Abstract: A high pressure metal halide lamp comprises an outer envelope and an inner fused silica arc tube whose fill includes sodium iodide. Notwithstanding the use of a divided mount side-rod-less construction, the arc tube is subject to loss of sodium by electrolysis through the walls. The sodium loss is reduced by means of a collector wire within the outer envelope having a control potential thereon which shadows the current carrying lead wire in order to collect electrons that otherwise drift to the arc tube and promote electrolysis.

Abstract: A titania-silicate glass zone or layer is formed at the surface in fused silica by first applying a thick opaque polycrystalline titania powder coating to the silica and then fusing the coating into the silica at a high temperature. Such a zone reduces the ultraviolet transmission of the silica and also lowers its sodium ion conductivity. The zone may usefully be formed on the fused silica arc tubes of metal halide lamps in order to inhibit sodium loss and on other discharge lamps required to be ozone free.

Abstract: An improved electrode particularly suitable for operation at high current densities in vapor discharge lamps in which the pressure is upwards of 1 atmosphere. It comprises a porous matrix of refractory metal impregnated with a glassy emission material which becomes fluid or produces a fluid component at the operating temperature. The emission material comprises a low work function metal oxide and a glass forming component, preferred emission materials being lanthanum borate and lanthanum silicate.

Abstract: An electric incandescent lamp comprising an axially extending filament in a tubular vitreous envelope has improved filament supports of wire whose outer turns are formed as hexagonal loops comprising straight segments with angles between successive segments. The sharp bends at the angles decrease the springback and unwinding of the support when it is released from the mandrel, so that variations in support loop diameter with wire tension and size are reduced. The support may be fabricated through a new method and apparatus on a forming mandrel by engaging a wire in a slot in an exposed end face simulating a shallow helicoid. As the mandrel revolves, at least one full turn is wound around its periphery (which may be hexagonal) to form the outer envelope-engaging loop. The wire is then bent radially inwards at the shoulder of the projecting portion of the helicoid face to wind filament-engaging turns around the filament and wire mandrel which extend through an axially aligned aperture in the forming mandrel.

Abstract: A jacketed high intensity discharge lamp utilizes a starter electrode voltage doubling circuit comprising a diode and a mica-dielectric capacitor which is electrically interposed between an inlead into the jacket and the frame side rod and forms an integral structural part of the frame which supports the arc tube. The starter electrode is resistively connected to the side rod to facilitate starting and the arrangement maintains a positive D.C. bias on the frame which reduces electrolysis of sodium through the arc tube walls.

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.

Abstract: A prefocused single-ended lamp comprises a hollow ceramic base having an open side in which the lamp end is cemented and having three protrusions or bosses in the opposite side which is clamped to a fixture plate. The fixture plate provides six constraints to the bosses in order to fix the lamp in a stable kinematic mounting. The envelope is adjusted in the basing cement to place the lamp filament in a predetermined location and attitude relative to the fixture plate-engaging surfaces of the bosses. Such location and attitude are then reproducible with respect to similar fixture plates to an accuracy determined by the tolerance limits to which the fixture plates are machined.

Abstract: An improved thermal switch permitting large temperature excursions beyond the design closure temperature without stressing the switch material beyond its elastic limits. It combines a bimetal portion with a spring portion through which movement is transmitted, the former providing sufficient deformation for closure at design temperature, and the latter accommodating excess deformation beyond closure caused by high temperature. It is particularly useful in metal halide lamps having gas filled outer envelopes and requiring shorting of an auxiliary starting electrode to the adjacent main electrode during operation.

Abstract: A one-piece sheet metal base for a tubular lamp having pinch-sealed ends is adapted to be simply pushed onto the lamp end by hand. It comprises a flat portion having longitudinally extending side wall portions exceeding slightly in height the thickness of the pinch seal with inwardly turned underbeveled extensions which resiliently grip the pinch seal for frictional retention. A distal end wall portion has a forwardly turned lip adapted to overlie a pigtail attached to the inlead. Mitered corners on the underbeveled extensions and on the end wall provide a passage for threading the pigtail through the base.

Abstract: In arc discharge lamps containing a mixture of metals and halogen, and especially where an unvaporized excess of one metal is present, lamp color is very sensitive to end chamber shape. Color uniformity in production lamps using quartz arc tubes varying appreciably in diameter and wall thickness is greatly improved by molding end chambers of constant size and shape in the ends. The chamber may be formed at the time the end is pinched and the electrodes sealed in by using pinching jaws having a mold defining portion and momentarily pressurizing the arc tube to expand the heated and still plastic end into the mold. In production all lamps will have their ends expanded or belled to some extent, more in lamps close to the minimum diameter limit and less in lamps close to the maximum diameter limit.

Abstract: A metal vapor arc lamp having a filling including pyrolitically decomposing metal halides such as thorium iodide uses a loop electrode which allows the heat from the hot spot to flow in two directions. Such electrodes are less expensive to manufacture and, in an environment where the decomposing metal halide provides activation, they are less subject to deformation and consume less energy than conventional electrodes comprising shank plus overwind.