Streamer Self-Focusing in External Longitudinal Magnetic Field

TL;DR

This paper uses numerical simulations to demonstrate how an external longitudinal magnetic field causes self-focusing of streamer discharges by altering electron dynamics, with implications for controlling high-voltage discharges.

Contribution

It introduces a new understanding of streamer self-focusing caused by magnetic fields and estimates the critical magnetic field strength for discharge control.

Findings

Self-focusing occurs due to deceleration of radial ionization waves.

Self-focusing observed for both positive and negative pulses.

Critical magnetic field value estimated for discharge control.

Abstract

The numerical simulation of the development of a streamer discharge in a gap with an external longitudinal magnetic field was used to demonstrate the self-focusing of such discharges. Self-focusing is caused by a sharp deceleration of the radial ionization wave due to a change in the electron energy distribution function, a decrease in the average electron energy, the rate of gas ionization and the electron mobility in crossed electric and magnetic fields as compared to the case of the discharge development without a magnetic field. The self-focusing effect of a streamer discharge in an external longitudinal magnetic field is observed for both positive and negative pulse polarities. The paper proposes an estimate of the critical value of the magnetic field, which makes it possible to control the development of pulsed high-voltage discharges at various gas pressures.