Abstract Details
Abstracts
Author: Thomas G Jenkins
Requested Type: Poster
Submitted: 2024-04-12 11:01:29
Co-authors: D. N. Smithe
Contact Info:
Tech-X Corporation
5621 Arapahoe Avenue Suite A
Boulder, CO 80303
USA
Abstract Text:
Ongoing efforts to develop a new delta-f particle-in-cell method, kinetics-only delta-f (KODF), are summarized. KODF models the nonlinear evolution of plasma species distribution functions in phase space in a manner similar to conventional delta-f methods, wherein computational markers ('particles') evolve along characteristic trajectories to model perturbations around a known equilibrium distribution function. The computational markers need not model the equilibrium distribution (as would be necessary if one used a total-f approach); instead, a marker weight variable tracks the deviation of the distribution function from equilibrium. KODF generalizes this concept to incorporate cold linear plasma waves into the known (quasi)analytic plasma behavior. Perturbations modeled by KODF PIC methods are thus nonlinear, finite-temperature perturbations atop cold linear waves whose evolution can be modeled without the noise associated with a PIC model. The KODF weight equation self-consistently tracks the deviation of the distribution function from an equilibrium upon which evolving cold linear waves are superposed.
We demonstrate the implementation of KODF in the VSim particle-in-cell code. VSim's semi-implicit FDTD methods [D. N. Smithe, Phys. Plasmas 14 056104 (2007)] are used to model the fluid behavior of cold plasma waves, and source terms that arise from these waves (e.g., from gradients of cold current or charge densities, or from quasilinear terms) appear in the KODF weight evolution equation to drive and evolve responsive warm plasma effects. We explore the noise-reduction capabilities of the KODF algorithm and its ability to model waves of interest in RF heating scenarios (e.g. mode-converted IBWs).
Research funded by US DoE, Office of Fusion Energy Sciences Award DE-SC0024063.
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