Experimental electronic stopping cross section of tungsten for light ions in a large energy interval

TL;DR

This study experimentally measured the electronic stopping cross section of tungsten for light ions across a broad energy range, providing high-precision data that extends understanding into lower energies relevant for fusion technology.

Contribution

The paper presents the first extensive experimental data on tungsten's electronic stopping for light ions over a wide energy interval, with high accuracy and cross-laboratory validation.

Findings

Data agrees well with existing models at higher energies.

Extended measurements into lower energies relevant for fusion.

Tungsten can be modeled as an electron gas at low energies.

Abstract

Electronic stopping cross section of tungsten for light ions was experimentally measured in a wide energy interval (20 to 6000 keV for protons and 50 to 9000 keV for helium) in backscattering and transmission geometries. The measurements were carried out in three laboratories (Austria, Germany and Sweden) using five different set-ups, the stopping data deduced from different data sets showed excellent agreement amongst each other, with total uncertainty varying within 1.5 - 3.8\% for protons and 2.2 - 5.5\% for helium, averaged over the respective energy range of each data set. The final data is compared to available data and to widely adopted semi-empirical and theoretical approaches, and found to be in good agreement with most adopted models at energies around and above the stopping maximum. Most importantly, our results extend the energy regime towards lower energies, and are thus of high technological relevance, e.g., in fusion research. At these low energies, our findings also revealed that tungsten - featured with fully and partially occupied f- and d-subshells, respectively, can be modeled as an electron gas for the energy loss process.