Two dimensional current and field distributions in vapour layers evolving over vaporizing surfaces subjected to hot plasmas

Abstract

A two dimensional, time dependent model has been developed for calculating the time evolution of the vapour layer characteristics over vaporizing surfaces subjected to magnetically confined energetic plasma particles. An essential part of this model is the proper determination of the electromagnetic field distributions in the vapour layer. In this analysis, the electric field and current distributions are determined self-consistently on the basis of a properly posed boundary value problem. The computational results presented show the existence of an E × B type drift which may notably influence the shielding characteristics of the evolving vapour layer. In addition, excessive ohmic heating and/or arc formation at the edges of conductor segments may cause additional erosion. Quantitative results are provided on the effect of the inner (baseplate) and outer (vapour-plasma interface) boundary conditions on the resulting erosion rates. The results show that the vapour shield evolution is a complex coupled electromagnetic-hydromagnetic phenomenon. Ignoring any of the fundamental physical processes present, such as shielding by electrostatic fields and sheaths, affects the reliability of the results obtained.