Intriguing (and Unique) Plasma Properties of Spherical Torus Have been Suggested Recently
- Current startup via coaxial helicity injection (Jarboe) or RF methods alone
- Naturally elongated plasma (k up to 3+) with enhanced vertical stability
- MHD-stable plasma at average toroidal beta (25%-45%) with well-aligned bootstrap current, strong magnetic shear, and deep magnetic well (up to 30%) (Menard, Miller, Hender)
- Strong flow shearing rate (by 1-2 orders of magnitude over tokamak), strong magnetic shear (near edge), and reversal of orbit precession, giving strong tendency to suppress plasma microinstabilities and improve confinement toward neoclassical limit (or introduce new instabilities?) (Synakowski, Rewoldt, Dorland, Stambaugh, etc.)
- Strong flow shear and magnetic well compress guiding center orbits and improve neoclassical confinement (Shaing etc.)
- Strong absorption of High Harmonic Fast Wave for plasma heating and current drive (for plasmas with large dielectric constant) (Ono etc.)
- Naturally diverted SOL in NSTX has large mirror ratio (up to 4-to-1) and flux expansion factor (up to ³10), dispersing particle and heat fluxes (Strickler)