Poroelectron emission induced erosion of materials

In high vacuum at low external field strength insufficient to induce FEE there arise processes in the volume of negative electrode surface pores responsible for poroelectron emission currents, microdischarges and vacuum arc (vacuum breakdown) appearing in the vacuum gap. The gas medium in pores results from resonance desorption of neutral and charged particles from surfaces caused by external electrical field sagging into the pore volume. Vacuum breakdown and microdischarge processes in pores erode the surface, thus producing sputtering of material on the opposite electrode. A set of microdischarges may build up a conductive bridge of electrode material some millimeters long, short circuiting the vacuum gap. This paper is an overview of the main results on porous surface studies obtained by the author as well as of some new data on the erosion of graphite. The results of experiments on porous foils are discussed. A new explanation of some known phenomena is suggested.