Integrated modeling of RF-Induced Tungsten Erosion at ICRH Antenna Structures in the WEST Tokamak

Abstract

This paper introduces STRIPE (Simulated Transport of RF Impurity Production and Emission), an advanced modeling framework designed to analyze material erosion and transport of these sputtered impurity at radio-frequency (RF) antenna structures in magnetic confinement fusion devices. STRIPE integrates multiple computational tools, each addressing different levels of physics fidelity: SolEdge3x provides scrape-off layer (SOL) plasma profiles, COMSOL models 3D RF rectified voltage fields on antenna structures, GITR calculates ion energy-angle distributions (IEADs) and particle tracking, and RustBCA determines material erosion yields and surface interaction dynamics. The framework is applied to an ion cyclotron radio-frequency heating (ICRH), L-mode discharge #57877 in the WEST Tokamak, where it predicts a tenfold increase in tungsten erosion at RF antenna limiters under RF-sheath rectification conditions, compared to cases with only a thermal sheath. Highly charged oxygen ions (O6+ and higher) emerge as dominant contributors to tungsten sputtering at the antenna limiters. To verify model accuracy, a synthetic diagnostic tool based on S/XB coefficients from the ColRadPy- collisional radiative model enables direct comparisons between simulation results and experimental spectroscopic data. Model predictions, assuming plasma composition of 1% oxygen and 99% deuterium, align closely with measured neutral tungsten (W-I) spectroscopic data for the discharge #57877, validating the framework's accuracy. Currently, the STRIPE framework is being extended to investigate plasma-material interactions in other RF-heated linear and toroidal devices, offering valuable insights for RF antenna design, impurity control, and performance optimization in future fusion reactors.