Numerical Evaluation of Hydrogen Outgassing from Copper Electrodes With Mitigation Based on a Tungsten Capping Layer

Outgassing remains a pertinent issue for high power applications and is exacerbated by the high field driven, localized heating environments commonly encountered. Here, molecular dynamics simulations are performed for a simple model-based assessment of outgassing from electrodes. Our results of temperature dependent diffusion coefficients for hydrogen in copper agree well with experimental reports over a wide range spanning 300 K to 1330 K. Separate results are also obtained for transport of hydrogen to ascertain whether a grain-boundary would facilitate channeled transport or work to impede flow by clustering the gas atoms. Finally, the use of a tungsten overlayer on copper is evaluated as a material-based strategy for mitigating outgassing. It is demonstrated that a few monolayers of tungsten coating on the outer surface can be effective in significantly reducing outdiffusion at 700 K.