Measurement of the space charges produced in streamers

Abstract

An investigation was made of the slow phase of cathode-directed streamers in gas discharges, which developed according to the streamer mechanism. A 3 cm gap was used with a uniform electric field and low overvoltages (about 20% above the DC breakdown voltage). All experiments were carried out in an N₂-CH₄mixture (total about 100 Torr). By means of a probe electron avalanche, the ionic space charge which accumulates in the gap during the development of the streamer was measured. Streak pictures of the discharge were recorded simultaneously, so it was possible to show the correlation of the ionic space charge with the growth of the streamer.