Simulation of high Q plasma by ICRF heating of alpha particles

The possibility of achieving a high effective Q plasma (Q is the fusion power multiplication factor) by increasing the power transfer from alpha particles to the background plasma through heating in the ion cyclotron range of frequencies (ICRF) is examined. The effective Q-value, Qeff, which is defined as the ratio of the indirect plasma heating power from ICRF heated alpha particles to the direct heating power, is evaluated by using the rate of wave absorption by alpha particles on the basis of the energy moments of the quasi-linear RF diffusion operator. The fourth harmonic alpha cyclotron wave, which is absorbed mainly by alpha particles in the absence of hydrogen, should be favourable for achieving a high Qeff plasma. In the high magnetic field, Qeff can also be quite well increased by the third harmonic wave. Effects of tail formation by ICRF waves and of wave absorption by hydrogens on Qeff are also discussed.