Bounce-Averaged Fokker-Planck Solver based on the MFEM Finite Element Library

The required toroidal currents for magnetic confinement in tokamaks can be driven by radio frequency (RF) waves. The resulting changes in the electron velocity distribution function are modeled by the Fokker-Planck (FP) equation. In the past, we built a FP solver based on the MFEM (www.mfem.org) finite element method library to take advantage of a modern GPU computing architecture the results of which were presented at the APS DPP 2020 Annual Meeting (JP13.00021). This initial work solved the FP equation for the steady-state distribution function of a uniform plasma with external RF-induced quasi-linear diffusion.  In order to apply it for toroidal devices, we extended our solver to include bounce averaging, relativistic effects, and temporal evolution. The simulation results of this solver are compared with a reference simulation computed using CQL3D.