Extrapolating the kinetic effects of energetic particles on resistive MHD stability to ITER

The effects energetic particles have on MHD instabilities is a key issue in the physics of burning plasma experiments such as ITER. Recent results indicate kinetic effects of energetic particles can play a crucial role in the stability of the m/n=2/1 tearing mode, especially in ITER where $\beta _{frac}=\beta _{h}$/$\beta $ is high ($\beta _{h}$ is energetic particle $\beta )$. Using realistic equilibria based on experimental reconstructions, the non-ideal MHD stability of the n=1 and 2 modes is calculated at a series of q$_{min}$, $\beta $, $\beta _{frac}$, and S=$\tau _{R}$/$\tau _{A}$, including the $\delta $f kinetic-MHD model in the 3-D extended MHD code NIMROD. Eigenvalue based computations using PEST-III and DCON give context to these results, and provide a basis for extrapolation. It is observed that for high q$_{min}$ the particles have significant stabilizing effects, while at low q$_{min} \ga $1 the interaction of the particles with the non-resonant response on axis causes destabilization of resistive modes. The requirements for directly computing energetic particle effects on resistive MHD modes in the burning plasma parameter regime are discussed.