Abstract: An electrode for a miniature high pressure metal vapor lamp comprises a slender tungsten shank joined to a molybdenum inlead by a weld knot. The shank diameter is chosen above the size where melt-back starts at the intended lamp current and is provided wth a fine wire overwind fitting loosely thereon and retained in place by frictional engagement with the weld knot. The overwind reduces breakdown voltage and assures rapid glow-to-arc transition.

Abstract: A system for handling hygroscopic metal halide pellets serving as fill material in high pressure metal halide lamps. The pellets are loaded into stoppered transport vials at their place of manufacture. At the place of utilization, the stoppered end of the vial is inserted into a self-sealing opening in a reservoir through which dry gas is flushed to remove any contaminants. The vial is then unstoppered without removing it from the opening and its contents spill out into the reservoir. A transfer device accommodating a set number of pellets is brought into conjunction with an outlet opening, the device is filled, and the pellets transported to their destination through a channel filled with dry gas.

Abstract: A mercury doser for automatically and accurately dosing arc tubes at high production rates comprises a rotatable stainless steel metering plate sandwiched between tetrafluoroethylene discs. The plate contains a graduated series of metering cavities of which one is selected. Mercury is fed by gravity into the selected cavity at a loading position where any trapped air or gas escapes through a vent port. The port is so small that surface tension prevents entry of the mercury. The plate is then advanced to an unloading position where a puff of argon gas expels the mercury charge into a delivery channel.

Abstract: An improved mounting of the ceramic arc tube on a support rod attached to one lead-in within an outer vitreous envelope allows for thermal expansion. The inlead at one end of the arc tube is fastened to the support rod which serves also as conductor, while that at the other end extends through an insulating bushing supported from the rod and is connected by a curved flexible conductor to the other lead-in of the outer envelope. Differential thermal expansion is accommodated by sliding of the inlead through the bushing and flexing of the curved conductor.

Abstract: The inlead for the electrode sealed into a quartz arc tube has a foil portion which is stiffened by reversely folded lateral edges. The folds overlap the tapering region of greater stiffness where the foil portion joins the end portions. In making a discharge lamp, the electrode-inlead assembly is self-centering as a result of making the overall width of the foil portion and its folded edges exceed slightly the internal diameter of the quartz tube or neck. The frictional engagement between the folded edges and the inside wall of the neck retains the assembly in place while the neck is heat-collapsed onto the foil to seal the electrode assembly in place.

Abstract: Polycrystalline alumina tubing is scribed by means of laser pulses which are reiteratively focused on the same spots at spaced time intervals. By drilling small holes, the laser need be on for a very short period of time only, and only the surface layers are vaporized, thereby minimizing heat shock. The holes are deepened by repeating the series of pulses and directing them sequentially into the same holes. For tubing, an encoder is used which senses the angular position of the tubing as it is rotated and causes the laser to deliver pulses at the same angles at every revolution. When the holes have been sufficiently deepened, the tubing is snapped and breaks clean in the plane of the holes.

Abstract: Highly purified metal halide salts are made into a frangible stick having uniformly spaced lines of weakness which permit the stick to be broken readily into cylindrical pellets of uniform size. The pellets are particularly useful to supply the vaporizable fill in high intensity metal halide discharge lamps. The stick is formed by intermittently loading salt powder into the sized entrance to a channel through which the salt is forced, and compressing the charge against the back end of previously formed salt stick by means of a polished plunger.

Abstract: The inner arc tube of some jacketed discharge lamps transmits ultaviolet radiation which is normlly intercepted by the glass outer envelope. To prevent harmful release of such radiation in the event the outer envelope should be shattered, a mechanical disconnect is provided in the interenvelope space comprising a springy conductor fastened to a conductive support and compressed between the outer envelope and an arc tube inlead. Upon fracture of the outer envelope, the conductor straightens out whereupon the circuit is opened and the arc tube is disabled.

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 seal into a fused silica envelope comprises a refractory metal wire extending through an aperture in a fused silica neck leading into the envelope. A bead of glass having a coefficient of expansion intermediate those of the refractory metal and of the fused silica is formed around and wets the wire inlead. A hermetic seal is achieved by causing fused silica from the neck to shrink around the bead and be wetted by it, forming an annular sealing zone spaced out from the wire inlead. The wire may be of tungsten in which case the electrode and inlead may be of one piece without a joint.

Abstract: Miniature metal vapor arc lamps containing mercury and one or more metal halides are subject to severe blackening of the arc tube and poor lumen maintenance unless a high pressure of starting gas is used. A Penning mixture of neon admixed with 0.01 to 10% argon, krypton or xenon at a fill pressure from about 100 to 200 torr provides lower starting voltage together with better lumen maintenance than can be achieved with the conventional argon starting gas.

Abstract: An improved sealing composition for use between alumina ceramic parts, or between alumina ceramic and refractory metal, is based on 40 wt% Al.sub.2 O.sub.3, 35 wt% CaO, 15 wt% BaO and 10 wt% SrO, and has an average thermal expansion coefficient of 95.times.10.sup.-7 /.degree.C. between 25.degree. C. and 600.degree. C. This composition after sealing achieves a closer match to the coefficient of thermal expansion of high density polycrystalline alumina (86.times.10.sup.-7 /.degree.C.) than previously available materials. In addition, it has a wider sealing range which facilitates seal processing.

Abstract: A screw base for high intensity discharge lamps or for larger sizes of incandescent lamps utilizes a threaded aluminum shell coated with a thin film of polytetrafluoroethylene. The thin film is penetrated at points of maximum contact pressure with the socket to provide electrical continuity while effecting a low friction surface preventing galling and sticking of the base in the socket and permitting easy lamp insertion and removal.

Abstract: Miniature high pressure metal vapor lamps containing mercury in a discharge volume of one cubic centimeter or less when operated at low frequencies have extremely high reignition voltages; the problem is compounded in metal halide lamps, particularly during warm-up. Ballast designs capable of coping with these conditions at 60 Hz have disadvantages. The discovery of the existence of resonance-free regions in the frequency range between 20 and 50 KHz has made stable and efficient lamp performance possible through the use of compact, practical and economical high frequency ballasts.

Abstract: Highly purified metal halide salts are made into a frangible stick having uniformly spaced lines of weakness which permit the stick to be broken readily into cylindrical pellets of uniform size. The pellets are particularly useful to supply the vaporizable fill in high intensity metal halide discharge lamps. The stick is formed by intermittently loading salt powder into the sized entrance to a channel through which the salt is forced, and compressing the charge against the back end of previously formed salt stick by means of a polished plunger.

Abstract: A combination lamp comprises a miniature arc tube, a standby filament and a thermal switch in a sealed vitreous envelope. The switch is connected in series with the filament, and the arc tube and the filament have separate inleads for external connections. The switch is closed at room temperature, allowing the filament to light up immediately at a cold start and providing an instant-on feature. During normal operation, heat and light radiated by the arc tube cause the switch to open and turn off the filament. The small size of the arc tube favors a heat balance which allows the thermal switch to cool and reclose quickly in the event of a current interruption, thereby assuring lighting after an acceptably brief delay in the event of a hot restart.

Abstract: High pressure discharge lamps containing a fill of mercury and metal halides, having a power input of 250 watts or below and useable for general illuminating purposes achieve higher efficacy by developing high end temperatures without excessively obstructing the transmission of light and without creating excessive thermal losses through radiation and conduction. To reduce the obstruction of light, heat-conserving coatings on the lamp ends are preferably omitted and small neck seals are used which serve also to reduce thermal losses. The lamps are constructed with an aspect ratio of arc chamber length to diameter from 0.9 to 2.5 and with an electrode insertion factor from 0.1 to 0.6 and operate with a wall loading from 10 to 35 watts/cm.sup.2 and with an arc loading from 60 to 150 watts/cm.

Abstract: An instant light lamp combining a miniature arc tube and a standby filament in a sealed vitreous envelope is operated by a high frequency power supply combined with a filament control circuit. The power supply comprises transforming means including voltage sensing means having an output proportional to the drop across the arc tube. The control circuit comprises an electronic switch for energizing the filament and a comparator circuit which has an output gating on the switch when the sensing means output is either above a high limit or below a low limit.

Abstract: High pressure sodium vapor lamps containing sodium or both sodium and mercury are raised in color temperature and improved in color rendition by pulse operation. During the pulse there is considerable enhancement and broadening of the sodium lines at 449, 467, 498 and 568 nm and the development of a continuum from 400 to 450 nms, and also the appearance of visible mercury lines in lamps containing mercury. Optimum results with lamps in size ratings from 50 to 1000 watts are obtained with pulse repetition rates from 500 to 2000 Hz and duty cycles from 10 to 35%. The color temperature may be increased from the common value of 2050.degree. K to 2500.degree. K with reduction in lamp efficacy of only about 20% from conventional 60 Hz operation. Even higher color temperatures may be obtained if further reduction of efficacy is acceptable.

Abstract: An electrode-inlead assembly comprises a small tungsten pin which is joined on axis to a fine molybdenum wire adapted to sealing through fused silica. The join is effected by a laser butt weld which permits a symmetric compact seal thereby making possible very small discharge envelopes having minimum end losses. The seal may be effected either by a foliated portion in the wire which is wetted by fused silica, or by a glass bead formed around the wire which wets both wire and fused silica.