Gyrokinetic simulation of MHD-regime instabilities in the global total-f code XGC

We present gyrokinetic pressure and current driven MHD-regime instabilities in the electromagnetic gyrokinetic total-f particle-in-cell code XGC, which is now equipped with a hybrid-spectral field solver for low to intermediate toroidal mode numbers n. The new solver allows for more accurate treatment of low and intermediate n as seen with, e.g. internal kink, edge-localized peeling-ballooning, or neoclassical tearing modes in tokamaks. It is used alongside XGC’s regular (higher-n) field solver. To achieve this increased accuracy, the new field solver utilizes a toroidally spectral formulation that does not approximate the poloidal magnetic field as small compared to the toroidal magnetic field. The new solver allows self-consistent interaction among MHD-regime modes, microturbulence and neoclassical physics.