Critical electron-hole processes in dielectric induced by synchronous action of high electric field and high-current-density electron beam

Injection of high-current-density (HCD) electron beam of nanosecond pulse duration into a dielectric creates strong electric field, from one side, and high density of electrons and holes trapped at the shallow levels in the band-gap, from the other side. Two types of high intensity electron emission from dielectric into vacuum are studied experimentally and considered theoretically. The first one is field electron emission from dielectric (FEED), which arises owing to intense detrapping electrons from shallow levels in high electric field. The second one is critical electron emission from dielectric (CEED), which arises when FEED current density exceeds critical value and induced point explosions of the microtips on the dielectric surface and ejects atom-ion plasmas from this points into vacuum. Full theoretical and computer simulation of FEED and CEED needs to take into account a lot of ultrafast excitation/relaxation processes in dielectric under HCD electron beam irradiation.