WAVES IN THE EDGE PLASMA DURING ION-CYCLOTRON RESONANCE HEATING

The waves that can propagate in the edge plasma during fast wave ion cyclotron resonance heating (ICRH) for densities sufficiently high that ω < ωpi are considered; in particular surface wave modes of the compressional Alfvén wave, the torsional Alfvén wave and the ion Bernstein wave. The basic properties of each wave type are outlined, and previous theoretical and experimental studies briefly reviewed. Evidence is presented that excitation of waves in the edge plasma by the antenna is responsible for the edge heating, and possibly indirectly the increase in impurities, generally observed during ICRH. It is shown that the torsional Alfvén wave and ion Bernstein wave may contribute to these effects under certain ICRH conditions. The surface modes of the compressional Alfvén wave are identified as a possible cause major of edge heating during all ICRH regimes. © 1990.