Kinetics of positive ions and electrically neutral active particles in afterglow in neon at low pressure

Kinetics of positive ions and electrically neutral active particles formed during breakdown and successive discharge in neon-filled tube at 6.6 millibars pressure had been analyzed. This analysis was performed on the basis of mean value of electrical breakdown time delay $t¯d$ dependence on afterglow period $τ$ (memory curve). It was shown that positive ions are present in the 1$μs$ < $τ$ < 30 ms interval, which is manifested through $t¯d$ slow increase with the increase of $τ$⁠. A rapid $t¯d$ increase in the 30 ms < $τ$ < 3 s interval is a consequence of significant decrease of positive ions concentration and dominant role in breakdown initiation have ground state nitrogen atoms, which further release secondary electrons from the cathode by catalytic recombination process. These atoms are formed during discharge by dissociation of ground state nitrogen molecules that are present as impurities in neon. For $τ$ > 3 s, breakdown is initiated by cosmic rays and natural radioactivity. The increase of discharge current leads to decrease of $t¯d$ due to the increase of positive ions concentration in inter electrode gap. The increase of applied voltage also decreases $t¯d$ for τ > 30 ms due to the increase of the probability for initial electron to initiate breakdown. The presence of UV radiation leads to the decrease of $t¯d$ due to the increased electron yield caused by photoelectrons. The influence of photoelectrons on breakdown initiation can be noticed for $τ$ > 0.1 ms, while they dominantly determine $t¯d$ for $τ$ > 30 ms.