Comparative study on extinction process of gas-blasted air and CO₂ arc discharge using two-dimensional electron density imaging sensor

Shack–Hartmann type laser wavefront sensors were applied to gas-blasted arc discharges under current-zero phases, generated in a 50 mm-long interelectrode gap confined by a gas flow nozzle, in order to conduct a systematic comparison of electron density decaying processes for two kinds of arc-quenching gas media: air and $\text{C}{\text{O}}_2$. The experimental results for the air and $\text{C}{\text{O}}_2$ arc plasmas showed that the electron densities and arc diameters became thinner toward the nozzle-throat inlet due to a stronger convection loss in the arc radial direction. In addition, $\text{C}{\text{O}}_2$ had a shorter electron density decaying time constant than air, which could be caused by convection loss and turbulent flow of $\text{C}{\text{O}}_2$ stronger than air. (paper)