An interferometric measurement of gas temperatures in corona discharges

Abstract
An optical interferometer has been used to measure the increase in gas temperature in a point-to-plane corona discharge in air as a function of radial and axial position. For a corona current of 150 mu A, a 10 mm gap and a point radius of 0.35 mm, a maximum change in temperature of approximately 6K was observed. The authors' results suggest that under these conditions, where the corona voltage is approaching the spark breakdown voltage, the predominant ionisation process is two-step ionisation.