#1 and #2.

Doc Created @ Tue Feb 10 2015 17:33:48 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:33:48 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:33:57 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:25:54 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:25:54 GMT-0500 (EST)

20

2/6/2015 10:22:14

High-Z reference discharge development

Mike

Jaworski

[email-masked]

none yet

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

Milestone R16-2

2

2

1

XMP

This XMP will develop the baseline shape and operation for M&PTSG experiments that will be conducted on the high-Z divertor tiles (row 2).

An isolver solution has already been created for this shape. Most important feature will be maintaining a consistent strike-point location/evolution for experiments on the high-Z divertor in 2016. This XMP will develop the shape and parameter scans needed for experiments in the future. A power scan, divertor gas puffing scan and Ip scan will provide a range of input powers and divertor conditions.

Diagnostics for locating the strike point: Langmuir probes, IR thermography, div. cameras, magnetic reconstruction.

Doc Created @ Tue Feb 10 2015 17:34:00 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:00 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:06 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:26:04 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:26:04 GMT-0500 (EST)

21

2/6/2015 10:50:56

Initial H-mode access on NSTX-U

Devon

Battaglia

[email-masked]

Dennis Mueller, Stan Kaye, Rajesh Maingi

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

none

1

0

1

Commissioning XMP. Follows development of a high current (0.5 - 1MA) flattop in L-mode. Goal is to identify suitable HFS fueling, timing of X-point formation, GDC length and NBI power to obtain reliable H-mode access at the start of flattop. Secondary goal is to optimize the mix of fueling locations and timing to reduce the H-mode power threshold and the amount of early fueling. A later XMP (Mueller) will work to optimize timing of H-mode access in Ip ramp for high-performance discharges.

Machine is clean enough to generate Ip > 0.5 MA, diverted L-mode flattop with NBI heating. TS to confirm pedestal development and filterscopes/USXR for evaluating H-mode access. All HFS/LFS gas under PCS control.

Doc Created @ Tue Feb 10 2015 17:34:09 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:09 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:14 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:26:14 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:26:15 GMT-0500 (EST)

22

2/6/2015 11:41:17

Granule Injector operational readiness assessment

Robert

Lunsford

[email-masked]

L. Roquemore, R. Kaita, M. Jaworski

United States

Princeton Plasma Physics Laboratory

Cross-Cutting and Enabling (CC)

ITPA Pedestal and Edge Physics Joint Experiment #30

0.5

0.5

0.5

Prior to experiments utilizing the NSTX-U granule injector it will be necessary to confirm operational readiness of the constituent components. While most of this can be done offline, a plasma is required to fully confirm dropper operation and time of flight calculations as well as the species specific particle alignment. Readiness check to be done with boron carbide particles to maintain a lithium free test cell. While an additional readiness check and possible impeller re-alignment will be necessary prior to lithium injection, we anticipate this to be a minor issue.

Granule injector operation can be assessed with any plasma robust enough to ablate the injected particles.

Doc Created @ Tue Feb 10 2015 17:34:17 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:18 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:23 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:26:24 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:26:24 GMT-0500 (EST)

23

2/6/2015 13:50:05

RWM state-space control with 6 coils - checkout XMP

S.A.

Sabbagh

[email-masked]

J.M. Bialek, J.W. Berkery, Y.S. Park

United States

Columbia University

Cross-cutting and Enabling (CC)

NSTX-U R(15-3), ITPA MDC-19

0.25

0

0.2

The new NSTX RWM state space controller has been upgraded to allow independent control of the six RWM coils. Some run time is needed to test this system once developed. However, most of the system checkout will be possible in piggyback operation alone. A couple to a few hours operation may be needed for system checkout with gains on the overall current requests set to values leading to normal SPA current levels. The piggyback tests would be conducted with the gains on the overall current requests set to produce insignificant SPA currents.

The initial implementation of the RWM state space controller (RWMSC) in 2010 was conducted entirely in piggyback mode. This was performed by setting the overall RWMSC scalar gain to a small value (1e-3), which allowed actual operation of the RWMSC with SPA currents going to the RWM coils without influencing machine operation.

Test independent control of the six RWM coils, using n = 1, and n = 2 input eigenfunctions to the RWMSC in piggyback mode with overall scalar gain = 1e-3. Once this test checks out, take the following shots (assuming successful shots):

A) With default RWMSC control matrices
(Gain for overall SPA current request set to 1.0)
- Pre-programmed n = 1 SPA configuration, square wave pulse (1 shot)
- Preprogrammed n = 2 SPA configuration, square wave pulse (1 shot)
- Choose one of the above, change overall observer gain (1 shot)

B) With a different set of setting on the RWMSC control matrices
(Gain for overall SPA current request set to 1.0)
- Pre-programmed n = 1 SPA configuration, square wave pulse (1 shot)
- Preprogrammed n = 2 SPA configuration, square wave pulse (1 shot)
- Choose one of the above, change overall observer gain (1 shot)

Requires RWM Bp sensors operational, RWM state space controller with independent RWM coil operational

Doc Created @ Tue Feb 10 2015 17:34:26 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:26 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:31 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:26:33 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:26:34 GMT-0500 (EST)

24

2/6/2015 13:38:17

XMP for MHD Spectroscopy Checkout

Jack

Berkery

[email-masked]

Steve Sabbagh, Zhirui Wang

United States

Columbia University

Cross-cutting and Enabling (CC)

R15-3: Develop physics+operational tools for high-performance discharges

0.25

0.25

0.2

MHD spectroscopy was utilized in NSTX to measure resonant field amplification (RFA) of applied n=1 AC magnetic fields and thereby determine the proximity to global stability boundaries [1]. The optimal frequency in NSTX was around 30 Hz in the co-rotating direction [2], but often 40 Hz was used since a higher frequency is preferable [1]. This technique will be used again in NSTX-U in various MS TSG experiments, and therefore the capability must be re-established. We will use the existing NSTX midplane coils to apply n=1 AC fields, the poloidal RWM magnetic sensors to measure the resulting field, and an existing analysis code to find the RFA.

Suggested shots (assuming good shots)

A) Plasma with NBI power to produce betaN near no-wall limit (betaN ~ 2.5)
1 co-rotating: 40 Hz, 55 Hz, 70 Hz (1 shot)
2) counter-rotating: 55 Hz, 40 Hz, 20 Hz (1 shot)

B) Plasma with NBI power to produce betaN above no-wall limit (betaN > 4.5)
1 co-rotating: 40 Hz, 55 Hz, 70 Hz (1 shot)
2) counter-rotating: 55 Hz, 40 Hz, 20 Hz (1 shot)

This XMP should be run after “Magnetics Calibration“ by Myers and “Software test for n=1 RWM and error field control with 6 SPAs” by Gerhardt, and after a good H-mode plasma has been established.

Diagnostics required: Magnetics, especially the RWM sensors.

Doc Created @ Tue Feb 10 2015 17:34:34 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:35 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:39 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:26:43 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:26:43 GMT-0500 (EST)

25

2/6/2015 13:49:59

Commission rtEFIT, ISOFLUX

Dan

Boyer

[email-masked]

S. Gerhardt, D. Gates, S. Sabbagh, E. Kolemen

United States

Princeton Plasma Physics Laboratory

Cross-cutting and Enabling (CC)

15-3

1

0

0.5

rtEFIT and ISOFLUX will enable precise control over the plasma boundary. Offline tests, development tests, and piggybacking shots will be used to check-out rtEFIT. A series of shots will be used to tune the ISOFLUX control gains for the outer gap and squareness.

Need the PCS code debugged offline. Parts of this XMP could be phased over multiple days.

Doc Created @ Tue Feb 10 2015 17:34:41 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:42 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:47 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:26:52 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:26:53 GMT-0500 (EST)

26

2/6/2015 13:51:45

Beam power and beta-N control

Dan

Boyer

[email-masked]

S. Gerhardt, D. Gates, E. Kolemen, D. Mueller, D. Battaglia

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

15-3

0.5

0

0.5

Beam algorithm will enable PCS control of total and individual beam powers. betaN control will use feedback control of the total power to track requested betaN trajectory. Offline testing will be done to check-out algorithm. Series of shots will be done to track different value of betaN, assess effect of beam ‘batting order’.

Need the PCS code debugged offline. Parts of this XMP could be phased over multiple days.

Doc Created @ Tue Feb 10 2015 17:34:51 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:51 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:34:56 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:27:02 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:27:02 GMT-0500 (EST)

27

2/19/2015 17:52:10

ELM-induced fueling effects on the pedestal evolution

Ahmed

Diallo

[email-masked]

D. Battaglia, F. Scotti, V. Soukhanovskii, J. Boedo, et al.

United States

Princeton Plasma Physics Laboratory

Pedestal Structure and Control (PS)

none

1

1

1

The goal of this experiment is to characterize the role of the wall outgassing, divertor fueling and gas fueling on the inter-ELM pedestal recovery rate. Motivated by recent experiments on DIII-D that have shown that the pedestal density increases on rather fast time scale (~ 3 -5 ms) while the temperature has a slow evolution until saturation. The recovery rate appears to be independent of plasma current. Simulation using UEGDE report in Pigarov JNM 2014 modeled the temporal evolution of the Deuterium inventories between ELMs on DIII-D. Similarly, modeling using XGC0 has shown the main contributor to the pedestal recovery is the recycling from the divertor. We propose a controlled experiment that will first scan the plasma positions (vertical position and outer gap), second utilized various gas puffs (including SGI), to vary the fueling between ELMs. We expect from this experiment to quantify the contribution from each sources (wall outgassing, divertor, and gas fuelling) in the pedestal recovery rate. This experiment will target reproducible NBI heated ELMy discharges (at high plasma current and high triangularity) in Boron and Li wall coatings. In the case of ELM-free regimes, RMP- or LGI- triggered ELMs will be used. In addition, the changes in edge turbulence will be investigated.

This XP should be executed once a good ELMy discharge at high current ( 1.2 to 1.5 MA) has been established.

Doc Created @ Tue Feb 10 2015 17:34:59 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:34:59 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:03 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:27:12 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:27:12 GMT-0500 (EST)

28

2/6/2015 14:49:10

Materials Analysis Particle Probe Commissioning

Jean Paul

Allain

[email-masked]

Felipe Bedoya, Robert Kaita, Robert Ellis, Matt Lucia, Charles Skinner

United States

University of Illinois

Cross-cutting and Enabling (CC)

none

1

1

0.5

The goal is to ensure proper functioning of the diagnostic capabilities of MAPP. This includes testing and troubleshooting of the control software and hardware on the chamber and instruments rack.
Operation of MAPP requires three major phases for initial commissioning of diagnostic and operational systems: instrumentation power-up including system warm-up (e.g. analyzer initialization, sample verification, vacuum systems operational checks), MAPP probe head insertion and retraction from NSTX-U divertor region and MAPP surface analysis operation. All of these phases must be functional during operation of NSTX-U plasmas.
The instrumentation power up and system warm up involves testing and possible troubleshooting of virtual instruments to control MAPP’s systems. It also accounts for testing of MAPP’s hardware. This step includes testing of: vacuum systems, xray gun, micro-channel plate detector, energy analyzer, gas manifold systems, irradiation tools and heating systems. The final component of this section contains implementation and testing of the hard interlock system to ensure safe operation in NSTX-U.
The second step includes testing of the samples holder probe head; it is dedicated to check proper alignment to prevent potential interferences during the insertion in the divertor region. Correct alignment will also ensure the proper synchronization of MAPP with other diagnostics i.e. Dalpha radiation measurements.
The final step is devoted to final calibration and checking the synchronization of the VIs running MAPP’s systems. A standard sequence of operation in MAPP will be:
1. X ray system on
2. X ray gun turn off
3. Sputtering or cleaning
4. Repeat steps from 1-2 if no more sputtering or cleaning is needed and an additional XPS scan is wanted. Repeat steps 1-3 in case several steps of sputtering are needed.
A successful run of this sequence means correct commissioning and installation of the diagnostic. This procedure is submitted as an XMP.

none

Doc Created @ Tue Feb 10 2015 17:35:06 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:07 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:11 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:27:21 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:27:22 GMT-0500 (EST)

29

2/6/2015 14:51:16

Flow rate calibration of gas valves

Devon

Battaglia

[email-masked]

none

United States

Princeton Plasma Physics Laboratory

Cross-cutting and Enabling (CC)

none

0

0

0

Calibrate puff valve flow rate vs plenum pressure and open time. Calibrate piezo flow rate vs PWM request.

Does not need run time. But must be done before operations.

Doc Created @ Tue Feb 10 2015 17:35:14 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:15 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:19 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:27:31 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:27:32 GMT-0500 (EST)

30

2/6/2015 15:10:29

Optimization of the between-shot helium GDC

Devon

Battaglia

[email-masked]

none

United States

Princeton Plasma Physics Laboratory

Cross-cutting and Enabling (CC)

none

0.25

0

0

The goal is to identify if there is any benefit to impurity and particle control if the shot cycle is lengthened in order to achieve a longer glow discharge. This could be an interesting 2-4 shot test during H-mode commissioning shots.

Repeatable H-mode shots.

Doc Created @ Tue Feb 10 2015 17:35:23 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:23 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:28 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:27:41 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:27:42 GMT-0500 (EST)

31

2/6/2015 15:31:55

IR thermography calibration and commissioning

Joon-Wook

Ahn

[email-masked]

[email-masked], [email-masked]

United States

Oak Ridge National Laboratory

Cross-cutting and Enabling (CC)

none

0

0

0

This XMP proposal is to commission IR thermography cameras and to perform intensity calibrations. The blackbody calibration data at the bench will be compared to the data taken during the bake-out. IR intensity with pristine PFC and in the presence of surface layer, and their impact on surface temperature measurement will be assessed. Temperature data from the fast eroding thermocouple, when available, will be also used to cross-check IR data.

This XMP can be done in the piggy-back basis.

Doc Created @ Tue Feb 10 2015 17:35:30 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:31 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:36 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:28:00 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:28:00 GMT-0500 (EST)

32

2/6/2015 17:36:08

3D plasma response data for MHD and transport code validations

Todd

Evans

[email-masked]

N. Ferraro, G. Canal,J-K. Park, J-W. Ahn, S. Sabbagh, O. Schmitz and H. Frerichs

United States

General Atomics

Macroscopic Stability (MS)

none

1.5

0

1

Validated MHD and kinetic/fluid transport models in numerical codes such as IPEC, M3D-C1, XGC and EMC3-Eirene are essential for designing advanced 3D field perturbation coil such as the NCC for NSTX-U. This experiment is proposed in order to acquire data that can be used to validate the physics models in these codes. The plan for the experiment is to run LSN L-mode and H-mode plasmas while applying n=1,2 and 3 perturbation fields from the external equatorial plane EFCC/RWM coil. For n=1 and 2 we will use the 6 SPAs to change the toroidal phase and acquire magnetic, kinetic profile, fluctuation and SOL/divertor data. For n=3 perturbation fields we will do 50Hz 60º phase flips. These will be done on a shot-by-shot basis with priority given to the n=3 and n=2 variations. A key parameter for validating the plasma response physics is the plasma rotation. Once we have acquired high rotation H-mode data we will attempt to reduce the toroidal and poloidal rotation by reducing the NBI acceleration voltage. As the NBI power and torque are reduced we expect to find a point where the discharge remains in an L-mode. Several EFCC/RWM coil configurations will be used during these L-mode discharges in order to document the L- versus H-mode plasma response to the 3D perturbation fields.

Key diagnostics are: calibrated high-n array magnetics (compensated for n=1,2 and 3 EFCC/RWM fields), toroidal array of Bp and Br, plasma TV, divertor IR and CCD, target Langmuir probes, toroidal and poloidal CHERS, edge recycling and impurity, MSE, BES, Thomson scattering, reflectometry, line density, edge SXR array, edge doppler spectroscopy, toroidal bolometer array, quadrature reflectometer, shunt tile array (set for high gain), visible continuum sensor.

Doc Created @ Tue Feb 10 2015 17:35:38 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:39 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:44 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:28:09 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:28:10 GMT-0500 (EST)

33

2/8/2015 16:45:45

X-point Control

Egemen

Kolemen

[email-masked]

Pat Vail

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

Essential step toward the implementation of full plasma control capabilities on the NSTX-U machine

1

0

0.5

This experiment will test the functionality of controlling the locations of the upper and lower x-points using the upgraded set of poloidal field coils. Verification of acceptable x-point control is an essential first step toward implementing full plasma shape control capabilities such as advanced magnetic divertor geometries (snowflake divertor).

Relay feedback control was used in NSTX for control tuning. We may have to bring that online before setting running this experiment. That might need some testing.

Doc Created @ Tue Feb 10 2015 17:35:47 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:48 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:35:53 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:28:20 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:28:21 GMT-0500 (EST)

34

2/8/2015 17:11:15

Snowflake Control

Egemen

Kolemen

[email-masked]

Pat Vail

United States

Princeton Plasma Physics Laboratory

Cross-cutting and Enabling (CC)

Having Snowflake ready in the first two years

1

0

0.5

NSTX-U is designed to work with a double snowflake divertor in order to handle the high flux we expect to get. This XMP will be the first checkout of the snowflake identification and control. We do not promise a fully functioning control from the get go.

rt-efit

Doc Created @ Tue Feb 10 2015 17:35:55 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:35:56 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:01 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:28:30 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:28:30 GMT-0500 (EST)

35

2/8/2015 17:18:38

Checkout real-time diagnostic connections into PCS

Egemen

Kolemen

[email-masked]

Ahmed Diallo

United States

Princeton Plasma Physics Laboratory

Cross-cutting and Enabling (CC)

NSTX-U Milestone: Density Control (specially pedestal), all the boundary/divertor control listed

2

2

0

There a list of diagnostics we want to connect to PCS for real-time control. The magnetics connections are being taken care of. Below are the ones that are currently not connected yet:

1. MSE - Howard
2. CHERS (rotation) - Mario
3. Thomson - Ahmed/Ben
4. Lithium pellet injector (slapper) - Dennis and the new postdoc
5. Bolometer channels -Luis
6. LNLL's new Divertor diagnostics

We want to connect these to PCS. This XMP includes many sub XMPs where we test the connections and check out that we are getting the correct data into PCS within the specified delays.

While it is possible to check some of these out in piggy back. Some will need specific plasma perturbations to make sure the data we are getting make sense (rotation needs RMP braking data).

We do not expect that all these connections will be ready to test but for the ones that are ready we need testing time.

Doc Created @ Tue Feb 10 2015 17:36:07 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:36:08 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:12 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:28:40 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:28:40 GMT-0500 (EST)

36

2/9/2015 14:42:06

Parametric dependence of TAE avalanches

Eric

Fredrickson

[email-masked]

Mario Podesta, Neal Crocker, Deyong Liu, Douglass Darrow

United States

Princeton Plasma Physics Laboratory

Energetic Particles (EP)

none

2

0

1

The goal of this experiment is to extend the existing data set on TAE avalanches to both higher toroidal field and higher beta, as well as to investigate the dependence on neutral beam tangency radius. TAE avalanches appear to be rare in conventional aspect ratio tokamaks, which generally operate at higher fields than NSTX for similar density. With the extension of the toroidal field to 7 kG, it might be possible to see some effect on the scaling with toroidal field that could be extrapolated to the conventional aspect ratio parameter range. As part of this experiment, I would also like to revisit the high beta regime explored by NSTX in the early years of operation. That would mean operation at toroidal field strength of 2 or 2.5 kG, and >1.2 MA of plasma current. In those original experiments, avalanche-like TAE bursts were seen. It would be valuable to document those modes with the more complete diagnostic set on NSTX-U. Additionally, those plasmas had fairly unique high frequency Alfvén wave activity.

This experiment would benefit from reliable operation which probably implies a need for lithium wall conditioning.

Doc Created @ Tue Feb 10 2015 17:36:15 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:36:15 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:20 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:28:49 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:28:50 GMT-0500 (EST)

37

2/9/2015 14:19:07

Measurement of Neutral beam driven current

Fred

Levinton

[email-masked]

Howard Yuh, Yancey Sechrest

United States

Nova Photonics

Advanced Scenarios and Control (ASC)

JRT-15, R(15-2)

1

0

1

Assess neutral beam driven current from second neutral beam. We propose to document the operating space of the NB driven current profiles from each source and in combination with the MSE-CIF diagnostic for various plasma currents and toroidal fields. This can be compared to predictions from TRANSP. Another part of this study will be to measure the effect of MHD on the fast ion driven current profile. The shot plan will be to to vary the combination of neutral beam sources, plasma current and toroidal field.

The MSE-CIF XMP to access the interference from the new neutral beams sources should be run before this XP. An Er correction will likely be necessary. Additional shots will probably be needed to obtain toroidal rotation profiles.

Doc Created @ Tue Feb 10 2015 17:36:27 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:36:27 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:31 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:29:00 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:29:00 GMT-0500 (EST)

38

2/9/2015 14:42:55

Scaling of HHFW suppression of Alfvénic waves

Eric

Fredrickson

[email-masked]

Mario Podesta, Neal Crocker, Deyong Liu, Nicola Bertelli, Gary Taylor, Joel Hosea, Douglass Darrow

United States

Princeton Plasma Physics Laboratory

Energetic Particles (EP)

none

2

0

1

Previous experiments on NSTX have found examples where ≈2 MW of heating with HHFW resulted in suppression of TAE and higher frequency GAE and CAE activity with 2 MW of neutral beam heating. The clearest examples were low current, 300 kA, helium target plasmas. The potential of using HHFW to suppress TAE could be very attractive for ITER, or a next-step ST device. The mechanism for suppression is presently not understood. The first part of the experiment would be to reproduce the original conditions with a more complete diagnostic set. When the experimental conditions are reproduced, then extend parameters to higher beam powers and higher plasma current. The new FIDA and ssNPA diagnostics, as well potentially as the lost fusion products diagnostic, will provide invaluable information on the affect of the HHFW on the fast ion population. The experiment will require reliable HHFW heating, thus should be scheduled before any unintended vacuum vessel venting, post lithium conditioning.

Requires reliable HHFW heating. Would strongly benefit from new confined fast ion diagnostics.

Doc Created @ Tue Feb 10 2015 17:36:34 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:36:35 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:39 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:29:09 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:29:10 GMT-0500 (EST)

39

2/9/2015 14:44:28

Affect of HHFW rotation control on TAE activity

Eric

Fredrickson

[email-masked]

Nicola Bertelli, Gary Taylor, Joel Hosea, Mario Podesta, Deyong Liu, Neal Crocker

United States

Princeton Plasma Physics Laboratory

Energetic Particles (EP)

none

1

0

0

The strong rotation of NSTX plasmas during beam injection affected the TAE continuum profiles, and thus the strength of the interaction of TAE with the continuum. Previous experimental attempts to study the affect of this rotation on TAE by using error field braking led to ambiguous results; the error field braking also resulted in degraded plasma performance. It has been noted that HHFW can also affect plasma rotation at power levels where HHFW has a small affect on equilibrium plasma parameters. It is proposed here to develop HHFW as rotation control tool, and use HHFW to explore the dependence of TAE activity on strong sheared plasma rotation. In particular, there is some suggestion that suppressing rotation may also suppress TAE activity.

Reliable HHFW heating would be desirable.

Doc Created @ Tue Feb 10 2015 17:36:42 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:36:43 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:48 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:29:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:29:20 GMT-0500 (EST)

40

2/9/2015 14:59:48

Initial TAE excitation with antenna

Eric

Fredrickson

[email-masked]

Mario Podesta

United States

Princeton Plasma Physics Laboratory

Energetic Particles (EP)

none

2

0

0

Excitation of otherwise stable TAE with an external antenna is a proven approach to directly measure the natural damping rate for TAE. The additional of an antenna dedicated to the Alfvén frequency range on NSTX opens the possibility for the first direct measurements of TAE damping rates in an ST plasma. Sorting out the TAE excited by an antenna in the presence of the typical strong band of TAE activity would be difficult, so TAE-quiescent regimes are desired. Two operational regimes on NSTX are suggested by the absence, or near absence, of TAE activity. The first would be the study of TAE damping in ohmic plasmas. While perhaps not obviously relevant, this would non-the-less provide a valuable benchmark for the NOVA-k code. The second regime, if it can be duplicated on NSTX-U, would be the so-called ‘quiescent’ regime seen even in high beam power NSTX plasmas. The ohmic experiments would probably require dedicated run-time. Potentially the beam-heated, quiescent plasmas could be studied in a piggy-back fashion. Most likely, the ohmic experiments should be done first as these would likely have the lowest ‘background noise’ problems.

The AR amplifier would need to be installed in the test cell, a D-A module or other suitable excitation source for the amplifier would need to be set up and the requisite connections be made. With RF/engineering/technician support, this could be done this year.

Doc Created @ Tue Feb 10 2015 17:36:51 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:36:51 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:36:56 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:29:29 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:29:30 GMT-0500 (EST)

41

2/9/2015 15:40:43

HHFW Heating of CHI-Only Discharges

Gary

Taylor

[email-masked]

N. Bertelli, J.B. Caughman, S. Gerhardt, J.C. Hosea, B.P. LeBlanc, D. Mueller, B.A. Nelson, R. J. Perkins, F. Poli, R. Raman, J. R. Wilson

United States

Princeton Plasma Physics Laboratory

Solenoid-free Start-up and Ramp-up (SR)

IR(15-2): “Establish Coaxial Helicity Injection start-up and perform initial tests of Neutral Beam Injection current ramp-up in inductively generated plasmas”

1

0

0.5

In NSTX-U the peak plasma current reached in CHI-only discharges is expected to be at least 400 kA. However the plasma current in these CHI-only discharges typically decays in about 30 ms due to the low electron temperature. RF heating can be used to mitigate this plasma current decay by rapidly heating the plasma. This experiment aims to heat CHI-only discharges with 20 ms pulses of at least 1 MW of HHFW power. It will be run immediately following experiments to establish CHI-only discharges in NSTX-U. The experiment will assess the effectiveness of HHFW heating to increase Te and the current persistence time. It will also study changes in the density profile, oxygen and carbon impurity levels when HHFW power is coupled to a CHI-only discharge. While CHI-only discharges can be reproducible there is no position control system that can tailor the gap between the CHI plasma and the HHFW antenna, this will present a significant challenge for achieving and maintaining efficient HHFW coupling. Also, because the CHI plasma is relatively cold the fast waves will make many passes through the plasma before being absorbed. Since the HHFW power will be coupled into a very low density plasma HHFW antenna tuning will be set to close to vacuum loading settings on the stubs and stretchers. HHFW antenna phasing should be set to launch a low kf in order to start the perpendicular propagation of the fast wave at a low density, reducing the width of the evanescent region between the antenna and the CHI plasma. This experiment will start with launches kφ = -8 m-1 (Δφ = 90o) HHFW heating using stub and stretcher settings from NSTX shot 129612. It will then use Δφ = -60o antenna phasing which launches a combination of kφ = -8 m-1 and
kφ = -3 m-1. The kφ = -8 m-1 power will heat the plasma increasing absorption of the kφ = -3 m-1 power closer to the antenna. A Δφ = 180o phasing may be tried if the edge density measured by Thomson scattering is > 5x1017m-3.

This experiment should follow the HHFW plasma conditioning XMP and should be run immediately following experiments to establish CHI-only discharges in NSTX-U. Thomson scattering Te and ne are required for core and edge electron heating data. For analysis of edge power loss and coupling efficiency, the experiment requires SOL reflectometry and edge ion heating data from the edge rotation diagnostic. Visible and IR camera imaging of the antenna and lower divertor are also required.

Doc Created @ Tue Feb 10 2015 17:37:00 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:37:00 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:37:06 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:29:39 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:29:40 GMT-0500 (EST)

42

2/9/2015 15:43:25

Low Plasma Current, Fully Non-Inductive, HHFW H-Mode Plasmas

Gary

Taylor

[email-masked]

N. Bertelli, J.B. Caughman, S. Gerhardt, J.C. Hosea, B.P. LeBlanc, D. Mueller, R. J. Perkins, F. Poli, R. Raman, J. R. Wilson

United States

Princeton Plasma Physics Laboratory

Solenoid-free Start-up and Ramp-up (SR)

IR(15-2): “Establish Coaxial Helicity Injection start-up and perform initial tests of Neutral Beam Injection current ramp-up in inductively generated plasmas”

2

0

1

HHFW heating and current drive may enable fully non-inductive plasma current (Ip) ramp-up in NSTX. The initial approach to achieving this goal has been to heat low Ip (250 - 350 kA) inductive plasmas with HHFW power in order to generate an H-mode with significant bootstrap and RF-driven current. In 2010 XP-1009 used 1.4 MW of kφ = -8 m-1 HHFW power to generate and sustain an H-mode and achieving a non inductive fraction, fNI ~ 0.65. This positive result was the consequence of better plasma control, improved RF coupling due to Li conditioning, a high Te(0) ~ 3 keV, and a relatively high RF current drive efficiency ~ 0.1 MA/MW. However, the RF antenna was poorly conditioned during XP-1009 and the maximum arc-free HHFW power was only ~ 1.4 MW, insufficient to achieve an fNI ≥ 1 at Ip ~ 300 kA. This experiment aims to achieve fNI ≥ 1 by coupling 3-4 MW of RF power into an Ip ~ 300 kA plasma. The proposed experiment should benefit from the improved FW coupling at the higher BT(0) achievable on NSTX-U and from recent modifications to the HHFW antenna grounding that significantly improved antenna stand off voltage during vacuum conditioning. The plan is to start with a discharge similar to the best HHFW-heated Ip = 300 kA plasma from XP-1009 (shot 138506) using kφ = -8 m-1 HHFW power. The toroidal magnetic field, BT(0) would be increased from 0.55 T to ~ 0.65 T. The HHFW heating pulse will be started as early as possible in order to maintain the HHFW heating for at least a current relaxation time (~ 200 ms). Once significant HHFW power is reliably coupled into the plasma, the q(R) and Ti evolution will be documented with source A beam blips stepped through the discharge. q(R) will also be measured with the MSE-LIF, if available. If it proves difficult to control the Ip = 300 kA discharge at high HHFW powers, Ip will be increased to ~ 350 kA. If reproducible Ip ~ 300 kA discharges with significant (3-4 MW) HHFW power can be produced, Ip will be reduced to ~ 250 kA.

Stable plasma operation at Ip = 250-350 kA, with reproducible outer gap = 0.05 – 0.1 m. Request D. Mueller as operator. For analysis of edge power loss and coupling efficiency the experiment requires SOL reflectometry and edge ion heating data from edge rotation diagnostic. Visible and IR camera imaging of the antenna and lower divertor are also required.

Doc Created @ Tue Feb 10 2015 17:37:09 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:37:09 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:37:13 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:29:50 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:29:51 GMT-0500 (EST)

43

2/17/2015 14:08:32

HHFW Ramp-up of Inductively Initiated Plasma from 250 to 400 kA

Gary

Taylor

[email-masked]

N. Bertelli, J.B. Caughman, S. Diem, S. Gerhardt, J.C. Hosea, C. Lau, B.P. LeBlanc, D. Mueller, B.A. Nelson, R. J. Perkins, F. Poli, R. Raman, J. R. Wilson

United States

Princeton Plasma Physics Laboratory

Solenoid-free Start-up and Ramp-up (SR)

IR(15-2): “Establish Coaxial Helicity Injection start-up and perform initial tests of Neutral Beam Injection current ramp-up in inductively generated plasmas”

1.5

0

1

In this experiment an Ip ~ 250 kA inductive plasma is heated with HHFW power in order to generate an
H-mode with significant bootstrap and RF-driven current to ramp Ip to ~ 400 kA. This experiment requires clamping the OH coil current, instead of feeding back on Ip. HHFW coupling is expected to improve at the higher BT(0) available on NSTX-U, so operation at BT(0) > 0.65 T is requested for this experiment. Shots without HHFW power will therefore have decaying Ip and when RF power is applied Ip will ramp-up, be sustained or decay more slowly depending on the amount of RF current drive and bootstrap current generated by HHFW heating. It may be necessary to run some ohmic discharges with Ip feedback on to gain an estimate of the OH current needed to minimize plasma motion at low Ip. The run plan is as follows: (1) Setup an ohmically-heated Ip = 300 kA deuterium discharge, and then add kφ = -8 m-1 HHFW power, coupled from 150 to 450 ms, with a 50 ms ramp-up in power at the start of the RF pulse. A 50 ms beam pulse for MSE and CHERS will be injected from 430 to 480 ms. The HHFW power will be increased to
3-4 MW, while adjusting the lithium evaporation, gas injection and the outer gap to optimize HHFW heating efficiency. When reproducible plasmas have been obtained a second 20 ms beam blip will be scanned from 400 ms to 250 ms over a sequence of 4 shots to acquire the time evolution of q(R) and Ti. RF power will be increased above 4 MW if more power is available. (2) Reduce Ip to 250 kA and apply
3-4 MW of kφ = -8 m-1 HHFW power. Optimize HHFW heating efficiency and measure q(r) and Ti as in step (1). (3) Adjust RF pulse to start as soon as Ip reaches the flattop value. Then use open loop OH programming to provide no ohmic drive after plasma current reaches the minimum value (< 200 kA at approximately 25 ms).

rtEFIT isoflux control for outer gap, and lithium deposition to maintain good RF coupling. 90 keV NBI blip from source A for MSE q(r) and CHERS Ti data. 20 ms 90 keV NBI blip from source A will be scanned through the RF pulse once reproducible RF heating has been established. For analysis of edge power loss and coupling efficiency require SOL reflectometry and edge ion heating data from edge rotation diagnostic. Visible and IR camera imaging of the antenna and lower divertor.

Doc Created @ Tue Feb 10 2015 17:37:16 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:37:17 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:37:22 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:30:09 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:30:10 GMT-0500 (EST)

44

2/10/2015 10:12:39

ENDD Midplane Neutral Density Profiles in NSTX-U

Daren

Stotler

[email-masked]

Filippo Scotti

United States

Princeton Plasma Physics Laboratory

Divertor and Scrape-off-layer (DS)

NSTX-U R(15-1)

0.5

0

0.25

Midplane neutral densities are needed to determine CX losses of neutral beam ions, to quantify fluxes of energetic charge exchange atoms to the wall, and in the interpretation of diagnostics like CHERS. These data are also useful in understanding the H-mode pedestal and edge plasma turbulence. A simulation-based technique for inferring midplane deuterium (atomic and molecular) profiles from ENDD data was developed and applied to a variety of 2010 shots. Interest has been expressed, particularly for assessing CX loss of beam ions, in a more routine use of this method on NSTX-U. Two related questions must be addressed to facilitate such applications. First, how do the neutral densities obtained with the current ENDD view across the neutral beam armor compare with those collected in 2010? Second, how much does the midplane neutral density vary toroidally? E.g., what do the ENDD data tell us about the toroidally distant densities in front of the NBI ports? This XP will target the first question by reproducing as closely as possible one or more of the previously studied 2010 discharges (from XP1029, in particular) to see how the neutral density profiles compare. Since the ENDD now looks across the path of the neutral beams, their effects on the neutral density profiles must be assessed explicitly, e.g., via beam notching and other specified timing. Data collected from other XPs will be examined and incorporated into a database that can be compared with that from 2010. The sum of these results, combined with other data and modeling, will provide some insight into the second question on toroidal variation. The method used to infer neutral density profiles from the ENDD images will benefit from higher spatial resolution Thomson scattering and other diagnostic improvements.

ENDD with D-beta filter, Thomson scattering (edge and into the SOL), CHERS ion temperature and density, midplane micro-ion gauge pressures, EFIT equilibria.

Doc Created @ Tue Feb 10 2015 17:37:25 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:37:26 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:37:31 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:30:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:30:19 GMT-0500 (EST)

45

2/10/2015 12:52:13

Optimize gas fueling for low density startup and H-mode access

Devon

Battaglia

[email-masked]

Rajesh Maingi, Stan Kaye, Stefan Gerhardt

United States

Princeton Plasma Physics Laboratory

Particle Control Task Force (PC)

None

1

0

0.5

An earlier commissioning XMP will establish a fueling scenario for ramp up and reliable H-mode access using the NSTX recipe as a starting point. This XP will investigate the limits for low density startup and reliable H-mode access using different mixes and timings of HFS and LFS gas valves. One goal is to access the impact early fueling has on the eventual density rise (and saturation?) in H-mode. Another goal is to document the dependence of H-mode access on fueling location using the new HFS gas valve capabilities. It would also be desirable to evaluate the utility of the SGI toward these goals.

It would be interesting to perform this experiment with both boron and lithium wall coatings to provide a mechanism to vary the recycling properties. This experiment requires good wall conditions for reproducible shots and enough beam power to get H-mode. Long shots to evaluate density rise and saturation are preferred.

Doc Created @ Tue Feb 10 2015 17:37:34 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:37:35 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:37:39 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:30:29 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:30:29 GMT-0500 (EST)

46

2/10/2015 14:42:34

Controlled introduction of Lithium into NSTX-U

Rajesh

Maingi

[email-masked]

Reps from several TSGs TBD

United States

Princeton Plasma Physics Laboratory

Particle Control Task Force (PC)

None

3

1

2

Goal and importance: introduce Lithium into NSTX-U in a controlled manner, to compare with well-characterized discharges with boronization. The idea is to determine if progressively higher amounts of lithium pre-discharge evaporation will lead to progressively larger impacts on the SOL/divertor, pedestal, and core.

Plan: starting with boronized discharges and inter-shot HeGDC, introduce Li via evaporation (or possibly with LGI?) at modest rates, and gradually increase those rates until ELM suppression is observed.

Good boronized baseline condition, availability of Li evaporators, and good profile and some fluctuation diagnostics.

Doc Created @ Tue Feb 10 2015 17:37:41 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:37:42 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:37:47 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:30:39 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:30:40 GMT-0500 (EST)

47

2/13/2015 18:45:33

Assess betaN and qmin n=1 tearing stability limits at the increased aspect ratio of NSTX-U

Robert

La Haye

[email-masked]

John Ferron, Josh King, Carlos Paz-Soldan, Ted Strait, Jack Berkery, Dylan Brennan, Stefan Gerhardt, Clayton Myers, Jong-Kyu Park, Steve Sabbagh, Zhiuri Wang

United States

General Atomics

Macroscopic Stability (MS)

FY 2015 Joint Research Target "Conduct experiments and analysis to quantify the impact of broadened current and pressure profiles on tokamak plasma confinement and stability"

1

0

1

In general qmin starts high (>1 if not >2) and decays with time; application of NBI wrt to the qmin value induces H-mode and increasing betaN. The goal of this XP is to investigate the role of qmin(betaN) for onset of n=1 tearing (or none or n=1 RWM). This will establish the "sweet spot" for n=1 tearing stable long pulse operation with a desired qmin target for eventual q-profile control. Previous work on DIII-D [1,2] showed that the timing of qmin(t) and betaN(t) allowed such "sweet spots" to be found for either m/n=3/2 tearing [1] or m/n=2/1 tearing [2].
In addition, some preprogramed NBI step-down in the longer pulse NSTX-U would be desirable to investigate marginal self-stabilization conditions as in XP10 (although a real-time mode detector and change of phase to reduce NBI power would be better).
1] R.J. La Haye, B.W. Rice, E.J. Strait,
"Increasing the beta limit due to neoclassical tearing modes by raising the axial safety factor q(0)>1” Nuclear Fusion 40, 53 (2000)
[2] C.T. Holcomb, J.R. Ferron, T.C. Luce, T.W. Petrie, J.M. Park, F. Turco, M.A. Van Zeeland, M. Okabayashi, C.T. Lasnier, J.M. Hanson, P.A. Politzter, Y. In, A.W. Hyatt, R.J. La Haye and M.J. Lanctot, “Steady state scenario development with elevated minimum safety factor on DIII-D” Nucl. Fusion 54, 093009 (2014)

Best is to be done after Li evaporation is made routine in order to achieve reproducible conditions. Do not want off-axis NBI for this but would investigate that in a later XP to be coordinated with DIII-D off-axis NBI use. Could be at NSTX-U reduced parameters (1.0MA, 0.5T) or full (2.0MA, 1.0T) or inbetween.

Doc Created @ Tue Feb 10 2015 17:43:47 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 17:43:48 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 17:43:52 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:30:48 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:30:49 GMT-0500 (EST)

48

2/10/2015 19:52:05

NBI overdrive

Francesca

Poli

[email-masked]

Bertelli, Taylor, Mueller

United States

Princeton Plasma Physics Laboratory

Solenoid-free Start-up and Ramp-up (SR)

R16-4

2

0

2

Inject NBI at low current (300kA) with and without HHFW on inductive target (or CHI + inductive, lower priority) to assess (a) current drive vs beam energy (b) current profiles and absorption of HHFW on fast ions. These experiments aim at optimizing broad current profiles at startup to minimize ballooning instabilities. Simulations indicate need for broadening of FW current profiles at low current and combination with NB might be the only way. However, fast ions absorption need to be reduced, maybe by modulating the NB or changing the antenna phasing. These experiments will contribute also to model validation of RF codes.

CHERS with 2nd NBI, MSE, rt-EFIT for Ip~300kA or below,

Doc Created @ Tue Feb 10 2015 19:52:09 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 19:52:10 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 19:52:13 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:30:58 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:30:58 GMT-0500 (EST)

49

2/10/2015 19:59:34

NB sustainment

Francesca

Poli

[email-masked]

Gerhardt, Battaglia

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

R16-4

1

0

1

Start with non-inductive startup and programmed inductive ramp-up. Will assume that beam characterization has been done before this XP.
Will start from discharge that achieves 100% NI current with NBI (current flattop value depends on beam configuration) and clamp OH progressively earlier in time to sustain non-inductive current from that time on. Results form this XP, in combination with the XP 'NB overdrive' will inform on how to proceed for non-inductive ramp-up from inductive startup (or from CHI+inductive) with HHFW and NB.

MSE at low current ~300kA, CHERS with second beam.

Doc Created @ Tue Feb 10 2015 19:59:42 GMT-0500 (EST); Doc Merged @ Tue Feb 10 2015 19:59:43 GMT-0500 (EST); Email Sent @ Tue Feb 10 2015 19:59:47 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:31:07 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:31:08 GMT-0500 (EST)

50

2/11/2015 21:10:22

Soft-Limiting of Coil Forces and Stresses

Stefan

Gerhardt

[email-masked]

D. Boyer

United States

Princeton Plasma Physics Laboratory

Cross-cutting and Enabling (CC)

none

0.5

0

0.5

Dan and I have some ideas on how to "soft limit" the coil currents so as to avoid DCPS trips. The idea still needs some flushing out, but it appears that it might be useful in saving shots. We would need an XMP to assess basic function. More profound tuning could occur later.

PCS code must be modified if we want to do this.

Doc Created @ Wed Feb 11 2015 21:10:31 GMT-0500 (EST); Doc Merged @ Wed Feb 11 2015 21:10:40 GMT-0500 (EST); Email Sent @ Wed Feb 11 2015 21:10:45 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:31:16 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:31:17 GMT-0500 (EST)

51

2/13/2015 14:13:37

Confinement scaling

Stan

Kaye

[email-masked]

Maingi, Gerhardt, Podesta, Soukhanovskii, Berkery, et al

United States

Princeton Plasma Physics Laboratory

Turbulence and Transport (TT)

R15-1, JRT

3

1.5

3

The XP will probe confinement scaling as a function of Ip and BT in NSTX-U, connecting back to NSTX but extending to newer operating regimes (at lower collisionality) in NSTX-U. This XP directly addresses the R15-1 milestone. Furthermore, the matrix of Ip/Bt values that will be accessed overlap with needs of XPs from many other TSGs. It is expected that other XPs will be submitted which will extend the parameter range of this one to satisfy the full needs of other TSGs.

Enough diagnostics to do TRANSP runs.

Doc Created @ Fri Feb 13 2015 14:13:49 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 14:13:49 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 14:13:55 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:31:26 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:31:27 GMT-0500 (EST)

52

2/13/2015 16:41:37

RWM Stabilization Dependence on Neutral Beam Deposition Angle

Jack

Berkery

[email-masked]

Steve Sabbagh, Jeremy Hanson

United States

Columbia University

Macroscopic Stability (MS)

R(15-2): Assess the effects of neutral beam injection parameters on the fast ion distribution function and neutral beam driven current profile, R15-3: Develop physics+operational tools for high-performance discharges

1

0

0.5

For future tokamaks to operate in a continuous, disruption-free manner, an understanding of how the RWM instability can be reliably stabilized must be gained. The theory of RWM stabilization that invokes kinetic effects as an energy dissipation mechanism has already been shown to unify results between experiments. In particular, rotational resonances between the mode, the plasma rotation, and thermal particle motions such as the precession drift of trapped thermal ions have been shown to explain RWM instability at intermediate rotation in NSTX, and resonant field amplification results in DIII-D. Energetic particles are also known to play an important role in kinetic RWM stabilization. It has been shown that it is important to take into account the anisotropy of neutral beam injected energetic ions to correctly account for their stabilizing effects on RWM stability. With NSTX-U’s new off-axis neutral beam it is important to assess the effects of profile and pitch angle dependence of energetic particles, and alteration of the rotation profile on stability.

NSTX-U plasmas with various on- and off-axis neutral beam injection (see Operations/Development) will be used to produce a variety of rotation profiles and energetic particle distribution functions (changing both the radial (Ψ) profile and the pitch angle dependence). Changes of the beam voltages can also be used to change the energy dependence of the EP distribution function, and the total number of energetic particles (or the ratio βEP/βtotal) as well. Standard techniques of determining the stability of the plasma will then be employed for these different EP distribution function plasmas. These include using n=3 non-resonant magnetic braking to slow the plasma rotation to the marginal stability point, or using n=1 AC fields to measure resonant field amplification (RFA) which indicates proximity to the marginal stability point.

This XP will utilize the results of the early-campaign XP to examine the effect of the new, second neutral beam. TRANSP analysis on these shots should be performed prior to this experiment to determine the extent of the change of the EP distribution function.

Required diagnostics: EFIT with MSE and flux iso-surface constraint (reduced error on q profile), CHERS toroidal rotation measurement, Internal RWM sensors, Thomson scattering, Diamagnetic loop, USXR, FIDA, Toroidal Mirnov array.

Doc Created @ Fri Feb 13 2015 16:41:43 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 16:41:43 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 16:41:47 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:31:36 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:31:37 GMT-0500 (EST)

53

2/13/2015 16:50:09

RWM Stabilization Physics at Reduced Collisionality

Jack

Berkery

[email-masked]

Steve Sabbagh

United States

Columbia University

Macroscopic Stability (MS)

R(15-3): Develop physics+operational tools for high-performance discharges; ITPA MDC-21

1

0

0.5

The theory of RWM stabilization that invokes kinetic effects as an energy dissipation mechanism has already been shown to unify results between experiments. In particular, rotational resonances between the mode, the plasma rotation, and thermal particle motions such as the precession drift of trapped thermal ions have been shown to explain RWM instability at intermediate rotation in NSTX. The role of collisions in both dissipating the mode energy and also in damping the resonant kinetic effects has been outlined. In future devices with lower collisionality, plasmas in rotational resonance will gain stability, but the plasma stability gradient with rotation will increase, making it especially important to avoid unfavorable plasma rotation profiles through rotation control or active mode control. Assessing the effect of collisionality on RWM stability experimentally and comparing to this theory is crucial for future devices, and for NSTX-U.

Using low collisionality targets, we will assess the stability dependence of the RWM on plasma rotation. From theory we expect that plasmas in rotational resonance will be more stable than at higher collisionality while plasmas with rotation between stabilizing resonances will be minimally affected and therefore close to marginally stable. Therefore the gradient in plasma stability with rotation will increase. We will look for this behavior in the experiment by using n=3 non-resonant magnetic braking to slow the plasma rotation. We will also use n=1 AC fields to measure resonant field amplification (RFA) which will give an indication of proximity to the marginal point. Additionally, lower density plasmas are expected to be subject to more energetic particle modes (EPMs). It is possible that we could find EPM-triggered RWMs in this experiment, as in JT-60U and DIII-D. Finally, techniques to diagnose the eigenfunction, with edge multi-energy soft X-ray, reflectometer, or beam emission spectrometry, can also be tried.

This XP intends to leverage the successful development of a reliably operating low collisionality target, which will be pursued in separate, dedicated XPs.
Diagnostics required: EFIT with MSE and flux iso-surface constraint (reduced error on q profile), CHERS toroidal rotation measurement, Internal RWM sensors, Thomson scattering, Diamagnetic loop, USXR, FIDA, Toroidal Mirnov array, Advanced USXR diagnostics

Doc Created @ Fri Feb 13 2015 16:50:13 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 16:50:13 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 16:50:20 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:31:48 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:31:48 GMT-0500 (EST)

54

2/13/2015 19:29:39

RWM PID control optimization based on theory and experiment

S.A.

Sabbagh

[email-masked]

J.M. Bialek, J.W. Berkery, Y.S. Park

United States

Columbia University

Macroscopic Stability (MS)

R(15-3), ITPA MDC-19, ITPA MDC-21

0.5

0

0.5

Experiments using n = 1 RWM control in 2010 and subsequent analysis using the VALEN code show that some settings for control using Br and Bp sensors are optimal, while others can be improved. In particular, the Bp feedback phase, and Br feedback gain presently differ in the most recent analysis than the experimental settings. Bp sensor gain will also be examined in this experiment. The experiment is meant to have scope limited to these parameters, and is suggested to run early in the CY2015 run once relatively high normalized beta operation is available, as it will optimize parameters for all subsequent experiments that want to use n = 1 control.

XP1023 run in 2010 made an extensive scan of parameters for the n = 1 proportional gain control system. Present VALEN analysis (ongoing), including time domain calculations of feedback, is reproducing the behavior observed in the experiment for a given set of input parameters. The Bp feedback phase is presently matching experiment the least well, and further analysis is being conducted to understand this. The Br feedback phase matches the experiment very well, and need not be changed. The Br sensor gain shows an optimal value in the analysis, and the present setting is somewhat smaller than the optimal value. These parameters will be scanned in a limited sense for fiducial and lower li plasmas to match the optimal expectations of both theory and past experiment based on the analysis performed between now and the time of this experiment.

The experiment will focus on variations of Br feedback gain, Bp feedback phase, and Bp feedback gain with a range limited to values near the computed optimal values. Plasma target will be changed as time allows. Half-day operation should allow at least two target plasma to be run (e.g. fiducial, and high li target plasmas.)

Operations/Development:

RWM PID control using Bp and Br sensors needed, NTV braking by n = 2 or 3 applied field configuration needed.

Diagnostics:
RWM sensors, CHERS, USXR, equilibrium magnetics, toroidal pickup probe array

Analysis:
NSTX-U EFIT with MSE, DCON, VALEN, MISK, RWMSC analysis codes

Doc Created @ Fri Feb 13 2015 18:28:24 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 18:28:24 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 18:28:29 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:31:59 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:31:59 GMT-0500 (EST)

55

2/13/2015 18:50:19

RWM state space control physics

S.A.

Sabbagh

[email-masked]

J.W. Berkery, J.M. Bialek, Y.S. Park

United States

Columbia University

Macroscopic Stability (MS)

R(15-3), ITPA MDC-19, ITPA MDC-21

1.5

0

1

The RWM state space controller (RWMSC) will be applied to high performance plasmas (high normalized beta, low li, etc.) to examine several aspects of mode control physics, as a logical next step to the initial experiments of 2010. The present experiment moves beyond the initial experiments in the following ways: (i) eigenfunctions of different target plasmas will be introduced, and several target plasmas will be used (high triangularity, high li-low A, snowflake divertor), (ii) eigenfunctions with n > 1 will be introduced to the controller, (iii) independent control of the 6 RWM coils will allow control of n > 1 perturbations, (iv) a more careful comparison of control with/without wall states will be conducted, (v) an initial set of shots will test compatibility with plasma rotation reduction by NTV, (vi) proportional feedback using Br sensors will be added. Gains and feedback phase will be adjusted as needed. NTV magnetic braking will be compatible if the eigenfunction and wall states used do not conflict with the applied field. This has never been tested. Proportional gain using RWM Br sensors has also never been used with the state space controller, and will be tested here.

Low li, high triangularity fiducial, and snowflake divertor targets will be used. The primary scans will be run on the target that is most applicable to future ST plasma applications. RWMSC control matrices with different numbers of input mode eigenfunctions will be tested (at least n = 1, 2, each with the ability to rotate). The RWMSC will independently control the six RWM coils and will allow n > 1 control. Performance and estimates of the sensors from the observer will be compared to more limited control. Scans to test the effects of the wall current, compatibility with NTV braking, and the addition of PID n = 1 Br sensor control will be made. The priority of these scans is yet to be determined.

Operations/Development:

NSTX RWMSC operation, RWM PID control of Br sensors desired, pre-programmed n NTV magnetic braking required. Both n = 2 or 3 NTV non-resonant braking will be used to test compatibility with the RWMSC.

Diagnostics:
RWM sensors, CHERS, USXR, equilibrium magnetics, toroidal pickup probe array

Analysis:
NSTX-U EFIT with MSE, DCON, VALEN, MISK, NTVTOK, RWMSC analysis codes

Doc Created @ Fri Feb 13 2015 18:50:25 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 18:50:26 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 18:50:31 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:32:09 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:32:09 GMT-0500 (EST)

56

2/13/2015 19:04:54

Neoclassical toroidal viscosity at reduced collisionality (independent coil control)

S.A.

Sabbagh

[email-masked]

J.W. Berkery, Y.S. Park, K.C. Shaing

United States

Columbia University

Macroscopic Stability (MS)

R(15-3), ITPA MDC-21

1

0

1

The dependence of neoclassical toroidal viscosity (NTV) on ion collisionality will be tested in the new NSTX-U plasma conditions to vary the plasma density and temperature where NTV torque is maximized in the plasma, focusing on the NTV scaling and comparison to theory at the lowest collisionality possible. At low collisionality, NTV is also observed to increase at sufficiently low OmegaE, corresponding to the superbanana plateau regime in theory. The increase of NTV at low OmegaE will be examined in steady plasma conditions. The increase in NTV strength in these regimes are important to understand from a physics perspective for extrapolation to future devices, but it also has more near-term practical importance in developing more accurate simple models for the expected rotation damping to be used in state-space rotation feedback control. The present experiment will apply the planned n = 2 and n = 3 applied field configurations expected for non-resonant braking, with and without n = 1 field correction. This will demonstrate the NTV braking profiles for closed loop operation.

Two key scans are: (i) nu*i and (ii) n*q*OmegaE. The latter will be changed by changing plasma rotation, and also by changing the primary n value of the applied field (n = 2, or n = 3). Different plasma targets and density variation will be used to vary nu*i. Plasma rotation will be varied, from fastest to slowest in NSTX-U, via non-resonant braking, number of NBI sources applied, and potentially via plasma density variation. Two new approaches will be used, allowed by new capabilities: (i) n = 2 and n = 3 configurations will be swapped after one of these configurations yields a quasi-steady-state rotation profile, to directly see how the braking caused by the n = 2 and n = 3 applied field configurations change the plasma rotation dynamically, and (ii) waveforms that demonstrate access to the superbanana plateau regime, and recovery from it to higher rotation will be demonstrated.

Operations/Development:

Low collisionality target development, with Some further development of low ion collisionality targets could be performed in this XP; use of the n = 3 applied field configuration is required, and use of the standard n = 2 applied field configuration is highly desired. Use of n = 1 feedback is desired.

Diagnostics:
RWM sensors, CHERS, USXR, ME-SXR, standard magnetics, etc.

Analysis:
NSTX-U EFIT with MSE (during NBI phase), NTVTOK, DCON, MISK, etc.

Doc Created @ Fri Feb 13 2015 19:05:03 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 19:05:03 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 19:05:08 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:32:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:32:19 GMT-0500 (EST)

57

2/13/2015 19:35:34

NTV steady-state offset velocity at reduced torque with HHFW

S.A.

Sabbagh

[email-masked]

J.W. Berkery, Y.S. Park, K.C. Shaing

United States

Columbia University

Macroscopic Stability (MS)

R(15-3)

1

0

0.5

Run time is requested to complete the RF component of XP1062, which has a unique approach to determine the NTV steady-state offset velocity, and the conclusion of which is still highly relevant. This is particularly important as the NTV offset velocity appears to have different characteristics in different devices that may not follow the expectations of present theory. This is high importance to ITER, and the topic of intrinsic rotation for plasma stabilization.

The experimental approach is close to an experiment conducted by Hosea and Podesta in 2009. An HHFW-heated plasma is created, and a brief period of NBI is used to measure the linear increase in plasma rotation. This data is extrapolated back in time to determine the rotation during HHFW heating alone. In the present experiment, varied levels non-resonant applied field will be used during the pulse, which should alter the plasma rotation on each flux surface by the NTV offset rotation speed. The difference between the cases with/without applied non-resonant field will give the NTV offset rotation value. Both n =2, and n = 3 applied field configurations will be attempted separately, and n = 1 field correction will be attempted to see how the results without such correction would change. This experiment would leverage the target development from experiments by Mario Podesta and RF XPs involving HHFW coupling to H-mode plasmas.

Operations/Development:

Ability to successfully run HHFW heated plasmas, maximum power is desired for the highest possible plasma temperature, a minimum of 2 MW is desired; use of the standard n = 3 applied field configuration is required, and use of the standard n = 2 applied field configuration is highly desired. The ability to use n = 1 feedback is desired.

Diagnostics:
RWM sensors, CHERS, standard magnetics, etc.

Analysis:
NSTX-U EFIT with MSE (during NBI phase), NTVTOV, DCON, MISK

Doc Created @ Fri Feb 13 2015 19:35:39 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 19:35:40 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 19:35:44 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:32:29 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:32:30 GMT-0500 (EST)

58

2/13/2015 19:45:01

RWM control physics with partial control coil coverage (JT-60SA)

Young-Seok

Park

[email-masked]

S.A. Sabbagh, J.W. Berkery, J.M. Bialek

United States

Columbia University

Macroscopic Stability (MS)

MDC-19, MDC-21

1

0

1

RWM control in NSTX will be attempted with partial coverage of the RWM coils to test the physics of RWM mode rigidity and the impact of coil loss on the ability to control the RWM. Control will be attempted with both n = 1 proportional gain, and the RWM state space controller (RWMSC). Other than testing the physics of mode rigidity (which addresses the RWM spectrum, which can be compared to multi-mode RWM theory using the VALEN code), the results will have impact on RWM control implementation schemes for JT-60SA (which has significant toroidal gaps between control coils), and will provide input on the impact of individual internal control coil failures for ITER, or future ST devices in which individual damaged control coils may not be able to be immediately repaired.

RWM control will be attempted with both n = 1 proportional gain, and the RWMSC while deactivating coils in a few ways: (i) single toroidal position, (ii) two toroidal positions, (iii) every other toroidal position. The first case has the potential of generating the greatest variation of the RWM n spectrum, as the perturbation in the control field is most localized. Proportional gain control of the n = 1 Fourier decomposed sensor signals is vulnerable to failure by a deactivated control coil by a resulting expanded n spectrum of the mode (less “mode rigidity”), and the reduced ability of the mode phase to be tracked toroidally if it is rotating. However, the RWMSC with n = 2, and perhaps n = 3 eigenfunctions will be able to provide a greater n spectrum for control, and so may show greater ability to control the mode. In the cases above, if RWM control is lost, (i) control parameters will be altered to attempt to regain control (e.g. vary feedback phase, vary gains), (ii) the case will be attempted again at reduced normalized beta/modified plasma rotation, until the plasma regains stability.

Operations/Development:
RWMSC operation (6 RWM control coils with independent power supplies) using n = 1 and n > 1 eigenfunctions, n = 1 RWM PID control with both Bp and Br sensors required. NBI feedback control of betaN is highly desired.

Diagnostics:
RWM sensors, CHERS, USXR, ME-SXR, BES, equilibrium magnetics, toroidal pickup probe array, etc.

Analysis:
NSTX-U EFIT with MSE, DCON, VALEN, MISK, IPEC, RWMSC analysis codes

Doc Created @ Fri Feb 13 2015 19:45:08 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 19:45:09 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 19:45:15 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:32:39 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:32:40 GMT-0500 (EST)

59

2/13/2015 19:49:00

RWM state space active control at reduced plasma rotation

Young-Seok

Park

[email-masked]

S.A. Sabbagh, J.W. Berkery, J.M. Bialek

United States

Columbia University

Macroscopic Stability (MS)

MDC-19, MDC-21

1

0

1

The NSTX-U RWM state space controller (RWMSC) will be applied to high performance plasmas (high normalized beta, low li, etc.) to demonstrate the capability of mode control at reduced plasma rotation, and especially near marginal stability points at intermediate rotation levels, and at the lowest rotation attainable in NSTX with non-resonant magnetic braking. Key controller parameters will be varied to determine superior parameters and to test controller physics. This study is especially important to demonstrate controller performance in next generation ST devices, and ITER, that will operate at low plasma rotation.

One or more plasma targets will be used, depending upon results of RWM control experiments that will precede this. The targets will be high performance plasmas that attempt to maximize pulse-averaged normalized beta, betaN, at high betaN, and that are of high applicability for ST fusion applications (e.g. ST-CTF, ST-Pilot) and NSTX-U. Other than plasma target, the key variable will be the plasma rotation profile, which will be changed by either n = 2 or 3 non-resonant NTV braking configurations.

RWMSC parameters are the other key variables in the study. An earlier experiment will attempt to determine optimal parameters for the RWMSC at relatively high plasma rotation, but some of these parameters will be changed in this study to investigate the controller physics including the mode eigenfunctions used and controller feedback phase. Controller gains may have to be adjusted, and will be included as an optional variable.

Operations/Development:
NSTX-U RWMSC operation, RWM PID control of Br sensors desired, pre-programmed n = 3 magnetic braking required. n = 2, 3 NTV non-resonant braking will be used.

Diagnostics:
RWM sensors, CHERS, USXR, equilibrium magnetics, toroidal pickup probe array

Analysis:
NSTX-U EFIT with MSE, DCON, VALEN, MISK, IPEC, RWMSC analysis codes

Doc Created @ Fri Feb 13 2015 19:49:06 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 19:49:07 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 19:49:13 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:32:50 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:32:50 GMT-0500 (EST)

60

2/13/2015 21:02:43

Multi-mode Error Field Correction with the RWM State-Space Controller

S.A.

Sabbagh

[email-masked]

Y.S. Park , J.M. Bialek, J.W. Berkery

United States

Columbia University

Macroscopic Stability (MS)

R(15-3), ITPA MDC-19, ITPA MDC-21

1

0

1

Multi-mode error field correction will be performed for the first time using the inherent capability of the NSTX-U RWM state space controller (RWMSC) through the straightforward addition of multiple MHD modes in the controller model. This new technique (in our field) will directly use MHD eigenfunctions of various n, and/or various poloidal mode spectra to test the relative effectiveness of the approach. The technique allows full bandwidth application, from DC to time-varying error fields up to frequencies approaching the eddy current decay time of nearby conducting structure.

The experimental plan will focus on the ability of the RWMSC to eliminate error fields of varying toroidal mode number, and will consist of demonstrating error field reduction of (i) intrinsic error fields of NSTX-U, (ii) dynamic error field reduction, and (iii) reduction of applied error fields. As a strawman shot plan:

1) Reduction of applied error fields:
(a) Apply n = 1 pre-programmed error field, and demonstrate reduction
(b) Apply n = 2 pre-programmed error field, and demonstrate reduction
(c) Apply n = 3 pre-programmed error field, and demonstrate reduction
(d) Attempt error field reduction with orthogonal eigenfunction
(e) Increase influence of wall states in model

2) Reduction of intrinsic error fields:
(using best control matrix set-up from Step (1)):
(a) Apply n = 1 eigenfunction for error field reduction
(b) Apply n = 2 eigenfunction for error field reduction
(c) Apply n = 3 eigenfunction for error field reduction
(d) Use n = 1,2,3 eigenfunctions in combination
(e) Increase influence of wall states in model

3) Reduction of dynamic error fields (at higher betaN):
(using best control matrix set-up from Step (2)):
(a) Use n = 1,2,3 eigenfunctions in combination
(b) Attempt error field reduction with orthogonal eigenfunction
(c) Increase influence of wall states in model

Operations/Development:

NSTX-U RWMSC operation, RWM PID control of Br sensors desired.

Diagnostics:
RWM sensors, CHERS, equilibrium magnetics, toroidal pickup probe array

Analysis:
NSTX-U EFIT with MSE, DCON, VALEN, MISK, NTVTOK, RWMSC analysis codes

Doc Created @ Fri Feb 13 2015 21:02:49 GMT-0500 (EST); Doc Merged @ Fri Feb 13 2015 21:02:49 GMT-0500 (EST); Email Sent @ Fri Feb 13 2015 21:02:54 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:33:07 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:33:08 GMT-0500 (EST)

61

2/20/2015 0:06:59

Assess NSTX-U ideal-wall limit with 2nd NBI

Jonathan

Menard

[email-masked]

Zhirui Wang, J-K Park, Yueqiang Liu

United States

Princeton Plasma Physics Laboratory

Macroscopic Stability (MS)

R(15-3)

1.5

0

1

Recent kinetic stability calculations have found that the magnitude and shape of the toroidal rotation profile can strongly influence the ideal-wall stability limit in high-beta ST plasmas. The fast-ion beta fraction can also be important, i.e. a high fraction can be destabilizing. This experiment will attempt to determine the IW beta limit with varied rotation profile and fast ion content by varying the NBI source, plasma density, and/or NTV braking.

Need target plasma that is passively stable to RWM (or feedback stabilizable) above the no-wall limit with sufficient confinement so the ideal-wall limit can be reached with the available heating power.

Doc Created @ Mon Feb 16 2015 10:41:24 GMT-0500 (EST); Doc Merged @ Mon Feb 16 2015 10:41:27 GMT-0500 (EST); Email Sent @ Mon Feb 16 2015 10:41:33 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:33:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:33:19 GMT-0500 (EST)

62

2/18/2015 14:14:53

Minimum Value of q_min/q_0 and q shear to avoid core n=1 kink/tearing

Clayton

Myers

[email-masked]

S. Gerhardt, D. Boyer, J. Menard

United States

Princeton Plasma Physics Laboratory

Macroscopic Stability (MS)

FY-15 JRT, 15-2, 15-3

1

0

0.75

Many long-pulse H-modes in NSTX were limited by n=1 kink/tearing modes [Menard 2005, Menard 2006, Gerhardt 2008?, Gerhardt 2010, Gerhardt 2012]. These modes typically turned on as q_min approached unity, although triggering physics could also play a role. Theory also suggests that reversed shear is important for the n=1 mode to be linearly unstable (Breslau, 20??) In any case, in this idea, variations of q_min will be achieved via changes in the NB configuration. The combinations of q_min and q_shear that lead to these modes onsetting will be assessed. Conditions for robustly avoiding these modes will be determined.

MSE system, Mirnov diagnostics. One might be able to do some cool eigenfunction reconstructions if there were all the various SXR systems and the high resolution MPTS (and pulse burst MPTS in the future!).

Doc Created @ Mon Feb 16 2015 14:01:49 GMT-0500 (EST); Doc Merged @ Mon Feb 16 2015 14:01:51 GMT-0500 (EST); Email Sent @ Mon Feb 16 2015 14:01:55 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:33:30 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:33:31 GMT-0500 (EST)

63

2/16/2015 17:10:56

Comparison of H-mode pedestal with RF and NBI

Rajesh

Maingi

[email-masked]

A. Diallo

United States

Princeton Plasma Physics Laboratory

Pedestal Structure and Control (PS)

None

1

0

1

Goal: systematically compare the pedestal characteristics of RF heated H-modes with NBI heated H-modes with everything similar except outer gap.

Importance: the density profiles are quite different between RF and NBI heated H-modes. This will help us understand the role of fueling in setting up the density pedestal structure.

Run plan:
Start with a double-null discharge with good H-mode access using RF heating
– In the previous XP505, this was optimized at low triangularity ~ 0.5, and Ip ~
0.6 MA to overlap with NBI H-modes, e.g. #117776 (RF) and #117752 (NBI)
– Consider a low Ip, higher triangularity fiducial-like shape, if H-mode access
with RF was established previously in the FY11 run in that configuration
• Tweak the outer gap to as large of a value as possible (but < 10 cm) to
get as close to an NBI shape and the high-resolution edge Thomson as
possible
• Perform a three-point power scan; time permitting, on a shot-to-shot
basis, otherwise with three power steps in a single discharge
• Time permitting, repeat the RF discharges with NBI blips
• Reproduce the obtained power ramps in RF with NBI
• Time permitting, use RF solely to access H-mode, and then replace the
RF with NBI after the L-H transition

Need RF operations, and Li operations. Candidate for late CY run.

Doc Created @ Mon Feb 16 2015 17:11:01 GMT-0500 (EST); Doc Merged @ Mon Feb 16 2015 17:11:02 GMT-0500 (EST); Email Sent @ Mon Feb 16 2015 17:11:06 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:33:40 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:33:40 GMT-0500 (EST)

64

2/16/2015 21:27:04

Tuning of the Automated Rampdown Software

Stefan

Gerhardt

[email-masked]

Boyer, Battaglia, Erickson, Berkery, Raman, Sabbagh, Myers,...

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

JRT2016

1

0

1

Having run the XMP that proves the system functions from a software view, this XP will "tune" the short shutdown mechanism. While the details are not worked out, it seems like it might take a plasma that works well and drive it to disruption in a couple of different ways (turning off vertical control, magnetic braking). Then things like the detection thresholds, Ip ramp down rate, and similar can be given at least an initial optimization.

Should run the XMP first, to prove that it is basically working from an architecture perspective. And before that, obviously need the software to be complete.

Doc Created @ Mon Feb 16 2015 21:27:22 GMT-0500 (EST); Doc Merged @ Mon Feb 16 2015 21:27:23 GMT-0500 (EST); Email Sent @ Mon Feb 16 2015 21:27:30 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:33:50 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:33:50 GMT-0500 (EST)

65

2/17/2015 9:33:53

HHFW effects on toroidal rotation

Nicola

Bertelli

[email-masked]

R. J. Perkins, R. Bell, M. Podestà, J.C. Hosea, G. Taylor, P. Bonoli, and J. Wilson

United States

Princeton Plasma Physics Laboratory

Wave Heating and Current Drive (RF)

none

1

0

0.5

The goal of this experiment is to investigate the effect of HHFW on the toroidal rotation in NBI heated plasma. In previous studies (Taylor et al. PoP 17, 056114 (2010)) have been shown that the toroidal rotation appears to lock at the edge plasma during HHFW operation. In particular, the edge toroidal rotation tends to slow down in the presence of HHFW and suddenly increase when HHFW is off, approximately to the same level of NBI alone. This effect could also be an attractive “tool” if confirmed and controlled.
At the same time, this experiment is useful to study the interaction of HHFW with edge energetic ions as previously done by Biewer et al. (PoP 12, 056108 (2005)) for possible RF power losses through PDI or other mechanisms.

The plan of the experiment is to perform a systematic study of edge rotation locking.
RF power scan and NB power scan (only NBI 1) will be performed with a combination of the two. Furthermore, a scan in the antenna phases will also be done.

NO NBI #2

Required diagnostics: Thomson scattering, CHERS, ERD
Desired diagnostics: all fast ions diagnostics and SOL reflectometer

Doc Created @ Tue Feb 17 2015 09:15:51 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 09:15:52 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 09:15:56 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:00 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:34:00 GMT-0500 (EST)

66

2/17/2015 9:32:33

HHFW CD measurements by MSE diagnostic and RF code validation

Nicola

Bertelli

[email-masked]

Howard Yuh, R. J. Perkins, J.C. Hosea, G. Taylor, P. Bonoli, C. Phillips, and J. Wilson

United States

Princeton Plasma Physics Laboratory

Wave Heating and Current Drive (RF)

none

1

0

0.5

The goal of this experiment is to measure HHFW current drive in plasma with and without (if MSE-LIF available) NBI by MSE diagnostic in order to (i) validate RF codes; (ii) compare heating vs. current drive regimes (different antenna phases, etc.) and (iii) link the HHFW absorption and current drive measurement with the SOL density measurement. Related to the last point the main question to answer is: “is current drive weakest when the electron density outside the LCFS is raised above the fast wave cut-off density?” (similar things discussed/measured in DIII-D – Petty et al. Nucl. Fus. 39 (1999!), 1421). Finally, another thing to look at is the impact of the HHFW current drive on the q profile and MHD avoidance. The plan is to have plasma with and without NBI (with one and two beams) using all HHFW antenna phases (k_phi = 8, 13, and 21 m^-1) with a different range of RF input power (2-4 MW).

Required diagnostics: Thomson scattering, CHERS, MSE-CIF/LIF,
Desired diagnostics: ERD, SOL reflectometer, and all fast ions diagnostics

Doc Created @ Tue Feb 17 2015 09:22:08 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 09:22:09 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 09:22:14 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:09 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:34:10 GMT-0500 (EST)

67

2/17/2015 9:33:23

HHFW absorption in Neutral-Beam heated plasmas

Nicola

Bertelli

[email-masked]

M. Podestà, Deyong Liu, B. LeBlanc, R. Harvey, R. J. Perkins, J.C. Hosea, G. Taylor, G. Kramer, P. Bonoli, C. Phillips, F. Poli and J. Wilson

United States

Princeton Plasma Physics Laboratory

Wave Heating and Current Drive (RF)

ITPA Energetic particles group is interested to study the interaction between RF waves and fast ions

2

0

1

The FW heating efficiency in NBI heated H-mode plasma has been challenging, and there is little data available on how much RF power is absorbed by fast and/or thermal ions. This is especially relevant for NSTX-U because (i) for ST geometry, ion acceleration to loss orbits can constitute a loss of FW and/or fast-ion power, and can be detrimental heat loads on PFCs (i.e. the HHFW antenna limiter) (ii) the increased magnetic field will reduce the harmonic number of the FW system and potentially enhance ion absorption. RF simulations show significant RF power absorption by fast ions in many cases and also large thermal ion absorption when Ti ≥ Te, with additional absorption dependence on the HHFW antenna phase in both cases. Quantifying the ion absorption is important to (a) benchmark RF codes, such as GENRAY/CQL3D (with ion orbit effects), TORIC, AORSA, and ORBIT-RF, (b) determine to what degree poor HHFW performance in beam-heated discharges is due to fast-ion absorption versus other mechanisms (e.g. SOL losse of FW power), and (c) determine the physics setting the outer gap limit in NBI discharges and to what extent this may be reduced (to increase FW coupling).
This experiment will characterize the HHFW absorption as a function of HHFW antenna phases, magnetic field strength, and neutral-beam mix (both tangency radius and injection voltage), starting with discharges similar to 2008 FIDA experiments. To the extent possible, we will vary the Te/Ti ratio by adjusting the timing and levels of NB and FW heating. Jogs in the outer gap will be used to assess the scraping off of fast ions on the antenna limiter. Time permitting, and if appropriate, take several shots in L-mode where HHFW coupling is generally improved. HHFW power from 2 to 4 MW RF power in H-mode plasma is requested.

Required diagnostics: All fast-ions diagnostics, Thomson scattering, CHERS, HHFW-antenna IR camera.
Desired diagnostics: SOL reflectometer and other IR cameras

Doc Created @ Tue Feb 17 2015 09:30:57 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 09:30:57 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 09:31:03 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:34:20 GMT-0500 (EST)

68

2/17/2015 13:20:01

Investigation of core energy transport via HHFW heating

Neal

Crocker

[email-masked]

Nikolai Goerlenkov, Elena Belova, Kevin Tritz, Walter Guttenfelder, Yang Ren, Gary Taylor, Joel Hosea

United States

University of California - Los Angeles

Turbulence and Transport (TT)

R(15-1), R(16-1)

0.5

0

0.25

Core (rho < ~ 0.4) energy transport was shown to be anomalous in NSTX beam heated plasmas. Two mechanisms have been proposed, both involving high frequency compressional (CAE) and global (GAE) Alfvén eigenmodes excited by beam ions: (1) enhanced heat diffusion resulting from stochastization of electron orbits resonant with the modes and (2) channeling of energy from the core, where beam ions excite the modes, to the edge, where the energy is dissipated via coupling to kinetic Alfvén waves. It is proposed to investigate the energy transport mechanism using HHFW to add extra heat in the core of a high power, beam heated plasma with a flat core temperature profile. The extra heating should be sufficently modest or broadly distributed to avoid grad-Te driven turbulence in the core. The two mechanisms lead to very different expectations for energy transport in the aftermath of the HHFW heating. For the first mechanism, it is expected that the energy added to the electon population by HHFW will rapidly diffuse out of the core since the post-HHFW plasma will have beam-excited high frequency AEs causing enhanced thermal diffusivity. For the second mechanism, the core temperature profile will relax more slowly since the extra heat was primarily delivered to the electron population, but the AE-KAW coupling only tranports beam ion energy away from the core. In performing the experiment, it will be important to monitor for excitation of core turbulence by the HHFW heating, since that could complicate interpretation of the results. It will also be important to monitor the fast-ion population in order to understand the heating source in the absence of HHFW.

Needed: CHERS. UCLA Reflectometer arrays. MPTS. high frequency edge magnetic coils (HN and HF arrays). High-K scattering or core DBS. FIDA, other fast-ion diagnostics
Desirable: BES, FIReTIP

Doc Created @ Tue Feb 17 2015 10:53:09 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 10:53:10 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 10:53:14 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:29 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:34:29 GMT-0500 (EST)

69

2/17/2015 11:00:13

TAE with high ß q2

Eric

Fredrickson

[email-masked]

Y. Kolesnichenko

United States

Princeton Plasma Physics Laboratory

Energetic Particles (EP)

none

1

0

1

One can expect that features of the Alfven continuum and, thus, Alfven eigenmodes and Alfven instabilities will drastically change in the regime with non-inductive current drive in NSTX-U and, possibly, in other regimes with (ß q2) >1 (q is the safety factor, beta is the ratio of the plasma pressure to the magnetic field pressure).  The matter is that, as shown recently in [1,2],  when (ß q2) >1, the EAE gap and some other gaps in the continuum  become very wide  and strongly dominate the frequency spectrum, so that  the conventional expressions for the characteristic frequencies of the GAM (geodesic acoustic modes), TAE (toroidicity-induced Alfven eigenmodes), EAE (ellipticity-induced Alfven eigenmodes), and NAE (noncircular triangularity induced Alfven eigenmodes) modes are no longer valid.  Moreover, when (ß q2) well exceeds unity, the frequencies of GAM, TAE, and lower branch of EAE almost coincide in the near-axis region.  Until now, nobody studied experimentally the influence of high (ß q2) on Alfven and GAM instabilities driven by energetic ions. There is also no theory, except for the mentioned papers [1,2] dealing with the continuum only.  Presumably, (ß q2) > 1 may take place in NSTX-U, too.   The goal of this proposal is to study the mode frequency spectrum (GAM, TAE, EAE, NAE), the destabilization of these modes, and the influence of the destabilized modes on the confinement of fast ions and plasma performance in the regime with high  (ß q2). This will be done for the first time. In order to reach this goal, a series of experiments should be carried out, with various magnitudes of the product (ß q2) and various injection power, which should be sufficient to excite Alfven and GAM instabilities.

[1] O. P. Fesenyuk, Ya. I. Kolesnichenko, Yu. V. Yakovenko, Plasma Phys. Control. Fusion 54 (2012) 085014.
[2] O. P. Fesenyuk, Ya. I. Kolesnichenko, Yu. V. Yakovenko, Phys. Plasmas 20 (2013) 122503.

High beta and q_min (<2) will probably be achieved in regimes with high non-inductive fraction.

Confined and lost fast ion diagnostics are strongly desired.

BES and reflectometers would also be desired.

Doc Created @ Tue Feb 17 2015 11:00:18 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 11:00:19 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 11:00:23 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:39 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:34:39 GMT-0500 (EST)

70

2/17/2015 11:47:02

Rotation effects on CAEs and GAEs

Neal

Crocker

[email-masked]

Eric Fredrickson, Nikolai Gorelenkov, Elena Belova, Håkan Smith, Kevin Tritz, Walter Guttenfelder, David Gates

United States

University of California - Los Angeles

Energetic Particles (EP)

R(15-1), R(16-1)

0.5

0

0.25

Compressional (CAE) and global (GAE) Alfvén eigenmodes play potentially signficant roles in core energy and fast-ion transport. Mode structure and frequency, which are key factors in determining the impact of the mode, are expected to be sensitive to toroidal rotation. An understanding of this sensitivity is critical to developing a predictive capability for CAEs and GAEs and, ultimately, their impact on core energy and fast-ion transport. The proposed experiment is to measure changes in the spatial structure of CAEs and GAEs as rotation is changed using n=3 braking and compare the measurements with the simulation of the mode by HYM and CAE3B.
The proposed experiment calls for a rotation scan consisting of several similar H-mode shots, with differing amounts of braking applied at the same time in each shot. Time permitting, rotation scans at multiple values of BT and with different combinations of beams are desirable. To optimize for mode structure measurements via reflectometery, monotonic density profiles are necessary with peak density < ~ 9e19 cm^-3. Constant density is also desirable if possible, since mode structure depends on the V_Alfven profile.

Needed: CHERS. UCLA Reflectometer arrays. MPTS, high frequency edge magnetic coils (HN and HF arrays)
Desirable: BES, FIReTIP, FIDA, other fast-ion diagnostics

Doc Created @ Tue Feb 17 2015 11:00:30 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 11:00:30 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 11:00:34 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:49 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:34:50 GMT-0500 (EST)

71

2/17/2015 17:02:57

Assessment of 3D field effects on the properties of the snowflake divertor

Gustavo

Canal

[email-masked]

T. Evans, N. Ferraro, E. Kolemen, V. Soukhanovskii, O. Schmitz and H. Frerichs

United States

General Atomics

Divertor and Scrape-off-layer (DS)

none

1.5

0

1

To be able to reliability extrapolate results from existing machines toward reactor-sized devices, the predictive capabilities of the present MHD and transport code models have to be improved. This experiment is being proposed in order to acquire data that can be used to validate the physical models in some of these codes. In this proposal, the particle and heat deposition pattern on the divertor plates of NSTX-U, measured during discharges with externally applied 3D perturbations, will be compared with those simulated using the transport code EMC3-Eirene. In order to evaluate the plasma response to these perturbations, the EMC3-Eirene will be run on computational grids generated using both the M3D-C1 and NIMROD codes. Since these MHD models are complementary, and with strength on different physics aspects, they can provide a better insight into the plasma response to externally applied perturbations. Experimental data during L- and H-mode discharges with various plasma densities are desired in order to have data at different SOL regimes: sheath limited, high recycling, cushioning (SOL electron temperature between 5 eV and 1 eV) and detachment. Studies in LSN and snowflake diverted plasmas are of interest. Since new physics effects are expected to become important in the snowflake divertor, this configuration will be used to challenge our models with the hope that this could lead to an improved understanding of the influence of 3D fields on tokamak plasmas.

Desirable Diagnostics: Calibrated high-n array magnetics (compensated for n = 3 EFCC/RWM fields), toroidal array of Bp and Br, plasma TV, divertor IR and CCD, target Langmuir probes, toroidal and poloidal CHERS, edge recycling and impurity, MSE, BES, Thomson scattering, reflectometry, line density, edge SXR array, edge Doppler spectroscopy, toroidal bolometer array, quadrature reflectometer, shunt tile array (set for high gain) and visible continuum sensor.

Doc Created @ Tue Feb 17 2015 21:20:08 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 21:20:09 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 21:20:14 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:34:59 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:35:00 GMT-0500 (EST)

72

2/17/2015 17:52:58

Massive Gas Injection Studies on NSTX-U

Roger

Raman

[email-masked]

S.P. Gerhardt, D. Mueller, many others

United States

University of Washington

Macroscopic Stability (MS)

2016 JRT, R16-1

3

0

2

At present, massive gas injection (MGI) appears to be the most promising method for safely terminating most discharges in ITER. MGI involves the rapid injection of large quantities of gas into the tokamak discharge; the quantity of gas is typically several times the inventory of the plasma discharge. Both tokamaks and STs carry substantial amounts of toroidal current, and so have the possibility of disrupting. An unmitigated major disruption is a very severe event that can damage internal vessel components.
NSTX-U will have the capability for Massive Gas Injection (MGI) from three poloidal locations. For any given experiment the mid-plane injection configuration could be made identical to either the top of the bottom gas injection conditions, making it, at present, a unique machine on which to conduct these poloidal injection comparison experiments. The initial goal of these MGI experiments on NSTX-U will be to compare the gas penetration efficiency as gas is injected from the three different poloidal locations. These are (1) the private flux region, (2) the mid-plane region, (3) high-field side outer SOL region, high-field side inner SOL region and (4) outer SOL region above the mid-plane. A second objective is to determine the uniformity of the radiated power profile. The third objective is to assess the reduction in divertor heat loads and halo currents, and to compare these to unmitigated disruptions. High and low triangularity discharges at BT ~0.4T will be run to provide the plasma target for these experiments.

Reliable plasma at BT ~ 0.4 to 0.45T, Ip > 700 kA, in LSN & USN or DN, in Low and High triangularity are required.

Approximately 200 Torr.L of Ne will be injected during a shot.

A number of diagnostics need to be tested during an MGI XMP that will precede this experiment.

Reproducible shots (with/without Li - TBD)

Doc Created @ Tue Feb 17 2015 17:53:04 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 17:53:05 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 17:53:12 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:35:10 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:35:10 GMT-0500 (EST)

73

2/17/2015 18:18:17

Transient CHI Plasma Start-up in NSTX-U

Roger

Raman

[email-masked]

D. Mueller, B.A. Nelson

United States

University of Washington

Solenoid-free Start-up and Ramp-up (SR)

FY17 milestone, NI RampUP

4

0

3

Solenoid-free plasma start-up, non-inductive current ramp-up, and sustained NI operations are major NSTX-U objectives. Transient CHI plasma generation is the first part of this programmatically important sequence. We will apply the “Transient CHI” scheme developed in HIT-II and NSTX to demonstrate persistent toroidal current in NSTX-U, following a pulse of coaxial helicity injection (CHI) applied with a capacitor bank. The hardware configuration of CHI on NSTX-U is different from that on NSTX. Thus, the first experiments will re-establish transient CHI start-up capability. Once this is accomplished, the numerous hardware improvements on NSTX will be used to increase the closed flux current magnitude to the extent possible, and with acceptable levels of low-Z impurities. The initial discharges will be with the TF at 0.5T, and this will be gradually increased to the maximum levels permitted. The injector flux is an important parameter, as it is directly proportional to the amount of closed poloidal flux the transient CHI discharge contains. The injector flux will be systematically increased using the PF1CL coil, while the currents in the other nearby coils will be adjusted to maintain a sufficiently narrow flux footprint width. Full Li coverage of the lower divertor plates (and if possible of the upper divertor plates) is desired to reduce the level of low-Z impurities. The eventual goal of these experiments is to genrate closed flux currents of about 400kA, which is necessary for eventual coupling of these plasmas to non-inductive current drive methods.

CHI capacitor bank tested and fully operational.
CHI cap bank operator.
Lower CHI gas injectors.
MOVs rated to support at least 2kV operations.
Divertor Li coating capability.
NSTX-U machine that is able to reliably generate 1MA discharges with low levels of surface impurities.

Doc Created @ Tue Feb 17 2015 18:18:24 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 18:18:25 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 18:18:30 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:35:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:35:20 GMT-0500 (EST)

74

2/17/2015 21:00:32

Why do some fast-ion driven modes chirp?

Bill

Heidbrink

[email-masked]

EP group

United States

University of California - Irvine

Energetic Particles (EP)

15-2

1

0

1

Some fast-ion instabilities "saturate" in steady burbling & could possibly be described by a critical gradient model but others have impulsive bursts that could deposit concentrated heat loads in future devices. The former is common in DIII-D; the latter was common in NSTX. Nobody knows why. A similarity experiment with DIII-D will test if this difference persists in NSTX-U. If it does, we will document conditions in both devices for analysis by theoretical collaborators. If it does not, we will scan parameters down to NSTX levels to recover chirping.

None

Doc Created @ Tue Feb 17 2015 21:00:52 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 21:00:53 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 21:00:58 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:35:29 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:35:30 GMT-0500 (EST)

75

2/17/2015 21:06:16

AE Critical Gradient

Bill

Heidbrink

[email-masked]

EP group

United States

University of California - Irvine

Energetic Particles (EP)

15-2

1

0

1

Critical gradient models hold promise as a predictive tool for fast-ion transport in future devices. The experiment will compare successful DIII-D experiments with NSTX data to test whether the same physics is operative in STs. A modulated source is used to measure the incremental fast-ion flux. A power scan of other sources varies the severity of Alfven eigenmode activity.

None

Doc Created @ Tue Feb 17 2015 21:06:22 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 21:06:23 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 21:06:27 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:35:38 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:35:39 GMT-0500 (EST)

76

2/17/2015 21:10:51

Light ion beam probe of Alfven eigenmode transport

Bill

Heidbrink

[email-masked]

Darrow

United States

University of California - Irvine

Energetic Particles (EP)

none

1

0

1

The goal of this experiment is to obtain an accurate measurement of the transport caused by individual Alfven eigenmodes. A prompt loss orbit is arranged to pass close to the SLIP. AEs perturb the orbit. Calculations yield the radial kick in a single pass through the mode.

The SLIP detector needs to have a high enough bandwidth to detect oscillations at the mode frequency.

Doc Created @ Tue Feb 17 2015 21:10:57 GMT-0500 (EST); Doc Merged @ Tue Feb 17 2015 21:10:58 GMT-0500 (EST); Email Sent @ Tue Feb 17 2015 21:11:03 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:35:51 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:35:51 GMT-0500 (EST)

77

2/18/2015 9:30:42

Ex-situ IBA of targets with implanted depth markers

Graham

Wright

[email-masked]

Zach Hartwig

United States

Massachusetts Institute of Technology

Materials and PFCs (MP)

Thrusts MP-1 and MP-2 from 5-year plan

1

0

0

CLASS (MIT) is home to a Cockroft-Walton 1.7 MV tandem accelerator as well as a 1.5 MV deuteron tandem accelerator (DANTE). We propose ex-situ ion beam analysis of targets inserted and removed from NSTX-U via MAPP with both “traditional” ion beam analysis (IBA) methods and deuteron IBA methods. This can yield data such as Li layer thickness, Li2O layer thickness, D retention and Li-C intermixing as a functions of depth, and at the same time cross-calibrate and refine data and analysis methods and demonstrate the capabilities of an AIMS diagnostic system on NSTX-U. Implanted ion depth markers are also proposed to study net erosion/deposition rates. The selected depth marker ions for implantation are Be and F as these are sensitive to both traditional and deuteron IBA methods. This will not only provide valuable net erosion/deposition data at the MAPP location, but also demonstrate the potential synergy between AIMS and implanted depth markers, which could provide shot-by-shot in-situ tracking of net erosion/deposition at many different locations within the tokamak.
While MAPP gives the ability to control exposure times in NSTX-U, IBA on NSTX-U tiles at other locations post-campaign also yields useful campaign integrated/long exposure surface and material behaviors. A single run day of operations where we would have control over divertor conditions would allow for a more systematic data set to be established, but, by using the MAPP system for target insertion and removal, this proposal can piggy-back on a wide range of other rundays and is very non-invasive. Since IBA is non-perturbing and deals mostly with the sub-surface it is also very complimentary to the MAPP diagnostics and IBA can be performed after in-situ surface analysis with MAPP (excluding thermal desorption spectroscopy). The IBA work can start immediately even on NSTX tiles from previous campaigns.

Samples will be inserted and removed via MAPP system, so MAPP must be operational and accessible

Doc Created @ Wed Feb 18 2015 09:30:51 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 09:30:51 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 09:30:56 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:36:02 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:36:02 GMT-0500 (EST)

78

2/18/2015 10:56:45

Real-time error field control using extremum seeking in NSTX-U

Matthew

Lanctot

[email-masked]

Dan Boyer, D. Humphreys, Rob La Haye, Erik Olofsson, Jong-Kyu Park, Steve Sabbagh

United States

General Atomics

Macroscopic Stability (MS)

Joint experiment in ITPA MHD group (MDC-19), possible 3D field control method for access to reduced collisionality and high beta

1

0

0.25

Deploy a new real-time algorithm for multi-harmonic 3D field optimization in NSTX-U. A new dynamic error field control algorithm based on extremum seeking control methods has been developed in DIII-D. The algorithm seeks to maximize the plasma toroidal rotation over the space of low-n (n=1,2,3) control coil currents. The potentially time-varying optimal coil currents are identified by signal processing the plasma rotation response to small magnetic perturbations (a dither) in order to extract the gradient of the rotation with respect to the coil currents. The approach offers some advantages over existing dynamic error field algorithms including robust convergence, direct optimization of an n=0 performance metric, and no reliance on a complex system model. This experiment will complete the commissioning of the algorithm on NSTX-U and will use it to identify optimal error field compensation in high beta H-mode plasmas at low collisionality. The results will be compared with existing methods. Magnetic plasma response measurements are obtained in parallel so this experiment could be merged with other plasma response studies. (One notable difference would be that the coil current offsets are not pre-programmed, but are under PCS control.)

(1) Implement algorithm in NSTX-U PCS. (2) Experiment should follow commissioning of real-time rotation algorithm in PCS. (3) Independent control of six RWM coils would allow optimization of multiple toroidal harmonics in a single discharge (depending on convergence properties in NSTX-U and pulse length), however single-n studies can be pursued with 3 independent coil circuits.

Doc Created @ Wed Feb 18 2015 10:56:50 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 10:56:50 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 10:56:54 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:36:13 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:36:13 GMT-0500 (EST)

79

2/18/2015 12:29:58

Parallel Correlation of SOL Turbulence

Stewart

Zweben

[email-masked]

F. Scotti, T. Gray, M. Jaworski, S. Kubota, R. Maqueda, N. Mandell, D. Smith, V. Soukhanovskii, D.A. D’Ippolito, J.R. Myra, D.A. Russell, C.S. Chang, R. Hager, M. Churchill, S. Ku, D. Stotler

United States

Princeton Plasma Physics Laboratory

Divertor and Scrape-off-layer (DS)

none

1

0.5

0.5

Goal:
Better understand the contribution of SOL turbulence and blobs to the SOL width, in part through theory and simulation

Method:
Measure the parallel (i.e. 3-D) structure of SOL turbulence and blobs using all available edge fluctuation diagnostics, and compare results with SOL widths, theory and simulation

see pdf to be presented in div/sol parallel session

Doc Created @ Wed Feb 18 2015 12:30:06 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 12:30:07 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 12:30:12 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:36:22 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:36:23 GMT-0500 (EST)

80

2/18/2015 12:36:35

Optimization of vertical control algorithm

Dan

Boyer

[email-masked]

S. Gerhardt, D. Gates, S. Sabbagh, E. Kolemen, D. Mueller, D. Battaglia

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

15-3

1.5

0

0.5

Operation at high elongation and larger aspect ratio will make vertical stabilization a more challenging problem on NSTX-U. This XP will study the highest achievable elongation as a function of li, by varying the current ramp rate and the ISOFLUX target shape. It is desired to split this XP into 3 half day experiments. Initial results will be used to determine the primary cause for loss of stability: controller tuning, actuator bandwidth, measurement noise, latency, actuator saturation, ELMs, etc. Initial results will also be used to verify/identify control-oriented models of the vertical instability to enable offline testing. Necessary corrections (re-tuning of controller gains, inclusion of additional coils in vertical stability loop, observer optimization, etc) will be determined offline and be tested in the subsequent half day experiments.

Need the updated PCS code for vertical stability debugged offline (code may require updates between experiment days depending on necessary corrective action). It is desired to split this XP into 3 half day experiments.

Doc Created @ Wed Feb 18 2015 12:36:47 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 12:36:49 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 12:36:54 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:36:32 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:36:33 GMT-0500 (EST)

81

2/18/2015 12:42:35

Combined betaN and li feedback control

Dan

Boyer

[email-masked]

S. Gerhardt, D. Gates, E. Koleman, D. Mueller, D. Battaglia

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

15-2,15-3

1

0

0.5

In order to operate safely near stability boundaries and to enable controlled experiments where other parameters are varied at fixed betaN and/or li, feedback control laws for simultaneous control of betaN and li will be tested. Plasma current, total and/or individual beam powers, and mid-plane outer gap size will be considered as actuators. Control during both the ramp-up and flattop phases will be considered. Initial testing scenarios will be guided by the results of TRANSP results and/or scoping studies performed using the 2nd neutral beam. Results will be compared to predictions of closed loop TRANSP simulations to verify the predictive capability of these simulations.

Need the updated PCS code for the control algorithm debugged offline. PCS control of beams and rtEFIT are required. Parts of this XP could be spread over multiple days.

Doc Created @ Wed Feb 18 2015 12:42:39 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 12:42:40 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 12:42:49 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:36:43 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:36:43 GMT-0500 (EST)

82

2/18/2015 13:29:32

rampdown studies

Francesca

Poli

[email-masked]

none

United States

Princeton Plasma Physics Laboratory

Advanced Scenarios and Control (ASC)

ITPA - plasma rampdown and termination

1

0

1

inform ITER on ramp-down and termination. This includes:
1) H-L transition (assisted by NB and/or RF).
2) Greenwald fraction
3) impurity accumulation

MSE, CHERS with 2nd beamline, spectroscopy.

Doc Created @ Wed Feb 18 2015 13:29:39 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 13:29:40 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 13:29:50 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:36:52 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:36:52 GMT-0500 (EST)

83

2/18/2015 13:34:13

RF-NB interaction at low current

francesca

poli

[email-masked]

none

United States

Princeton Plasma Physics Laboratory

Energetic Particles (EP)

non-inductive rampup

1

0

0.5

change phasing of HHFW antenna and combine to NBI. Aim: broaden IC current profiles and reduce absorption to Fast Ions. Model validation of RF codes.

CHERS if use 2nd beamline, MSE, spectroscopy

Doc Created @ Wed Feb 18 2015 13:34:18 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 13:34:19 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 13:34:23 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:37:02 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:37:02 GMT-0500 (EST)

84

2/18/2015 13:53:07

Inductive Flux Savings of Inductively-driven Transient CHI Plasmas

Brian

Nelson

[email-masked]

R. Raman, D. Mueller

United States

University of Washington

Solenoid-free Start-up and Ramp-up (SR)

Contributes to FY17 milestone, and full NI operations.

2

0

1

Solenoid-free plasma start-up, non-inductive current ramp-up, and sustained NI operations are major NSTX-U objectives. Transient CHI plasma generation is the first part of this programmatically important sequence.
Transient CHI generated plasmas with >200 kA will be driven inductively using the central solenoid. The primary objective is to ramp them to high current (~1 MA) and assess the savings in inductive flux, and to compare these results to those obtained on NSTX. The current ramp-up methods developed on NSTX for the CHI plasmas will be applied to the NSTX-U CHI plasmas. For these experiments, a zero pre-charge in the solenoid will be initially used, but some pre-charge may be added after establishing flux savings in zero pre-charge cases. Because of the higher-temperature bakeout possible on NSTX-U, and the capability for full Li coverage, higher levels of flux savings are anticipated on NSTX-U, due to reduced levels of low-Z impurities. Flux savings is a measure of the quality of the CHI seed plasma, and its successful coupling to induction is a pre-requisite, before these plasmas can be directly coupled to NI current drive systems, as is desired to meet the eventual goal of full non-inductive current ramp-up and sustainment.

CHI capacitor bank tested and fully operational.
CHI cap bank operator.
Lower CHI gas injectors.
MOVs rated to support at least 2kV operations.
Divertor Li coating capability.
NSTX-U machine that is able to reliably generate 1 MA discharges with low levels of surface impurities.

Doc Created @ Wed Feb 18 2015 13:53:11 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 13:53:18 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 13:53:21 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:37:13 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:37:14 GMT-0500 (EST)

85

2/18/2015 21:10:37

Perturbative particle transport experiment with SGI in NSTX-U L and H-mode plasmas

Yang

Ren

[email-masked]

W. Guttenfelder, S.M. Kaye, A. Diallo, S. Kubota, J. Lang, B.P. LeBlanc, R.E. Bell, V. Soukhanovskii, D.R. Smith, W. Wang, H. Yuh

United States

Princeton Plasma Physics Laboratory

Turbulence and Transport (TT)

none

1

0

0.5

Particle transport in STs is not well understood, and its understanding is important for predicting density profile for future devices, e.g. to correctly predict bootstrap current. Recent particle balance analysis in NSTX L-mode plasmas shows that particle transport is close to neoclassical level in the core (r/a<~0.5) and seems to be somewhat decoupled with ion thermal transport. However, particle balance analysis at r/a>0.6 is very uncertain due to the unknown of neutral particle source. In addition, particle balance analysis cannot separate particle diffusion and pinch. These concerns signify the need of a better way of measuring particle transport. Perturbative particle transport measurement has been established in conventional tokamaks: density perturbation resulting from repetitive gas puff is measured by reflectometry, and particle diffusivity and pinch are inferred from the amplitude and phase of the induced density perturbations.
NSTX-U has a fast gas puff system (SGI) and with appropriate modulation cycle, NSTX-U’s multi-point Thomson scattering system can be used to measure density perturbations (DIII-D Thomson scattering system has recently been used in density perturbation experiment as well). Thus it is of interest to conduct perturbative particle transport experiments on NSTX-U to assess the mechanisms (neoclassical or turbulent) underlying particle transport coupled with low-k turbulence measurements (BES, reflectometry etc.). The plan is to start with MHD-quiescent long-pulse NBI-heated L-mode plasmas (similar to shot 141716). Toroidal field and plasma current scan (maybe coupled with 2nd NBI) will be carried out to change neoclassical/turbulent transport. If time permits and MHD-quiescent long-pulse NBI-heated H-mode plasmas are achieved, particle transport with 3D fields and in H-mode plasmas will also be investigated.

Achieve MHD-quiescent long-pulse NBI-heated L-mode plasmas
SGI, MPTS, CHERS, MSE, BES, reflectometer and other diagnostics required for conducting TRANSP analysis

Doc Created @ Wed Feb 18 2015 21:10:43 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 21:10:43 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 21:10:51 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:37:23 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:37:23 GMT-0500 (EST)

86

2/18/2015 22:37:37

Validation of gyrokinetic codes in NSTX-U NBI-heated L-mode plasmas

Yang

Ren

[email-masked]

W. Guttenfelder, S.M. Kaye, A. Diallo, S. Kubota, J. Lang, B.P. LeBlanc, R.E. Bell, V. Soukhanovskii, D.R. Smith, W. Wang, H. Yuh

United States

Princeton Plasma Physics Laboratory

Turbulence and Transport (TT)

none

1

0

0.5

Validation of first-principle gyrokinetic codes is important for our ultimate goal of achieving predictive capabilities for future devices. The validation should not only compare transport level between experiments and nonlinear gyrokinetic simulations, but also compare fluctuations through synthetic diagnostics. L-mode plasmas offer some favorable properties to facilitate this study: easier to obtain stationary profiles; easier to maintain MHD quiescence; no complications from edge transport barrier. Here we present an experimental proposal for a comprehensive validation study of gyrokinetic codes in NSTX-U NBI-heated L-mode plasmas. The plan is to exploit MHD-quiescent quasi-stationary NBI-heated L-mode plasmas (similar to shot 141716). Toroidal field and plasma current scan (maybe coupled with 2nd NBI) will be carried out to change neoclassical/turbulent transport. If time permits, shaping effects, e.g. elongation, on plasma confinement and turbulence will also be assessed. In particular, if long-pulse MHD-quiescent quasi-stationary NBI-heated L-mode plasmas are achieved earlier in the run, this experiment could share shots with the perturbative particle transport experiment because of similar Bt and Ip scans. The experimental measurements will be compared with GYRO, GTS and XGC1 nonlinear simulations through TRANSP analysis and synthetic diagnostics. The experiments will also allow us to assess L-mode transport shortfall seen in DIII-D L-mode plasmas (not yet seen in a set of NSTX L-mode plasmas) under different conditions, e.g. different q profile. Furthermore, this experiment will also provide a database for developing reduced transport models, e.g. TGLF, for NSTX-U parameter regimes. Cross-code comparison will also be carried out.

Achieve MHD-quiescent quasi-stationary NBI-heated L-mode plasmas
MPTS, CHERS, MSE, BES, reflectometer and other diagnostics required for conducting TRANSP analysis

Doc Created @ Wed Feb 18 2015 22:32:02 GMT-0500 (EST); Doc Merged @ Wed Feb 18 2015 22:32:03 GMT-0500 (EST); Email Sent @ Wed Feb 18 2015 22:32:08 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:37:32 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:37:32 GMT-0500 (EST)

87

2/19/2015 10:01:06

Behaviour of High-Z Impurities in NSTX-U

Matthew

Reinke

[email-masked]

Luis Delgado-Aparicio, Kevin Tritz

United Kingdom

University of York (United Kingdom)

Materials and PFCs (MP)

Assess high-Z plasma facing components

1

0

0.5

To begin to assess the impact of high-Z PFCs on NSTX-U operations we will seed perturbing amounts of krypton and xenon (separately) into ELMy H-mode plasmas. This will qualitatively demonstrate the radial and poloidal transport and enable an estimate the level of impurity source necessary to significantly impact the core plasma. If available, HHFW heating will be used to provide an initial demonstration of any impact core electron heating has on high-Z impurity equilibration.

Experimental plan is straightforward:
- establish stationary ELMy H-mode scenario w/o impurity seeding (NBI only)
- main-chamber fueling of Kr at x3 levels (low, med, high) (x3 shots)
- main-chamber fueling of Xe at x3 levels (low, med. high) (x3 shots)
- repeat stationary case(s) from Kr or Xe seeding with modulated HHFW heating (if available)

Data will be used to demonstrate diagnostic analysis workflow for future quantitative impurity transport investigations and to provide design input on any spectroscopic diagnostic upgrades. By using both krypton and xenon, this experiment can isolate any (unexpectedly) strong Z or mass dependence that would impact a near-term decision between TZM and tungsten PFCs.

Standard ELMy H-mode scenario w/ NBI heating. HHFW availability preferred but not required.

Full set of radiation diagnostics (spectroscopy, SXR & AXUV diodes, etc.) and electron kinetic (Te, ne) profile tools.

Special gases: Kr and Xe

Doc Created @ Thu Feb 19 2015 03:53:23 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 03:53:24 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 03:53:27 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:37:47 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:37:48 GMT-0500 (EST)

88

2/19/2015 14:31:15

Development of Small ELM regimes

Travis

Gray

[email-masked]

J-W Ahn

United States

Oak Ridge National Laboratory

Particle Control Task Force (PC)

none

2

1

1

Small ELM regimes are potentially an attractive scenario for edge particle control without the deleterious effects associated large type I ELMs. Small ELM regimes were previously observed in NSTX [R. Maingi, et al, Nucl. Fusion 45 (2005) 264–270] and found to have high stored energy (~ 300 kJ). We propose to scan dr_sep between -20 -- 0 mm as well as the triangularity to determine the operating window for these scenarios first under boronized conditions. These scans will then be repeated again once Li is introduced into NSTX-U with minimal between shot Li evaporation to develop scenarios with Li wall conditioning and without impurity accumulation.

Development of DN discharge scenarios established and plasma shape control

Doc Created @ Thu Feb 19 2015 14:31:25 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 14:31:26 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 14:31:33 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 05:37:58 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 05:37:59 GMT-0500 (EST)

89

2/19/2015 14:36:20

Compare the benefits of off-axis NBI for advanced scenarios in low and medium aspect ratio devices

John

Ferron

[email-masked]

Chris Holcomb

United States

General Atomics

Advanced Scenarios and Control (ASC)

JRT-15, ITPA-IOS 3.2 and 3.3

3

0

1

Goal: Make a comparison between NSTX-U and DIII-D of the effect of off-axis neutral beam injection on the current, pressure and rotation profiles and the betaN limit. Perform experiments on NSTX-U that parallel those initially performed on DIII-D after the installation of off-axis injection capability and those planned for 2015.

Importance: The results of this experiment would be contributions to the Joint Research Target report for 2015. This JRT addresses the effect of the current and pressure profiles on stability and confinement. The most and least tangential sources in the new beamline on NSTX-U are expected to generate NBCD profiles quite similar to those produced by the beams in DIII-D, so these experiments would generate data that highlight the similarities and differences as the aspect ratio changes.

Plan:
1. Access q_min >2 using off-axis neutral beam injection. Document the accessible q_min vs choice of beam sources and density. Use an early H-mode transition and heating during the Ip rampup.
2. Compare confinement, density and temperature profiles with on-axis injection and with off-axis injection. Assess the pressure peaking factor as a function of q_min and injection location.
3. Map the calculated ideal MHD stability limit for measured pressure and current profiles as a function of q_min and li.
4. Determine the effectiveness of off-axis injection in broadening the fast ion profile at high betaN.
5. Assess the experimentally achievable betaN as a function of q_min and pressure profile width. Document the effect of increasing betaN on the pressure profile width and the maximum betaN that can be maintained for multiple tauR.
6. Assess the maximum achievable current profile width with large outer gap. Assess changes in the ideal wall stability limit.
7. Look for anomalous fast ion loss that limits the accessible betaN.
8. Compare the current density profile evolution at high betaN with transport code calculations. Aim for f_NI = 1.

Prior check out of the fast ion profiles produced by the individual injection of the three new neutral beam sources to verify that the profiles at low betaN and zero MHD activity are as expected.
Capability to determine the current density profile using the MSE diagnostic.
Use of the FIDA diagnostic to measure fast ion profiles in high betaN discharges.

Doc Created @ Thu Feb 19 2015 14:37:06 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 14:37:07 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 14:37:27 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:23:06 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:23:06 GMT-0500 (EST)

90

2/19/2015 14:36:44

Heat flux and SOL width Scaling in NSTX-U

Travis

Gray

[email-masked]

J-W Ahn, K Gan

United States

Oak Ridge National Laboratory

Divertor and Scrape-off-layer (DS)

15-1

2

1

1

The multi-machine database created as part of the 2010 Joint Research Target on SOL width established that there was a strong inverse dependence with Ip. At the full upgrade capabilities (eg - Ip = 2 MA), a SOL width of ~ 3mm is predicted based on these established scalings. Further, given the expected reduced SOL width and increased divertor heat flux, routine operation of NSTX-U in double-null shapes may be required to reduce the incident heat flux to acceptable levels. With the addition of a 2nd, fast IR camera for the upper divertor, we will extend the SOL width scaling measurements to double-null operation in preparation for full upgrade capabilities in later year. We propose to study SOL width scaling under boronized conditions for 0.6 ≤ Ip ≤ 1.4 MA at a constant PNBI to connect with the original database in lower single-null and to create a new database for double-null operation. However, the addition of lithium has also been shown to greatly affect the SOL width. Therefore, this will be repeated once lithium has been introduced into NSTX-U with several amounts of Li evaporation (10, 100, 300mg, etc) both in LSN and DN configurations to measure the effect of Li on the SOL width.

none

Doc Created @ Sun Feb 22 2015 13:50:05 GMT-0500 (EST); Doc Merged @ Sun Feb 22 2015 13:50:06 GMT-0500 (EST); Email Sent @ Sun Feb 22 2015 13:50:15 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:23:19 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:23:20 GMT-0500 (EST)

91

2/19/2015 14:40:15

Validating HHFW coupling/loading models with experimental measurements in NSTX-U

Cornwall

Lau

[email-masked]

Nicola Bertelli, John Caughman, Joel Hosea, Rory Perkins, Gary Taylor

United States

Oak Ridge National Laboratory

Wave Heating and Current Drive (RF)

none

1

0

1

Antenna loading and coupling through the SOL is a well-known issue in determining HHFW power into the core plasma. SOL density in front of the antenna is critical in determining plasma impedance and therefore the reflected and transmitted power from the HHFW antenna into the plasma. Recent experiments and simulations have also suggested that SOL density in front of the antenna is critical in determining HHFW associated SOL power losses that have been observed recently on NSTX-U. The SOL reflectometer has been recently upgraded with the intent of measuring SOL density profiles in front of the antenna for detailed comparison and benchmarking to theoretical/computational models (AORSA/COMSOL) to experimental measurement in order to understand these coupling issues. As part of the upgrade, the SOL reflectometer still maintains the capability to measure RF density fluctuations that may be related to parametric decay instabilities or RF waves. This capability, along with HHFW-induced SOL density modifications, may identify and quantify possible physical mechanisms leading to HHFW power losses in the SOL.

Shot plan will repeat and try different density, outer gap, HHFW power and phasing scans with HHFW in order to optimize coupling with the additional benefit of the improved diagnostic set. No neutral beam is desired here in order to simplify the comparison between experiment and theory.

HHFW antenna, SOL reflectometer, Thomson scattering, IR camera imaging antenna is necessary
CHERS is desired

Doc Created @ Thu Feb 19 2015 14:40:19 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 14:40:19 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 14:41:05 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:23:29 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:23:29 GMT-0500 (EST)

92

2/19/2015 14:40:49

Establish minimum SOF density vs Ip ramp rate

Devon

Battaglia

[email-masked]

Dennis Mueller, Rajesh Maingi, Stefan Gerhardt

United States

Princeton Plasma Physics Laboratory

Particle Control Task Force (PC)

none

1.5

1

0.5

Gas fueling during the Ip ramp in NSTX was required to avoid disruptive MHD. It is thought that the gas puff increased the current penetration by cooling the plasma edge, thus avoiding the most unstable current profiles. If this picture is correct, slowing the Ip ramp rate should reduce the gas flow rate required for a stable plasma startup. This experiment would examine if the minimum density at the start of flattop (SOF) depends on the initial ramp rate of Ip prior to the LH transition. If time, the impact of small and large bore startup on the gas requirements will be characterized. It would be useful to run 1 day with Boronized walls, then test the key result with Lithiated walls in another 0.5 days.

Thomson, mode spec, HFS/LFS gas control, EFIT

Doc Created @ Thu Feb 19 2015 14:41:11 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 14:41:12 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 14:41:17 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:23:47 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:23:47 GMT-0500 (EST)

93

2/19/2015 14:54:19

Compare the benefits of off-axis NBI for advanced scenarios in low and medium aspect ratio devices

John

Ferron

[email-masked]

Chris Holcomb

United States

General Atomics

Macroscopic Stability (MS)

JRT-15

3

0

1

Goal: Make a comparison between NSTX-U and DIII-D of the effect of off-axis neutral beam injection on the current, pressure and rotation profiles and the betaN limit. Perform experiments on NSTX-U that parallel those initially performed on DIII-D after the installation of off-axis injection capability and those planned for 2015.

Importance: The results of this experiment would be contributions to the Joint Research Target report for 2015. This JRT addresses the effect of the current and pressure profiles on stability and confinement. The most and least tangential sources in the new beamline on NSTX-U are expected to generate NBCD profiles quite similar to those produced by the beams in DIII-D, so these experiments would generate data that highlight the similarities and differences as the aspect ratio changes.

Plan:
1. Access q_min >2 using off-axis neutral beam injection. Document the accessible q_min vs choice of beam sources and density. Use an early H-mode transition and heating during the Ip rampup.
2. Compare confinement, density and temperature profiles with on-axis injection and with off-axis injection. Assess the pressure peaking factor as a function of q_min and injection location.
3. Map the calculated ideal MHD stability limit for measured pressure and current profiles as a function of q_min and li.
4. Determine the effectiveness of off-axis injection in broadening the fast ion profile at high betaN.
5. Assess the experimentally achievable betaN as a function of q_min and pressure profile width. Document the effect of increasing betaN on the pressure profile width and the maximum betaN that can be maintained for multiple tauR.
6. Assess the maximum achievable current profile width with large outer gap. Assess changes in the ideal wall stability limit.
7. Look for anomalous fast ion loss that limits the accessible betaN.
8. Compare the current density profile evolution at high betaN with transport code calculations. Aim for f_NI = 1.

Prior check out of the fast ion profiles produced by the individual injection of the three new neutral beam sources to verify that the profiles at low betaN and zero MHD activity are as expected.
Capability to determine the current density profile using the MSE diagnostic.
Use of the FIDA diagnostic to measure fast ion profiles in high betaN discharges.

Doc Created @ Thu Feb 19 2015 14:54:25 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 14:54:26 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 14:54:32 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:23:56 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:23:57 GMT-0500 (EST)

94

2/19/2015 15:19:59

drsep Control Check-out

Travis

Gray

[email-masked]

E. Kolemen, K Gan

United States

Oak Ridge National Laboratory

Cross-cutting and Enabling (CC)

none

1

1

0.5

Due to the upgraded capabilities of NSTX-U, it is expected that routine operation with the full capabilities will require discharges run in double null configuration to mitigate the increased divertor heat flux. This XMP seeks to check out the basic drsep control algorithms in the NSTX real-time plasma control system and evaluate its preliminary performance.

none

Doc Created @ Thu Feb 19 2015 15:20:06 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 15:20:06 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 15:20:21 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:24:06 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:24:06 GMT-0500 (EST)

95

2/19/2015 15:22:51

Discharge Development of Double Null Plasmas

Travis

Gray

[email-masked]

K Gan, E Kolemen

United States

Oak Ridge National Laboratory

Cross-cutting and Enabling (CC)

none

1

1

0.5

This XMP seeks to develop high performance discharges with drsep ~ 0 or as close to it as possible for later XPs that require double-null or close to double-null operations. If time permits, this will be extended to upper single null operation. Discharges will begin in lower single-null and drsep will be ramped to until drsep ~ 0. Ramp rates will be varied to optimize the performance of double null discharges.

Completion of XMP on drsep control check-out and time to have evaluated the results.

Doc Created @ Thu Feb 19 2015 15:22:56 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 15:22:57 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 15:23:02 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:24:15 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:24:15 GMT-0500 (EST)

96

2/19/2015 15:43:49

Plasmoid instabiltiy during CHI startup

Fatima

Ebrahimi

[email-masked]

H. Ji, R. Raman

United States

Princeton University

Solenoid-free Start-up and Ramp-up (SR)

None

1

0

1

Understanding the reconnection process during CHI and finding the conditions for possible instabilities during the reconnection would help to optimize the maximum good flux closure (and CHI-generated plasma current). Motivated by recent predictive MHD simulations, we propose a systematic study of reconnection physics during CHI, with a focus on the plasmoid instability. Understanding reconnecting plasmoids may also be necessary for predicting how transient CHI scales as it is extrapolated to future (larger) devices. The goal is to explore and better understand conditions under which small and large plasmoids are generated. Key parameters governing Lundquist number and the current sheet (including plasma temperature, poloidal injector flux, injector flux footprint) will be controlled and varied. For example, in addition to using ECH, plasma temperature could be increased by increasing the voltage at reduced density. Improved, dedicated and high-resolution diagnostics are needed to measure the reconnection flows and current sheets around the injector region. The formation of plasmoids will be detected via high resolution fast framing camera with optical filters.

In addition to the all requirements for transient CHI start up, high resolution camera with optical filters.

Doc Created @ Thu Feb 19 2015 15:43:56 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 15:43:56 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 15:44:02 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:24:25 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:24:25 GMT-0500 (EST)

97

2/22/2015 19:51:34

Resonant error field threshold with non-resonant braking

Jong-Kyu

Park

[email-masked]

J. E. Menard, C. Myer, S. P. Gerhardt, Z. R. Wang, N. Logan, M. Lanctot, R. E. Bell, L. Delgado-Aparicio

South Korea

Princeton Plasma Physics Laboratory

Macroscopic Stability (MS)

MDC-19

1

0

0.5

This experiment is to test n=1 error field threshold while n=2 or n=3 field is applied and so in the presence of non-resonant NTV braking, utilizing the new 6-independent control capability. Experiments in NSTX and also in other machines have shown that non-resonant braking can cause NTV rotation damping and subsequently reduce n=1 error field threshold as expected. This is however less clearly demonstrated in Ohmic plasmas, since (a) theory indicates the additional viscosity by NTV may increase tolerance to electromagnetic torque induced by error field, and (b) there is an observation in KSTAR that shows non-resonant braking can rather mitigate locking-induced disruption.

So first this experiment will use (1) Ohmic targets, and test resonant error field threshold by ramping up n=1 field while applying n=2 and n=3 non-resonant fields. The level of non-resonant fields and also density will be varied. Density control is desired if available to any extent, but otherwise n=1 ramping period will be adjusted to minimize density variation during n=1 application. Then this experiment can be repeated in (2) H-mode targets and compared with Ohmic cases as well as results in other machine such as DIII-D.

The information about intrinsic error field can be critical especially when the level of intrinsic non-axisymmetry is large, and so this experiment is desired after the investigation of non-axisymmetry in plasma response. Also rotation measurement available in Ohmic plasmas, such as passive CHERS, will be very important to further quantify error field threshold vs. rotation and torque.

Diagnostics: Magnetic measurements, CHERS, Soft X-ray, IR camera
Analysis: IPEC-PENT, MARS-K, POCA

Doc Created @ Thu Feb 19 2015 19:34:59 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 19:35:00 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 19:35:05 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:24:42 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:24:42 GMT-0500 (EST)

98

2/22/2015 19:47:14

Localized 3d field effects on momentum transport and confinement

Jong-Kyu

Park

[email-masked]

Z. R. Wang, M. Lanctot, S. A. Sabbagh, J.-W. Ahn, D. Liu, G. Z. Hao, G. Kramer, W. Guttenfelder, S. M. Kaye

South Korea

Princeton Plasma Physics Laboratory

Turbulence and Transport (TT)

none

0.5

0

0.5

This experiment is to apply a single coil perturbation, utilizing the 6-independent coil control capability, and measure the effects on NTV momentum transport and confinement including fast ions. Tokamaks such as ITER can have a localized error field source as expected from Test Blanket Module (TBM). It has been shown in the DIII-D TBM mock-up test that this localized 3d field can degrade confinement up to ~20% when measured by H98 factor, fast ion loss up to ~30% and toroidal rotation up to ~60%. Effects became stronger in high-β plasmas, indicating importance of the TBM error field control in high performance plasmas. The field from a present midplane coil in NSTX-U is much broader in wavelength than the TBM field, but contains many toroidal harmonic components with Gaussian-type distribution that characterizes a localized error field source. Note a single coil application was never tested before in NSTX.

So this experiment will apply a single coil perturbation and measure NTV damping, confinement change, fast ion transport, as well as the effects on divertor heat flux or fluctuations, as a function of β and also applied field strength. These parameters can be varied or adjusted in various levels during a discharge depending on shot duration and evolution. Then other coils can be used to remove a part of this proxy localized error field, especially n=1 component, and to quantify recovery of confinement or from loss by this partial correction.

Diagnostics: Magnetic measurements, CHERS, FIDA, SFLIP, Soft X-ray, IR camera, BES
Analysis: IPEC-PENT, MARS-K, POCA, TRANSP, SPIRAL, GYRO, etc

Doc Created @ Thu Feb 19 2015 19:57:17 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 19:57:18 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 19:57:23 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:24:52 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:24:53 GMT-0500 (EST)

99

2/19/2015 20:43:43

Low-beta, low-density locked mode studies

Clayton

Myers

[email-masked]

S. P. Gerhardt, J.-K. Park, and J. E. Menard

United States

Princeton Plasma Physics Laboratory

Macroscopic Stability (MS)

R15-3

1

0

0.5

The intrinsic error fields in NSTX-U are expected to have changed from NSTX as a result of differences in the PF5 coil mechanical supports as well as modifications to the vacuum vessel (e.g., the NB2 beam port). Characterization of these intrinsic error fields early in the run will be key to achieving high performance discharges and improving startup, especially at low density.

In this XP, we will conduct “compass” scans of the n=1 applied field using the RWM/EF non-axisymmetric coils. This will include changes to both the amplitude and the phase of the applied n=1 fields. The primary diagnostic for this XP will be the onset of locked modes and ensuing disruptions. Given that the XP is likely to run early in the campaign, the status of the CHERS rotation data is unknown, though it will be used if available. Time permitting, a brief optimization of the n=2 and n=3 intrinsic error field correction will also be performed.

Shot conditions: Low-beta, L-mode discharges (early in campaign)
Need: RWM/EF coils with 6 SPA capabilities, magnetics, RWM sensor data.
Want: CHERS rotation data.

Doc Created @ Thu Feb 19 2015 20:43:49 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 20:43:49 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 20:43:54 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:25:01 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:25:02 GMT-0500 (EST)

100

2/19/2015 20:46:46

High-beta n=1,2,3 feed-forward error field correction

Clayton

Myers

[email-masked]

S. P. Gerhardt, J.-K. Park, J. Berkery, and J. E. Menard

United States

Princeton Plasma Physics Laboratory

Macroscopic Stability (MS)

R15-3

1

0

0.5

The intrinsic error fields in NSTX-U are expected to have changed from NSTX as a result of differences in the PF5 coil mechanical supports as well as modifications to the vacuum vessel (e.g., the NB2 beam port). The intrinsic error fields that will be identified in low-beta, L-mode discharges will differ from those that are modified/amplified in high-beta, H-mode discharges. Consequently, scans are required to evaluate intrinsic error fields in high performance discharges.

In this XP, compass scans will be performed in long pulse, high performance discharges utilizing “spiral” scans where the amplitude and phase of the applied non-axisymmetric fields (n=1,2) are gradually increased over the course of the discharge. The primary diagnostic for this XP will be CHERS rotation. The XP will be most effective if inter-shot CHERS is available, so this may dictate when the XP can/should be run. The n=3 portion of the XP will involve flipping the n=3 applied field polarity and scanning its amplitude. The amplitude will be scanned sufficiently to study magnetic braking as a result of the applied n=3 fields.

Shot conditions: High-beta, H-mode discharges
Need: RWM/EF coils with 6 SPA capabilities, Magnetics, RWM sensor data, CHERS rotation data.

Doc Created @ Thu Feb 19 2015 20:46:49 GMT-0500 (EST); Doc Merged @ Thu Feb 19 2015 20:46:50 GMT-0500 (EST); Email Sent @ Thu Feb 19 2015 20:46:55 GMT-0500 (EST)([email-masked],[email-masked])

Doc Created @ Wed Feb 25 2015 06:25:10 GMT-0500 (EST); Doc Merged @ Wed Feb 25 2015 06:25:11 GMT-0500 (EST)

Loading...

| Quotes may be delayed up to 20 minutes. Information is provided 'as is' and solely for informational purposes, not for trading purposes or advice.Disclaimer

Form Responses 1

autoCrat_MergeData_DO_NOT_DELETE

NVScriptsProperties

A browser error has occurred.
Please press Ctrl-F5 to refresh the page and try again.

A browser error has occurred.
Please hold the Shift key and click the Refresh button to try again.