Kinetic-MHD simulation of pressure-driven instabilities in stellarators using M3D-C1

Pressure-driven MHD instabilities play a pivotal role in limiting plasma beta and overall performance in magnetized fusion devices, including both tokamaks and stellarators. Beyond linear stability analysis, it is crucial to predict the nonlinear evolution of these instabilities to determine whether mode excitation results in benign saturation or a catastrophic collapse of pressure confinement. The M3D-C1 code enables nonlinear MHD simulations for both tokamaks and stellarators, and its kinetic module has recently been upgraded to incorporate the effects of kinetic thermal ions (KTI) for both configurations. In this talk, we present several key results from the new kinetic module applied to stellarator simulations, with a focus on the influence of KTI on ballooning instabilities. The KTI module enables a self-consistent treatment of parallel thermal conduction due to Landau damping, as well as ion finite orbit width effects—both of which are critical in determining the nonlinear saturation behavior of ballooning modes.