Electric Field on the Surface of a Metal Electrode Covered by a Dielectric Film in Plasma

tElectric field on the surface of a metal electrode covered by a continuous dielectric film and immersed in plasma is calculated at negative electrode potential Psi when parameter e Psi substantially exceeds electron temperature T-e (e Psi/T-e >> 1). It is established that strong electric field with a magnitude of 1-10 MV/cm can appear inside the film at plasma density of 10(12)-10(13) cm(-3) and electron temperature of T-e = 10 eV as a result of charging of the outer film 10-1000 nm in thickness surface by a flux of positive ions from plasma. The magnitude of the electric field at film discontinuities is comparable to that inside the film. The magnitude of the electric field at the surface of the dielectric film and at the film-free clean metal surface in plasma is substantially lower than that inside the film. Strong electric fields inside the film and at its discontinuities can lead to electrical breakdown inside the film and at its discontinuities. The electrical breakdown of the dielectric film can initiate the unipolar arcing on metals, drive microplasma discharges and form centers of explosive electron emission on metal surfaces in plasma.