Osram-Stud Short Arc Xenon XBO1001

Presented here is the world's first commercial xenon arc lamp, introduced by Osram in 1952. Interest in xenon was aroused following Schultz's 1944 discovery of its high colour rendering white light. Owing to wartime limitations this was not further pogressed until John Aldington of British Siemens published his work in 1949. German Osram then developed the technology for cinema projection, to replace carbon arcs. Xenon arcs are not only more stable without need for continual adjustment, their non-consumable electrodes also allowed longer films to be shown without interruptions.

Osram's primary contribution was its thorough research of xenon discharge physics, which directed its developments to very short arcs for DC operation with a particular electrode and bulb geometry. The cathode is kept small to reach high temperatures for thermionic emission, the anode being larger to dissipate the heat generated as incoming electrons are decelerated. Most light is generated immediately in front of the cathode tip, where arc temperatures reach 10,000°C. The plasma is accelerated towards the anode and stabilised by the electrode shapes plus intrinsic magnetic compression generated by the current flow, and convection effects.

The cathode has a rough surface of zirconium getter paste to eliminate hydrogen impurities, and is internally drilled to optimise heat flow. Both electrodes are mounted on heavy tungsten rods, supported by quartz capillaries through which they can slide thanks to a surrounding sleeve of moly tubing. The end seals have a re-entrant shape and consist of three different glasses having intermediate coefficients of thermal expansion - forming a more reliable high-current feedthrough vs the usual molybdenum foils to quartz seals.
Manufacturer: Osram GmbH
Lamp Power: 1000 Watts
Lamp Current: 45 Amps
Lamp Voltage: 22 Volts 33 kV ignition
Cap Type: SFc25-12 (Anode) SFc25-10 (Cathode)
Bulb Type: BTT-40 BTT-13 in eighths/inch
Bulb Finish: Clear Open Quartz
Electrodes: Solid Tungsten (thoriated) Zr getter on anode
Arc Length: 3.4 mm 1.7 mm arc width
Atmosphere: Xenon 8/30 bar cold/hot
Luminous Flux: 32,000 lm (@ 100 hrs)
Luminous Efficacy: 32.0 lm/W (@ 100 hrs)
Colour Temperature & CRI: 6305K Ra
Chromaticity Co-ordinates: CCx: 0.316 CCy: 0.319
Rated Lifetime: 1200 hours to 75% flux
Warm-up & Re-strike Time: Instant Instant
Burning Position: Vertical Cathode Down ± 30°
Overall Length: 330 mm 111/2 inches
Light Centre Length: 125 mm Cathode base to arc centre
Factory: Bath, NH U.S.A.
Date of Manufacture: Approx. 1954 Date Code: 2028
Original Value: DM 590,- (1958)
References: 1) Osram Lamp Catalogue, December 1958, Germany.
2) Xenon-Hochdrucklampen - hohe Leuchtdichte und Lichtstärke, K.Larché, Lichttechnik V.7 No.6 (1955), pp.221-224.
3) Die Neuen Xenon-Hochdrucklampen, K.Ittig, K.Larché, F.Michalk, Technisch-wissenschaftliche Abhandlungen der Osram-Gesellchaft, V.6 (1953) pp.33-38.
4) Gas Arcs, J.N.Aldington, Transactions of the Illuminating Engineering Society (London), V.14 (1949), pp.19-51.
5) Technik der Spezialentladungslampen, Osram GmbH, 1989, pp.24-35