Abstract: A low wattage metal halide discharge lamp includes an evacuated envelope wherein is disposed a heat reducing member having an arc tube therein. The heat reducing member and the arc tube have a metal band an outer strap member adjacent one another and adjacent an electrode with the metal band, strap member and electrode all electrically connected to an electrical lead of one polarity whereby sodium losses from the arc tube are reduced. Importantly, the evacuated envelope includes a getter and the heat reducing member is in the form of a domed sleeve having an open end directed away from the getters.

Abstract: A low wattage single-ended metal halide arc discharge lamp has an isothermal arc chamber with an outer diameter (t) substantially equal to the product of a first constant and the lamp wattage plus a second constant; a fill gas and a pair of electrical conductors sealed into and passing through one end of the arc chamber to provide a pair of electrodes therein having a spacing therebetween of about a distance to provide a substantially uniform current for lamps in the range of about 35 to 150 watts.

Abstract: A high intensity discharge lamp includes a hermetically sealed outer envelope having an arc tube therein containing a fill gas which includes sodium and having a wall member with a portion of increased thickness wherein the portion of increased thickness of the wall member of the arc tube is positioned adjacent to a metal conductor disposed within the outer envelope whereby loss of sodium from the arc tube is inhibited.

Abstract: A metal halide arc discharge lamp having a gaseous fill within the outer envelope and means for suppressing convection currents within such fill; and methods of operating and constructing such lamps. A light-transmissive sleeve or enclosure surrounding the arc tube laterally and about at least one end thereof is so shaped and mounted with respect to the arc tube as to insure that the Rayleigh Number, a quantitative measure of convective flow, in the atmosphere laterally surrounding the arc tube will be less than 5.times.10.sup.4 during operation of the lamp whereby excessive convective heat loss in such lamp will be effectively suppressed.

Abstract: A metal halide arc discharge lamp having a gaseous fill within the outer envelope and means for suppressing convection currents within such fill; and methods of operating and constructing such lamps. A light-transmissive sleeve or enclosure surrounding the arc tube laterally and about at least one end thereof is so shaped and mounted with respect to the arc tube as to insure that the Rayleigh Number, a quantitative measure of convection flow, in the atmosphere laterally surrounding the arc tube will be less than 5.times.10.sup.4 during operation of the lamp whereby excessive convective heat loss in such lamp will be effectively suppressed.

Abstract: A miniature, low-wattage, discharge lamp operable on direct current employs substantially parallel electrodes sealed in a single press seal. The electrodes are configured to provide an arc which is substantially parallel to the longitudinal axis of the lamp with the cathode being substantially longer than the anode. Heat generated at the anode is dissipated through the seal to the cathode allowing the cathode to operate hot enough to be stable. The chemical fill for the lamp employs a mol ratio of thorium to cesium to permit good light output and good color rendition.

Abstract: A D.C. operable, miniature, low-wattage, single ended, arc discharge lamp. The cathode electrode includes electrical field modifying means to insure that the arc strikes between the electrode tips. During high pressure (.about.10 atm) operation electrode heating of the anode is dominated by electron bombardment, which creates substantially higher heat at the anode tip than at the cathode tip (the cathode being heated by ion bombardment and cooled by thermionic electron emission). Heat conducted down the anode electrode is dissipated in the single press and contributes to the heat conduction in the closely adjacent cathode electrode thereby reducing the net heat loss therein and helping to maintain the desired cathode temperature.

Abstract: A projection lamp comprises a single-ended metal halide arc discharge lamp disposed within a curved reflector and an interference filter disposed in front of the reflector, the filter being highly transmissive of visible light and reflective of radiation for which the metal halide, in molten salt form, is highly absorptive.

Abstract: A shield is disposed about the electrode of a metal halide arc discharge lamp in order to improve lamp performance. The construction and location of the shield are such as to not lower the cold-spot temperature of the arc tube.

Abstract: A single ended, low-wattage, high pressure, metal vapor discharge lamp includes first and second main electrodes and an auxiliary electrode resistively coupled to one of the main electrodes. The lamp provides a glow region remote from the main arc region and keeps wall blackening confined to areas remote from the main arc region. The lamp starts easier and minimizes detrimental glow time.

Abstract: A low wattage metal halide arc discharge lamp has a press seal at one end thereof with two main electrodes sealed therein. The ratio of the distance from an electrode tip to the nearest arc tube wall over the arc length is greater than 0.4.

Abstract: A high intensity discharge device operable in any orientation employs electrodes whose major portions are parallel and whose minor portions converge toward each other. The converging minor portions can be loops of electrode material.

Abstract: A single ended, short arc, low wattage, high pressure, metal vapor discharge lamp is electrode stabilized and employs arc constrictors selected from the group of lanthanides, actinides and thorium to provide a brightness of 175,000 cd/in.sup.2 when operated at 75 watts.

Abstract: A single ended metal halide arc discharge lamp contains mercury, sodium halide, scandium, scandium halide and a starting gas. The molar ratio of sodium halide to scandium halide is between about 5 to 8 in order to obtain optimum luminous efficacy.

Abstract: A high pressure arc discharge lamp comprises an elongated arc tube disposed substantially axially within a concave shaped outer jacket.

Abstract: An electrode for a metal halide arc discharge lamp comprises a coiled coil on a tungsten rod, the rod diameter being equal to W.sup.0.56 /0.784 mils, where W is the input power to the lamp in watts. The primary wire for the coiled coil equals D.sup.1.8 /80.8, where D is the rod diameter in mils, and is equal to half the diameter of the mandrel wire of the coiled coil.

Abstract: In a metal halide arc discharge lamp having an arched arc tube with an electrode at each end thereof, each electrode is located about midway between the arc tube lower wall and the axis of the arc tube.

Abstract: The emitter material on the electrode of a high intensity discharge lamp comprises hafnium oxide, barium oxide and calcium oxide.

Abstract: In a metal arc discharge lamp having a high silica glass arc tube, the arc tube ends are coated with a heat reflective coating from a suspension contaning zirconium dioxide and zirconium diboride, the ratio of the two being between about 30 to 1 and 250 to 1.

Abstract: A thin foil of hafnium or a hafnium alloy is disposed within a high pressure metal halide discharge lamp for selectively gettering any hydrogen contaminant within the lamp. In one embodiment a long strip of hafnium foil is welded along the current return wire which extends from the remote end of the arc tube to the base of the lamp, while in another embodiment, bowed-out strips are welded to support straps on each of the arc tube press seals. In this manner, a significant portion of the hafnium getter is disposed in a location where it is subjected to operating temperatures lower than about 330.degree.C.