Study of argon ions density and electron temperature and density in magnetron plasma by optical emission spectroscopy and collisional-radiative model

摘要

Abstract Optical emission spectroscopy (OES) combined with the models of plasma light emission becomes non-intrusive and versatile method of plasma parameters determination. In this paper we have studied the densities of charge carriers and electron temperature in Ar plasma of pulsed {DC} magnetron in different experimental conditions. Electron density and temperature were determined by fitting of relative emission line intensities calculated from collisional-radiative model (CRM) to experimental ones. The model describes the kinetics of the first 40 excited states of neutral argon Ar and takes into account the following processes: electron impact excitation/deexcitation, spontaneous light emission, radiation trapping, electron impact ionization, and metastable quenching due to diffusion to walls. Then, ions density was determined from relative intensity of 488 nm Ar+ emission line and simple {CRM} accounting excitation from ground states of neutral Ar and ion Ar+. The values of electron and ion density agree very well. To test the stability of results, we performed Monte-Carlo calculations with random variation of experimental spectrum as well as of excitation cross-sections and estimated confidence intervals and errors for plasma parameters. Also, we validated {OES} study by comparison with Langmuir probe measurements. The agreement between optical and probe techniques is satisfactory.