| 摘要 |
PROBLEM TO BE SOLVED: To prevent a floating up phenomenon of a foil generated between a quartz member 57 for a seal internally contacting with a metallic foil 56 arranged at a foil seal portion 61, and prevent a crack generated in the foil seal portion 61, a leakage from a lamp, and further a breakdown of the lamp in an early period. SOLUTION: An electrode arranged in a light emission space, a metallic foil electrically connected to the electrode, a quartz tube part externally connected with the metallic foil, a quartz member for the seal internally connected to the metallic foil, and a metal member inserted into the quartz member for the seal and electrically connected to the metallic foil are equipped at a short arc discharge lamp, and the length of the part inserted into the quartz member for the seal in the metal member to be inserted into the quartz member for the seal is made to be not less than about 40% of the total length of the quartz member for the seal in the short arc discharge lamp of direct current lighting wherein a foil seal part which seals the metallic foils, the quartz tube and the quartz member for the seal, and which is keeping air-tightness of the light emission space is formed, wherein an input electric power of the lamp is not less than 4 kw, and wherein a working pressure at the time of lighting becomes not less than 2×106 Pa.
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