In a light source device, a control unit causes an energy density of a laser light in a lighting start region RS when a laser support light is maintained to be lower than an energy density of the laser light in the lighting start region RS when the laser support light is put on. For this reason, when the laser support light is maintained, a laser light L is radiated to the lighting start region RS at an energy density of a degree where sputtering does not occur. Therefore, in the light source device, because sputtering in a light emission sealing body can be suppressed, a sufficiently long life can be realized.

A DC gas discharge lamp includes an anode and a cathode having a first cathode segment, which forms the surface of the cathode at least in a region of the cathode which faces the anode and has an arc attachment region, within which an arc burning between the cathode and the anode attaches during lamp operation as intended. The first cathode segment consists of tungsten with at least one emitter material for reducing the work function of electrons from the cathode. The cathode is embodied in a manner free of thorium. The at least one emitter material has a melting point of less than 3200 K. At least one part of the surface of the cathode outside the arc attachment region is formed by a diffusion barrier for the at least one emitter material.

In a light source device, a control unit causes an energy density of a laser light in a lighting start region RS when a laser support light is maintained to be lower than an energy density of the laser light in the lighting start region RS when the laser support light is put on. For this reason, when the laser support light is maintained, a laser light L is radiated to the lighting start region RS at an energy density of a degree where sputtering does not occur. Therefore, in the light source device, because sputtering in a light emission sealing body can be suppressed, a sufficiently long life can be realized.

In a light-emitting sealed body, a metal structure (electron emission structure) containing an easily electron-emitting material is used, so that it is not necessary to perform feeding for discharge between electrodes. Therefore, a feeding member does not need to be connected to the metal structure from the outside of a bulb. In addition, in the light-emitting sealed body, the metal structure is disposed in an internal space S of the bulb and a positioning unit of the metal structure is disposed only in the bulb. Therefore, in the light-emitting sealed body, the metal structure and the positioning unit do not penetrate the bulb and are not buried in the bulb and weakened portions are not formed in the bulb made of glass. Therefore, a sealing state of the bulb can be maintained surely.

In a light source device, a control unit causes an energy density of a laser light in a lighting start region RS when a laser support light is maintained to be lower than an energy density of the laser light in the lighting start region RS when the laser support light is put on. For this reason, when the laser support light is maintained, a laser light L is radiated to the lighting start region RS at an energy density of a degree where sputtering does not occur. Therefore, in the light source device, because sputtering in a light emission sealing body can be suppressed, a sufficiently long life can be realized.

In a light source device, a control unit causes an energy density of a laser light in a lighting start region RS when a laser support light is maintained to be lower than an energy density of the laser light in the lighting start region RS when the laser support light is put on. For this reason, when the laser support light is maintained, a laser light L is radiated to the lighting start region RS at an energy density of a degree where sputtering does not occur. Therefore, in the light source device, because sputtering in a light emission sealing body can be suppressed, a sufficiently long life can be realized.

In a light source device, a control unit causes an energy density of a laser light in a lighting start region RS when a laser support light is maintained to be lower than an energy density of the laser light in the lighting start region RS when the laser support light is put on. For this reason, when the laser support light is maintained, a laser light L is radiated to the lighting start region RS at an energy density of a degree where sputtering does not occur. Therefore, in the light source device, because sputtering in a light emission sealing body can be suppressed, a sufficiently long life can be realized.

A discharge lamp includes an emitter other than thorium, which is added to a cathode in a luminous tube. Early depletion of the emitter due to excessive vaporization of the emitter from the cathode is prevented, while achieving stable lighting even at the start-up of the lighting. A main body part (31) of the cathode (3) is made from a high-melting-point metal material that contains no thorium, and a front end part (32) thereof is made from a high-melting-point metal material that contains an emitter (other than thorium). A sintered compact (34), which contains an emitter (other than thorium) at a concentration higher than the emitter contained in the front end part (32), is buried in a sealed space (33) that is formed within the main body part (31) and/or the front end part (32). The sintered compact (34) abuts against the front end part (32).

A DC gas discharge lamp includes an anode and a cathode having a first cathode segment, which forms the surface of the cathode at least in a region of the cathode which faces the anode and has an arc attachment region, within which an arc burning between the cathode and the anode attaches during lamp operation as intended. The first cathode segment consists of tungsten with at least one emitter material for reducing the work function of electrons from the cathode. The cathode is embodied in a manner free of thorium. The at least one emitter material has a melting point of less than 3200 K. At least one part of the surface of the cathode outside the arc attachment region is formed by a diffusion barrier for the at least one emitter material.

An electrode (1) of a discharge device (e.g. the cathode of a discharge lamp) having a side area (4) and a tip area (5) implanted with an emissive material dopant induced by ion implantation is disclosed. The side area (4) of the electrode (1) may be masked (3) during ion implantation or a diffusion barrier layer (7) may be added on the side area (4) after ion implantation.