Optimization of tokamak plasma pressure profile against high n ideal MHD ballooning modes

Under the assumption that the local plasma pressure gradient is limited by high n ideal MHD ballooning modes, the optimized pressure profile is examined for noncirclar tokamaks. It is found that the q profile strongly affects the resultant average beta value <β>, as well as the central beta value β0 and that the readially decreasing q profile is always favourable for enhancing the beta value. The effects of both elliptical and triangular deformations are analysed and rather stronger stabilizing effect of the latter is found