Spatiotemporal dynamics of nanosecond pulsed discharge in the form of a fast ionization wave: self-consistent two-dimensional modeling and comparison with experiments under negative and positive polarity

TL;DR

This paper models the spatiotemporal behavior of nanosecond pulsed discharges as fast ionization waves using a 2D plasma fluid approach, validated by experiments, to better understand plasma chemistry processes.

Contribution

It provides a self-consistent 2D modeling framework for nanosecond discharges, including photoionization, and compares results with experimental data for different polarities.

Findings

Simulation accurately predicts FIW velocity and electron density.

Model captures electric field and emission distribution on nanosecond timescale.

Results validate the modeling approach against experimental measurements.

Abstract

Nanosecond discharges are characterized by a shift in energy branching toward the excitation of electronic levels and dissociation, making them particularly attractive for plasma chemistry. Understanding the spatiotemporal structure of these discharges is especially important. This paper presents a detailed 2D-axisymmetric numerical analysis of a nanosecond discharge propagating in a long tube and in pure nitrogen. The modeling is conducted using a self-consistent plasma fluid solver under the local mean energy approximation (LMEA), including photoionization. The discharge develops at moderate pressures, 1 - 10 Torr, in the form of a fast ionization wave (FIW). Simulations are performed for both negative and positive polarities of the voltage pulse applied to the high-voltage electrode. The computational results are validated against available experimental data, including FIW velocity within the studied pressure range, electron density, longitudinal electric field, and the radial distribution of N2(C) emission on a nanosecond timescale.