Nanosecond pulsed barrier discharge in argon for various frequencies and theoretical analysis of 2p states density ratios for E/N determination

TL;DR

This paper develops a fluid-Poisson simulation and a semi-automated intensity ratio method for diagnosing electric fields in nanosecond pulsed argon discharges, enabling sub-nanosecond plasma diagnostics and improved E/N determination.

Contribution

It introduces a new semi-automated approach linking 2p state density ratios to electric field strength using a time-dependent collisional-radiative model for nanosecond discharges.

Findings

The method accurately identifies 2p states for E/N determination.

Different effective lifetime approaches are validated against measured data.

Radial and axial integration effects on the intensity ratio are analyzed.

Abstract

Nanosecond pulsed barrier discharges in atmospheric pressure argon are simulated using spatially one- and two-dimensional fluid-Poisson models using the reaction kinetics model presented by Stankov et al. [1], which considers all ten argon 2p states (Paschen notation) separately. The very first (single) discharge and repetitive discharges with frequencies from 5kHz to 100kHz are considered and a semi-automated procedure is utilized to find appropriate 2p states for electric field determination using an intensity ratio method. The proposed method is based on a time-dependent collisional-radiative model enabling a sub-nanosecond plasma diagnostics, it links the 2p state density ratios to the reduced electric field strength E/N by quantifying the excitation rate coefficients and by computing 2p states effective lifetimes from the fluid model simulation. The semi-automated procedure identifies several candidates for determination of E/N from given temporal profiles of the 2p state densities. Different approaches for effective lifetime determination are tested and applied also to measured data. The influence of radial and axial 2p state density integration on the intensity ratio method is discussed. The above mentioned models and procedures result in a flexible theory-based methodology applicable for development of new diagnostic techniques.