Measurements of electron density and electron temperature of arc discharge plasmas containing metallic vapors using laser thomson scattering

Laser Thomson scattering (LTS) has been applied to arc discharges generated in the atmospheric air to measure electron density (n_e) and electron temperature (T_e). As electrode materials, tungsten and tungsten-copper (30%) were used. The electrode gap was 0.8 mm and its diameter was 1 mm. The applied voltage was 6 kV, the peak current was 600 A and the decay time of the voltage and the current was 25 μs. Spatiotemporal evolutions of n_e and T_e were measured at 10 μs, 30 μs and 50 μs after the discharge initiation. At these times, obtained values of n _e and T_e were estimated to be in the ranges of (0.8 -2.0)×10²³ m^-3 and 1.0 -2.2 eV, respectively. These values were consistent with those evaluated from Saha's thermodynamic equation at 1 atm. It was also found that the decay of the arc discharge produced using the tungsten-copper electrodes was much faster than that produced using the tungsten electrodes.