Influence of the cathode surface conditions on V –A characteristics in low-pressure nitrogen discharge

In this paper we demonstrate and analyse the influence of cathode surface inhomogeneities on the breakdown, volt–ampere (V –A) characteristics and the spatial structure of the low-pressure non-equilibrium discharges. The idea for this work came from the need to explain the non-typical V –A characteristics (positive slope of the characteristics in low-current regime of the discharge) that we observed in a parallel-plate, dc discharge in nitrogen. It was found that the cathode was locally conditioned by the discharge that operated in the constricted glow regime. Spatial inhomogeneity of the cathode surface strongly affected the subsequent operation in the breakdown-Townsend regime where discharge is supposed to be uniform.