Time-resolved radial temperature profiles for 10 kA SF6 arcs

Radial temperature profiles for pulsed SF6 arcs burning in high-pressure, approximately 5 bar, supersonic gas flow have been measured in the range 10 kA-1.0 kA. The temperature distribution was obtained from the emission intensities of spectral lines due to excited fluorine and ionized sulphur. The results for currents above 3.5 kA show that the axis temperature is 20000K+or-1000K and is independent of the arc current. Also the temperature profile is essentially parabolic, and any increase in arc current is accompanied by a corresponding increase in arc cross section to maintain a constant current density. Below 3.5 kA the axis temperature falls rapidly with current down to 15500K+or-1000K at kA and the temperature profiles show very steep temperature gradients less than 1 mm from the arc axis.