| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a discharge lamp having a long life, by including in a cathode 5 lanthanum oxide (La<SB>2</SB>O<SB>3</SB>) as an electron easily-emissive material and supplying the lanthanum (La<SB>2</SB>O<SB>3</SB>) 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/mm<SP>2</SP>. Ž<P>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/mm<SP>2</SP>is applied. The particle of the electron easily-emissive material has a smaller aspect ratio in comparison with a tungsten particle. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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