Streamer self-focusing in an external longitudinal magnetic field.

Area of Science:

• Plasma Physics
• Computational Electromagnetics
• High-Voltage Engineering

Background:

• Streamer discharges are crucial in various applications, including plasma processing and electrical insulation.
• Understanding discharge behavior under external fields is vital for controlling plasma phenomena.
• Previous studies have explored magnetic field effects on electrical discharges, but self-focusing mechanisms require further elucidation.

Purpose of the Study:

• To numerically simulate and demonstrate the self-focusing phenomenon in streamer discharges within an external longitudinal magnetic field.
• To investigate the underlying physical mechanisms responsible for self-focusing.
• To determine the critical magnetic field strength for controlling pulsed high-voltage discharges.

Main Methods:

• Numerical simulation of streamer discharge development.
• Analysis of electron energy distribution function, average electron energy, ionization rate, and electron mobility.
• Investigation of crossed electric and magnetic field effects.

Main Results:

• Demonstrated self-focusing of streamer discharges in an external longitudinal magnetic field.
• Identified sharp deceleration of the radial ionization wave as the cause of self-focusing.
• Observed self-focusing for both positive and negative pulse polarities.
• Proposed an estimate for the critical magnetic field value.

Conclusions:

• External longitudinal magnetic fields can induce self-focusing in streamer discharges.
• The self-focusing is attributed to changes in electron kinetics within crossed electric and magnetic fields.
• A critical magnetic field threshold exists for controlling pulsed high-voltage discharges.