Abstract: In a high pressure sodium vapor lamp, sufficiently small quantities of sodium and mercury are inserted therein so that all of the added sodium and mercury will be vaporized when the lamp is operated. The quantities are so selected that a completed lamp exhibits high efficiency, remarkable color rendition and durability. Also, the lamp can produce a suitable arc voltage by means of a less expensive ballast. The small quantity of sodium added is accurately controlled by decomposing sodium azide NaN3. The small quantity of mercury is accurately controlled by decomposing Ti-Hg alloy or Al-Zr-Ti-Hg alloy.

Abstract: In a high pressure sodium vapor lamp, sufficiently small quantities of sodium and mercury are inserted therein so that all of the added sodium and mercury will be vaporized when the lamp is operated. The quantities are so selected that a completed lamp exhibits high efficiency, remarkable color rendition and durability. Also, the lamp can produce a suitable arc voltage by means of a less expensive ballast.The small quantity of sodium added is accurately controlled by decomposing sodium azide NaN3. The small quantity of mercury is accurately controlled by decomposing Ti-Hg alloy or Al-Zr-Ti-Hg alloy. In order to assure the perfect vaporization of the sodium and mercury filling the lamp, the exterior portions of the ends of the arc tube have wound thereon heat insulatng sleeves composed of a refractory insulating packing material. Metal plates are tightly wound around the packing materials to hold the sleeves on the tube without any securing means.