Anode Layer in a High-Current Atmospheric Pressure Nitrogen Arc

Abstract

Summary form only given. Anode layer in a high-current atmospheric nitrogen arc was modeled. Calculations were made in 1D approximation at current densities in the range from 200 A/cm2 to 2000 A/cm 2. Two-temperature approximation was used. Along with heat and electricity transfer, we considered the processes of ionization and dissociation. For kinetics of these processes, we used the Park model. We calculated the distributions of both electrons and heavy particles temperatures, the concentrations of charged and neutral particles, and the electric field inside the anode layer. It was shown that for the conditions that exist in the anode layer of a high-current atmospheric pressure arc in nitrogen: a) concentration of the molecular ions is negligible; b) concentration of atoms exceeds concentration of molecules everywhere in the anode layer except a narrow region close to the anode. Electric field decreases towards the anode. However, contrary to what happens in argon plasma, the field does not change its sign. Nevertheless, the field decrease, combined with the negative voltage drop in the Langmuir sheath (VL), lead to the negative anode voltage drop defined as VL+int[E(x)-Einf]dx, where Einf is the electric field far from the anode