Microparticle charge acquisition and reversal at impact

Abstract

An extended analysis is presented of a previously proposed model for electrical breakdown in vacuum initiated by microparticle impact. It discusses the low-voltage cathode-selective microcratering observed with an electrode geometry that gives rise to non-uniform interelectrode fields. Detailed consideration has been given to the mechanisms of microparticle formation and charge acquisition, their probable geometry, and the electrode surface conditions required for elastic reflection with efficient charge reversal. Measurements have shown that stainless stell has a mechanically strong, high-resistance, dielectric surface layer; properties which have been interpreted as being responsible for the suppressing action of low-voltage microcratering by this electrode material. The technological implications of these findings are discussed.