HEAVY-LOAD AND HIGH-INTENSITY DISCHARGE LAMP

PROBLEM TO BE SOLVED: To provide a high-load and high-intensity discharge lamp equipped with a cathode fit for use for a high heat-load cathode material not containing thorium and capable of attaining long life and high stability equivalent to thoritung(R) (thoriated tungusten). SOLUTION: In the discharge lamp provided with a sealed light-transmitting vessel, electrodes arranged in opposition inside the vessel, and a sealing part protruded at either end of the vessel for keeping the light-transmitting vessel airtight, at least one of the electrodes has at least a kind of metal oxide selected from easily electron-emitting material such as lanthanum and at least a kind of metal oxide selected from stabilizing materials such as zirconium coexist in a high-melting-point metal base body with tungsten as a main component, coexisting matters, in which the easily electron-emitting material and the stabilizing material coexist, with a reduced grain size of 15 μm or more exist in the plural number in the high-melting-point metal base body. COPYRIGHT: (C)2007,JPO&INPIT