A detailed collisional radiative model for diagnostics of the argon plasma using Ar and Ar⁺ emission lines

 In many high-density argon plasma along with its emissions lines, significant emissions from higher ionic states of Ar, particularly from Ar⁺, are also observed . It would be interesting to carry out plasma diagnostics using both the emitted Ar and Ar⁺ lines by developing a reliable CR model. An extensive collisional radiative model is developed which consists of 42 fine-structure levels of Ar and 114 fine-structure levels of Ar⁺.  Mechanisms such as electron-impact excitation/de-excitation, electron-impact ionization, radiation trapping, diffusion, two-body, and three-body recombination are incorporated [1]. A complete set of fully relativistic electron-impact fine structure excitation cross-sections linking different excited levels in Ar and Ar⁺ are included. We applied  our model to characterize the Helicon plasma through its optical emission measurements reported by  [2]. The key plasma parameters such as electron density and electron temperature using the Ar and Ar⁺ lines are obtained and compared with experimental predictions[2]. 

[1]      N. Shukla, R. K. Gangwar, and R. Srivastava, Spectrochim. Acta - Part B At. Spectrosc. 175, 106019 (2021).

[2]      B. Soltani and M. Habibi, J. Fusion Energy 36, 152 (2017).