Influence of the hot filament on the electrical breakdown characteristics in the presence of Ar/N2

Abstract

The influence of a hot filament on the electrical breakdown characteristics is studied for different ratios of argon and nitrogen gases for a wide range of pressure. The vacuum tube consists of two parallel plane stainless steels used as cathode and anode accompanied with a tungsten filament located behind the cathode. Paschen’s curves are obtained for different ratios of argon and nitrogen as a function of pressure for various electric currents of the hot filament. The first and second Townsend coefficients as well as the ionization efficiency and secondary ionization coefficient are obtained for different filament currents. In addition, the influences of the nitrogen partial pressure on the forgoing parameters are obtained. It is shown that, increase of the filament current causes the decrease of the electrical breakdown voltage which is more pronounced in low pressures. Furthermore, introducing the nitrogen gas leads to the increase of the breakdown voltage and decrease of the ionization efficiency as well as the first and second Townsend coefficients. Moreover, it is concluded that, in the middle range of pressure, the presence of the hot filament results to the electrical breakdown which reveals the linear features.