Some Experimental Observations of the Propagation of Streamers in ``Low Field'' Regions of an Asymmetrical Gap

Abstract

Positive corona streamers are observed photographically and by a photomultiplier in a 3.17 cm point‐to‐plane gap which has a third electrode (a metal ring or disk with a center hole) placed 1.50 cm from the point between the point and plane. The experiments are conducted in room air at room temperature and pressure. Streamers are triggered by voltage pulses superimposed on the direct voltages (sufficiently large that visible steady corona occurs at the 40 μ radius point tip but too small to permit breakdown between any of the electrodes) applied to the gap. For the voltages considered, the experiments support the conclusions and model of Dawson and Winn as opposed to the model of Wright and the evidence of Nasser in that the streamers easily pass through the ring, showing that the streamers do not drastically distort the potential distribution in the gap as they propagate. However, the experiments also show that the value of the electric field far from the point (between the disk and plane) significantly affects the distance a streamer propagates, an effect ignored by Dawson and Winn, and that for a field value of 4.6 kV/cm between the disk and plane, many of the triggered streamers propagate completely across the gap.