抄録
Auxiliary heated confinement data are being accumulated from medium-size spherical tokamaks MAST and NSTX with aspect ratio A=R/a≈1.5. It has already been demonstrated that high beta (normalized beta βN > 5) and good confinement (enhancement over tokamak H-mode confinement scaling HH98y2 > 1) can be achieved simultaneously. Both L-mode and H-mode plasmas have energy confinement times comparable to or exceeding predictions of scaling laws based on conventional aspect ratio tokamak data. Analyses of kinetic profile data indicate that ion transport is near neoclassical in most cases, but electron transport is highly anomalous and is the dominant power loss channel. Indications of internal transport barrier formation are observed in both ion and electron temperature profiles, contributing to the core pressure increase.
