Influence of Previous Positive Streamers on Streamer Propagation and Breakdown in a Positive Point-to-Plane Gap

Abstract

The influence of a positive streamer upon its successor in a sequence of streamers is experimentally studied in a 3.17-cm positive point-to-plane gap using room air at room temperature. Streamers are triggered either by natural processes or by voltage perturbations (pulses) superimposed on the steady gap voltage. Despite the fact that a streamer has an inhibiting effect on the triggering of a later streamer, if another streamer is successfully triggered within a few tenths of a millisecond of the earlier streamer, using gap voltages of 16–25 kV, the later streamer will follow the same path and propagate faster than if the time interval between streamers was longer. Observations are made of the buildup and speed of primary and secondary streamers in sequences culminating in breakdown, and the filamentary spark breakdown of the gap is shown to have different current and light characteristics as a function of time from a streamer. A qualitative model of the streamer buildup mechanism involving metastable atoms or molecules is presented.

Repetitively pulsed gas discharges: memory effect and discharge mode transition

“…Acker and Penney [49], Hartmann and Gallimberti [50], and Shao et al [19] proposed that high‐density metastable species were the dominant memory effect agents because of the super‐elastic collision, the extra energy gain, and relatively long lifetimes concerning the conventional ‘pulse off’ period. Acker and Penney [49] measured the propagation time of a positive streamer under repetitive pulses based on a photomultiplier (PMT) array. The propagation velocity of subsequent streamers was significantly higher than previous ones inside the same ‘metastable trail’ as shown in Fig.…”

“…The propagation velocity of subsequent streamers was significantly higher than previous ones inside the same ‘metastable trail’ as shown in Fig. 4, which was related to lower ionisation thresholds of metastable species [49]. Hartmann and Gallimberti [50] suggested that the lower ionisation threshold could not adequately explain the streamer development mechanism.…”

“… Evolution of the streamer propagation time under repetitive pulses (PRF: 50 kHz) [49 ]. Replotted from the literature raw data …”

1981 annual report :

“…given that one can detect a 1 ppm change in the dielectric constant of the gas, what would that indicate about the 89 change in polar contaminant concentrations, e.g., the amount of H 2 O present? Would a precision measurement of the dielectric constant be an accurate indicator of polar contaminants?…”

“…The importance of metastable atoms and molecules in electrical discharges has been recognized in the literature for many years [64, [88][89][90][91][92][93].…”