Abstract: The in-line transmission of a translucent polycrystalline alumina arc tube for a high-pressure sodium discharge lamp is improved by as much as 50% by dipping the "green" tubular compact in an aqueous slurry containing finely-divided alumina particles and, after the slurry-dipped compact has been dried, subjecting it to the usual pre-sintering and sintering operations required to convert the compact into a dense ceramic body. The slurry is preferably prepared from the same slurry which contains the blended alumina powder, magnesia and other additives that comprise the raw-mix slurry which is spray-dried to produce the larger size generally spherical particles that are compressed or extruded to form the green compact.

Abstract: The reliability of a photoflash lamp which is fired by a high-voltage pulse is improved by fabricating the flash-ignition mount from a glass bead, a glass sleeve and a pair of lead-in wires that have inwardly-bent end portions which define a gap of precise length that is uniform from lamp to lamp. The sleeve and bead are fused together and around parts of the lead-in wires such that only the bent tips of the wires protrude beyond the end face of the bead. The gap is filled with primer material that is deposited on the end face of the bead and completely covers the lead wire tips. The fused glass sleeve encloses one of the lead-in wires below the bead and is embedded in the envelope seal, thus not only insuring that the mount assembly is properly positioned within the envelope but insulating one of the lead-in wires and preventing the filling of combustible metal strands from accidentally touching both lead-in wires and internally short-circuiting the unfired lamp.