3D benchmark experiments of tritium in tungsten for tritium measurements by detecting β-ray induced X-rays

Abstract

Tungsten is one of the most promising materials for plasma facing components (PFCs), and β-ray induced X-ray spectrometry (BIXS) is an important non-destructive method to obtain tritium depth profile and retention information for the development of PFCs, recovery of fuel and control of tritium safety in a fusion reactor. In this article, benchmark experiments to obtain tritium 3D profile in tungsten have been firstly performed using layer-by-layer chemical etching (LLCE) and imaging plate (IP) techniques. BIXS spectra have been detected at each layer. The average layer thickness of each erosion was controlled to be around 150 nm and 8 layers (the total thickness was 1.21 μm) were eroded, and the maximum uncertainty of tritium activity was 7.91 % in the LLCE experiments. Monte-Carlo simulations of BIXS spectra with Geant 4 code and four kinds of physical packages (Penelope, Livermore, EmStd. Opt1 and EmStd. Opt4) have been benchmarked against to the experimental results. Results show that all the four physical packages are not suitable to calculate the intensity of the BIXS spectra, and the current mode or cross sections should be improved to simulate the interaction between low electron/photon and tungsten accurately. However, the relative intensity of W-Mα peak and W-Lα can be simulated well using current physical packages such as EmStd. Opt4 and Livermore, which is a good indicator for tritium depth profile in tungsten.