Understanding vacuum arc ignition by concurrent multi-physics simulations

Vacuum arcs have been studied intensively for more than a century. Yet, the physical mechanisms involved in their ignition remain unclear, mainly due to the extreme nature and high complexity of the physical processes involved. In order to investigate such complex phenomena, multi-scale and multi-physics simulations that concurrently capture the various processes are necessary. This work gives an overview of recent advancements in multi-scale multi-physics simulations of vacuum arc ignition phenomena. Such simulations include molecular dynamics to model the movement of atoms under heating and electromagnetic field stress, concurrently coupled with particle-in-cell plasma simulations and finite element analysis for electrostatics, electron emission, and heat transfer. These simulations capture the processes that occur when nanoscopic field emitting metal protrusions enter thermal runaway, evaporate and ignite vacuum arc plasma, with the purpose of quantitatively understanding the plasma ignition mechanisms. The quantitative description of this process opens new pathways for understanding and thus exploiting the limitation of vacuum arc ignitions, especially with regard to electromagnetic power coupling.