Molecular dynamics simulations of nanoscale metal tips under electric fields

Abstract

Vacuum arcing is a plasma discharge over a metal surface under high electric fields. Plasma formation requires the supply of neutral atoms, which under high vacuum condition can only come from the surface itself. Nevertheless, the mechanisms by which the atoms are supplied are not known. In the present work, we propose a model for the onset of surface roughness and field-enhanced atom evaporation. Specifically, we describe a dislocation mechanism of tip growth from near-surface voids. We also simulate surface charging and resistive heating using a hybrid electrodynamics and molecular dynamics (ED&MD) code for dynamic simulations of electronic effects. We study the morphological evolution of the nanoscale protrusion under the electronic effects, such as the stretching of the tip by the stress induced by the electric field.