A computational study of positive streamers interacting with dielectrics

Abstract

We use numerical simulations to study the dynamics of surface discharges, which are common in high-voltage engineering. We simulate positive streamer discharges that propagate towards a dielectric surface, attach to it, and then propagate over the surface. The simulations are performed in air with a two-dimensional plasma fluid model, in which a flat dielectric is placed between two plate electrodes. Electrostatic attraction is the main mechanism that causes streamers to grow towards the dielectric. Due to the net charge in the streamer head, the dielectric gets polarized, and the electric field between the streamer and the dielectric is increased. Compared to streamers in bulk gas, surface streamers have a smaller radius, a higher electric field, a higher electron density, and higher propagation velocity. A higher applied voltage leads to faster inception and faster propagation of the surface discharge. A higher dielectric permittivity leads to more rapid attachment of the streamer to the surface and a thinner surface streamer. Secondary emission coefficients are shown to play a modest role, which is due to relatively strong photoionization in air. In the simulations, a high electric field is present between the positive streamers and the dielectric surface. We show that the magnitude and decay of this field are affected by the positive ion mobility.

arXiv comment13 pages, 18 figures, 47 references

References in corpus (4)

• Simulating streamer discharges in 3D with the parallel adaptive Afivo framework
• Density models for streamer discharges: beyond cylindrical symmetry and homogeneous media
• Afivo: a framework for quadtree/octree AMR with shared-memory parallelization and geometric multigrid methods
• The effect of the stochasticity of photoionization on 3D streamer simulations

Cited by in corpus (4)

• A Computational Study of Negative Surface Discharges: Characteristics of Surface Streamers and Surface Charges
• Comparing simulations and experiments of positive streamers in air: steps toward model validation
• Evolution of positive streamers in air over non-planar dielectrics: Experiments and simulations
• Unveiling the role of dielectric trap states on capacitively coupled radio-frequency plasma discharge: dynamic charging behaviors