Similarity Relations for Low Pressure Glow Discharges in Noble Gases

A simple three level atomic model that includes excitation, ionization, stepwise ionization, and diffusion is used to determine similarity relations for low pressure noble gas discharges. A two-temperature electron energy distribution is also included in the model. Similarity relations involving the reduced electric field, the electron main body temperature, the electron tail temperature, and the pressure-radius product are developed. It is found that the reduced electric field and the electron tail temperature depend on the discharge current as well as the pressure-radius product. Good agreement is obtained between the similarity relation predictions and experimental results in helium and neon discharges.