Effect of the electrode shape on the hollow cathode discharge

Abstract

The hollow cathode discharges are characterized by a low maintaining voltage and high current density. This unique feature of the hollow cathode discharge, however, is the effect of the cathode geometry, in that electrons are trapped between the two plates due to potential distribution of the cathode fall and then can undergo a limited number of collisions with plasma particles, reverse direction and repeatedly across the cathode fall region. This possibility of making multiple passage of electrons greatly increase the ion-and photon producing effectiveness. Aims of this research are to determine the optimal shape and geometry among three typical shapes of the hollow cathode, a pair of two parallel plates, a square shaped cylinder and a circular cylinder. It is concluded that the most suitable shape of the hollow cathode is the long circular cylinder because of the lowest maintaining voltage and high current density among these three.