Modeling and Measurement of the Initial Anode Heat Fluxes in Pulsed High-Current Arcs

An anode heat flux model has been developed for pulsed high-intensity dc arcs. The model is based on temperature-time-history measurements of the rear face of a very thin plane anode and high-speed streak photographs of the arc. The arc heat flux model is derived from a comparison of experimental data with an analytical solution of the one-dimensional heat conduction equation and the arc intensity and timing information obtained from high-speed photographs. A simplified input heat flux model consisting of connected segments of linearly varying heat fluxes with respect to time is used. Duration of the individual segments is determined from the streak photographs and the graphical match of measured rear-face temperature history and the numerical solution. Results using argon gas at atmospheric pressure indicate an initial transient heat flux regime of 100-μs duration with a peak heat flux of 2 × 109 W/m2 followed by a quasi-steady heat flux regime with a heat flux of 1 × 108 W/m2.