Verification of electromagnetic fully-kinetic-ion simulations of high-frequency waves in toroidal geometry

In recent fusion experiments, several high-frequency modes driven by energetic particles (EPs) have been observed on the order of the ion cyclotron frequency, such as compressional Alfvén eigenmodes (CAEs), global Alfvén eigenmodes (GAEs) and ion cyclotron emission (ICE). To study these waves, an electromagnetic simulation model, in which the ion dynamics is described by a six-dimensional Vlasov equation is formulated and implemented in the global gyrokinetic toroidal code (GTC). Linear simulations of generalized ion Bernstein waves (propagation perpendicular to equilibrium magnetic field) and shear Alfvén waves (propagation parallel to equilibrium magnetic field) are verified by comparing simulation results with analytic dispersion relation in cylindrical geometry. Simulation of the ICE excitation by EPs has been verified by comparing with magnetoacoustic cyclotron instability theory. Using a set of typical plasma parameters from the DIII-D tokamak experiment, the electromagnetic fully-kinetic-ion simulations find the ICE frequency spectra qualitatively consistent with the experimental results. Kinetic simulation of the ICE global structure is needed for the development of the ICE as a diagnostic tool for alpha particles in future burning plasma experiments.