Abstract: A method for producing a metal-halide discharge lamp with a ceramic dische vessel is distinguished in that first both ends (6a, 6b) are equipped with electrode systems and sealed off, but a filling bore (15) remains in the vicinity of the pump end (6a) and is not closed until after the filling.

Abstract: To provide a sealed through arrangement for electrical leads through a ceramic end plug, suitable for discharge lamps of between about 50 to 250 W power rating, the lead-through (9) is made of a material having a thermal coefficient of expansion which is substantially less than that of a ceramic sealing plug (10), for example of tungsten, molybdenum or rhenium, but so small that the individual, actual expansion of the ceramic material will not cause separation from the metal, and/or a glass melt, ceramic melt or sintar connection therewith. The electrical connection is formed by at least two, and preferably more than two, thin wires or pins (23) having a diameter, each, of up to only about 0.25 mm, and preferably less. Each of the wires, then, will carry currents in the tenths ampere ranges, sufficient for operation of the lamp, and passed through melt-sealed capillary openings in the ceramic sealing plug (10).

Abstract: To simply and reliably retain a heat retention tube or sleeve (10) within envelope (1) and surrounding the arc tube or discharge vessel (4) of the lamp, end regions of the heat retention or conservation tube are pinched around current supply leads (7) which pass through the pinch or press region (11). To prevent dislocation of the tube or sleeve (10), axially as well as rotationally with respect to the arc tube, the current supply leads are deformed in the region of the pinch or press (11), for example by being flattened or deflected in a bend or V-shape from a straight wire. An exhaust tube (12) can be passed through the pinch (11) if the pinch extends across the entire diameter of the heat retention tube; otherwise, the pinch need only extend over a portion thereof, thus providing for pneumatic communication between the interior of the heat retention tube and the envelope (1).

Abstract: To protect a niobium tube (9) forming a current supply lead through a thrh-opening (14) in an end plug (10) in a ceramic discharge vessel against attack by halides or condensed sodium, the through-opening is formed in two portions, of different diameters. The outer portion (16), remote from the discharge vessel, has a diameter which is matched to the diameter of the tube (9), leaving only a capillary between the plug opening and the tube; the second, inner portion (17) is narrower than the first one, that is, outer portion, and surrounds the shaft of the electrode by a sufficient distance to permit expansion of the electrode, typically of tungsten, under operating conditions, without cracking the plug by forced engagement with the wall of the inner portion (17) of the aperture. A sealing glass, melt-sealed into the capillary of the outer portion, seals the niobium tube.