Discharge lamp having a cathode and emitter assembly composed of tungsten and thorium oxide and joined through a carbide interface region

摘要

A high pressure discharge lamp, in which an anode and a cathode are disposed opposite each other in a bulb, achieves a long service life due to thorium (Th) being stably supplied to the cathode tip for a long time after lamp operation has been commence since the formation of the flicker phenomenon is suppressed over a long time due to the cathode being made of tungsten which contains thorium oxide on a surface space from the cathode tip, a carbide layer of tungsten carbide is formed and the cathode being bordered by an emitter containing body of tungsten which contains thorium dioxide, and a carbide layer of tungsten carbide being formed at least in a region bordering the cathode.