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MFEM Facilitates the Design of More Robust Tokamak RF Antennas:�High-order Methods on Adaptive Unstructured Meshes

Scientific Achievement

MFEM’s high-order methods, AMR, preconditioners, and GPU support, make possible the design of more robust RF antennas and other plasma facing components in tokamak fusion reactors.

Significance and Impact

The RF-SciDAC application partnership can utilize the new, FASTMath developed, algorithms for more accurate and efficient simulations.

Research Details

• High-order finite element methods coupled with efficient CPU and GPU implementations and robust preconditioners allow for efficient and accurate simulations of RF antennas on modern HPC platforms.
• We can perform adaptive solutions in RF heaters and automatically detect/modify the lower-hybrid-resonance regions in the cold plasma to increase simulation accuracy while keeping the number of DOFs low.

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Adaptive solutions in RF heaters: left: initial mesh/solution; right: mesh/solution after 5 adaptive steps.�(M. Siboni, RPI)

M. Siboni, M. Shephard, "Adaptive Workflow for Simulation of RF Heaters", Computer Physics Communications, p.108434, 2022.

First fully resolved 3D HHFW field on NSTX-U (S. Shiraiwa, PPPL)

Stix miniapp: frequency domain Maxwell equation with an anisotropic cold plasma dielectric tensor. (M. Stowell, LLNL)

D. Green, X. Hu, J. Lore, L. Mu, M. Stowell, "An Efficient High-order Numerical Solver for Diffusion Equations with Strong Anisotropy”, Computer Physics Communications, 276, p.108333, 2022.