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Atlas KolorSON 400W |
The arc tube is made of "Stellox", a polycrystalline alumina doped with magnesia and yttria to produce the unique bi-phase grain structure invented at the Rugby works of AEI Lamp & Lighting Co. The properties of Stellox are similar to GE's Lucalox, the first translucent polycrystalline alumina, but its different grain structure was of crucial importance in circumventing the GE patent.
The arc tube ends are closed with pressed cups of niobium. These are brazed to the Stellox using a reactive alloy of titanium, zirconium and vanadium. Ti is the element forming the reactive seal to the ceramic, however its melting point is inconveniently high at around 1800-1850°C. The addition of the other metals forms an alloy that can be fused at around 1400°C which is much more desirable for seal fabrication. Typically, the seal of this type was made by sandwiching three thin washers of each metal over the end of the arc tube and capping them with the niobium cup, before heating in a vacuum furnace. The titanium washer is always the one in contact with the alumina, to form the most reactive seal. One end is blind, while the other is extended into a niobium exhaust tube. This has been pinched-off by cold fusion to permanently seal the sodium amalgam and xenon gas within the arc tube. The outer bulb is coated with a diffusing layer of ground glass in an effort to reduce glare, and enable use in luminaires for mercury fluorescent lamps.
| Manufacturer: | Thorn Lighting Ltd. | |
| Lamp Power: | 400 Watts | |
| Lamp Current: | 4.4 Amps | |
| Lamp Voltage: | 105 ± 15 Volts | |
| Cap Type: | E40s/45 | Ni plated brass + vitrite |
| Bulb Type: | ED-120 | ED-37 in eighths/inch |
| Bulb Finish: | Diffuse coated | Borosilicate glass |
| Electrodes: | Backwound Tungsten | BCT Emitter |
| Arc Length: | ||
| Atmosphere: | Inner: Na,Hg | Xe | Outer: Hard Vacuum |
| Luminous Flux: | 44,000 lm (@ 100 hrs) | 40,000 lm (average) |
| Luminous Efficacy: | 110.0 lm/W (@ 100 hrs) | |
| Colour Temperature & CRI: | CCT: 2100K | CRI: Ra 12 |
| Chromaticity Co-ordinates: | CCx: 0.534 | CCy: 0.431 |
| Lifetime: | Not rated | |
| Warm-up & Re-strike Time: | 3-4 minutes | 1 minute |
| Burning Position: | Universal | |
| Overall Length: | 280±6 mm | 11 inches |
| Light Centre Length: | ||
| Factory: | Leicester | England |
| Date of Manufacture: | December 1974 | Date Code: 12 |
| Original & Present Value: | £18.38 (1972) | |
