Emission properties of the plasma faced materials covered with thin films

Electric field between the plasma and the plasma faced components can be high enough for appearance of prebreakdown currents measured in the experiments on vacuum insulation. In turn, thin insulating films on plasma faced surfaces can significantly change its emission properties and generate surface-plasma instabilities. In this paper, the results of current-voltage characteristic measurement accompanied with in situ diagnostics of the surfaces covered by non-metal films and water adsorption layers by using low angle ion spectroscopy are presented.