| Currently we are working on a theoretical model of surface behavior under high electric fields. 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-assisted 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. The main emphasis of the presentation will be the triggering process of an electrical breakdown event due to the effect of a high electric field. A possible mechanism for formation of a surface protrusion mediated by dislocations nucleated on a near surface void under high electric field will be discussed in detail. The modified molecular dynamics code, which includes the effects of electric fields such as partial charge on surface atoms as well as the Joule heating of surface asperities due to electron currents will also be presented. This information is plugged to the simulation of plasma development, whose output is used to simulate the surface damage. Comparison to the available experiments will also be made. |
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