Optical Diagnostics of Shock-induced Argon Plasmas Based on a Simple Collisional-Radiative Model

Abstract

In the present study, the optical diagnostics of nonequilibrium argon plasma induced by a hypersonic shock wave are conducted based on a simple collisional-radiative (CR) model. Spectroscopic measurements show that line spectra of argon atoms are predominant and clearly seen in the near-infrared region. Line spectra of argon atoms and ion are observed in the visible region. However, the influence of contaminated gases is significant. The electron excitation population is deduced by applying the Boltzmann plot method to the measured line spectra of argon atom. The result shows that the electron excitation population is much different from the Boltzmann distribution, indicating that the argon plasma is in a thermal nonequilibrium state. Finally, the spatial distribution of the electron temperature is obtained by applying the CR model to the measured spectra and compared with that of the calculated one. It is found that the electron temperature obtained using the CR model qualitatively agrees well with the calculated one. The present result has indicated the possibility of using the simple CR model for determining the electron temperature of nonequilibrium argon plasma induced by a hypersonic shock wave.

Optical Emission Spectroscopic (OES) analysis for diagnostics of electron density and temperature in non-equilibrium argon plasma based on collisional-radiative model

“…Even for the arc-discharge conditions, validity of the LTE condition is being examined in terms of the excitation population kinetics with the Ar-CR model [50]. Recently, the OES line-intensity measurement assisted with the CR model is being applied to understand the electron temperature of atmospheric-pressure discharge argon-based plasmas for various applications of material applications [51][52][53][54][55], energy applications [56][57][58], or aeronautical applications [59]. Of course, many reports are published relevant to the electron temperature measurement of argon-based lowpressure discharge plasmas by the OES measurement assisted with the CR model [60].…”