Research on Similarity Law of Glow Discharge in Argon at Low Pressure by Numerical Simulation

In order to investigate the validity of the similarity law of glow discharge between two similar discharge gaps, a 2-D fluid model of argon discharge was established and solved with finite-element method. In the two similar discharge gaps, the gap length d, electrode radius r, and gas pressure p were set to meet the relations of p₁d₁ = p₂d₂ and p₁r₁ = p₂r₂, respectively, and the reduced field E/p was kept constant as well. The parameters of the larger gap were 20 mm in gap length, 10 mm in diameter, and 1 torr in pressure, while those of the scale-down gap were 10 mm, 5 mm, and 2 torr. The simulation results indicate that the discharge was a typical normal glow discharge, and the discharge physical parameters, such as electric potential, electric field, current density, electron density, and ion density, were obtained. The voltage-current characteristic curves of the two similar gaps were approximately the same, and the physical parameters of the two similar gaps show the proportional relationships derived by similarity law. The results could offer theoretical instructions in extrapolating the discharge properties of two similar gaps.