HIGH-PRESSURE MERCURY LAMP

摘要

PROBLEM TO BE SOLVED: To satisfactorily stabilize the ark during lighting in a high-pressure mercury lamp having an extremely high mercury vapor pressure and also an extremely high tube wall load. SOLUTION: A pair of tungsten electrodes 4 is arranged opposite to each other in a discharge vessel 2 consisting of quartz glass, 0.16 mg/mm<3> or more of mercury and a rare gas are sealed in the discharge vessel 2. The tube wall loads is 0.8 W/cm<2> or more. A metal halide having an ionization voltage 0.87 times or less the ionization voltage of mercury is added to the discharge vessel 2 within the range of 2×10<-4> -7×10<-2>μmol/mm<3> .