Ushio Denki Kabushiki Kaisha

Keisuke Okubo

Mitsuru Ikeuchi

Shoji Miyanaga

Tuneo Okanuma

A short arc discharge lamp in which the wear on the cathode tip area is suppressed, in which moreover in the arc discharge only little polarization occurs and flickering in the arc discharge occurs only rarely, and thus, a reduction of illuminance or flickering on the light irradiation surface of a device or the like in which the short arc discharge lamp has been installed is prevented. Furthermore, a short arc discharge lamp is devised in which the radiance is hardly impaired and stable light emission is enabled, even when it is operated over a long time. To obtain these advantages, a short arc discharge lamp which has an essentially spherical arc tube in which there are a cathode and an anode opposite one another, is provided with a cathode in which the cathode tip area has a crystal structure formed of several crystals which, as compared to the crystal size in the back end area of the cathode, are coarsened, and in which the emissive material contained in the cathode tip area is less than or equal to 0.1% by mass.

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Himeji, Japan

Keisuke Okubo