Estimation of sparking voltage in high-temperature nitrogen gas present under a constant volume condition

Concerning an electrical breakdown of a high-temperature gas, theoretical calculations were carried out to obtain a sparking voltage from an ionization coefficient on the basis of the Townsend breakdown theory. The calculations were made for a nitrogen gas with a mass-density of 1.14 kg/m³ under a constant volume, in consideration of a dissociation and an ionization reactions of N₂. The calculation result for the sparking voltage V_s showed that V_s is 2.9 × 10⁴ V at 300 K and also remains almost unchanged in a temperature range from 300 to 4000 K. The result also revealed that V_s decreases from 2.9×10⁴ to 1.3×10⁴ V with the temperature from 4000 to 6000 K. This reduction in V_s was found to arise from the production of N and to result from the lower ionization potential of N.