Modelling of hydrogen reflection on tungsten fuzzy surface in an erosive hydrogen plasma

Abstract

Modelling of the reflection of energetic hydrogen atoms from tungsten fuzz under hydrogen plasma exposure has been performed using the three-dimensional kinetic Monte Carlo program SURO-FUZZ. The simulation results show that the hydrogen reflection coefficient on a porous tungsten fuzzy surface is 50% lower in comparison with a smooth tungsten surface, which shows good agreement with the measurements. The time evolution of the tungsten fuzzy structure has been investigated under energetic hydrogen bombardment. A sustained removal of the porous tungsten fuzzy structure is obtained, which results in a reduced height of tungsten fuzz with exposure time and finally a smoothing of the tungsten fuzz. The erosion-induced degradation of the tungsten fuzzy structure leads to a high hydrogen reflection coefficient with exposure time. The simulated temporal evolution of the hydrogen reflection coefficient is in reasonable agreement with the experimental data. The simulation results show that the reflection coefficient of hydrogen atoms on fuzzy surfaces is decreased with increasing porosity. Parametric studies with varying porous structures have been performed to gain insights into hydrogen reflection characteristics on tungsten fuzzy surfaces.

Studies on the impacts of the pore size and shape on deuterium retention in tungsten fuzzy nanostructures

“…While, the complicated physical processes involved during W fuzz growth necessitate a lot of time to simulate. Consequently, a constructed fuzzy surface morphology has been subsequently developed as the construction module to save computational resource, which can form porous structure according to a predefined porosity distribution using MC method [18][19][20]. In this work, the construction module in SURO-FUZZ has been momentously improved by adopting a more advanced approach, which is termed the quartet structure generation set (QSGS) [23].…”

“…In this work, the construction module in SURO-FUZZ has been momentously improved by adopting a more advanced approach, which is termed the quartet structure generation set (QSGS) [23]. The QSGS approach allows for more flexible adjustment of the porous structure, in comparison with the previous approach used in SUOR-FUZZ [18][19][20].…”

“…However, numerical simulations of W fuzz growth are fairly time-consuming because of the complex mechanisms involved. For this reason, a fuzzy surface construction module with the predefined porosity has been incorporated into the three-dimensional (3D) kinetic MC code SURO-FUZZ, which has been used to reproduce and interpret the reflection of hydrogen ion in the laboratory device [18,19].…”