Control of surface charge on insulating hollow cylinder by using shield ring in vacuum

This paper deals with the charge depression effect of a shield ring, a ring type electrode, which is applied to high voltage vacuum devices in order to relax the electric field near the triple junction on a cathode. In the present study the shield ring is located in an insulating hollow cylinder made of Al₂O₃, and the charge distribution on the inner surface is measured by employing an electrostatic method. As a result, we have obtained the charge distribution patterns for several ring heights. The results are discussed together with calculated charge distributions.