Spectroscopic Analysis of Temperature Variation of EDM Arc Plasma

This paper describes the measurement of temperature variation of the arc plasma generated by the EDM pulse discharges in air using the spectroscopic analysis. Intensities of two radiation lines from copper atoms in the arc plasma are measured simultaneously using two monochrometers, and the temperature is obtained based on the line pair method. Although the measured radiant flux is significantly affected by the configurations of the electrodes, the obtained apparent temperatures during the discharge duration is between 6, 000 to 7, 000K regardless of the electrode configurations, discharge current or discharge duration. In the discharge interval, however, it takes longer time to decrease the plasma temperature and deionize the plasma, when the discharge current is higher, the discharge duration is longer or the rate of heat transfer from the plasma to the electrodes is lower. In a series of pulse discharges, the plasma temperature increases with the lapse of time as the surface temperatures of the electrodes are elevated.