Influence of different cathode surfaces on the breakdown time delay in neon DC glow discharge

The breakdown time delay t(d) in neon DC glow discharge with a galvanic gold layer on the cathode is studied and compared to the measurements on the gas tube with the vacuum deposited gold layer. The influence of the different cathode surfaces is analysed by measuring the breakdown time delay as a function of the afterglow period (t(d)) over bar(tau) (the memory curve) and by measuring the formative time delay dependence on working voltages (t(f)) over bar (U). In the case of the galvanic gold layer the surface charges remain on the regions with reduced conductivity (cathode spots) whose presence is confirmed by scanning electron microscopy (SEM) image and energy dispersive X-ray (EDS) spectrum. The trapped charges change the cathode secondary electron yield and affect the processes of initiation and formation of gas discharge. Furthermore, it is found that deposited surface charges introduce a new mechanism of surface initiation that is manifested by double-Gaussian distributions of the formative and statistical time delay. (C) 2012 Elsevier Ltd. All rights reserved.