Abstract: A discharge lamp has a discharge vessel for generating an arc discharge between two electrodes. The discharge vessel contains an inert gas, and metal halides. The lamp further comprises an outer envelope surrounding the discharge vessel. The outer envelope is made of transparent material containing Potassium in a maximum concentration of 10 ppm by relation to the weight. The metal halides are contained in the discharge vessel in an amount of 3-6 ?g/?l of the inner volume of the vessel, preferably 5±0.5 ?g/?l. The lamp exhibits an improved long term lumen maintenance and may have a physical lifetime exceeding 4000 h net burning time.

Abstract: A discharge lamp has a discharge vessel for generating an arc discharge between two electrodes. The discharge vessel contains an inert gas, and metal halides. The lamp further comprises an outer envelope surrounding the discharge vessel. The outer envelope is made of transparent material containing Potassium in a maximum concentration of 10 ppm by relation to the weight. The metal halides are contained in the discharge vessel in an amount of 3-6 ?g/?l of the inner volume of the vessel, preferably 5±0.5 ?g/?l. The lamp exhibits an improved long term lumen maintenance and may have a physical lifetime exceeding 4000 h net burning time.

Abstract: A discharge lamp is disclosed comprising an enclosed discharge vessel for the generation of an electrical discharge and a casing made of glass which surrounds the discharge vessel. In order to achieve as constant properties as possible over the service life of the lamp, it is proposed that the glass material of the casing be doped with sodium in a concentration of at least 10 ppm, and preferably at least 30 ppm. According to a further embodiment, it is proposed that other alkali metals (except for sodium) be contained in a maximum concentration of 25 ppm. Surprisingly, by the appropriate choice of the outer bulb, not in direct contact with the actual discharge, the diffusion of sodium from the discharge vessel is reduced. In addition to this, the material of the outer bulb has a reduced inclination to crystallization.

Abstract: Tungsten electrodes are arranged on two rhenium rods in an electrode chamber in a high-pressure gas discharge lamp, such that the rhenium rods project to inside the electrode chamber.

Abstract: The high-pressure discharge lamp comprises a sealed lamp vessel (1) having a quartz glass wall (2) enclosing a discharge space (3). Metal foils (4) are embedded in the wall, connected to electrode rods (6) projecting from the wall into the discharge space. The electrode rods (6) have a first part (7a) and a second part (7b) with a diameter of between 250 and 350 &mgr;m and at least an envelope (7c) made of rhenium. The second part, which is positioned within the wall (2), prevents premature failure of the lamp caused by leakage.

Abstract: A discharge lamp is disclosed comprising an enclosed discharge vessel for the generation of an electrical discharge and a casing made of glass which surrounds the discharge vessel. In order to achieve as constant properties as possible over the service life of the lamp, it is proposed that the glass material of the casing be doped with sodium in a concentration of at least 10 ppm, and preferably at least 30 ppm. According to a further embodiment, it is proposed that other alkali metals (except for sodium) be contained in a maximum concentration of 25 ppm. Surprisingly, by the appropriate choice of the outer bulb, not in direct contact with the actual discharge, the diffusion of sodium from the discharge vessel is reduced. In addition to this, the material of the outer bulb has a reduced inclination to crystallization.

Abstract: A high-pressure metal halide discharge lamp has opposed tungsten electrodes carried by electrode rods. These rods have a first portion of tungsten adjacent the electrodes and a second portion made of at least 25% by weight of rhenium. Their common boundaries are at a location having an operating temperature in the range of 1900-2100° K. The gas filling contains metal oxyhalide and is devoid of rare earth metal compounds.

Abstract: The high-pressure metal halide discharge lamp has opposite tungsten electrodes (5) carried by electrode rods (7). These rods (7) have a first portion (71) of tungsten adjacent the electrodes (5) and a second portion (72) having a core of tungsten and a skin of at least 90% by weight of rhenium. Their common boundaries are at a location having during operation a temperature in the range of 1900-2100 K. The gas filling contains metal oxyhalide and is devoid of rare earth metal compounds. The lamp has a long life and a high luminous maintenance.

Abstract: A thin-film solar cell in which between a TCO layer and a p-doped layer an n-doped intermediate layer is provided and at least the intermediate layer or the neighboring p-doped layer is composed of a microcrystalline material, especially microcrystalline SiC or SiO.

Abstract: Apparatus and method for detecting geological anomalies occuring in geological formations. The instrumentation comprises a medium frequency continuous wave narrowband FM transmitter and receiver pair. Two instrument configurations are downhole instruments for insertion into boreholes. Survey procedures are provided to detect anomalies through signal attenuation, path attenuation and signal phase shift. Continuity measurements at different depths in the drillholes provide data to determine the existence of anomalies. Tomographic techniques are employed to provide a visual image of the anomaly. Computer aided reconstruction techniques provide such visual images from the generated data.