Investigation of a fully developed DC hollow cathode discharge

Summary form only given, as follows. The voltage V/sub A/ of a DC cylindrical hollow cathode discharge at different helium pressures p is plotted for fixed discharge current I/sub A/. The portion which shows positive gradient is identified as the optimum pressure range for which a fully developed hollow cathode discharge may be defined This optimum pressure range coincide with the occurrences of a full column of coalesced negative glow in the centre of the cylindrical hollow cathode and the current magnification. The width of this optimum pressure range is compared to that shown by other workers and it is deduced that the optimum pressure range is dependent of the cathode material. The cathode dark space width d/sub K/ estimated from the radial intensity distribution within the hollow cathode is observed to be almost constant at this optimum pressure range. A numerical estimate is made to relate the minimum of the function V/sub A/ against p to the fundamental processes in the hollow cathode discharge.