Der Einfluß metastabiler Atome auf den statischen Durchschlag in Argon

Abstract

A gas discharge in argon is initiated by an ultraviolet light pulse which releases 10⁵ electrons at the cathode within 20 nsec. The time of built-up for the static breakdown is found to be in the order of msec. The oscillogram of the current near breakdown shows a fast component consisting of several successive avalanches caused by secondary electrons liberated by ions at the cathode and a slow component which is due to the electrons liberated by metastable atoms at the cathode. The second Townsend coefficient for argon ions and a nickel cathode is determined to beγ ₊= 2.5·10⁻³. The amount of electrons liberated by metastables at static breakdown is 25% of the total number of secondary electrons. The mean life-time of the metastables at 1,1 Torr and an electrode separation of 10 mm is found to be 2.2 msec, which is mainly due to de-exciting collisions at the electrodes.