# Dynamic coupling between particle-in-cell and atomistic simulations

## TL;DR

This paper introduces a coupled simulation method combining molecular dynamics, finite element, and particle-in-cell techniques to study metal surface responses under high electric fields, revealing cyclic thermal runaway behaviors.

## Contribution

It presents a novel integrated simulation approach for metal surface response to electric fields, including 3D space-charge effects and comparisons of different emitter geometries.

## Key findings

- Thermal runaway occurs in cycles for narrow emitters.
- Intensive evaporation can ignite plasma arcs.
- The method accurately captures complex surface phenomena.

## Abstract

We propose a method to directly couple molecular dynamics, finite element method and particle-in-cell techniques to simulate metal surface response to high electric fields. We use this method to simulate the evolution of a field emitting tip under thermal runaway by fully including the 3D space-charge effects. We also present a comparison of the runaway process between the two tip geometries of different widths. The results show with high statistical significance that in case of sufficiently narrow field emitters, the thermal runaway occurs in cycles where intensive neutral evaporation alternates with the cooling periods. The comparison with previous works shows, that the evaporation rate in the regime of intensive evaporation is sufficient to ignite a plasma arc above the simulated field emitters.