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

G. Brochard (1) , Rémi Dumont (1) , H. Lütjens (2) , Xavier Garbet (1)

1 IRFM - Institut de Recherche sur la Fusion par confinement Magnétique
2 CPHT - Centre de Physique Théorique [Palaiseau]

The stability of the n = m = 1 alpha-fishbone kinetic-MHD mode on the ITER 15 MA baseline scenario [1] 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 [2] 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% [1].

Domaines: Physique des plasmas [physics.plasm-ph]

G. Brochard, Rémi Dumont, H. Lütjens, Xavier Garbet. Linear stability of the ITER 15 MA scenario against the alpha fishbone. Nuclear Fusion, 2020, 60 (8), pp.086002. ⟨10.1088/1741-4326/ab9255⟩. ⟨hal-02950497⟩