Non-local effect in Petra-M RF simulation

Petra-M is an open source FEM platform based on a scalable MFEM finite element library. In RF SciDAC, it has been used for performing a large-scale RF fullwave simulation including realistic 3D antenna models. Here, we investigate the feasibility of expanding the RF wave physics model within FEM discretization. The finite temperature effects make the plasma response from imposed RF electric fields non-local. An accurate treatment of these effects requires extending the FEM assembly process to accumulate the contribution from the neighboring mesh element. Both the first order finite temperature correction term and an all-order term based on a convolution integral [O. Sauter and J. Vaclavik, Nucl. Fusion 32, 1455 (1992)] were implemented. Simulation result of 1D electron Bernstein wave mode-conversion shows that this approach can resolve the thermal EBW. Extension of convolution integral in 2D will be discussed. We also discuss the implementation of various non-linear RF rectified potential models including its asymptotic limit to Petra-M. These models are compared with previous analytic and numerical results [H. Kohno and J. Myra, CPC 220, 129 (2017), W. Tierens et. al., PoP 26, 083501 (2019)] , showing satisfactory agreement.