Two-electron group model and electron energy balance in low-pressure gas discharges

The two-electron group model (2-EGM) provides a simple and powerful method to account for deviations from a Maxwellian shape of the electron energy distribution function in calculations on the positive column of low-pressure gas discharges. An analysis is given of the electron energy balance in this 2-EGM. Analytical expressions are obtained for the electron energy flow terms due to electron-electron interactions, elastic collisions, and the external electric field. The results obtained differ from those used thus far. The 2-EGM is applied in a simplified calculation for a low-pressure Hg-Ar discharge to obtain excited state densities. Good agreement is obtained with experimental data from literature.