Alpha current driven by ion cyclotron resonance heating in a tokamak fusion reactor

Abstract

Generation of plasma current by magnetic trapping of passing alpha particles through ion cyclotron resonance heating (ICRH) is studied. It is found that the efficiency of the ICRH-driven alpha current can be comparable to the known efficiency of the usual fast-wave-driven electron current (e-FWCD). However, the radial dependence can be quite different from the known behavior of e-FWCD. Since a substantial fraction of the fast wave energy can be absorbed by the fusion-born alpha particles through ICRH, the fast wave current drive in a deuterium-tritium reactor plasma may be substantially modified by the synergistic alpha current effect. The present study suggests that, without a careful choice of the wave properties, the synergism may yield a destructive fast-wave-driven radial current profile for plasma equilibrium. However, it also suggests that a proper choice can produce a more favorable result than the e-FWCD can alone. (C) 1995 American Institute of Physics.