Gas Temperature Measurement of Low-Current DC Arc in Air by Shadow Imaging

The gas temperature of arc plasma is an essential parameter in studies of the motion and extinguishment of arc, the recovery of gas insulation, and electrode erosion caused by arc discharge. This work measured the spatial distribution of the gas temperature by high-speed shadow imaging of the variation of the arc-induced flow field, which was confirmed by the Boltzmann plot method of the emission of the excited states of copper atoms. A typical low-current dc arc from photovoltaic arc faults was generated in the open air. The results showed that the gas temperature near the cathode was higher than that near the anode, which was different from the arc discharge of a high-current dc arc. It was interesting to observe a dispersed high-temperature region in the upper left, away from the cathode, which was independent of the direction of the electrode movement. When the arc current increased, the high-temperature region became elongated and then connected with the cathode. Detailed analysis of the flow field and the radiation light of the arc showed that the high-temperature region was probably caused by the electrode jet phenomenon of arc discharge.