Evolution of positive streamers in air over non-planar dielectrics: Experiments and simulations

TL;DR

This study investigates how small-scale surface profiles on dielectric plates affect the development and propagation of positive streamers in air, using experiments and simulations to reveal slower streamer speeds and shorter lengths.

Contribution

It provides the first combined experimental and simulation analysis of positive streamer behavior over non-planar dielectric surfaces with different surface profiles.

Findings

Surface profiles slow down streamer propagation.

Rectangular profiles obstruct streamers more than semi-circular ones.

Simulations and experiments show quantitative agreement.

Abstract

We study positive streamers in air propagating along polycarbonate dielectric plates with and without small-scale surface profiles. The streamer development was documented using light-sensitive high-speed cameras and a photo-multiplier tube, and the experimental results were compared with 2D fluid streamer simulations. Two profiles were tested, one with 0.5 mm deep semi-circular corrugations and one with 0.5 mm deep rectangular corrugations. A non-profiled surface was used as a reference. Both experiments and simulations show that the surface profiles lead to significantly slower surface streamers, and also reduce their length. The rectangular-cut profile obstructs the surface streamer more than the semi-circular profile. We find quantitative agreement between simulations and experiments. For the surface with rectangular grooves, the simulations also reveal a complex propagation mechanism where new positive streamers re-ignite inside the surface profile corrugations. The results are of importance for technological applications involving streamers and solid dielectrics.