Experiments on propagating and branching positive streamers in air

TL;DR

This paper presents experimental results on positive streamer discharges in air, exploring how gap length and voltage influence streamer propagation and branching, using a new large-scale setup with detailed visualizations.

Contribution

It introduces a new experimental setup with a vacuum enclosure for studying positive streamers in air and provides novel visual data on streamer behavior at different gap lengths and voltages.

Findings

Shorter gaps lead to more streamer survival and branching.

Lower voltages reduce streamer branching or prevent it beyond certain distances.

Figures of discharges at various gap lengths are provided for the first time.

Abstract

This proceedings paper from 2004 contains figures of discharges in different gap lengths at the same potential that are not available elsewhere. The 2004 abstract: The evolution of streamers is known to depend on gas composition and electrode geometry, on polarity and size of the voltage and also on the electric circuit that produces the high voltage pulse. To characterize the phenomena better and to compare with theory, a new larger experimental setup with vacuum enclosure has been built. We here present first results in this setup on positive streamers in air at fixed voltage and varying electrode distance. While next to the emitting anode tip, a similar number of streamers seems to emerge due to multiple branching, more streamers seem to survive over a fixed distance, when the gap is shorter. When lowering the voltage, streamers branch less at all distances from the anode tip or do not branch at all beyond a certain distance.