Electrical breakdown time delay in nitrogen filled tube with small inter electrode gap

The processes which are responsible for breakdown initiation in nitrogen-filled tube at 6.6×10² Pa (6.6 mbar) and inter electrode gap 0.1 mm have been investigated. These processes have been monitored based on experimental data of electrical breakdown time delay t_d as a function of relaxation time τ. It was shown that, for τ<; 300 ms, the dominant role in breakdown initiation is taken by positive ions, while in the 300 ms<; τ<;150 s interval N(⁴S) nitrogen atoms in ground state initiate breakdown. For τ>150 s breakdown is initiated by cosmic rays. Also, it was shown that the increase in applied voltage and glow current, as well as presence of external radiation, lead to the decrease of t_d value.