Collisional–radiative model of neon discharge: determination of E/N in the positive column of low pressure discharge

Abstract

A method for the determination of the reduced electric field strength (E/N) in a neon discharge from the optical emission spectra was developed. This method is based on a collisional–radiative model, which was used to calculate the emission spectra of the neon plasma. In the model, populations of 30 excited levels of the neon atom were studied. Various elementary collision processes were taken into account: electron impact excitation, de-excitation and ionization of neon atoms, emission and absorption of radiation, metastable–metastable collisions, metastable and radiative dimer production, Penning ionization, etc. To determine the rates of electron collisions, the Boltzmann kinetic equation for the electron distribution function (EDF) was solved for given E/N, and thus the dependence of the emission spectra on E/N could be determined. The EDF was expanded in terms of Legendre polynomials and the first two terms of this approximation were taken into account. The theoretical emission spectra were fitted by the non-linear least-squares method to the measured spectra with respect to the unknown parameter E/N.The method was applied to the study of low pressure dc glow discharge in neon. In such a discharge the calculated reduced electric field strength could be compared with the independent results of simultaneously performed electric probe measurements of E/N. Generally, close agreement of the calculated values with the experimental data was achieved.