DISCHARGE LAMP

PROBLEM TO BE SOLVED: To provide a discharge lamp having a long life, by including in a cathode 5 lanthanum oxide (La2O3) as an electron easily-emissive material and supplying the lanthanum (La2O3) to a tip portion 51 over a long time in the discharge lamp having a high load and high luminance in which current density applied to the cathode 5 becomes not less than 50A/mm2. SOLUTION: In this discharge lamp, an anode 4 and the cathode 5 disposed so as to face each other in the tube axial direction of a discharge vessel 1 are provided in the inside of the discharge vessel 1, the cathode 5 is formed of a material in which the electron easily-emissive material composed of a metal oxide of lanthanum and a metal oxide of zirconium is contained in a tungsten metal substrate, and the current density of not less than 50A/mm2is applied. The particle of the electron easily-emissive material has a smaller aspect ratio in comparison with a tungsten particle. COPYRIGHT: (C)2010,JPO&INPIT