Diagnostics of Ar/N2 mixture plasma with detailed electron-impact argon fine-structure excitation cross sections

Abstract

A collisional-radiative model is developed for the Ar/N2 mixture plasma using reliable fully relativistic electron impact excitation cross sections of argon. We consider several fine structure transitions of argon and their corresponding cross sections used in the model have been obtained using fully relativistic distorted wave (RDW) theory. Processes, which account for the coupling of argon with nitrogen molecules, have been further added in the model. The applicability of the model with the RDW cross sections is tested by coupling it to the recent available spectroscopic measurements for a low pressure electron beam generated Ar/N2 plasma. The plasma parameters viz. electron density (ne) and electron temperature (Te) are evaluated by optimizing the model simulated intensities with the eight emission lines (out of 3p54p (2pi) → 3p54s (1si) transitions) observed through the measurements. We find from our study that as the concentration of N2 increases in the Ar/N2 mixture from 0 to 10%, our extracted electron density varies from 2.3 × 1011 to 2.8 × 1011 cm−3 and the electron temperature decreases from 1.0 to 0.43 eV which are in good agreement with the available probe measurement. Using present collisional radiative model, the individual contributions from the ground and 1si states to the radiating states are also evaluated as a function of N2 concentrations.