Abstract Details
Abstracts
Author: Mikhail Dorf
Requested Type: Poster
Submitted: 2025-03-12 15:26:32
Co-authors: M. Dorr, D. Ghosh, M. Umansky, V. Geyko, J. Angus, and V. Soukhanovskii
Contact Info:
Lawrence Livermore National Laboratory
7000 East Ave.
Livermore, CA 94550
USA
Abstract Text:
The development and application of implicit time integration capabilities for gyrokinetic simulations of collisional plasma transport is reported. The time integration approach involves the implicit treatment of the gyrokinetic Vlasov equation coupled with a nonlinear Fokker-Planck collision model. To facilitate implicit simulations, advanced preconditioning of individual physics operators is developed, whereas the global multi-physics preconditioner is constructed by adapting the operator splitting methodology. Notably, the preconditioning of the gyrokinetic Vlasov advection operator is enhanced by making use of algebraic multigrid solvers that utilize the recently developed Approximate Ideal Restriction approach. The implicit algorithms are implemented in the finite-volume code COGENT and applied to simulations of (i) 1D-2V weakly collisional ion transport in a magnetic mirror for the parameters characteristic of the WHAM facility and (ii) 2D-2V (axisymmetric) full-F neoclassical transport of the main ion species and lithium impurity species in the closed-field-line region of the LTX-beta tokamak. In particular, we address the relaxation of high-energy beams in the WHAM mirror and describe the nonlocal transport effects and poloidal impurity asymmetries in LTX-beta. Significant speedup over the corresponding explicit simulations is demonstrated for both applications.
Work performed for USDOE, at LLNL under contract DE-AC52-07NA27344.
Characterization: 4.0
Comments: