Uniform-field breakdown in air

Abstract

Experiments on the breakdown processes in a uniform-field gap at the minimum d.c. breakdown voltage in air at atmospheric pressure are described. It is shown that the breakdown processes consist of two phases, (1) a diffuse glow completely bridging the gap, followed by (2) a filamentary channel moving from the cathode to the anode, and bridging a 0.77 cm gap in about 3 × 10-9 s in a 13 Ω coaxial system. Spectrograms of the stages of the discharge are also given. These experimental results are in disagreement with both the Townsend and the Streamer theories.