Anode Temperature Evolution in a Vacuum Arc with a Black Body Electrode Configuration

Anode temperature in a Vacuum Arc with a Black Body Assembly (VABBA) was measured as a function of time. The arc was ignited in an electrode assembly operated as a black body for the macroparticles (MPs). The cathode was a 30 mm diameter Cu rod and the refractory anode was 50 mm in diameter, and constructed from Ta. Plasma was ejected through an array of 250 holes of 0.6 mm diameter in the anode. The arc currents were 1=175 & 225 A and the arc duration was 180 s. The anode temperature was measured using high -temperature thermocouples at two points (TC-top, TC-side) inside the anode body. The observed anode temperature increased sharply during a transient time of 90 s and then it slightly increased with time up to 180 s reaching at TC-top 1650K (1=175 A) and 1850K (1=225 A). The anode temperature at the top surface exceeded that at side surface by similar to 150-20 degrees C.