A comparative study of thermal effects on cold rolled copper induced by cathode spots and short laser pulses

Heat-induced structural changes within the cathode material caused by vacuum arc spots were studied by scanning electron microscopy in order to obtain information on the temperature field and the active spot life time. Cold rolled copper was chosen as the cathode material because of its low recrystallization temperature and its fine grain structure. These structural changes were compared to those obtained by irradiating the same material with laser pulses of definite duration and energy. In the latter case, heat conduction and evaporation as well as the removal of melt by the vapor pressure acting on the surface were simulated numerically. The comparison of ablation rates, heat-affected zones and simulation results for laser irradiation and for the arc spot allows conclusions to the unknown active life time of the arc spots.