Molecular Dynamics Simulation of the Hydrogen Isotope Sputtering of Graphite

TL;DR

This study uses molecular dynamics simulations to analyze how hydrogen isotopes erode graphite surfaces, revealing that isotopic differences affect erosion speed and yield, with implications for nuclear material durability.

Contribution

It introduces a modified Brenner potential for simulating isotope-specific erosion of graphite, highlighting differences in erosion dynamics among hydrogen isotopes.

Findings

Erosion speed is higher for hydrogen isotopes than for hydrogen atoms.

Erosion yield flux increases linearly with incident energy.

Erosion start time is shorter for hydrogen isotopes.

Abstract

We used a molecular dynamics simulation with the modified Brenner reactive empirical bond order potential to investigate the erosion of a graphite surface due to the incidence of hydrogen, deuterium, and tritium atoms. Incident particles cause pressure on the graphite surface, and the chemical bond between graphene layers then generates heat to erode the graphite surface. We evaluated the speed of surface destruction by calculating the pseudo-radial distribution function. The speed of surface destruction due to incident hydrogen isotopes was higher than that due to hydrogen atoms. The surface destruction increased exponentially and its decay time constant was a power function of the incident energy. We measured the erosion yield, which indicated a steady state for the graphite erosion. The erosion yield flux in the steady state increased linearly with the incident energy. The erosion yield flux was almost independent of the type of incident particle, and the erosion yield start time was smaller for hydrogen isotopes than for hydrogen atoms.