Abstract: In the high-pressure sodium discharge lamp according to the invention, the electrodes (17) are surrounded by a hollow cylindrical body (18), which limits an annular space accommodating an electron emitter (19). The cylindrical body (18 l ) extends against the current conductor (6) supporting the electrode (17). Means for screening the electron emitter (19) are provided at the end of the annular space facing the electrode tip (20). A shield (21) extends from against the electrode tip (20) laterally beyond the hollow cylindrical body (18).

Abstract: The invention relates to a high-pressure discharge lamp having a discharge envelope (3) with a ceramic wall provided with at least one electrode (4). The electrode (4) comprises a rod (41) which is connected to a tubular lead-through member (40) and on which an emitter-containing element (42) is arranged. By means of a screening body (43), the emitter-containing element (42) is screened on its outer side. According to the invention, the screening body (43) extends with a constant cross-section from the tubular lead-through member (40) to the end of the emitter-containing element (42) facing the discharge path. Thus, an improved temperature control is obtained within the discharge envelope (3) during operation of the lamp.

Abstract: Composite body, a gas discharge lamp having a sodium pressure from 300-600 torr in particular, having an envelope of densely sintered aluminium oxide or of other sodium vapor-resistant materials and a feed-through member of tantalum, niobium or other metals equivalent thereto, the bonding material consisting of a finely dispersed polycrystalline product having a composition in mole % between the following limits:Al.sub.2 O.sub.3 --5-70at least one oxide chosen from Sc.sub.2 O.sub.3 and Ti.sub.2 O.sub.x, wherein2<.times.<4--2-70and at least one oxide chosen from:Y.sub.2 O.sub.3, Gd.sub.2 O.sub.3, Tb.sub.2 O.sub.3, Dy.sub.2 O.sub.3, Ho.sub.2 O.sub.3, Er.sub.2 O.sub.3, Eu.sub.2 O.sub.3, Pr.sub.2 O.sub.3, Ce.sub.2 O.sub.3, Sm.sub.2 O.sub.3, Tm.sub.2 O.sub.3, Yb.sub.2 O.sub.3, Lu.sub.2 O.sub.3, La.sub.2 O.sub.3 and Nd.sub.2 O.sub.3 --10-80.

Abstract: The invention relates to a discharge lamp which has a discharge vessel provided with an external auxiliary electrode. The lamp also has a bimetal which in the inoperative condition of the lamp causes the external auxiliary electrode to bear against the discharge vessel. According to the invention the auxiliary electrode is connected to an end of only one bimetallic strip and in the operating condition of the lamp the auxiliary electrode is remote for the greater part from the discharge vessel due to the action of the bimetal. Combined with an operating condition of the lamp in which no hindrance is experienced from the auxiliary electrode.

Abstract: The invention relates to a high-pressure sodium-vapor discharge lamp having substantially the same color temperature as an incandescent lamp. The invention provides a high-pressure sodium-vapor discharge lamp having a low re-ignition voltage.This is achieved by including xenon and mercury in the discharge tube such that (i) the weight of mercury is between 50% and 90% of the combined weight of the mercury and sodium, (ii) the pressure of the xenon at room temperature is between 100 and 1000 torr, and (iii) the sodium vapor pressure is between 300 and 800 torr in the operating condition of the lamp. The power consumed by such a lamp is typically one-fifth of that consumed by an incandescent lamp having the same light output.

Abstract: The current leadthrough for the auxiliary electrode of a discharge lamp with ceramic lamp vessel is constructed as a cylindrical tube concentric with the leadthrough of the main electrode. The cylindrical tube which serves as a current leadthrough can extend in the lamp vessel and serve itself as an auxiliary electrode. This construction avoids cracking of the lamp vessel. Niobium and tantalum, tungsten molybdenum, rhenium and alloys thereof may be used for the current leadthrough.