Triangularity effect on ideal MHD stability of JT-60SU plasma

摘要

Ideal MHD stability, the low-n free-boundary kink mode and the infinite-n ballooning mode of a high-elongated JT-60SU plasma are investigated. Equilibria are obtained for the plasma with steady-state neutral-beam-driven and bootstrap currents. It is shown that without the shell stabilizing effect the maximum value of normalized beta is mainly limited by the localized external mode at the plasma surface, when the equilibrium surface current by the bootstrap current is increased. The triangularity is shown to have a stabilizing effect on the localized external modes, while the external modes, which have a relatively bred structure, and the internal modes are not affected as much by the triangularity. It is also shown that the localized external modes can be unstable for a wide range of q(surf) values. Even infinite-n ballooning modes driven at the plasma surface are destabilized if the triangularity is increased for JT-60SU equilibrium. [References: 30]