| 摘要 |
PROBLEM TO BE SOLVED: To improve a thermal radiation property from an electrode, and efficiently reduce the temperature of the electrode wherein an input electric power is made larger in order to increase an irradiated amount of light in a short arc type high-pressure discharge lamp. SOLUTION: The short arc type high-pressure discharge lamp (10) has a pair of electrodes (20, 30) in a light emitting tube (11), and groove parts (24) have been formed at least in a part of a side face of the electrodes (20, 30), and a depth D of these groove parts (24) is not more than 12% of the diameter of the electrode, and the relationship between the depth D of the groove parts (24) and a pitch P of the groove parts is W/P>=2.
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