Critical beta analyses of low aspect ratio tokamak, 2

Kurita, Genichi; Tobita, Kenji; Asakura, Nobuyuki; Aiba, Nobuyuki; Nagashima, Keisuke

It is necessary to obtain the stable high beta plasma in order to realize the economically superior magnetically confined fusion reactor. In these analyses, we mainly investigate the effect of plasma pressure pedestal near plasma edge region considering the bootstrap current effect due to edge plasma pressure pedestal. The following results are obtained. Increase of edge plasma pressure induces a rise of critical beta because of reduction of internal plasma pressure gradient, until the edge plasma pressure gradient and bootstrap current induces the new instability near the plasma edge. For comparatively peaked plasma pressure profiles, we have another higher door-knob like stable region near the maximum critical beta region.