Gte Laboratories Incorporated

Gte Products Corporation

Osram Sylvania Inc.

Alfred E Feuersanger

William H Rhodes

Paul O Haugsjaa

Carl F Buhrer

William H McNeill

Rodrigue Thibodeau

Robert J Regan

Charles Brecher

Leslie A Riseberg

Frank C Palilla

Carmine Persiani

Brian A Shortt

James P Drummey, Jr

Alumina arc tube sealing members including a highly pure, fine alumina doped with yttrium oxide, and magnesium oxide. The sealing members are used in the formation of sintered hermetic seals to a green, prefired, or fully sintered translucent alumina arc tube and niobium electrical feedthrough assemblies with or without the use of sealing frits or brazing alloys.

Sealing members for alumina arc tubes and method of making same

Sealing members for alumina arc tubes and method of making the same

A process for sealing of niobium-ceramic through-wall assemblies for ceramic or metal vessels for high temperature and high pressure or vacuum applications, for example an electrical feedthrough and sealable fill opening in an alumina arc tube for a high intensity discharge (HID) lamp. The process produces a fritless hermetic seal while maintaining the ductility of the niobium components. The niobium-ceramic through-wall assembly includes an axially bored alumina or yttria sealing means having a ductile niobium throughpiece close fitted to and extending through the bore. The throughpiece is preferably essentially pure niobium, but may contain up to about 2% zirconium. The assembly is fired at about 1400.degree.-2000.degree. C. in a pure oxygen- and hydrogen-free (&lt;5 ppm each) inert, preferably flowing, atmosphere or vacuum for a time sufficient to form a hermetic seal between the throughpiece and the sealing means. The fired assembly is then cooled to below 250.degree. C. while maintaining the pure inert atmosphere or vacuum. The end of the niobium throughpiece retains sufficient ductility after firing to permit pinching off of the end.

Niobium-ceramic feedthrough assembly

Niobium-ceramic feedthrough assembly and ductility-preserving sealing

A high pressure sodium lamp brightness was increased 8.9%, its relative voltage stability was improved by a factor of 4, and its relative maintenance was improved by a factor of 3 over a 24,000 hour lifetest. These improvements were accomplished by the application of a fine grained alumina protctive coating on the surface of the polycrystalline alumina arc tube. The process for applying the protective coating comprises the deposition of Al(NO.sub.3).sub.3 from solution on the surface of the arc tube followed by the thermal decomposition of the Al(NO.sub.3).sub.3 to form an alumina coating on the surface of the alumina arc tube.

Discharge lamps with coated ceramic arc tubes and fabrication thereof

The present invention relates to a dosing composition useful in high pressure sodium lamps. The invention relates specifically to new multicomponent alloy fills for HPS lamps and the design of such fills. The present invention provides an HPS lamp dosing composition that will supply the required amount of sodium and mercury for proper lamp operation, but which will have a lower vapor pressure during the sealing operation, such that mercury loss from the composition will be lower than that from the presently used sodium amalgam. In the present invention, either one of the compounds, Ti.sub.3 Hg or Zr.sub.3 Hg, is mixed with an intermetallic compound of sodium that has a melting point above about 600.degree. C., such that both the mercury and sodium metal are stabilized to avoid melting or vaporization at about 600.degree. C. The preferred sodium compound is Na.sub.3 Bi, which melts at 755.degree. C., although Na.sub.3 Sb and Na.sub.2 Te with higher melting points may be used. The dosing mixture for HPS lamps is preferably a mixture of Ti.sub.3 Hg and Na.sub.3 Bi.

Dosing composition for high pressure sodium lamps

This invention provides a method of electric current welding in a flowing inert gas atmosphere of an electric feedthrough assembly for an electric lamp, and an apparatus for performing such welds. The method and apparatus are well suited to welding refractory metals, e.g., a molybdenum-titanium-nickel alloy feedthrough body a tungsten electrode for use in an alumina arc tube of a high-pressure sodium lamp, and a molybdenum lead-in wire pin. When the tungsten electrode is inserted into a receiving cavity in the feedthrough body and appropriate pressure applied, the electrical resistance of the solid-to-solid rough interface is greater than that of either the electrode pin or feedthrough so that application of an appropriate electrical pulse causes melting to occur only in the immediate vicinity of the interface whereby extensive recrystallization of the feedthrough body does not occur. A welding electrode in the form of a plate having a thickness approximately equal to the insertion depth of the lamp electrode into the feedthrough body has a cylindrical hole into which the feedthrough body is mounted so that the electrical current applied during the welding process flows primarily radially through the feedthrough body whereby the feedthrough body is further protected against extensive heating during the welding process. Provision of welding electrodes of substantial mass and high thermal conductivity draws heat from the feedthrough during and after the weld so that the feedthrough body is further protected from extensive heating.

Method of welding a lamp feedthrough assembly; and apparatus therefor

A vacuum-tight assembly, such as a discharge tube for a sodium vapor arc lamp, includes a high density polycrystalline ceramic body, such as alumina or yttria, having a cavity, at least one closure member, and a sealing material. The closure member is formed from a molybdenum-titanium alloy containing a small amount of nickel, cobalt, or copper. The nickel, cobalt, or copper forms a relatively low melting eutectic with titanium, thereby facilitating fabrication of closure members by sintering. The closure member and the sealing material have thermal coefficients of expansion closely matched to the thermal coefficient of expansion of the ceramic body over a wide temperature range.

Vacuum-tight assembly

A light source including two high intensity discharge devices, such as metal vapor discharge tubes, electrically coupled in parallel to provide fast restart and immediate illumination after a momentary power interruption. Upon application of power, one of the discharge devices starts and operates while the other discharge device remains below its maximum starting temperature and in readiness for immediate restart. The discharge devices can be enclosed by a common outer envelope. The discharge devices can alternatively be high pressure electrodeless lamps coupled in parallel to provide fast restart.

High pressure discharge lamps with fast restart

An electromagnetic discharge apparatus has a power coupling fixture which couples power to both ends of an electrodeless discharge vessel and produces a substantially uniform arc. Power can be coupled to the fixture from two high frequency power sources or can be coupled from a single high frequency power source by using a power divider. If power is coupled to the electrodeless discharge vessel from a single source, power transfer to the vessel is optimized when the electrical length of the circuit is an integral number of wavelengths. In an alternative embodiment, a second coupler is utilized in a conventional electrodeless light source to shape the electric fields and produce a more uniform arc.

Electromagnetic discharge apparatus with double-ended power coupling

Improved efficacy is obtained in an electrodeless light source of the type having a high frequency electrodeless lamp disposed at the ends of inner and outer conductors of a termination fixture by evacuating the region between the lamp envelope and the outer conductor to reduce conductive and convective heat losses.

Electrodeless light source with reduced heat losses

A bonded bubble memory device includes a non-magnetic first substrate, a thin film layer of magnetic material located on a planar surface of the first substrate, the layer being adapted to sustain cylindrical wall magnetic domains, a second substrate made of a non-magnetic and non-conductive material, a desired pattern of magnetic elements and electrically conductive elements deposited on a planar surface of the second substrate, the pattern including at least three spaced points, the heights of which are equal and predetermined, the thin film layer on the first substrate being in contact with the spaced points on the second substrate so that a controlled spacing is maintained between the thin film layer and the pattern of magnetic elements. A cement composition is applied to portions of the space between the substrates to hold the substrates in a juxtaposed orientation. Advantageous methods of producing the device are also described.

Bonded magnetic bubble memory

In a magnetic domain memory, a domain detector system includes a passive domain splitter in a domain propagation track, a first detector in the propagation track for detecting one of the domains from the splitter, and a second detector in an auxiliary propagation track which extends from the splitter, the detector outputs being combined to enhance the total output signal. The relative angular orientation of the detectors may be varied to provide any desired signal shaping. The passive splitter has features which ensure reliable domain splitting characteristics.

Growing community of inventors

Framingham, MA, United States of America

Alfred E Feuersanger