Investigations on the ignition of high-voltage glow discharges

The ignition of high-voltage glow discharges at voltages of several kilovolts cannot be described by the Townsend theory. Therefore a simulation code was developed, which allows one to estimate the influence of several elementary processes during the ignition process and to calculate ignition curves. One result of these simulations is that secondary electron emission by electron impact at the anode is very important for production of charged particles. Experimental measurements of ignition voltage yield that the similarity law Un=f(pd) is not valid. The ignition voltage decreases with increasing electric field, which can be related to changes in ionization cross sections and secondary emission coefficients due to the high electric fields of several kilovolts per centimetre.