High-temperature superconducting (HTS) magnetic mirrors exploit strong fields with high mirror ratio to compress loss cones and enhance confinement, and may result in cheaper, more compact fusion power plants. Yet these devices may exhibit interchange instabilities, which can be studied with gyrokinetics given the strong magnetization and prevalence of kinetic effects. In this work [1] we aim to (a) determine if oft-used gyrokinetic models for open field lines produce the electron-confining (Pastukhov) electrostatic potential and (b) examine and address challenges faced by gyrokinetic codes in studying HTS mirrors. We show that a one-dimensional limit of said models self-consistently develops a potential qualitatively approaching the analytical Pastukhov level. Additionally, we describe the computational challenges of studying high mirror ratios with open field line gyrokinetic solvers and offer a method to mitigate small time steps needed for time integration in colossal magnetic field gradients produced by HTS coils, providing a 19X speedup. Additional algorithmic solutions will be discussed.
[1] M. Francisquez, et al. Phys. Plasmas 30, 102504 (2023)