Modeling Intense-Electron-Beam Generated Plasmas Using a Rigid-Beam Approximation

TL;DR

This paper introduces a simplified rigid-beam model to simulate electron-beam generated plasmas, effectively capturing electric field dynamics and matching experimental electron density measurements at pressures above 1 Torr.

Contribution

The paper presents a novel rigid-beam approximation for modeling electron-beam plasma interactions, enabling efficient comparison of plasma dynamics and chemistry with experimental data.

Findings

Simulated electron densities agree within a factor of two with measurements at pressures ≥1 Torr.

The model reproduces the pressure-dependent trend of electron densities observed experimentally.

Coupled plasma and chemistry models demonstrate the utility of the rigid-beam approach.

Abstract

A model of an electron-beam-plasma system is introduced to model the electrical breakdown physics of low-pressure nitrogen irradiated by an intense pulsed electron beam. The rapidly rising beam current induces an electric field which drives a return current in the plasma. The rigid-beam model is a reduction of the problem geometry to cylindrical coordinates and simplifications to Maxwell's equations that are driven by a prescribed electron beam current density. The model is convenient for comparing various reductions of the plasma dynamics and plasma chemistry while maintaining a good approximation to the overall magnitude of the beam-created electric field. The usefulness of this model is demonstrated by coupling the rigid-beam model to a fluid plasma model and a simplified nitrogen plasma chemistry. The dynamics of this coupled system are computed for a range of background gas pressures, and the results are compared with experimental measurements. At pressures 1 Torr and above, the simulated line-integrated electron densities are within a factor of two of measurements, and show the same trend with pressure as observed in experiment.