Nonself-sustained arc discharge in anode material vapors

Abstract

The basic characteristics of the nonself-sustained arc discharge in a vapor of the anode material are studied. The influence of thermoemission parameters of the cathode on volt-ampere characteristics of the discharge is described. It is established that in a free mode of the discharge cathode operation, when the discharge current I/sub D/ is lower than the current of the thermoelectron emission from the discharge cathode I/sub C/, the deposition rate of the films q is directly proportional to the discharge current I/sub D/. In the compelled mode of the cathode operation, when I/sub D/>I/sub C/, q/spl sim/W/sub D//sup 2/, where W/sub D/=I/sub D/U/sub D/ with U/sub D/ being the discharge voltage. It is shown that the magnetic field increases the plasma density and changes the density profile from n(x)-1/x/sup 2/ to n(x)-1/x with x being a distance along the flow. The motion of created plasma flow is shown to have a noncollisional character with constant electron temperature of 5-7 eV along the flow. The values of plasma potential and electric field in the flow are determined; the values of cathodic and anodic potential drops in the discharge are evaluated. The angular distributions of ion and neutral fluxes in the created plasma flow are described. It is shown that the plasma flows parameters depend substantially on the working material. With use of crossed electric and magnetic fields, the flow ionization coefficient was enhanced up to 85% for the discharge in Ti vapors, and 35% for the discharge in Cu vapors.