Sulfur lamp
The microwave energy excites the gas to five atmospheres pressure, which in turn heats the sulfur to an extreme degree forming a brightly glowing plasma capable of illuminating a large area.
It reaches 80% of its final luminous flux within 20 seconds, and the lamp can be restarted approximately five minutes after a power cut.
[2] By comparison, cost-effective commercially available LED chips are available with around 160 lumens per Watt (2023) efficacy, with a typical light output depreciation of 10% after 50,000 hours, dependent on operating environment.
Such a filter was used on the lamps at the National Air and Space Museum in Washington, D.C.[3] The addition of other chemicals in the bulb might improve color rendition.
Sulfur lamp bulbs with calcium bromide (CaBr2) added produce a similar spectrum plus a spike in red wavelengths at 625 nm.
[8] Fusion Lighting closed its Rockville, MD location in early 2002-February 2003, after consuming approximately $90 million in venture capital.
In 2006, LG Electronics began production of its sulfur lamps, called Plasma Lighting System (PLS).
The magnetrons in these lamps may cause electromagnetic interference in the 2.4 GHz wireless spectrum, which is used by Wi-Fi, cordless phones and satellite radio in North America.
Fearing interference with their broadcasts, Sirius and XM satellite radio petitioned the United States Federal Communications Commission (FCC) to force Fusion Lighting to reduce the electromagnetic emissions of their lamps by 99.9%.
If there is evidence that any entity will seek to operate RF lights in the 2.45 GHz band and cause harmful interference to satellite radio receivers as a consequence, and our existing limits prove inadequate, we will at that time take appropriate action.Unlike fluorescent and high-intensity discharge lamps, sulfur lamps contain no mercury.
At Sundsvall-Härnösand Airport near Sundsvall, Sweden, airfield lighting is provided by sulfur lamps mounted on towers 30 metres tall.
At the entrance to University Hospital in Lund, Sweden, secondary reflectors on the ceiling are clad with highly reflective films, but shaped so as to avoid any glare.
The fact that the reflectors move the light source far away from the eye of anyone who would happen to look into them helps to further eliminate glare problems.
[13] At the Sacramento Municipal Utility District (SMUD) headquarters building, two sulfur lamps were installed in the tops of free-standing kiosks.
The installation at Hill Air Force Base contains lamps with light pipes as well as downlight fixtures mounted high in an aircraft hangar.
The development of an affordable, efficient, and long-lived microwave source is a technological hurdle to cost reduction and commercial success.
The lamp prototypes were only available in high wattages (1000+ W), which impeded adoption in applications where light output demands were not great.
The sulfur lamp has problems with the life of the magnetron and the motor that rotates the bulb and noise from the cooling fan.
[2] Researchers have had some success at eliminating the need to rotate the bulb by using circularly polarized microwaves to spin the plasma discharge instead.
