Linear stability of the ITER 15 MA scenario against the alpha fishbone

The stability of the $n=m=1$ alpha-fishbone kinetic-MHD mode on the ITER 15 MA baseline scenario \cite{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 \cite{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 $β_{α,thres}/β_{tot} = 6-10\%$, whereas the expected beta ratio on ITER is $β_α/β_{tot} = 15-20\%$ \cite{ITERB}.

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