NEGATIVE ELECTRODE FOR DISCHARGE LAMP AND METHOD FOR MANUFACTURING SAME

摘要

Provided is a negative electrode for a discharge lamp, having a pillar-shaped trunk section and a tapered tip section. At least a part of the negative electrode has a tungsten alloy containing a thorium component at a proportion of 0.5-3.0% by weight in oxide conversion, with the thorium component dispersed in particle form. When the particle diameter of tungsten crystals in the tungsten alloy is observed in a 300 × 300 µm2 area along a radial cross section and a lateral cross section, at least 90% of the tungsten crystals have particle diameters within the range of 1-100 µm in the radial cross section and at least 90% of the tungsten crystals have particle diameters within the range of 5-120 µm in the lateral cross section.