Determination of local anode heat fluxes in high intensity, thermal arcs

A new method is presented suitable for measuring extremely high local heat fluxes on surfaces. The method is applied for measuring peak anode heat fluxes in 5 kA pulsed arcs using nitrogen and argon at 1 atm. as working gases and tungsten, molybdenum, copper, and titanium as anode materials. The electrode geometry for the reported data consists of a pointed (60° included angle) tungsten cathode positioned approximately 1 cm above a planar anode. The anode heat flux is deduced from the temperature history of the rear face of very thin anodes. Temperature measurements with sufficiently rapid response and noise insensitivity are accomplished with a calibrated light fiber-photomultiplier arrangement. The results show that the cathode jet and the working gas may have a strong influence on peak anode heat fluxes which are in the order of 100kW/cm
²
.