Numerical evaluation of hydrogen outgassing from copper electrodes with mitigation based on a tungsten capping layer

J Acharjee and RP Joshi, PHYSICS OF PLASMAS, 26 (2019).

DOI: 10.1063/1.5109682

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 300K to 1330K. 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 700K.

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