Energy consumption characteristics of pulsed arc discharge in high pressure carbon dioxide up to supercritical phase

Energy consumption of pulsed arc discharge E in high pressure CO
₂
up to supercritical (SC) phase was investigated under positive pulsed voltage that was applied to needle-to-plane electrode by a magnetic pulse compression circuit. The gap distance of approximately several hundred μm was set inside a high pressure chamber. The peak current of pulsed arc discharge was in the range of 400-600 amperes at gas and supercritical phases. The E was calculated by the dumped oscillatory voltage and current under the post-breakdown. In the gas phase, the E increased with medium density up to sub-critical phase. Meanwhile, the E was almost stable irrespective of medium density in the supercritical phase. Spectroscopic measurement was also carried out to confirm the local thermal equilibrium of the arc plasma at SC phase. The spectral distribution was characterized by the black body (Planck) radiation and line spectra of atomic oxygen (777 and 845 nm).