The Role of Space Charge Transport in the Self-Pulsating Behavior of Streamer Coronas

Self-pulsating streamer coronas triggered by DC or ramped voltage are relevant in atmospheric electricity studies, as components of electrostatic discharge and precursors of lightning. The burst termination is typically explained by near-electrode accumulation of space charge, which needs to be dispersed prior to the next burst to occur. This evacuation of the space charge is due to electric drift effects, or wind if present. In this work we present laboratory experiments using DC voltage in a tip-to-plate configuration, with cm-gaps, in atmospheric pressure air to characterize the self-pulsating nature of streamer corona discharges. Under these conditions, the current pulses have widths on the order of hundreds of nanoseconds, pulsation frequencies on the order of kilohertz, and amplitudes of order 10 mA. First, we exploit recent advancements in laser diagnostics to measure the electric field evolution during a streamer corona burst and its afterglow, using the electric field induced second harmonic generation (E-FISH) technique. The measurements show some unexpected behavior that does not support that the self-pulsating behavior is exclusively driven by field recovery at the anode. Second, we explore the impact of enhancing charge transport through wind addition. The results for the wind tunnel campaign show that wind advection can increase the frequency of pulsations, but some populations of very high frequency streamer bursts (of 100kHz) are also observed, which cannot be explained exclusively by charge transport.

The E-FISH experiments were conducted at the Princeton Collaborative Low Temperature Plasma Research Facility (PCRF) supported by the U.S. Department of Energy (DOE) under contract DE-AC02-09CH11466. Part of this work was funded by The Boeing Company through the Strategic Universities for Boeing Research and Technology Program.