Temperature-Dependent In-Situ LEIS Measurement of W Surface Enrichment by 250 eV D Sputtering of EUROFER

TL;DR

This study investigates how temperature affects tungsten surface enrichment on EUROFER steel caused by deuterium sputtering, revealing temperature-dependent enrichment levels and estimating tungsten diffusion activation energy.

Contribution

It provides the first in-situ measurements of tungsten enrichment on EUROFER under varying temperatures during D sputtering, and estimates the diffusion activation energy.

Findings

W surface enrichment decreases with increasing temperature.

No enrichment detected at 800 K.

Upper limit of 1.6 eV for tungsten diffusion activation energy.

Abstract

Tungsten surface enrichment of EUROFER steel by 250 eV deuterium sputtering is in-situ measured using low energy He$^{+}$ ion scattering spectroscopy. The samples are irradiated at various temperatures between 300 K and 800 K with a deuterium atom flux of 2e18 m$^{-2}$s$^{-1}$ and maximum fluence up to 1.1e23 m$^{-2}$. The measurements at room temperature show a clear increase of tungsten surface density, but already at 520 K the observed enrichment is only half as large. At a temperature of 800 K no tungsten surface enrichment is detectable. The obtained data allows to determine an upper limit of 1.6 eV for the diffusion activation energy of tungsten in EUROFER.