Diagnostics of Argon Plasma Using Reliable Electron-Impact Excitation Cross Sections of Ar and Ar⁺

Abstract

Comprehensive collisional radiative (CR) models have been developed for the diagnostic of argon plasma using Ar and Ar+ emission lines. The present CR models consist of 42 and 114 fine-structure levels of Ar and Ar+, respectively. Various populating and depopulating mechanisms are incorporated in the model. A complete set of electron-impact fine-structure resolved excitation cross-sections for different excited levels in Ar and Ar+ are used, which are obtained by employing relativistic distorted wave theory. Along with this, the electron-impact ionization, radiation trapping, diffusion, and three-body recombination are also considered. Further, to demonstrate the applicability of the present CR model, we applied it to characterize the Helicon-plasma utilizing the optical emission spectroscopy measurements. The key plasma parameters, such as electron density and electron temperature, are obtained using their measured Ar and Ar+ emission line intensities. Our results are in reasonable agreement with their anticipated estimates. The matching of our calculated intensities of the different Ar and Ar+ lines shows excellent agreement with the measured intensities at various powers.

Keywords

• Ar and Ar⁺ collisional radiative model
• relativistic distorted wave theory
• electron-impact excitation cross-sections
• argon plasma