Time and space resolved video spectroscopy of the vacuum arc during the formation of high-current anode modes

This paper presents the results of time and space resolved optical investigations of high-current vacuum arcs by means of video spectroscopy. Especially, the transition from the diffuse mode to constricted modes (footpoint, intense or spot mode) has been studied in dependency on the arc current and instantaneous electrode distance. The driving current pulse from a high-current generator which corresponds to the pulsed DC 10 ms was applied. Spectral lines of Cu I, Cu II, and Cu III have been analyzed for various anode modes using a combination of spectrograph and high-speed camera.