Density estimation techniques for multiscale coupling of kinetic models of the plasma material interface

JOURNAL OF COMPUTATIONAL PHYSICS

卷:400

Article

Keniley, Shane¹  Curreli, Davide¹ 

[1] Univ Illinois, Dept Nucl Plasma & Radiol Engn, Urbana, IL 61801 USA

关键词: Density estimation;    Gaussian mixture model;    Kernel density estimation;    Vlasov-Poisson equation;    Binary collision approximation;   

DOI  :  10.1016/j.jcp.2019.108965

来源: Elsevier

【 摘 要 】

In this work we analyze two classes of Density-Estimation techniques which can be used to consistently couple different kinetic models of the plasma-material interface, intended as the region of plasma immediately interacting with the first surface layers of a material wall. In particular, we handle the general problem of interfacing a continuum multi-species Vlasov-Poisson-BGK plasma model to discrete surface erosion models. The continuum model solves for the energy-angle distributions of the particles striking the surface, which are then driving the surface response. A modification to the classical Binary-Collision Approximation (BCA) method is here utilized as a prototype discrete model of the surface, to provide boundary conditions and impurity distributions representative of the material behavior during plasma irradiation. The numerical tests revealed the superior convergence properties of Gaussian Mixture Models over Kernel Density Estimation methods, with Gaussian Mixtures and Epanechnikov-KDEs both being up to two orders of magnitude faster than Gaussian-KDEs. The methodology here presented allows a self-consistent treatment of the plasma-material interface in magnetic fusion devices, including both the near-surface plasma (plasma sheath and presheath) in magnetized conditions, and surface effects such as sputtering, back-scattering, and ion implantation. The same coupling techniques can also be utilized for other discrete material models such as Molecular Dynamics. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

Free