Abstract: Operation of an HID lamp may be improved by forming a glow generating recess on an exterior side the electrode. The lamp may be of standard construction with a light transmissive lamp envelope having a wall defining an enclosed volume. At least one electrode assembly is extended in a sealed fashion from the exterior of the lamp through the lamp envelope wall to be exposed at an inner end of the electrode assembly to the enclosed volume. A metal halide lamp fill is enclosed with an inert fill gas. The inner end of the electrode is formed with a recess having a least spanning dimension S and a recess depth of D where S is greater the electron ionization mean free path but less than twice the cathode fall plus negative glow distances, throughout the glow discharge phase of starting, for the chosen fill gas composition and pressure (cold).

Abstract: A method of operating an arc discharge lamp and a lamp in which a light transmissive envelope encloses electrode tips, a salt and a fill that includes iodine, and in which after turning the lamp off, a first part of the light transmissive envelope is locally cooled relative to other parts of the light transmissive envelope to provide a condensation site for the iodine that is spaced from the electrode tips, the first part of the light transmissive envelope being where a salt reservoir forms and where the salt is cooled by the local cooling. The local cooling may be provided by an indentation in an outer sleeve around the light transmissive envelope, where the indentation contacts the first part to provide a heat sink.

Abstract: An arc discharge light source (10) for automotive headlight applications comprises an arc tube (12) having a hollow body (14) arrayed a long a longitudinal axis (16) and provided with first and second ends (18, 20). The first and second ends have, respectively, first and second jointure areas (22, 24) with the hollow body (14). Electrodes (26, 28) are sealed respectively in each of the first and second ends (18, 20). An arc generating and sustaining medium is contained within the hollow body. a low-voltage-pulse starting aid (30) is associated with the arc tube and comprises an electrically conductive member (32) having an intermediate portion (34) and proximal and distal ends (36, 38). The intermediate portion (34) extends the length of the hollow body (14) and the proximal and distal ends (36, 38) each terminating in a loop (40, 42) comprised of a single turn of electrically conductive material.