On the Delayed Gas Breakdown in a Ringing Theta-Pinch with Bias Magnetic Field

Abstract

A single particle model and particle-in-cell simulations are used to elucidate the breakdown physics in a ringing theta-pinch with a bias magnetic field. Previous experimental results show that gas breakdown occurs when the bias magnetic field is nullified by the theta-pinchmagnetic field. The analyses presented here agree with the experimental results and show that electron kinetic energy does not exceed the ionization threshold of deuterium until the net magnetic field is approximately zero. Despite the presence of a strong electric field, the gyromotion of electrons within the bias magnetic field prevents them from gaining energy necessary to ionize the gas. Parametric analysis of the peak electron energy as a function of the bias and pre-ionization magnetic fields reveals that: (1) when the bias magnetic field is ≈97% of the pre-ionization magnetic field, peak electron energies are highly erratic resulting in poor overall ionization, and (2) full ionization with repeatable behavior requires a pre-ionization to bias magnetic field ratio of approximately 2 to 1 or higher.

Department(s)

Mechanical and Aerospace Engineering

Keywords and Phrases

Magnetic Fields; Theta Pinch; Electric Fields; Ionization; Particle-In-Cell Method

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2012 American Institute of Physics (AIP), All rights reserved.

Publication Date

01 Jan 2012

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