Abstract Details
Abstracts
Author: Benjamin J Sturdevant
Requested Type: Poster
Submitted: 2023-03-31 20:15:56
Co-authors: L. Chacon, S. Ku, M. Adams, C.S. Chang
Contact Info:
Princeton Plasma Physics Laboratory
P.O. Box 451
Princeton, 08543
USA
Abstract Text:
An implicit particle-in-cell method for electromagnetic gyrokinetics using parallel velocity as a coordinate has been developed in the XGC code as a means of avoiding the Ampère cancellation problem for long-wavelength MHD-type modes [1]. Here, we present an improved formulation for the implicit method, based on the work in [2], which demonstrates robust stability properties with respect to both finite-grid and temporal instabilities. The improved formulation also offers advantages for the computational efficiency of the iterative scheme used to solve the implicit equations. In particular, the improved formulation enforces discrete charge conservation, which leads to an exact cancellation between two problematic terms appearing in the residual formulation. This removes a key sensitivity that can hinder the convergence of the scheme. We present simulation results including the ITG-KBM transition and shear Alfven waves comparing the new formulation with results using the previously reported scheme.
[1] B. Sturdevant, S. Ku, L. Chacón, et al., Phys. Plasmas, 28, 072505 (2021).
[2] B. Sturdevant and L. Chacón, J. Comput. Phys., 464, 111330 (2022).
Comments: