Different Modes of Arc Attachment to HID lamp Electrodes in the Cathodic Phase of AC Operation

摘要

At hot tungsten cathodes of high intensity discharges different modes of current transfer can be found: a diffuse mode characterized by a low current density and a high global electrode temperature with a uniform distribution, and a spot mode, characterized by a spot with a high current density and a high surface temperature. For the DC case an investigation on these different modes is presented in two accompanying papers. These different modes of arc attachment also occur in AC operation. In this paper experimental investigations at the Bochum model lamp concerning the different modes of arc attachment in AC operation are presented.