The hollow-cathode hot filament arc

A discharge system with a hot filament mounted inside a cylindrical hollow cathode designed to produce a low-pressure arc discharge is described together with the discharge characteristics. The combination of a hot filament and a hollow cathode allows a decrease in discharge operating voltage and a 3-4-fold increase in discharge current as compared to a configuration containing only a hot filament, without formation of a cathode spot. A discharge in argon with the pressure 1.5×10^-1 Pa, the operating voltage 54 V, and the discharge current 90 A, produced plasma whose density in the central region of the working space (0.25 m³) was 10¹⁰ cm ^-3 with the plasma density distribution being uniform within ±20% of the average density. At a reduced pressure (~10^-2 Pa), under the conditions of hindered discharge operation, the floating potential in the plasma acquires values 20-30 V below that of the cathode. A plasma generator based on the above type of discharge was used for finishing the material surface before and during the process of plasma-assisted deposition of coatings