Simulation of anisotropic heat transport in fusion plasma with MFEM

The simulation of magnetized plasma transport using the fluid approximation is ubiquitous in the study of fusion devices. However, the extreme anisotropy in the ratio of heat diffusivity in the direction parallel to the confining magnetic field to that in the perpendicular direction can range from 10^6 at the periphery of the plasma, to more than 10^12 in the core. This presents a challenge to discretization schemes which must avoid contamination of the perpendicular transport by numerical errors associated with the parallel transport. Typical solutions to this problem involve aligning the coordinate system with the magnetic field. However, for problems requiring complex domain boundaries (non-coordinate aligned), alternatives must be investigated. Here we present progress on the utilization of the high-order capabilities of the MFEM [1] library, combined with advanced meshing techniques to address this problem targeting simulations of the far scrape-off-layer (SOL) for investigating the nonlinear modification of the SOL properties by application of RF power.

[1] R. Anderson, et al., MFEM: A Modular Finite Element Library, in preparation, 2018 (http://mfem.org/publications/).