Electric Fields and Secondary Emission near a Dielectric-Metal Interface

Dielectric surface charge distributions near a metaldielectric interface in vacuum depend upon secondary emission processes in the presence of normal and tangential components of electric field. From measured charge distributions created by exposing a specimen of fluorinated-ethylene-propylene to monoenergetic electron fluxes, it has been possible to calculate potentials and fields on and near the dielectric surface. The effect of normal electric field upon secondaryemission is measured directly and the effect of thetangential field is inferred from the charge distributiondata. The critical point (unity crossover)for secondary emission is shifted by the applicationof fields so that it occurs at much higher primaryenergies than normally. Primary beams having energiesup to 20 keV are used and surface fields are as highas 20 kV/mm.