An efficient numerical method for charged particle transport based on hybrid collision model and machine learning

作     者：Liu, Chang Du, Bao Song, Peng 

作者机构：Institute of Applied Physics and Computational Mathematics Beijing China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing China 

出 版 物：《arXiv》 (arXiv)

年 卷 期：2023年

核心收录：

主　　题：Monte Carlo methods 

摘      要：The plasma heating by the α particle transport is a main self-heating source in inertial confinement fusion (ICF) that determines the capsule implosion performance. Due to the high energy of α particle and the high temperature in the ICF capsule hot spot, significant non-equilibrium effect exists and the continuum mechanics breaks down. For the numerical simulation of implosion and charged particle transport, the Boltzmann equation needs to be solved to capture the kinetic effects. However, the 7-dimensional Boltzmann equation, the highly frequent Coulomb collision, and the multi-folded integral stopping power formulation greatly limits the computational efficiency and challenges the computational power. To overcome the high computational cost of high-frequent coulomb collisions, we propose a hybrid collision model according to which the collisions are categorized into low frequent large-angle collisions and high frequent small-angle grazing collisions. The large-angle collision process is precisely solved based on the Coulomb cross-section. For the highly frequent small-angle grazing, a statistic model is constructed with second-order accuracy in time. The hybrid collision model reduces the computational cost of scattering calculation by two magnitudes. For the multi-folded integral stopping power formulation, a neural network is used to improve computational efficiency. Based on the proposed algorithm, we develop one-dimensional to three-dimensional module code to directly solve the the α particle transport Boltzmann equation. The α transport module code is integrated into the multi-physics LARED-S program. The MC version ICF software is verified by a simulation study of the N191110 experiment. Copyright © 2023, The Authors. All rights reserved.