Multiscale multiphysics modelling of electrical breakdown phenomenon

by Dr Flyura Djurabekova (University of Helsinki)

Monday 22 May 2017, 15:15 → 16:15 Europe/Stockholm

Oseenska rummet (Å73121)

Abstract: Vacuum arc electrical breakdowns cause problems in many appliances operating in high electric field, such as the Compact Linear Collider (CLIC), a proposed next-generation particle accelerator in CERN. The breakdown phenomenon is not well-understood despite decades of research devoted to investigation of this phenomenon. The complicated nature shows itself differently under different circumstances. Even in such technologically high-level of demand condition as in accelerating structures of future particle colliders, the electric fields near metal surfaces of the structures cannot exceed a certain value, which is well below the theoretical expectation. What triggers the surface to break when high electric fields are applied, is the main focus of the research in our group. Currently we are working on an atom-level theoretical model of surface behavior under high electric fields. The model covers many stages of plasma development and includes different physical processes evolving on different time scales. Our model aims to explain the physical limitation of a metal surface due to electrical breakdowns at the fields well below the critical values known to cause field evaporation of atoms. We model all three main stages of plasma development ignited in ultra-high vacuum, i.e. plasma onset, plasma evolution and surface damage due to the plasma discharge. In the presentation, the main emphasis will be made on triggering processes of what causes plasma ignition due to effect of a high electric field. The overview of different approaches used and developed within the group as well as the achieved results will be discussed in particular detail.