Abstract: A discharge lamp includes a coaxial waveguide for high-frequency electromagnetic wave transmission and a discharge tube for emitting light of discharge by plasma generated by electromagnetic waves. The coaxial waveguide includes an internal conductor and a pipe-shaped external conductor surrounding the internal conductor. The discharge tube is attached to a top of the coaxial waveguide, and is constructed in a double end shape in which both ends of a glass tube are pinched and sealed. The glass tube includes an ellipse spherical bulged part formed in a middle of a longitudinal direction. An inside of the ellipse spherical bulged part forms discharge space. A conductor assembly is sealed and attached to at least a proximal side pinch seal part. The proximal side pinch seal part of the discharge tube is inserted and held in a top opening of the coaxial waveguide.

Abstract: A high-frequency discharge lamp includes a coaxial waveguide including an internal conductor and a pipe-shaped external conductor surrounding said internal conductor, and a discharge tube including a ceramic or glass tube having an approximately ellipse spherical bulged part formed in a middle of a longitudinal direction, and both ends pinched and sealed; a conductor assembly sealed and attached to an end of the ceramic or glass tube; and an auxiliary electrode for starting disposed near the approximately ellipse spherical bulged part. A rare gas for starting with 1 atmospheric pressure or more at room temperature together with a light emission substance is enclosed inside of the approximately ellipse spherical bulged part. The discharge tube is inserted conductor assembly end first and held in a top opening of the coaxial waveguide. A high-voltage pulse generated by a high-voltage pulse generator is applied to the auxiliary electrode through a pulse transmission line.

Abstract: A discharge bulb is equipped with an arc tube in which discharge electrodes are provided face to face and a luminescent material is filled together with a starting rare gas inside a ceramic tube. A metallic pipe is jointed into the pore of a tube end communicating with a discharge light emitting chamber. The rear end of an electrode rod inserted into the pipe is jointed to the pipe and its tip protrudes into the discharge light emitting chamber. A recess is circumferentially arranged on the inner peripheral surface of the pore between the tip of the pipe and the discharge light emitting chamber. The coldest point is in the recess so that a metal halide is not gathered in the micro-space and the metal halide contributing to discharge light emission does not decrease thus obtaining a desired luminous flux.

Abstract: In the transient electric power control of a discharge lamp containing no mercury or a small amount of mercury, a change value relating to a lamp voltage from the initial value thereof is detected. A control unit is provided to change the temporal change rate of electric power supplied to the discharge lamp during the transient time period in accordance with the increase of the change value or the time lapse.