Abstract: High pressure sodium arc vapor discharge lamps employing an alumina arc tube exhibit less voltage rise and better lumen maintenance over the life of the lamp when the arc tube is coated with an oxide of a metal selected from the group consisting essentially of yttrium, zirconium, hafnium, lanthanum, dysprosium, scandium and mixture thereof.

Abstract: Increased optical transmission is provided for a body of optically transparent polycrystalline alumina by coating at least one major surface of said alumina body with a solid glaze coating and subsequently melting said coating at elevated temperatures to dissolve the surface alumina grains in physical content therewith to provide a smoother surface when the coating residue has been removed. More particularly, a solid glaze coating is first deposited on said major surface of the alumina body and the coated alumina body thereafter heated to sufficiently elevated temperatures for the glaze liquification whereupon surface alumina grains in physical contact therewith are dissolved in a manner which reduces the high spots on the individual surface alumina grains without materially introducing low spots at the grain boundaries and wherein the individual alumina surface grains have been preferentially etched in certain of the crystalline axis directions.

Abstract: Increased optical transmission is provided for a body of optically transparent polycrystalline alumina by coating at least one major surface of said alumina body with a solid glaze coating and subsequently melting said coating at elevated temperatures to dissolve the surface alumina grains in physical content therewith to provide a smoother surface when the coating residue has been removed. More particularly, a solid glaze coating is first deposited on said major surface of the alumina body and the coated alumina body thereafter heated to sufficiently elevated temperatures for the glaze liquification whereupon surface alumina grains in physical contact therewith are dissolved in a manner which reduces the high spots on the individual surface alumina grains without materially introducing low spots at the grain boundaries and wherein the individual alumina surface grains have been preferentially etched in certain of the crystalline axis directions.

Abstract: A high pressure sodium lamp having an inner arc tube operated at an increased wall temperature so as to improve the efficacy of the lamp is disclosed. The improved high pressure sodium lamp has an arc tube which reduces the sodium losses typically experienced by high temperature operation. Also disclosed are desired parameters of the arc tube.

Abstract: An electrode structure for sodium vapor lamps is disclosed having molybdenum metal wire coils wound around a tungsten shank to replace the customary all-tungsten electrode structure in these lamps. The improved electrode structures provide increased initial lumens with acceptable lumen maintenance.

Abstract: An improved end closure for a tubular light-transmitting ceramic envelope used in sodium vapor lamps is disclosed which comprises assembly of a ceramic disc fitted into one end of a metal sleeve having a different diameter opening at its opposite end for circumferential engagement with the arc tube inserted therein with all of the assembled members being hermetically sealed together by a ceramic sealing frit. The improved end closure permits thermionic electrodes to be inserted through openings in the ceramic discs with said electrodes being hermetically sealed at said openings with additional ceramic sealing frit.

Abstract: An improved high pressure sodium vapor lamp is described having resistance heater means contained within a tubular light-transmitting ceramic envelope that further contains a reservoir of sodium-mercury amalgam in excess of the quantity vaporized during lamp operation and which are supplied by electric current other than the lamp current responsive to a rise in the lamp operating voltage to reduce the quantity of amalgam being vaporized during lamp operation to help maintain said lamp operation at a relatively constant voltage. In a preferred embodiment, said resistance heater means comprises a refractory metal coil wound around the tungsten shank at one thermionic electrode and electrically insulated therefrom, with said thermionic electrode including a tubular metal inlead serving as the amalgam reservoir, and with the electric current being supplied at a lower value to said refractory metal coil than being supplied to said thermionic electrode.

Abstract: An improved high pressure sodium vapor lamp is described having resistance heater means contained within a tubular light-transmitting ceramic envelope that further contains a reservoir of sodium-mercury amalgam in excess of the quantity vaporized during lamp operation in order to heat the ceramic envelope before lamp starting and thereby reduce the starting voltage requirements. In the preferred embodiment, said resistance heater means comprises a refractory metal coil wound around the tungsten shank of one thermionic electrode and electrically insulated therefrom and which is supplied with lower current than is subsequently applied to said electrodes for the lamp operation.

Abstract: An improved high pressure sodium vapor lamp is described having resistance heater means contained within a tubular light-transmitting ceramic envelope that further contains a reservoir of sodium-mercury amalgam in excess of the quantity vaporized during lamp operation in order to increase the quantity of amalgam being vaporized during lamp operation and thereby help maintain the desired lamp color temperature. In a preferred embodiment, said resistance heater means comprises a refractory metal coil wound around the tungsten shank of one thermionic electrode and electrically insulated therefrom with said thermionic electrode including a tubular metal inlead serving as the amalgam reservoir.

Abstract: A high pressure alkali metal vapor lamp envelope of alumina ceramic having wire inleads sealed into opposite ends and no external amalgam reservoir, has an internal amalgam retention compartment for reducing sensitivity to shock and vibration. The compartment is formed by a metal partition substantially coextensive with the end wall and spaced from it a distance within the range of capillary attraction for the amalgam used. A preferred construction uses for the partition an apertured niobium disc fitting snugly in the alumina arc tube.

Abstract: An improved sealing composition for use between alumina ceramic parts, or between alumina ceramic and refractory metal, is based on 47 weight percent Al.sub.2 O.sub.3, 37 weight percent CaO and 16 weight percent BaO. Up to 3 weight percent B.sub.2 O.sub.3 may be added for improved wetting and flow characteristics. The composition has a lower liquidus temperature (1325.degree. C.) than an otherwise similar one previously used which included 5% MgO, and its thermal expansion coefficient is less affected by dissolved Al.sub.2 O.sub.3. As a result, a closer thermal match with alumina ceramic can be maintained during seal processing and the rejection rate is reduced.

Abstract: A coating of zirconium is bonded to niobium by applying to the niobium a paint of Mo and Zr powder which is fired above 1520.degree. C but below the zirconium-niobium liquidus temperature of 1740.degree. C. Such coating is used in making an improved seal by juxtaposing the metal body to the ceramic body, applying a powdered alumina sealing glass or frit and firing to the melting temperature of the frit.

Abstract: A high pressure alkali metal vapor lamp envelope of alumina ceramic has an end closure which includes an externally projecting thin-walled metal tube serving as in inlead and as a reservoir for excess alkali metal. An electrode is mounted on a tungsten shank which projects into the metal tube and is locked in place by crimping the tube about it externally of the envelope. The crimping leaves restricted channels which allow passage of the alkali in vapor form but prevent its movement as a liquid.

Abstract: A metal vapor arc lamp comprises an alumina ceramic arc tube having an end closed by an apertured ceramic plug sealed by sealing frit. A metal lead wire extending through the aperture is also sealed therein by sealing frit and supports an electrode within the arc tube. A cross wire attached to the inlead immediately above the plug forms a wick equalizing the distribution of sealing frit between the plug seal and the inlead seal and also serves as a hanger for supporting the plug and electrode assembly in the arc tube during sealing.

Abstract: A high pressure sodium vapor lamp utilizing an alumina arc tube within an outer envelope has a getter structure comprising a niobium portion operating in a high temperature range and a titanium portion operating in a lower temperature range. The niobium portion includes a connection extending from a niobium end closure structure of the arc tube to the titanium portion. The titanium portion may form one of the lead supports within the outer envelope or it may merely extend along one of the lead supports. This eliminates the need for the conventional barium getter flash which tends to coat the outer envelope and absorb light.

Abstract: The adherence of an optically reflective coating of refractory metal oxide particles such as ZrO.sub.2 or Al.sub.2 O.sub.3 on a fused silica discharge tube surface is improved severalfold by an adhesion layer consisting of colloidal aluminum oxide and boric oxide powders. The adhesion layer may be first applied and dried, the refractory metal oxide coating then applied, and the quartz tube then heated to a temperature greater than 460.degree. C., the melting point of boric oxide. The refractory metal oxide particles may also be applied admixed with the colloidal aluminum oxide and the boric oxide. The improved coating strength permits the use of a thicker layer of refractory metal oxide for higher optical and thermal reflection.

Abstract: A metal vapor arc lamp comprises an alumina ceramic arc tube having an end sealed by an apertured ceramic plug. A metal lead wire extending through the aperture is sealed therein, and supports an electrode within the arc tube. Thermal isolation of the lead wire seal from the electrode is necessary and is achieved by providing a loop in the supporting conductor intervening between the electrode and the lead wire seal region.

Abstract: A high intensity sodium vapor lamp comprises a tubular envelope of alumina ceramic provided with end closures and containing a charge of sodium mercury amalgam in excess of that vaporized during operation. One closure includes a refractory metal tube sealed off at its tip and wherein unvaporized excess of amalgam collects as a liquid pool. In order to have a sufficiently high temperature at the amalgam pool, a metal slug of high heat conductivity such as molybdenum is placed in it and extends from the seal region towards the tip. Such slug also prevents overheating the seal between the ceramic tube and the end cap.