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The kinetic–magnetohydrodynamic (MHD) hybrid simulation approach for macroscopic instabilities in plasmas can be extended to include the kinetic effects of both thermal ions and energetic ions. The new coupling scheme includes synchronization of the density and parallel velocity between thermal ions and MHD, in addition to pressure coupling, to ensure the quasineutrality condition and avoid numerical errors. The new approach has been implemented in the kinetic-MHD code M3D-C1-K, and was used to study the thermal ion kinetic effects and Landau damping in fishbone modes in both DIII-D and NSTX. It is found that the thermal ion kinetic effects can cause an increase of the frequencies of the non-resonant $n=1$ fishbone modes driven by energetic particles for $q_\mathrm {min}>1$ , and Landau damping can provide additional stabilization effects. A nonlinear simulation for $n=1$ fishbone mode in NSTX is also performed, and the perturbation on magnetic flux surfaces and the transport of energetic particles are calculated. [ABSTRACT FROM AUTHOR]

Abrupt large events in the Alfvénic and sub-Alfvénic frequency bands in tokamaks are typically correlated with increased fast-ion loss. Here, machine learning is used to speed up the laborious process of characterizing the behavior of magnetic perturbations from corresponding frequency spectrograms that are typically identified by humans. The analysis allows for comparison between different mode character (such as quiescent, fixed frequency, chirping, and avalanching) and plasma parameters obtained from the TRANSP code, such as the ratio of the neutral beam injection (NBI) velocity and the Alfvén velocity ($v_{\textrm {inj.}}/v_{A}$), the $q$ -profile, and the ratio of the neutral beam beta and the total plasma beta ($\beta _{\textrm {beam},i}/\beta $). In agreement with the previous work by Fredrickson et al., we find a correlation between $\beta _{\textrm {beam},i}$ and mode character. In addition, previously unknown correlations are found between moments of the spectrograms and mode character. Character transition from quiescent to nonquiescent behavior for magnetic fluctuations in the 50–200 kHz frequency band is observed along the boundary $v_{\varphi } \lessapprox ({1}/{4})(v_{\textrm {inj.}} - 3v_{A})$ , where $v_{\varphi }$ is the rotation velocity. [ABSTRACT FROM AUTHOR]