GE-Mazda Sunlight Mercury-Tungsten S-2

In 1929 GE introduced the first succesful ultraviolet lamp, the S-1 Sunlight. It had been conceived by Royal Strickland and Matthew Luckiesh to deliver a spectrum having a mild ultraviolet content resembling that of the sun. It was believed that irradiating people with this light would give them vitality and maintain health.

The S-1 was a large 400W source for general irradiation in public areas, and a smaller domestic source was soon in demand for residential use. By 1932 this 130W S-2 variant had been launched. Initially it had a clear glass bulb, but owing to its use at short ranges its high brightness produced too much glare. From 1939 onwards both this and the larger S-1 were only made with inside frosted pearl bulb.

It is a most unusual kind of hybrid incandescent-discharge lamp. The bulb is made of a special hardglass transmitting UV down to 280nm, and is filled with an enormous quantity of mercury plus low pressure argon. It contains a V-shaped tungsten filament, whose ends have extra windings to increase their thermal mass such that they can function as electrodes. When illuminated on a low voltage transformer, the filament lights and thermionic emission causes a glow discharge to form. This quickly transitions into an arc across the ends of the filament, ballasted by the transformer. As the bulb temperature increases the mercury vapour pressure rises, and the arc gradually draws more current but the filament remains lighted at all times. It produces a neutral white light plus infrared radiation, while the mercury arc contributes ultraviolet rays. The lower power of this S-2 lamp required the addition of the metal cap, to raise the temperature of the mercury pool and increase UV output.
Manufacturer: General Electric Co. of U.S.A.
Lamp Power: 130 Watts
Lamp Voltage: 15 Volts Approx. 30V at starting
Lamp Current: 8.5 Amps 2A at starting
Cap Type: E29s/30 Admedium Brass
Bulb Type: PS-54 PS-17 (in eighths/inch)
Bulb Finish: Clear #776 borosilicate glass
Electrodes: C-2V filament Overwound plugged tails
Atmosphere: Hg | Ar 0.9 atm. during operation
Luminous Flux: 1,600 lm @ 100 hours
Luminous Efficacy: 12.3 lm/W @ 100 hours
Radiant Flux: UV-A 1.05W, UV-B 0.65W Visible 8.4W
Colour Temperature & CRI: CCT: 4050K CRI: Ra67
Chromaticity Co-ordinates: CCx: 0.381 CCy: 0.383
Rated Life: 300 hours 50% survival, ~100% UV flux
Warm Up / Re-strike Time: 8 minutes to full output Instantaneous restrike
Burning Position: Vertical base up to horizontal
Overall Length: 122.5 mm 47/8 inches
Light Centre Length: 95.25 mm 33/4 inches
Factory: NELA Park, Cleveland (OH) U.S.A.
Date of Manufacture: 1939 December Date Code: 96.16
Original Value: US $3.75 (1939)
References: 1) GE Lamp Catalogue, USA, 1937, p.27
2) GE Brochure, Sunlight Mazda S-Lamps & Mercury Mazda H-Lamps, Prices & Essential Technical Data, USA, 1939
3) GE-Mazda Lamps - Characteristics & Applications (Bulletin LD-1), C.E. Weitz, General Electric U.S.A., 1939
4) GE-Mazda Advertisement for S1 Sunlight lamp, 1929
5) GE-Mazda Advertisement for S1 & S2 Sunlight lamps, 1932
6) GE-Mazda Advertisement for S2 Sunlight lamp, 1933
7) A Century of Light, J.A. Cox, publ. Benjamin Company / Rutledge, 1979, p.217
8) Lamps for a Brighter America, P.W. Keating, publ. McGraw-Hill, 1954, pp.163-164,205.
9) Biography of Royal Strickland
10) Biography of Matthew Luckiesh
11) US Patent 2,047,042 - Enclosed Arc Device, R.F.Strickland (General Electric USA), Filed 1929-Nov-18
12) US Patent 2,081,776 - Enclosed Arc Device having improved electrodes (S-2), R.F.Strickland (General Electric USA), Filed 1931-May-19
13) US Patent 2,104,680 - Enclosed Arc Device having improved UV flux and starting, R.F.Strickland (General Electric USA), Filed 1931-Feb-25
14) Integrating sphere measurement 380-800nm VBU to determine visible radiant flux, luminous flux and colorimetric data
15) Spectroradiometer measurement 200-800nm VBU @ 1m to determine spectrum, scaled to integrating sphere measurement to determine UV flux