Linear stability of the ITER 15 MA scenario against the alpha fishbone
Abstract
The stability of the n=m=1 alpha-fishbone kinetic-MHD mode on the ITER 15 MA baseline scenario ITERB is analyzed using the nonlinear hybrid Kinetic-MHD code XTOR-K. Quantitative agreement is found between the complex frequencies ω + iγ computed with the linear model in Brochard2018 and XTOR-K's linear simulations. Identical precessional resonance positions in phase space are also found between the linear model and XTOR-K. Linear hybrid simulations performed with XTOR-K on the ITER 15 MA scenario reveal that this configuration is likely to be unstable against the alpha fishbone mode. The fishbone thresholds for kinetic-MHD equilibria with flat q profiles with on-axis safety factor just below unity lies between βα,thres/βtot = 6-10\%, whereas the expected beta ratio on ITER is βα/βtot = 15-20\% ITERB.