Analysis of kinetic-diffusion Monte Carlo simulation and source term estimation scheme in nuclear fusion applications

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Main Authors: Tang, Zhirui, Koellermeier, Julian, Løvbak, Emil, Samaey, Giovanni
Format: Preprint
Published: 2025
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author Tang, Zhirui
Koellermeier, Julian
Løvbak, Emil
Samaey, Giovanni
author_facet Tang, Zhirui
Koellermeier, Julian
Løvbak, Emil
Samaey, Giovanni
contents In plasma edge simulations, the behavior of neutral particles is often described by a Boltzmann--BGK equation. Solving this kinetic equation and estimating the moments of its solution are essential tasks, typically carried out using Monte Carlo (MC) methods. However, for large-sized reactors, like ITER and DEMO, high collision rates lead to a substantial computational cost. To accelerate the calculation, an asymptotic-preserving kinetic-diffusion Monte Carlo (KDMC) simulation method (Mortier et al., SIAM J. Sci. Comput., 2022) and a corresponding fluid estimation technique (Mortier et al., Contrib. Plasma Phys., 2022) have recently been proposed. In this work, we present a comprehensive analysis of the convergence of KDMC combined with the associated fluid estimation. The analysis consists of proving theoretical upper bounds for both KDMC and the fluid estimation, and numerical verifications of these bounds. In addition, we compare the analyzed algorithm with a purely fluid-based method using the fully kinetic MC method as a reference. The algorithm consistently achieves lower error than the fluid-based method, and even one order of magnitude lower in a fusion-relevant test case. Moreover, the algorithm exhibits a significant speedup compared to the reference kinetic MC method. Overall, our analysis confirms the effectiveness of KDMC with the associated fluid estimation in nuclear fusion applications.
format Preprint
id arxiv_https___arxiv_org_abs_2512_23580
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Analysis of kinetic-diffusion Monte Carlo simulation and source term estimation scheme in nuclear fusion applications
Tang, Zhirui
Koellermeier, Julian
Løvbak, Emil
Samaey, Giovanni
Numerical Analysis
In plasma edge simulations, the behavior of neutral particles is often described by a Boltzmann--BGK equation. Solving this kinetic equation and estimating the moments of its solution are essential tasks, typically carried out using Monte Carlo (MC) methods. However, for large-sized reactors, like ITER and DEMO, high collision rates lead to a substantial computational cost. To accelerate the calculation, an asymptotic-preserving kinetic-diffusion Monte Carlo (KDMC) simulation method (Mortier et al., SIAM J. Sci. Comput., 2022) and a corresponding fluid estimation technique (Mortier et al., Contrib. Plasma Phys., 2022) have recently been proposed. In this work, we present a comprehensive analysis of the convergence of KDMC combined with the associated fluid estimation. The analysis consists of proving theoretical upper bounds for both KDMC and the fluid estimation, and numerical verifications of these bounds. In addition, we compare the analyzed algorithm with a purely fluid-based method using the fully kinetic MC method as a reference. The algorithm consistently achieves lower error than the fluid-based method, and even one order of magnitude lower in a fusion-relevant test case. Moreover, the algorithm exhibits a significant speedup compared to the reference kinetic MC method. Overall, our analysis confirms the effectiveness of KDMC with the associated fluid estimation in nuclear fusion applications.
title Analysis of kinetic-diffusion Monte Carlo simulation and source term estimation scheme in nuclear fusion applications
topic Numerical Analysis
url https://arxiv.org/abs/2512.23580