Laser-monitor-assisted investigation of the regions of closure of current on the electrodes of an atmospheric-pressure low-current carbon arc

The results are given of observations of regions of closure of current on t he electrodes of an atmospheric-pressure low-current carbon arc, performed using a laser monitor immediately during the time of burning of the arc. It is found that the time of existence of a cathode crater on a graphite cath ode is 0.2-0.3 s. An analysis of images of the region of closure of current on a pyrographite cathode reveals evidence of melting of pyrographite. A c omparison of images of the region of closure of current on the electrodes o f a carbon arc with the available literature data on the conditions of clos ure of current on the anode and cathode enables one to establish the origin s of the various details of images of the region of closure of current on t he cathode and anode of a low-current carbon arc. The results of this compa rison further lead one to conclude that a low-current electric arc is an ar c with liquid cathode and anode spots, and that the melting process is a st abilizing factor as regards the current density in those spots.