IMPACT OF ROTATIONAL TRANSFORM PROFILE CONTROL ON PLASMA CONFINEMENT AND STABILITY IN CHS

摘要

In neutral beam heated plasmas of CHS, which is a low aspect ratio heliotron/torsatron device, the effect of rotational transform (l) profile shape on plasma confinement and stability is studied by inducing a net plasma current (I_p). When the external l is increased by I_p, a very rapid H mode transition (within ～ 0.2 ms) is observed at the thresholds of I_p and heating power, and the discharge shows all the characteristics found in the tokamak H mode. There is no obvious difference in the H mode characteristics between deuterium and hydrogen plasmas. In the opposite case, when the external l is decreased by reversing I_p, the H mode transition is not observed.