Simulation of the plasma-wall interaction in a tokamak with the Monte Carlo code ERO-TEXTOR

TLDR

Plasma–wall interaction limits fusion device performance by causing erosion that shortens wall lifetime and injects impurities that dilute the plasma and increase radiation losses, with low‑Z materials suffering high sputtering, high‑Z materials suffering high radiation, and carbon also undergoing chemical erosion. The study aims to identify wall materials that optimally balance fuel dilution, radiation losses, wall lifetime, and fuel inventory for steady‑state fusion plasmas. A 3‑D Monte Carlo code, ERO‑TEXTOR, was developed to model plasma‑wall interaction and transport processes near a TEXTOR boundary‑layer surface. The paper presents ERO‑TEXTOR’s key features and simulation examples that demonstrate its application to erosion and redeposition of various wall materials.

Abstract

The interaction of plasma with the walls has been one of the critical issues in the development of fusion energy research. On the one hand, plasma induced erosion can seriously limit the lifetime of the wall components, while, on the other hand, eroded particles can be transported into the core plasma where they lead to dilution of the fusion plasma and to energy losses due to radiation. Low-Z wall materials induce only small radiation losses in the plasma core but suffer from large physical sputtering rates. Carbon based materials in addition suffer from chemically induced erosion. High-Z wall materials show significantly smaller erosion but lead to large radiation losses. One of the main goals of present plasma-wall studies is to find a special choice of wall materials for steady state plasma scenarios that will provide an optimum with respect to fuel dilution, radiation losses, wall lifetime and fuel inventory in the walls. To obtain a better understanding of the processes and to estimate the plasma-wall interaction behaviour in future fusion devices the 3-D Monte Carlo code ERO-TEXTOR, based originally on the ERO code, has been developed. It models the plasma-wall interaction and transport processes in the vicinity of a surface positioned in the boundary layer of TEXTOR. The main aim is to simulate the erosion and redeposition behaviour of different wall materials under various plasma conditions and to compare this with experimental results. This contribution describes the main features of the ERO-TEXTOR code and gives some examples of simulation calculations to illustrate the application of the code.