CATHODE COMPONENT FOR DISCHARGE LAMPS, DISCHARGE LAMP AND METHOD FOR PRODUCING CATHODE COMPONENT FOR DISCHARGE LAMPS

摘要

A cathode component for discharge lamps according to the present invention is provided with: a body part that has a wire diameter of from 2 mm to 35 mm (inclusive); and a tip part that is tapered from the body part. This cathode component contains a tungsten alloy that contains from 0.5% by mass to 3% by mass of thorium in terms of ThO₂. If an electron back scattering diffraction analysis is performed on a region which includes the center of a cross-section that passes through the center of the body part and extends along the length direction of the body part, and which has a unit area of 90 μm × 90 μm, the crystal grain map obtained by this electron back scattering diffraction analysis comprises tungsten crystal grains containing tungsten and thorium crystal grains containing thorium. With respect to the cumulative distribution graph of the particle size distribution of the plurality of thorium crystal grains in the crystal grain map, the particle size at the cumulative frequency of 90% is 3.0 μm or more.