Abstract: A short arc type mercury lamp in which a cathode and an anode are disposed opposite one another inside an arc tube, at least a noble gas and mercury are filled into the arc tube, cathode contains thorium oxide, a cone-shaped part that continues on from a cathode body is formed on the cathode, and a protruding part that continues on from the cone-shaped part is formed, wherein the number of grain boundaries on a straight line that passes through the approximate center of an arbitrary section in the radial direction of the protruding part is at least 0.5 per mm but not more than 100 per mm.

Abstract: A mercury lamp of the short arc type which can stably emit an intense spectrum at a wavelength of 365 nm with an extremely narrowed band region over a long time, and which has an anode and a cathode disposed opposite one another in a silica glass arc tube which is filled with mercury and a rare gas, is achieved by the amount of mercury being less than or equal to 1.0 mg/cc of the inside volume of the arc tube and at least one of the gases argon (Ar) and krypton (Kr) are used as the rare gas at room temperature with 1.0 to 8.0 atm.

Abstract: A short arc type mercury lamp in which a cathode and an anode are disposed opposite one another inside an arc tube, at least a noble gas and mercury are filled into the arc tube, cathode contains thorium oxide, a cone-shaped part that continues on from a cathode body is formed on the cathode, and a protruding part that continues on from the cone-shaped part is formed, wherein the number of grain boundaries on a straight line that passes through the approximate center of an arbitrary section in the radial direction of the protruding part is at least 0.5 per mm but not more than 100 per mm.

Abstract: A short arc mercury discharge lamp including an arc tube filled with at least mercury and a rare gas, a cathode and an anode positioned opposite to each other within the arc tube, the cathode having an tapered area which tapers in a direction towards the anode and a projection which protrudes from the tapered area in a direction towards the anode. The amount of mercury to be added in the arc tube is in a range of 0.2≦n≦52, where n is the weight (mg/cm3) of the mercury per unit of volume, and a pressure of the rare gas to be added in the arc tube is in a range of 0.1≦p≦800, where p is the pressure (kPa) of the rare gas at an ambient temperature of 25° C.

Abstract: To devise a mercury lamp of the short arc type with high radiant efficiency and increased arc stability which meets the demand for increasing the amount of radiation from the light source. In a mercury lamp of the short arc type, a cathode and an anode are disposed opposite one another within an arc tube filled with mercury and a rare gas. At least argon (Ar) and/or krypton (Kr) in an amount from 1.0 to 8.0 atm at room temperature is added as the rare gas. In addition, the relationship between various dimensions of the lamp is fixed such that conditions 0.3≦X/L≦0.6, (X+5)/D≦0.85, and (L−(X+5))/D≦0.85 are satisfied, L (mm) being the length of the bulb in the axial direction, X (mm) being the length of the cathode which projects in the axial direction into the emission space, and D (mm) being the maximum outside diameter of the bulb in the radial direction.

Abstract: To maintain the relative positional relationship between an inner tube and an inner electrode of a dielectric barrier discharge tube having a roughly cylindrical, double tube arrangement of an outer tube coaxially arranged about an inner tube with a discharge space defined therebetween, an outer electrode on an outer surface of the outer tube, an inner electrode on an inner surface of the inner tube, and a discharge gas which forms excimer molecules by a dielectric barrier discharge filling said discharge space, despite repeated expansion and contraction of the inner electrode due to the dielectric barrier discharge lamp being repeatedly turned on and off, according to the invention, the inner electrode is formed of a substantially tubular metal component or the like, and a motion preventing component is provided at opposite ends of the inner electrode for maintaining an axial position of the inner electrode relative to the inner tube.

Abstract: A dielectric barrier discharge lamp having a generally cylindrical double-tube arrangement of an outer tube coaxially disposed about an inner tube, with an outer electrode disposed on an outside surface of the outer tube, an inner electrode disposed on an inside surface of the inner tube, and a discharge space provided between the outer tube and the inner tube which is filled with a discharge gas for formation of excimer molecules by dielectric barrier discharge achieves firm engagement of the inner electrode against the inner tube and a stable discharge over a long time even if part of the electrode corrodes due to the ozone produced or it wears. This is achieved by embodiments in which the inner electrode is a generally tubular part which is slit in an axial direction along the full length thereof. The tubular part can be a single cylindrically sheet having opposite longitudinally extending edges spaced from each other by a gap or overlapped.