Abstract: The invention relates to a high-pressure discharge lamp of the ceramic metal halide type of the Philips MasterColor® series having power ranges of about 150 W to about 1000 W. Such lamps are provided with a discharge vessel which encloses a discharge space. The discharge vessel has a ceramic wall and is closed by a ceramic plug. An electrode which is located inside the discharge space is connected to an electric conductor by way of a leadthrough element. The leadthrough element projects through the ceramic plug with a close fit and is connected thereto in a gas-tight manner by way of a sealing ceramic. The leadthrough element has a first part which is formed by a cermet at the area of the gas-tight connection.

Abstract: A lighting system includes a fluorescent lamp 4 and a main body 1 for attaching the fluorescent lamp 4 thereto. The main body 1 is provided with a socket assembly 6 for the attachment of the fluorescent lamp 4, and an electronic ballast 7 for operating the fluorescent lamp 4 at dimmed levels (as well as at the full light level). The fluorescent lamp 4 is composed of a discharge tube formed of four U-shaped glass tubes that are connected together to form a square in plan view. Each glass tube has an inner diameter of 13.5 mm, and the discharge tube is filled with a rare gas containing neon and argon (at 50:50 ratio by volume).

Abstract: A metal halide lamp for an automobile headlight is provided, which includes an arc tube in which a pair of tungsten electrodes are provided at both ends and a metal halide as a main component of a luminescent material and xenon gas as a buffer gas are sealed, wherein the tungsten electrodes contain not more than 0.4 wt % of thorium oxide, the metal halide contains scandium iodide, and a pressure of the xenon sealed in the arc tube is at least 0.4 MPa. This makes it possible to provide a long-life metal halide lamp for an automobile headlight that can achieve a further improved lumen maintenance factor and other life characteristics during 2000 hours or more of lighting.

Abstract: A high-pressure mercury-vapor discharge lamp according to the present invention includes: an emission tube, which is made of quartz glass and which has a substantially ellipsoidal inner space; at least mercury and a rare gas, which are sealed in the inner space of the emission tube; and at least two electrodes, which are arranged in the inner space of the emission tube so as to face each other. The lamp satisfies W≧150 watts, P≧250 atm, t≦5 mm and rl≦0.0103×W−0.00562×P−0.316×rs+0.615×t+1.93, where W [watts] is the power of the lamp during its lighting operation, P [atm] is an operating pressure in the inner space of the emission tube, rs [mm] is the shorter radius of the inner space, rl [mm] is the longer radius of the inner space (where rl≧rs), and t [mm] is the thickness of a swollen portion that defines the inner space.

Abstract: A discharge lamp which maintains a high lumen maintenance factor even when operated for a long time is obtained in a discharge lamp which has a silica glass discharge vessel and a pair of opposed electrodes in the discharge vessel and in which the discharge vessel is filled with at least 0.

Abstract: A [thallium free] high pressure ceramic metal halide lamp having superior dimming characteristics with a fill composition including MgI2 and/or MgBr2.

Abstract: A light source with a sealed, light-transmissive tube filled with high pressure gases or high pressure gas mixtures and a microhollow cathode (MHC) discharge capable of excimer production are provided.

Abstract: A high-pressure discharge lamp comprises a lamp tube made of quartz glass and having a central portion formed in a spherical shape, and a pair of opposing tungsten electrodes inserted into the lamp tube. At least one of the tungsten electrodes is made of a tungsten material which contains more than 10 ppm of one of Co and Ni, or 10 ppm of Co and Ni in total, or a tungsten material which contains 20 ppm or more of at least two of Fe, Co and Ni in total, or a tungsten material which contains 20 ppm or more of Fe. Fe, Co and Ni belong to iron-group metals. The inter-electrode distance, i.e., distance between the leading ends of both tungsten electrodes is set to approximately 1-2 mm or less.

Abstract: A solid halogen-containing lamp fill material and a method of introducing small amounts of halogen into a HID lamp are disclosed. The solid material may include an admixture of a metal and a metal halide in the form of spheres of high purity, uniform size and uniform composition. Solid lamp fill material and methods of introducing small quantities of one or more metals into a HID lamp are also disclosed.

Abstract: To realize high irradiation efficiency and intensity stability for extending lifetime of the short-arc discharge lamp to be used for IC exposure apparatus or the like. For this end, mercury and rare gases are sealed in the inner space 21 of the discharge tube 1. The rare gases are a mixture of a relatively high molecular weight rare gas such as xenon, krypton, argon, etc. and 5%-40% by volume of a relatively low molecular weight rare gas such as helium, neon, etc. And pressure of the mixed rare gases is set to 2 atmospheric pressure or higher. The anode 3 comprises the columnar body portion 14, the tapered portion 13 and the flat portion 12.

Abstract: The object of the present invention is to provide a metal vapor discharge lamp offering a favorable performance in that it can restrain increase in metal vapor pressure inside the arc tube incident to the reduction in nitrogen gas in its outer tube, and so has smaller changes in life properties, than conventionally, when the lamp is illuminated.

Abstract: A mercury vapor discharge fluorescent lamp is provided that has a mercury barrier. The mercury barrier is effective to inhibit mercury atoms from absorbing into the glass envelope and amalgamating with sodium atoms in the envelope. The mercury barrier is substantially non-mercury absorptive, both when the lamp is on and when it is off.

Abstract: A low-pressure mercury-vapor discharge lamp is provided with a discharge vessel and a first and a second end portion (12a). The discharge vessel encloses a discharge space provided with a filling of mercury and an inert gas in a gastight manner. Each end portion (12a) supports an electrode (20a) arranged in the discharge space. An electrode shield (22a) encompasses the electrodes (20a) and, according to the invention, carries an electric current during operation, and is at a temperature ≧250° C., preferably ≧450° C., during nominal operation of the discharge lamp. Preferably, a first current supply conductor (30a) electrically contacts a first current divider (23a), which is electrically connected to a second current divider (23a′) via a shell-shaped body (24a).

Abstract: A glow starter comprises a discharge vessel, filled with a filling including a rare gas, substantially transmitting ultraviolet rays of about 300 nm or less. A pair of electrodes, which are arranged in the discharge vessel, is adapted and arranged to touch each other by being heated by a glow discharge. The glow starter may be used for a high pressure discharge lamp, a high pressure discharge lamp apparatus, or a lighting fixture.

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: The present invention is a microwave excited electrodeless bulb and a process of generating ultraviolet light with a microwave excited electrodeless bulb. A process of generating ultraviolet light with a microwave excited electrodeless bulb in accordance with the invention includes providing an electrodeless bulb (19) with an envelope (32) containing an ultraviolet emissive material which emits ultraviolet light in response to microwave excitation. The envelope is filled with an ultraviolet emissive material. The envelope has a major internal dimension (30) between ⅓ and ½&lgr; to which a strong field of the microwave excitation is coupled during emission of ultraviolet light with &lgr; being the free space wavelength of the microwave excitation which varies between 2.4 and 2.5 GHz. The strong field is produced by a microwave source having a steady state rated output power of no greater than 0.85 kW. The bulb is rotated at a rotational velocity of at least 20 revolutions per minute.

Abstract: The present invention is directed to a lamp assembly for use in a point-of-use water treatment system or other device. The lamp assembly includes a condensing element to condense mercury in a bulb within the arc path of opposing filaments when the bulb is de-energized. In one embodiment, the time required for the lamp assembly to produce light upon subsequent re-energization of the bulb is significantly reduced because the mercury is in the intermediate portion of the bulb, within the filament arc path.

Abstract: The invention relates to a high-pressure discharge lamp of the ceramic metal halide type of the Philips MasterColor® series having power ranges of about 150W to about 1000W. Such lamps are provided with a discharge vessel which encloses a discharge space. The discharge vessel has a ceramic wall and is closed by a ceramic plug. An electrode which is located inside the discharge space is connected to an electric conductor by way of a leadthrough element. The leadthrough element projects through the ceramic plug with a close fit and is connected thereto in a gas-tight manner by way of a sealing ceramic. The leadthrough element has a first part which is formed by a cermet at the area of the gas-tight connection.

Abstract: To realize high irradiation efficiency and intensity stability for extending lifetime of the short-arc discharge lamp to be used for IC exposure apparatus or the like. For this end, mercury and rare gases are sealed in the inner space 21 of the discharge tube 1. The rare gases are a mixture of a relatively high molecular weight rare gas such as xenon, krypton, argon, etc. and 5%-40% by volume of a relatively low molecular weight rare gas such as helium, neon, etc. And pressure of the mixed rare gases is set to 2 atmospheric pressure or higher. The anode 3 comprises the columnar body portion 14, the tapered portion 13 and the flat portion 12.

Abstract: A super-high pressure mercury lamp with an internal pressure during operation of one hundred and some dozen atm, which has a new arrangement in which in the hermetically sealed portions neither damage the lamp nor shortening its operating service life is achieved, in a high pressure mercury lamp in which a silica glass discharge vessel contains a pair of spaced apart, opposed electrodes and which is filled with a rare gas and with mercury in an amount of greater than or equal to 0.16 mg/mm3, and in which the wall load is greater than or equal to 0.

Abstract: The invention relates to a high pressure mercury lamp which is operated with an internal pressure at least equal to one hundred and some dozen atm and in which the thermal load and gas convection are considered. A fused silica glass discharge vessel is filled with mercury in an amount at least equal to 0.15 mg/mm3 and rare gas. The length of the electrode which projects into the discharge vessel and which is positioned at the top is greater than the length of the electrode which projects into the discharge vessel and which is positioned at the bottom. Where the lamp wattage is W (W) and the maximum value of the inside diameter in the direction perpendicular to the axis which extends between the pair of electrodes within the discharge vessel is D (mm), the following conditions are met: 0.35×(W)½≦L1≦0.69×(W)½ L2≦0.76×(W){fraction (1/2.64)} and at the same time (2.50)e0.0022W≦D≦(5.0)e0.0034W.

Abstract: The present invention provides a high pressure discharge lamp which is provided with a discharge tube containing a pair of electrodes therein and being filled with mercury, an inert gas and a halogen gas, the amount of the mercury filled being 0.12 to 0.35 mg/mm3, the halogen gas being at least one gas selected from the group consisting of Cl, Br and I and being present in an amount of 10−7 to 10−2 &mgr;mol/mm3, and the electrodes being mainly composed of tungsten, and the tungsten as a material of the electrodes contains not more than 12 ppm of potassium oxide (K2O). In such a high pressure discharge lamp, blackening of the discharge tube due to the potassium oxide (K2O) contained in the tungsten, and decrease in illumination maintenance can be prevented, thus providing a high pressure discharge lamp with a long lifetime, a lighting optical apparatus using the high pressure discharge lamp as a light source, and an image display system using the lighting optical apparatus.

Abstract: A metal halide lamp comprises a pair of electrodes and a discharge vessel filled with at least one metal halide comprising at least one rare earth metal halide, halogen in excess of the stoichiometry of the metal halide(s), mercury, and a rare gas. The amount of the mercury is between 7.7 mg/cc and 9.9 mg/cc, the excess halogen is 25-100% (in terms of atoms) of the halogen included in the metal halide(s), and the rated tube power for 200V rated tube voltage is 2000 W-3000 W.

Abstract: In a metal halide lamp which includes a discharge tube (2) retaining a fill of mercury and at least one metal halide added as a luminous material, an energy density of the arc discharge portion (3) represented by a product E.times.j is in the range of 70.0.ltoreq.E.times.j.ltoreq.150.0 (VA/mm.sup.3) where E=V/d, j=I/S, assuming that I is a lamp current in amperes with a lamp voltage of V volts applied between the paired discharge electrodes in a stable lighting condition of the lamp and that each of the electrodes has a tip face (1a, 1a') of which a cut area in section is S mm.sup.2 and the gap distance is d in millimeters, and thus a high luminous flux retention rate and high luminance of an arc discharge portion can be accomplished with a longer life of the lamp, suppressing a lamp voltage varying rate, and avoiding a change in color temperature, which remarkably improves additional merits when in utilization as a light source in various display apparatuses such as optical projection systems.

Abstract: A discharge lamp is provided with a tubular discharge vessel having an internal diameter of at most 5 mm, with a luminescent screen, and with a filling which comprises mercury and a rare gas. The rare gas comprises more than 98 mole % neon, and the luminescent screen comprises a first group and a second group of luminescent substances, which first group comprises luminescent substances for converting UV radiation generated by mercury into visible light, and which second group comprises luminescent substances for converting the UV radiation generated by neon into visible light. The discharge lamp has a comparatively high luminous flux immediately after ignition even in cold surroundings.

Abstract: A high pressure mercury lamp with an extremely high mercury vapor pressure and extremely high tube wall load in which the arc during operation is advantageously stabilized is achieved in a high pressure mercury lamp having a discharge vessel of fused silica glass which contains a pair of opposed tungsten electrodes, mercury in an amount at least equal to 0.16 mg/mm.sup.3 and a rare gas, and in which the discharge tube has a tube wall load at least equal to 0.8 W/mm.sup.2, by at least one metal halide with a metal having an ionization potential that is at most 0.87 times as high as the mercury ionization potential being added to the discharge tube in a range of from 2.times.10.sup.-4 to 7.times.10.sup.-2 .mu.mole/mm.sup.3.

Abstract: The high-pressure sodium discharge lamp of low power described here is chcterized by a very high xenon cold filling pressure of at least 1 bar. The pressure ratio to the sodium operating pressures lies between 10 and 30. Luminous efficacies of approximately 100 lm/W and more can be obtained with a lamp power of 50 to 100 W.

Abstract: A metal halide lamp in which the radiant efficiency is not adversely affected, in which outstanding color reproducibility is obtained, and which is suitable for a light source of an OHP or a direct projector is achieved, according to the invention, by the fact that, within an arc tube provided with a pair of electrodes, together with mercury and a starting rare gas, halides of dysprosium (Dy), yttrium (Y) and cesium (Cs) are encapsulated with the molar ratio of the encapsulated metals Dy to Y is being fixed in the range of 0.3.ltoreq.Dy/Y.ltoreq.1.0. In this way the green portion to which there is a sensitive visual reaction is reduced, the blue portion increased, and thus the color reproducibility is increased.

Abstract: A lamp for providing visible radiation includes tellurium or a tellurium compound in the fill. This substance is present in an amount such that when the fill is excited with sufficient power, substantially all of the radiation resulting from tellurium is emitted at wavelengths exceeding 400 nm. When tellurium is added to a sulfur or selenium based lamp for emitting visible radition, the spectrum is shifted towards the red region.

Abstract: A mercury lamp of the short arc type with high radiant efficiency which satisfies the demand for an increase of the radiation amount of the light source, by suppressing the motion of the bright spot in the vicinity of the cathode tip suppresses the flickering of the irradiance and thus increases the arc stability, is achieved in a mercury lamp of the short arc type in which within an arc tube mercury and at least one rare gas are encapsulated, by either at least Ar being filled as the rare gas at an filling pressure of from 1 to 8 atm, and by the current density in the tip area of the cathode being 10 to 250 A/mm.sup.2 or alternatively, at least Kr being filled as the rare gas at an filling pressure of from 1 to 8 atm, and the current density in the tip area of the cathode being 10 to 310 A/mm.sup.2 during operation of the lamp.

Abstract: An active matrix liquid crystal display (AMLCD) system is for use in avionic applications. The system includes an integral cathode fall indicator. The indicator relies on a gas fill mixture to provide an orange glow when the cathode fall region has an abnormally high potential across it. During normal operation, the gas fill mixture provides a light blue glow. The gas mixture includes helium, neon, argon, krypton, and xenon.

Abstract: High-pressure sodium vapor lamp with high color rendering including, in an arc tube of a light transmitting material formed in a substantially cylindrical shape sealed hermetically at both axial ends, a pair of electrodes disposed internally at both axial ends of the tube and xenon gas of at least 2.5.times.10.sup.4 (Pa) sealed in the tube together with sodium vapor, is so constituted that a lamp voltage upon lighting of the lamp and represented by V (V as a unit), lamp power represented by W (watt), internal diameter of the arc tube represented by .phi. (mm) and distance between the pair of electrodes represented by d (mm) will satisfy the following formulas:2.0.ltoreq.V/d.ltoreq.2.7 (1)and20.ltoreq.W/.phi..ltoreq.

Abstract: A low-pressure mercury vapor discharge lamp according to the invention is provided with a discharge vessel having a tubular portion and a first and a second end portion. The discharge vessel encloses a discharge space provided with a filling of mercury and a rare gas in a gastight manner. Each end portion supports an electrode which is arranged in the discharge space. Current supply conductors extend from the electrodes through the end portions to outside the discharge vessel. The tubular portion of the discharge vessel is provided with a metal oxide layer on a surface which faces the discharge space. The first and the second end portion are also provided with metal oxide layers at surfaces which face the discharge space. The lamp according to the invention has a comparatively low mercury consumption.

Abstract: A metal-halide discharge lamp for photo-optical purposes contains an ionisable fill, comprising mercury, at least one noble gas, at least one halogen, aluminum (Al) and indium (In) as well as gallium (Ga) in addition. By the addition of Ga, typically in the range between 0.02 mg/cm.sup.3 and 1 mg/cm.sup.3, a reduction in the starting voltage is attained, while maintaining an Ra>85 at color temperatures typically between 5000 K and 11000 K.

Abstract: A xenon light assembly having a gas filled glass tube bent into a suitable shape and mounted to a base pedestal material. A glass dome is sized and mounted to seal and fit over the glass tube and about the base pedestal to provide a weather seal for the glass tube and to provide a superior color filtration to the light produced by the lamp.

Abstract: A sodium containing lamp constructed to include of a fused quartz or fused silica arc chamber wherein the fused quartz and/or fused silica contains less than about 0.05 parts per million sodium. The arc chamber of the invention demonstrates a resistance to sodium diffusion resulting in a longer lived lamp with excellent color maintenance.

Abstract: A good discharge lamp which can emit light with wavelengths in the range of 220 nm in an amount sufficient for industrial applications and at the same time can adequately maintain a transmission factor of the radiant light and emits neither water nor hydrogen or the like during luminous operation is achieved by the fact that, in a discharge lamp in which a pair of electrodes are located adjacent to one another encapsulated within a quartz glass fluorescent tube together with mercury and an inert gas, the quartz glass contains an OH radical concentration of a weight of in the range of 300 to 800 ppm. Furthermore, the content of metallic impurities in the quartz glass is limited to a weight less than or equal to 1 ppm.

Abstract: A high-pressure metal halide lamp which is particularly suitable for inclon in optical systems is run at specific power between 100 and 180 W per mm arc length. The lamp includes, per cm.sup.3 chamber volume, between 0.3 and 3 .mu.mol dysprosium, hafnium and lithium respectively and between 0.2 and 2 .mu.mol indium, whereby luminance of between 25 and 75 kcd/cm.sup.2 can be generated at color temperature of between 4500 and 7000 K. Light spots with a diameter of about 4 mm and a color reproduction index Ra of 80 are achieved by means of a special reflector. This makes it possible to use the lamp in combination with thin glass-fiber bunches for illumination purpose, e.g. in endoscopy.

Abstract: A lamp for providing visible radiation includes tellurium or a tellurium compound in the fill. This substance is present in an amount such that when the fill is excited with sufficient power, substantially all of the radiation resulting from tellurium is emitted at wavelengths exceeding 400 nm. When tellurium is added to a sulfur or selenium based lamp for emitting visible radiation, the spectrum is shifted towards the red region.

Abstract: A high-pressure sodium discharge lamp provided with a ceramic discharge vessel, in which sodium, mercury and xenon are present, of which the xenon is at a pressure at 300K of at least 26.7 kPa. The sodium and the mercury are present in a weight ratio Na/Hg which is at least 0.075 and at most 0.125. The lamp generates in the operating condition a spectrum, in which at a wavelength of 589.3 nm a self-absorption band is present, which is limited by spectral flanks each flank having a respective maximum. There is a wavelength difference .DELTA..lambda. of at least 3.5 nm and at most 6 nm between the maxima.

Abstract: A metal halide lamp for producing high-intensity ultraviolet radiation contains an inert gas and a filler. The filler includes iodine and/or bromine in an overall concentration of from about 0.030-1.110 mg/cm.sup.3, mercury in a concentration of from about 0.318-5.250 mg/cm.sup.3, iron in a concentration of from about 0.005-0.036 mg/cm.sup.3, molybdenum in a concentration of from about 0.006-0.120 mg/cm.sup.3, and optionally, cobalt in a concentration of from about 0.0045-0.036 mg/cm.sup.3. The molybdenum is preferably introduced in the form of metal powder. The iodine and/or bromine is preferably introduced in the form of the corresponding mercury halides.

Abstract: An emission device which operates a cadmium lamp with a light intensity sufficient for used in industrial applications is achieved by an emission device having a cadmium lamp with a fluorescent tube within which a cathode and an anode are space a small distance apart and a buffer gas for easier initiation of luminous operation and metallic cadmium in an amount per unit volume of the fluorescent tube of 1.times.10.sup.-4 g/cm.sup.3 to 3.times.10.sup.-3 g/cm.sup.3 are encapsulated, and a power source device for supplying an electrical input between the cathode and the anode in an electrical input range from 0.5 kW to 5.0 kW with the condition:6.03+2.79 W.ltoreq.r.ltoreq.40being satisfied, where the electrical input of the power source device into the cadmium lamp in steady-state luminous operation is W (kW) and the maximum inside radius of the fluorescent tube is r (mm).

Abstract: An electric discharge lamp has a discharge vessel including pair of opposing planar seals each having a pair of major faces and a pair of minor, side faces. A containment shield surrounds the discharge vessel and includes a glass sleeve and a helically coiled wire secured on the glass sleeve. The glass sleeve is pinched to bevelled ends of the minor, side faces of the seals only and substantially does not engage the major faces of the seal. The wire is fixed around the sleeve in an electrically floating manner, e.g. by clamping fit. With the sleeve secured to the discharge vessel, MH quality photometrics are obtained with a tubular body arc tube without an end coat. The construction of the lamp is simple and effective to protect the outer bulb from being damaged by an explosion of the discharge vessel, and to prevent sodium from disappearing from the discharge vessel as a result of photoemission.

Abstract: A nearly pure neon is described along with a method of operating the lamp. A phosphor is coated on the lamp wall. By properly stimulating the neon, ultraviolet light may be emitted, that can stimulate the phosphor to a first light emission. The lamp may then be operated to produce a visible light emission that is the result of neon emission or of intermediate combinations of the neon and phosphor emissions. A single neon lamp may then produce in one instance, an amber color, or in other instance, a red color without the cold environment problems typical of a mercury based lamp. The output efficiency is enhanced when the lamp is formed as an aperture lamp. The narrow source is also useful as a source in reflector and lens systems. High pressure neon lamps offer a small source size, direct color with no filtering, good tolerance of impact and jarring, moderate cost, and increased vehicle styling potential.

Abstract: The high pressure metal halide lamp has in a light transmitting discharge vessel discharge electrodes and a filling made of a rare gas, a buffer gas and at least one halide chosen from hafnium and zirconium bromide and chloride. The filling also includes a metal chosen from tin, tantalum and antimony in elementary form and is free from iodine in an amount exceeding 0.5 .mu.mol/cm.sup.3 discharge space. The lamp has considerably improved light generating properties.

Abstract: The high pressure mercury discharge lamp comprises a quartz glass lamp vessel (1) having a region (2) surrounding a discharge space (3), spaced-apart tungsten electrodes (4) defining a discharge path (5) disposed in the lamp vessel, and connected to current conductors (6) which extend from the lamp vessel to the exterior and a filling of mercury, rare gas and bromine. The lamp has an operating pressure of at least about 200 bar. The discharge space (3) is spheroidal in shape and has specified dimensions. The lamp consumes a power of 70 to 150 W. The lamp has favourable properties which render the lamp suitable for use in optical systems, e.g. for projection purposes.

Abstract: The method of conducting a lighting operation of a metallic vapour discharge lamp, to maintain a suitable arc tube temperature, even if the lamp is operated at an input power higher than 160 W/cm of lighting length. A metallic vapour discharge lamp, in which mercury, rare gas, iron and halogen are encapsulated wherein an arc tube is used and which is operated with an internal pressure of 0.5 to 10 psi, an input power of higher than 160 W/cm of lighting length and within a heater having an air injection cooling system. The lamp characteristics are D.ltoreq.28 and simultaneously P/D.ltoreq.14, where the arc tube external diameter is designated D (mm) and the input power/cm of lighting length is designated P (W/m).

Abstract: A metal halide discharge lamp operated from a D.C. power source, which is suitable for an optical light source, has a quartz arc tube. Anode and cathode electrodes are disposed in the arc tube. The gap length between electrodes is so short that the metal halide discharge lamp functions as a point light source. The arc tube contains an inert gas, mercury and metal halide additives including metal bromine. By utilizing the catephoresis effects, the transformation of silica (SiO.sub.2) of the arc tube to cristobalite or the formation of an opaque substance on the arc tube is prevented. Atomic percent of bromine to halogen contained in the arc tube is about 60% to 90% and a wall load developed in the arc tube is substantially greater than 40 W/cm.sup.2.

Abstract: A high pressure discharge lamp having a discharge vessel with opposing end chambers includes discharge electrodes each consisting of an open elongate filament of refractory metal wire having a plurality of succesive coil turns extending transverse to the longitudinal axis of the discharge vessel. The filament electrodes are dimensioned so that the discharge arc which terminates thereon is sufficiently retracted into the end chamber of the discharge vessel so that the fill constituents condense on a region of the discharge vessel which is primarily axially between the filament electrodes. In a favorable embodiment, the lamp is a metal halide lamp in which the electrode and the discharge sustaining fill is free of thoria and its compounds.

Abstract: This invention relates to a high pressure sodium vapor discharge lamp the discharge space of which is enclosed by a ceramic vessel having hermetically sealed ceramic end members with electric lead wires connected with electrodes inside the discharge vessel and the discharge vessel contains sodium, noble gas, mercury in a concentration of 0-5 mg/cm.sup.3 and at least one further metal additive having a vapor pressure not exceeding 7.5 torr at 1000K temperature. The discharge lamp according to the invention is further characterized in that the molar fraction of sodium in the total metal additive exceeds 0.5 and the molar fraction of sodium is greater than four times the molar fraction of mercury.