Patent ID: 7569994

Claim:
A high-load and high-intensity discharge lamp comprising: an optically-transparent container that is sealed; an anode and a cathode that are disposed in the container so as to face each other; and sealing sections that project at both ends of the container so as to maintain the air-tightness of the optically-transparent container, electric power being supplied to the anode and the cathode through the sealing sections, wherein the cathode is made from a metal base having a high melting point, which is mainly made of tungsten, the metal base includes coexisting substances in which an oxide of at least one kind of metal selected from lanthanum, cerium, yttrium, scandium, and gadolinium and an oxide of at least one kind of metal selected from titanium, zirconium, hafnium, niobium, and tantalum are coexistent, and a conversion grain size of the coexisting substances is 15 μm or greater.