Investigation of cathode spots on the electrodes of pulsed lamps

Cathode spots produced by a pulsed arc discharge between electrodes of pure and thoriated tungsten are investigated theoretically and experimentally. High-speed photography is used to study the development of cathode spots during the discharge, their relationship to electrode erosion is indicated. The electric field voltage, the temperature, and the fraction of current density carried by electrons in a spot are calculated from the measured spot parameters. The experimentally observed features of electrode erosion are explained.