Fundamental Studies of Gas Insulation Breakdown Processes Using Optical Emission Spectroscopy

In order to clarify the mechanism of discharge characteristics in dry air, we have developed a spectroscopic method that can directly measure the electric field strength in the discharge. In this work, by using this spectroscopic method and observing streak records of the light emitted by the discharge, we investigated the characteristics of positive streamer discharges in needle-to-plane electrodes in 0.1 - 0.5 MPa (absolute pressure) dry air. The streak records of discharges showed that, as the gas pressure increased, the lengths and the duration times of both the primary streamer and the secondary streamer became short. The electric fields in the discharges were estimated by the ratio of emission intensities both of the second positive system band of molecular nitrogen and of the first…