Global Sensitivity Analysis of a coupled multiphysics model to predict surface evolution in fusion plasma-surface interactions

TL;DR

This paper develops a global sensitivity analysis framework for a coupled multiphysics model predicting surface evolution in fusion plasma-surface interactions, combining particle dynamics and cluster dynamics simulations.

Contribution

It introduces a sparse polynomial chaos expansion surrogate model to efficiently perform sensitivity analysis on a complex coupled model.

Findings

Identifies key parameters influencing helium implantation and bubble growth.

Demonstrates differences in parameter sensitivities between ITER-like and PISCES-A conditions.

Provides physical insights into plasma-material interactions in fusion environments.

Abstract

We construct a global sensitivity analysis framework for a coupled multiphysics model used to predict the changes in material properties and surface morphology of helium plasma-facing components in future fusion reactors. The model combines the particle dynamics simulator F-TRIDYN, that predicts the helium implantation profile, with the cluster dynamics simulator Xolotl, that predicts the growth and evolution of subsurface helium gas bubbles. In order to keep the sensitivity analysis tractable, we first construct a sparse, high-dimensional polynomial chaos expansion surrogate model for each output quantity of interest, which allows the efficient extraction of sensitivity information. The sensitivity analysis is performed for two problem settings: one for ITER-like conditions, and one that resembles conditions inside the PISCES-A linear plasma device. We present a systematic comparison of important parameters, for both F-TRIDYN and Xolotl in isolation as well as for the coupled model, and discuss the physical interpretation of these results.