Development progress for a far-SOL anisotropic fluid transport solver

Fluid transport in fusion plasmas can be highly anisotropic due to the strong confining magnetic field, with diffusion coefficients D_||/D⟂ ranging from 10³ to 10⁹. Although a field aligned mesh can be used to avoid error pollution in the cross-field direction, in the far scrape-off layer (SOL) a geometry conforming grid is required to resolve complicated radio frequency (RF) antenna structures. A new fluid plasma solver MAPS (MFEM Anisotropic Plasma Solver) is being developed to simulate the far-SOL plasma using unstructured meshes, where high order finite elements are used to address the highly anisotropic behaviour. The ion and neutral continuity, ion parallel momentum, and the ion and electron temperature equations are solved using the Symmetric Interior Penalty Discontinuous Galerkin (SIPG) method with arbitrary order. The time integration uses a high-order singly diagonal Runge-Kutta (SDIRK) method with PID controlled time-step selection. Novel preconditioning methods have also been implemented for solving the linear system in highly anisotropic cases. Initial benchmarking efforts for the MAPS code in 1- and 2D will be presented. We will also discuss future applications of the MAPS code, including coupling to an MFEM-based RF solver to investigate issues in the antenna near-field region of the plasma.