Impact of plasma rotation on linear MHD physics in tokamaks; Theory and numerical applications

Aiba, Nobuyuki; Shiraishi, Junya; Hirota, Makoto; Cooper, W.*; Gruber, R.*

The authors identified that plasma poloidal rotation sometimes plays an important role for ideal MHD stability due to changing the Doppler-shift frequency. As the result, the stability of edge localized MHD mode can depends on the direction of toroidal rotation; this dependence is qualitatively consistent with the experimental results observed in JT-60U. Plasma rotation is also responsible for the stability of resistive wall mode (RWM). In reversed shear plasmas, plasma rotation once stabilize RWM but destabilize this again when rotation frequency reaches to certain frequency. This re-destabilization is thought to be related to the coupling between RWM and a stable MHD wave. By developing a new numerical matching method, we realize to identify rotation effect on RWM stability in more detail, and as one of examples, we identified the most important resonant surface responsible for stabilizing RWM.