ICRF heating and its effect on single-particle confinement in tokamaks

Abstract

Ion cyclotron resonance heating (ICRH) and its intrinsic effect on confinement in tokamaks is investigated. The stochastic nature of ICRH in the absence of collisions is examined through finite-mapping equations. The threshold RF amplitude for the transition from superadiabatic to stochastic behaviour is found to be exceeded in present-day experiments. The effect of heating on confinement is evaluated by studying the drift orbit changes due to heating with collisions included through a Monte-Carlo method. The results indicate that transport induced by the ion cyclotron range of frequencies (ICRF) could be significant at the higher RF power levels planned for the next generation of experiments.