High pressure discharge lamp cathode has a locally carbonized conical front end portion

摘要

A high pressure discharge lamp cathode has a conical front end with a carbonized sloping portion and an untreated adjoining edge or tip. A high pressure discharge lamp electrode arrangement includes an electron emitter-doped refractory metal cathode which has the design described above. An Independent claim is also included for production of a high pressure discharge lamp electrode by: (a) applying a liquid containing a graphite-containing sintering medium onto a cathode and optionally also onto an anode, with exception of the edge region, and then drying; (b) preheat treating in vacuum to remove contaminants and then heating to the sintering temperature; (c) removing the sintered applied medium; and (d) heating the electrode in vacuum to a carbonizing temperature to achieve a desired carbonized layer depth.