High pressure discharge lamp

摘要

The lamp has a discharge vessel (2) contg. an axially mounted cathode (4) and anode (3) and an ionisable filling. The cathode has a cylindrical base body (8) which narrows to a point (10) and the cathode is at least partially coated by a carbide film. The whole of the narrowing region between the tip and the base body is free of carbide, whilst the base body is at least partly coated with carbide. The lamp contains mercury in a quantity of 70 to 130 mg/cm3, the electrode separation is 0.4 to 0.8 mm. and the working voltage is about 20 to 29 volts, esp. about 23 volts.