Abstract: A plasma crucible has a through bore and two tubes butt scaled on to the end faces of the crucible. One of the tubes is closed prior to the filling of the crucible. The tube is tipped off and worked in a glass lathe to form it to have a flat end. After evacuation, dosing and gas fill, the other tube is tipped off in the similar manner.

Abstract: A lamp 1 comprises an oscillator and amplifier source 2 of microwave energy, typically operating at 2.45 or 5.8 GHz or other frequencies within an ISM band. The source passes the microwaves via a matching circuit 3 to an antenna 4 extending into a re-entrant 5 in a lucent waveguide 6. This is of quartz and has a central cavity 7 accommodating a bulb 8. The bulb is a sealed tube 9 of quartz and contains a fill of noble gas and a microwave excitable material, which radiates visible light when excited by microwaves. The bulb has a stem 10 received in a stem bore 11 extending from the central cavity. The waveguide is transparent and light from the bulb can leave it in any direction, subject to any reflective surfaces. Microwaves cannot leave the waveguide, which is limited at its surfaces by a Faraday cage.

Abstract: A light source comprising a lucent waveguide of solid dielectric material having: an at least partially light transmitting Faraday cage surrounding the waveguide, a bulb cavity within the waveguide and the Faraday cage and an antenna re-entrant within the waveguide and the Faraday cage and a bulb having a microwave excitable fill, the bulb being received in the bulb cavity.

Abstract: A discharge tube of glass, filled with a halogen/noble-gas mix, which passes through a ½ lambda wave guide of alumina at an aperture ¼ lambda from one end. The wave guide is silver plated to establish resonance between its opposed ends. An antenna/probe is provided in another aperture, driven via a matching circuit from an amplifier. The discharge tube has a length greater than twice the thickness of the wave guide, extending from the wave guide on at least one side thereof.

Abstract: An electrodeless bulb (1) has a hollow quartz tube (2), with a solid stem (3) extending from one end and a short hollow tip (4) extending from the other end. The hollow interior (5) of the tube extends into the tip (4) with the same diameter as in the tube (2), but the wall thickness (6) of the tip is reduced from that (7) of the tube (2). The bulb is charged with an amount (8) of indium bromide and traces of other metal halides to adjust light spectrum and a filling of xenon gas.

Abstract: An improved seal for an electric lamp is provided. An oxidation-resistant coating is provided on the current conductor where the outer lead joins the seal foil, preferably at the pinch seal. The coating is preferably a chromium layer covered by a chromium layer or a silver layer covered by a layer of hydrogenated silicon oxy carbon polymer. The coating is preferably applied via sputtering where the coating is subject to high energy electron or ion bombardment during sputtering. Preferably the coating is applied via sputtering at increased deposition pressure.

Abstract: A high pressure arc discharge lamp apparatus comprises a lamp and operating means therefor, the lamp comprising an envelope containing a dose of mercury and a pair of electrodes with their tips (32, 34) spaced apart from one another to define an arc gap. At least one of the electrode tips is formed with a hollow (44, 46) in its surface (40, 42) facing the other electrode, and the operating means includes means for driving the lamp at an A.C. frequency of at least 200 Hz.

Abstract: An improved seal for an electric lamp is provided. An oxidation-resistant coating is provided on the current conductor where the outer lead joins the seal foil, preferably at the pinch seal. The coating is preferably a chromium layer covered by a chromium layer or a silver layer covered by a layer of hydrogenated silicon oxy carbon polymer. The coating is preferably applied via sputtering where the coating is subject to high energy electron or ion bombardment during sputtering. Preferably the coating is applied via sputtering at increased deposition pressure.

Abstract: Metal halide discharge lamps based on sodium and scandium iodides show improved color rendering without important loss of efficacy by the inclusion of lithium iodide, especially in the molar proportion of 10-50% LiI based on the total of Li, Na and Sc iodides. The ratio of alkali metal of SC iodides should be between 5.4:1 and 57.5:1. Especially preferred are lamps with less than 10 molar % ScI and the lamps may additionally contain caesium iodide to broaden the emission spectrum.