The glow-discharge-to-arc transition instability

Abstract

If the cathode fall potential of an abnormal glow discharge with a cold cathode exceeds an upper limit the discharge is converted into a vapour arc. The discharge voltage and current density at transition have been measured in Hg vapour and in Xe. The transition voltage decreases with rising ambient gas density and depends only slightly on the nature of the gas, whereas the transition current density rises linearly with gas density and is 90 times larger in Xe. In the proposed theory of the instability, a current density perturbation changes the gas density distribution causing an increase in total secondary electron emission and leading to a transition to the arc.