A low-pressure steady-state arc with a positive anode drop of potential and its use in coating processes

A low-pressure steady-state arc discharge was investigated in a plasma source devised for nitride coating deposition by the vacuum-arc method. Titanium was used as a consumable cathode material. Nitrogen served as a working gas. The pressures under study ranged from 10/sup -3/ to 20 Pa. The discharge transition to the positive anode drop mode was investigated. It is found that a decisive role in creating conditions for this transition belongs to the geometry of the discharge system, in particular, electrodes not involved in current transport, and also to molecular gases such as acetylene and oxygen which enhance the rate of charged particle recombination in a plasma. Results of experiments on titanium nitride based coating deposition under conditions of arcs with a positive anode drop are presented.