Lucalox High Pressure Sodium - 2ndGeneration
When the first samples of polycrystalline alumina were produced by General Electric in 1955, they immediately attracted the attention of the company's Lamp Department.  However it took a further seven years of developing methods of closing the ceramic tube and sealing metallic conductors through the ends before the company was ready to announce the high pressure sodium lamp to the world in 1962.  Still there were many manufacturing difficulties, and the first lamps were not sold until 1965.

This product was made in August 1971 and is an early example of the technology which was still being finalised.  The arc tube seals take the form of niobium cups brazed over the end of the arc tube.  The first lamps used a similar seal which had a larger central amalgam reservoir portion.  But later, niobium cup sealing was abandoned in favour of the niobium tube or wire sealing technology.

The first lamps were intended for vertical burning only and two versions were supplied - this being the "BD" version for cap down operation, but a separate "BU" cap up version was also offered.  The early lamps were particularly susceptible to variations in the vapour pressure of the sodium amalgam filling, and small temperature differences resulted in large changes in luminous flux and colour temperature.  To control the temperature of the amalgam pool it is situated in an external reservoir, the surface of which is either sandblasted to make it radiate more heat (as in this example) , or the arc tube end was insulated with niobium foil to make it run hotter.  The reservoir is at the coolest point, therefore in this lamp it is at the cap end.  "BU" lamps were made with arc tubes having the reservoir at the opposite end of the bulb.
Manufacturer: General Electric Company U.S.A.
Lamp Power: 400 Watts
Lamp Current: 4.4 Amps
Lamp Voltage: 99 Volts
Cap Type: E39s/41 Ni plated brass with vitrite
Bulb Finish: Clear Leaded Hard glass
Bulb Type: ED-57 ED-18 in eighths/inch
Overall Length: 248 mm 9¾ inches
Light Centre Length: 146 mm 5¾ inches
Arc Length:
Electrodes: Backwound Tungsten Barium Calcium Tungstate
Atmosphere: Na,Hg | Xe Outer: Hard Vacuum
Luminous Flux: 47,000 lm (@ 100 hrs) 42,300 lm (@ 7,500 hrs)
Luminous Efficacy: 117.5 lm/W (@ 100 hrs) 105.8 lm/W (@ 7,500 hrs)
Colour Temperature & CRI: CCT: 2000K CRI: Ra 25
Chromaticity Co-ordinates: CCx: 0.530 CCy: 0.430
Burning Position: Vertical Base Down ± 90°
Rated Lifetime: 15,000 hours to 50% survival
Warm-up & Re-strike Time: 4 mins 15 minutes
Factory: NELA Park (Cuyahoga) Cleveland, U.S.A.
Date of Manufacture: August 1971 Date Code 92 -
Original & Present Value: US $55.00 (1972) £176.81 (2005)
 
References: 1) General Electric Large Lamp Catalogue, Form 9200, 1972.