Sulfur lamp
Encyclopedia
The sulfur lamp is a highly efficient full-spectrum
electrodeless lighting system whose light is generated by sulfur
plasma
that has been excited
by microwave
radiation. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was a commercial failure by the late 1990s. Since 2005, lamps are again being manufactured for commercial use.
-sized (30 mm) fused-quartz bulb containing several milligrams of sulfur
powder and argon
gas at the end of a thin glass spindle. The bulb is enclosed in a microwave-resonant wire-mesh
cage. A magnetron, much like the ones in home microwave oven
s, bombards the bulb, via a waveguide
, with 2.45 GHz
microwaves. 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. Because the bulb heats considerably, it is necessary to provide forced air cooling to prevent it from melting. The bulb is usually placed at the focus
of a parabolic reflector
to direct all the light in one direction.
It would be impossible to excite the sulfur using traditional electrode
s; the sulfur would quickly react with and destroy any metal
lic electrode. A patent pending to employ coated electrodes is discussed in Future prospects, below. The absence of electrodes allows for a much greater variety of light-generating substances to be used than those used in traditional lamps.
The design life of the bulb is approximately 60,000 hours. The design life of the magnetron has been improved by the Germany/England based Plasma International so it can also last for that same period.
The warm-up time of the sulfur lamp is notably shorter than for other gas discharge lamps, with the exception of fluorescent lamp
s, even at low ambient temperatures. It reaches 80% of its final luminous flux
within twenty seconds, and the lamp can be restarted approximately five minutes after a power cut.
The first prototype lamps were 5.9 kW units, with a system efficiency
of 80 lumen
s per watt
. The first production models were 1.4 kW with an output of 135,000 lumens. Later models were able to eliminate the cooling fan and improve luminous efficacy to 100 lumens per watt.
is continuous throughout the visible spectrum
. As much as 73% of the emitted radiation is in the visible spectrum, with a small amount in infrared
energy and less than 1% in ultraviolet
light.
The spectral output peaks at 510 nanometres, imparting a greenish hue to the illuminated environment. The correlated color temperature
is about 6,000 kelvin
s with a CRI of 79. The lamp can be dimmed to 15% without affecting the light quality.
A magenta
filter can be used to give the light a warmer feel. Such a filter was used on the lamps at the National Air and Space Museum
in Washington, D.C.
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. Other additives such as lithium iodide
(LiI) and sodium iodide
(NaI) can be used to modify the output spectra.
Michael Ury, physicist
Charles Wood and their colleagues in 1990. With support from the United States Department of Energy
, it was further developed in 1994 by Fusion Lighting of Rockville, Maryland
, a spinoff of the Fusion UV division of Fusion Systems Corporation. Its origins are in microwave discharge light sources used for ultraviolet curing
in the semiconductor and printing industries. The Fusion UV division was later sold to Spectris plc, and the rest of Fusion Systems was later acquired by the Eaton Corporation
.
Only two production models were developed, both with similar specifications: the Solar 1000 in 1994 and the Light Drive 1000 in 1997, which was a refinement of the previous model.
Production of these lamps ended in 1998. Fusion Lighting closed its doors in early 2002, after having used up approximately $90 million in venture capital
. Their patents were licensed to the LG Group
. The Internet Archive
has a copy of Fusion Lighting's defunct website. Their lamps were installed in more than one hundred facilities worldwide, but many of them have already been removed.
In 2001, Ningbo Youhe New Lighting Source Co., Ltd, in Ningbo
, China
, produced its own sulfur lamp version. The company's website is no longer online and may be out of business, but information on these lamps is available from its archived copy at the Internet Archive.
In 2006, LG Electronics
began production of its sulfur lamps, called Plasma Lighting System (PLS).
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%. In 2001, Fusion Lighting agreed to install metal shielding
around their lamps to reduce electromagnetic emissions by 95%.
In May 2003, the FCC terminated the proceeding that would have defined out-of-band emission limits for radio-frequency lights operating at 2.45 GHz, saying the record of the proceeding had become outdated and Fusion Lighting had stopped working on such lamps. The order concluded:
s, sulfur lamps contain no mercury
. Therefore, sulfur lamps do not pose a threat to the environment nor require special disposal. In addition, use of sulfur lamps has the potential to reduce the total amount of energy required for lighting.
with a prismatic
surface developed by 3M
that distributes the light uniformly over its length. Light pipes can be as long as 40 metres (131.2 ft) and are assembled on site from shorter, modular units. The light pipe is attached to the parabolic reflector of the sulfur lamp. For shorter pipes, there will be a mirror at the opposite end; for longer ones, there will be a lamp at each end. The overall appearance of a light pipe has been compared to that of a giant-sized fluorescent tube. One sulfur lamp with a light pipe can replace dozens of HID lamp
s. In the National Air and Space Museum
, three lamps, each with a 27 metres (88.6 ft) pipe, replaced 94 HID lamps while greatly increasing the amount of light delivered.
The greatly reduced number of lamps may simplify maintenance and reduce installation costs but may also require a backup system for areas where lighting is critical. The light pipes allow the lamp to be placed in an easily accessible area for maintenance and away from places where the heat of the lamp may be a problem.
At Sundsvall-Härnösand Airport
near Sundsvall
, Sweden
, airfield lighting is provided by sulfur lamps mounted on towers 30 metres tall. The lamps are directed upward and shine their light onto wing-shaped secondary reflectors that spread the light out and direct it downward. In this way, one lamp can illuminate an area 30 by.
At the headquarters of DONG Energy
, an energy company in Denmark, a single sulfur lamp directs its light onto numerous specular reflectors and diffusers to illuminate the entrance hall as well as several sculptures outside of the building.
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. Moreover, since these films have a microprismatic surface
structure that splits up the beams, the risk of glare problems is further reduced. 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.
At the Sacramento Municipal Utility District (SMUD) headquarters building, two sulfur lamps were installed in the tops of free-standing kiosk
s. The 4.2 metre high ceiling was retrofit with high reflectance (90%), white acoustic ceiling tile
. The lamps direct their light upward, and it is reflected off the ceiling providing indirect light. Narrow, medium, or wide beam patterns can be created by choosing various reflector elements.
Light pipes would not be necessary in applications such as stadium
lighting, where a plain fixture can be mounted high enough so that the light can spread over a large area. The installation at Hill Air Force Base
contains lamps with light pipes as well as downlight fixtures mounted high in an aircraft hangar
.
s have been studied as a distribution system for sulfur lamps, but no practical system has ever been marketed.
Researchers have had some success at eliminating the need to rotate the bulb by using circularly polarized
microwaves to spin the plasma discharge instead. Other experiments have used sodium iodide
, scandium
iodide
, indium monobromide (InBr), or tellurium as the light-generating medium.
A patent #20070075617 is pending since 2006 for a sulfur lamp with electrodes — in fact, a more traditional gas–discharge lamp where a magnetron is not required. Various electrode coatings are suggested to combat high chemical activity of sulfur. As usual with patents, though, only commercial applications will reveal whether this design is viable.
Many of the installations of the lamps were for testing purposes only, but there remain a few sites where the lamps are in use as the primary lighting source. Perhaps the most visible of these would be the glass atria
in the National Air and Space Museum
.
Full-spectrum
Full-spectrum light is light that covers the electromagnetic spectrum from infrared through near-ultraviolet, or all wavelengths that are useful to plant or animal life; in particular, sunlight is considered full spectrum, even though the solar spectral distribution reaching Earth changes with time...
electrodeless lighting system whose light is generated by sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
plasma
Plasma (physics)
In physics and chemistry, plasma is a state of matter similar to gas in which a certain portion of the particles are ionized. Heating a gas may ionize its molecules or atoms , thus turning it into a plasma, which contains charged particles: positive ions and negative electrons or ions...
that has been excited
Electron excitation
Electron excitation is the movement of an electron to a higher energy state. This can either be done by photoexcitation , where the original electron absorbs the photon and gains all the photon's energy or by electrical excitation , where the original electron absorbs the energy of another,...
by microwave
Microwave
Microwaves, a subset of radio waves, have wavelengths ranging from as long as one meter to as short as one millimeter, or equivalently, with frequencies between 300 MHz and 300 GHz. This broad definition includes both UHF and EHF , and various sources use different boundaries...
radiation. The technology was developed in the early 1990s, but, although it appeared initially to be very promising, sulfur lighting was a commercial failure by the late 1990s. Since 2005, lamps are again being manufactured for commercial use.
Mechanism
The sulfur lamp consists of a golf ballGolf ball
A golf ball is a ball designed to be used in the game of golf.Under the Rules of Golf, a golf ball weighs no more than 1.620 oz , has a diameter not less than 1.680 in , and performs within specified velocity, distance, and symmetry limits...
-sized (30 mm) fused-quartz bulb containing several milligrams of sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
powder and argon
Argon
Argon is a chemical element represented by the symbol Ar. Argon has atomic number 18 and is the third element in group 18 of the periodic table . Argon is the third most common gas in the Earth's atmosphere, at 0.93%, making it more common than carbon dioxide...
gas at the end of a thin glass spindle. The bulb is enclosed in a microwave-resonant wire-mesh
Mesh
Mesh consists of semi-permeable barrier made of connected strands of metal, fiber, or other flexible/ductile material. Mesh is similar to web or net in that it has many attached or woven strands.-Types of mesh:...
cage. A magnetron, much like the ones in home microwave oven
Microwave oven
A microwave oven is a kitchen appliance that heats food by dielectric heating, using microwave radiation to heat polarized molecules within the food...
s, bombards the bulb, via a waveguide
Waveguide (electromagnetism)
In electromagnetics and communications engineering, the term waveguide may refer to any linear structure that conveys electromagnetic waves between its endpoints. However, the original and most common meaning is a hollow metal pipe used to carry radio waves...
, with 2.45 GHz
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
microwaves. The microwave energy excites the gas to five atmospheres
Atmosphere (unit)
The standard atmosphere is an international reference pressure defined as 101325 Pa and formerly used as unit of pressure. For practical purposes it has been replaced by the bar which is 105 Pa...
pressure, which in turn heats the sulfur to an extreme degree forming a brightly glowing plasma capable of illuminating a large area. Because the bulb heats considerably, it is necessary to provide forced air cooling to prevent it from melting. The bulb is usually placed at the focus
Focus (optics)
In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...
of a parabolic reflector
Parabolic reflector
A parabolic reflector is a reflective device used to collect or project energy such as light, sound, or radio waves. Its shape is that of a circular paraboloid, that is, the surface generated by a parabola revolving around its axis...
to direct all the light in one direction.
It would be impossible to excite the sulfur using traditional electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s; the sulfur would quickly react with and destroy any metal
Metal
A metal , is an element, compound, or alloy that is a good conductor of both electricity and heat. Metals are usually malleable and shiny, that is they reflect most of incident light...
lic electrode. A patent pending to employ coated electrodes is discussed in Future prospects, below. The absence of electrodes allows for a much greater variety of light-generating substances to be used than those used in traditional lamps.
The design life of the bulb is approximately 60,000 hours. The design life of the magnetron has been improved by the Germany/England based Plasma International so it can also last for that same period.
The warm-up time of the sulfur lamp is notably shorter than for other gas discharge lamps, with the exception of fluorescent lamp
Fluorescent lamp
A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. A fluorescent lamp converts electrical power into useful...
s, even at low ambient temperatures. It reaches 80% of its final luminous flux
Luminous flux
In photometry, luminous flux or luminous power is the measure of the perceived power of light. It differs from radiant flux, the measure of the total power of light emitted, in that luminous flux is adjusted to reflect the varying sensitivity of the human eye to different wavelengths of...
within twenty seconds, and the lamp can be restarted approximately five minutes after a power cut.
The first prototype lamps were 5.9 kW units, with a system efficiency
Luminous efficacy
Luminous efficacy is a measure of how well a light source produces visible light. It is the ratio of luminous flux to power. Depending on context, the power can be either the radiant flux of the source's output, or it can be the total electric power consumed by the source.Which sense of the term is...
of 80 lumen
Lumen (unit)
The lumen is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux...
s per watt
Watt
The watt is a derived unit of power in the International System of Units , named after the Scottish engineer James Watt . The unit, defined as one joule per second, measures the rate of energy conversion.-Definition:...
. The first production models were 1.4 kW with an output of 135,000 lumens. Later models were able to eliminate the cooling fan and improve luminous efficacy to 100 lumens per watt.
Quality of emitted light
The sulfur plasma consists mainly of dimer molecules (S2), which generate the light through molecular emission. Unlike atomic emission, the emission spectrumEmission spectrum
The emission spectrum of a chemical element or chemical compound is the spectrum of frequencies of electromagnetic radiation emitted by the element's atoms or the compound's molecules when they are returned to a lower energy state....
is continuous throughout the visible spectrum
Visible spectrum
The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm. In terms of...
. As much as 73% of the emitted radiation is in the visible spectrum, with a small amount in infrared
Infrared
Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm...
energy and less than 1% in ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
light.
The spectral output peaks at 510 nanometres, imparting a greenish hue to the illuminated environment. The correlated color temperature
Color temperature
Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of...
is about 6,000 kelvin
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...
s with a CRI of 79. The lamp can be dimmed to 15% without affecting the light quality.
A magenta
Magenta
Magenta is a color evoked by light stronger in blue and red wavelengths than in yellowish-green wavelengths . In light experiments, magenta can be produced by removing the lime-green wavelengths from white light...
filter can be used to give the light a warmer feel. Such a filter was used on the lamps at the National Air and Space Museum
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
in Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....
The addition of other chemicals in the bulb might improve color rendition. Sulfur lamp bulbs with calcium bromide
Calcium bromide
Calcium bromide is the calcium salt of hydrobromic acid with the chemical formula of CaBr2. In its solid state, it is a white powder. CaBr2 can be found in drilling fluids, neuroses medication, freezing mixtures, food preservatives, photography and fire retardants.When strongly heated in air,...
(CaBr2) added produce a similar spectrum plus a spike in red wavelengths at 625 nm. Other additives such as lithium iodide
Lithium iodide
Lithium iodide, or LiI, is a compound of lithium and iodine. When exposed to air, it becomes yellow in color, due to the oxidation of iodide to iodine.-Applications:...
(LiI) and sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....
(NaI) can be used to modify the output spectra.
History
The technology was conceived by engineerEngineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
Michael Ury, physicist
Physicist
A physicist is a scientist who studies or practices physics. Physicists study a wide range of physical phenomena in many branches of physics spanning all length scales: from sub-atomic particles of which all ordinary matter is made to the behavior of the material Universe as a whole...
Charles Wood and their colleagues in 1990. With support from the United States Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
, it was further developed in 1994 by Fusion Lighting of Rockville, Maryland
Rockville, Maryland
Rockville is the county seat of Montgomery County, Maryland, United States. It is a major incorporated city in the central part of Montgomery County and forms part of the Baltimore-Washington Metropolitan Area. The 2010 U.S...
, a spinoff of the Fusion UV division of Fusion Systems Corporation. Its origins are in microwave discharge light sources used for ultraviolet curing
Curing (chemistry)
Curing is a term in polymer chemistry and process engineering that refers to the toughening or hardening of a polymer material by cross-linking of polymer chains, brought about by chemical additives, ultraviolet radiation, electron beam or heat...
in the semiconductor and printing industries. The Fusion UV division was later sold to Spectris plc, and the rest of Fusion Systems was later acquired by the Eaton Corporation
Eaton Corporation
Eaton Corporation is a global diversified power management company with 2010 sales of $13.7 billion. The company is a leading provider of electrical components and systems for power quality, distribution and control; hydraulics components, systems and services for industrial and mobile equipment;...
.
Only two production models were developed, both with similar specifications: the Solar 1000 in 1994 and the Light Drive 1000 in 1997, which was a refinement of the previous model.
Production of these lamps ended in 1998. Fusion Lighting closed its doors in early 2002, after having used up approximately $90 million in venture capital
Venture capital
Venture capital is financial capital provided to early-stage, high-potential, high risk, growth startup companies. The venture capital fund makes money by owning equity in the companies it invests in, which usually have a novel technology or business model in high technology industries, such as...
. Their patents were licensed to the LG Group
LG Group
LG Corp. is the second-largest South Korean conglomerate company following Samsung, and it is headquartered in the LG Twin Towers in Yeouido-dong, Yeongdeungpo-gu, Seoul. LG produces electronics, chemicals, and telecommunications products and operates subsidiaries like LG Electronics, LG Display,...
. The Internet Archive
Internet Archive
The Internet Archive is a non-profit digital library with the stated mission of "universal access to all knowledge". It offers permanent storage and access to collections of digitized materials, including websites, music, moving images, and nearly 3 million public domain books. The Internet Archive...
has a copy of Fusion Lighting's defunct website. Their lamps were installed in more than one hundred facilities worldwide, but many of them have already been removed.
In 2001, Ningbo Youhe New Lighting Source Co., Ltd, in Ningbo
Ningbo
Ningbo is a seaport city of northeastern Zhejiang province, Eastern China. Holding sub-provincial administrative status, the municipality has a population of 7,605,700 inhabitants at the 2010 census whom 3,089,180 in the built up area made of 6 urban districts. It lies south of the Hangzhou Bay,...
, China
People's Republic of China
China , officially the People's Republic of China , is the most populous country in the world, with over 1.3 billion citizens. Located in East Asia, the country covers approximately 9.6 million square kilometres...
, produced its own sulfur lamp version. The company's website is no longer online and may be out of business, but information on these lamps is available from its archived copy at the Internet Archive.
In 2006, LG Electronics
LG Electronics
LG Electronics is a global electronics and telecommunications company headquartered in Yeouido, Seoul, South Korea. The company operates its business through five divisions: mobile communications, home entertainment, home appliance, air conditioning and business solution...
began production of its sulfur lamps, called Plasma Lighting System (PLS).
Electromagnetic interference
The magnetrons in these lamps may cause electromagnetic interferenceElectromagnetic interference
Electromagnetic interference is disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source. The disturbance may interrupt, obstruct, or otherwise degrade or limit the effective performance of the circuit...
in the 2.4 GHz wireless spectrum
S band
The S band is defined by an IEEE standard for radio waves with frequencies that range from 2 to 4 GHz, crossing the conventional boundary between UHF and SHF at 3.0 GHz. It is part of the microwave band of the electromagnetic spectrum...
, which is used by Wi-Fi
Wi-Fi
Wi-Fi or Wifi, is a mechanism for wirelessly connecting electronic devices. A device enabled with Wi-Fi, such as a personal computer, video game console, smartphone, or digital audio player, can connect to the Internet via a wireless network access point. An access point has a range of about 20...
, cordless phones and satellite radio
Satellite radio
Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...
in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Fearing interference with their broadcasts, Sirius
Sirius Satellite Radio
Sirius Satellite Radio is a satellite radio service operating in North America, owned by Sirius XM Radio.Headquartered in New York City, with smaller studios in Los Angeles and Memphis, Sirius was officially launched on July 1, 2002 and currently provides 69 streams of music and 65 streams of...
and XM
XM Satellite Radio
XM Satellite Radio is one of two satellite radio services in the United States and Canada, operated by Sirius XM Radio. It provides pay-for-service radio, analogous to cable television. Its service includes 73 different music channels, 39 news, sports, talk and entertainment channels, 21 regional...
satellite radio
Satellite radio
Satellite radio is an analogue or digital radio signal that is relayed through one or more satellites and thus can be received in a much wider geographical area than terrestrial FM radio stations...
petitioned the United States Federal Communications Commission
Federal Communications Commission
The Federal Communications Commission is an independent agency of the United States government, created, Congressional statute , and with the majority of its commissioners appointed by the current President. The FCC works towards six goals in the areas of broadband, competition, the spectrum, the...
(FCC) to force Fusion Lighting to reduce the electromagnetic emissions of their lamps by 99.9%. In 2001, Fusion Lighting agreed to install metal shielding
Electromagnetic shielding
Electromagnetic shielding is the process of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive and/or magnetic materials. Shielding is typically applied to enclosures to isolate electrical devices from the 'outside world' and to cables to isolate...
around their lamps to reduce electromagnetic emissions by 95%.
In May 2003, the FCC terminated the proceeding that would have defined out-of-band emission limits for radio-frequency lights operating at 2.45 GHz, saying the record of the proceeding had become outdated and Fusion Lighting had stopped working on such lamps. The order concluded:
Environmental issues
Unlike fluorescent and high-intensity discharge lampHigh-intensity discharge lamp
High-intensity discharge lamps are a type of electrical lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with both gas and metal salts. The gas facilitates the...
s, sulfur lamps contain no mercury
Mercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
. Therefore, sulfur lamps do not pose a threat to the environment nor require special disposal. In addition, use of sulfur lamps has the potential to reduce the total amount of energy required for lighting.
Light distribution systems
Because the amount of light produced from one bulb is so great, it is usually necessary to distribute the light to areas far removed from the lamp. The most common method used is light pipes.Light pipes
The 3M light pipe is a long, transparent, hollow cylinderCylinder (geometry)
A cylinder is one of the most basic curvilinear geometric shapes, the surface formed by the points at a fixed distance from a given line segment, the axis of the cylinder. The solid enclosed by this surface and by two planes perpendicular to the axis is also called a cylinder...
with a prismatic
Prism (optics)
In optics, a prism is a transparent optical element with flat, polished surfaces that refract light. The exact angles between the surfaces depend on the application. The traditional geometrical shape is that of a triangular prism with a triangular base and rectangular sides, and in colloquial use...
surface developed by 3M
3M
3M Company , formerly known as the Minnesota Mining and Manufacturing Company, is an American multinational conglomerate corporation based in Maplewood, Minnesota, United States....
that distributes the light uniformly over its length. Light pipes can be as long as 40 metres (131.2 ft) and are assembled on site from shorter, modular units. The light pipe is attached to the parabolic reflector of the sulfur lamp. For shorter pipes, there will be a mirror at the opposite end; for longer ones, there will be a lamp at each end. The overall appearance of a light pipe has been compared to that of a giant-sized fluorescent tube. One sulfur lamp with a light pipe can replace dozens of HID lamp
High-intensity discharge lamp
High-intensity discharge lamps are a type of electrical lamp which produces light by means of an electric arc between tungsten electrodes housed inside a translucent or transparent fused quartz or fused alumina arc tube. This tube is filled with both gas and metal salts. The gas facilitates the...
s. In the National Air and Space Museum
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
, three lamps, each with a 27 metres (88.6 ft) pipe, replaced 94 HID lamps while greatly increasing the amount of light delivered.
The greatly reduced number of lamps may simplify maintenance and reduce installation costs but may also require a backup system for areas where lighting is critical. The light pipes allow the lamp to be placed in an easily accessible area for maintenance and away from places where the heat of the lamp may be a problem.
Secondary reflectors
A secondary reflector is a structure with a mirrored surface placed directly into the path of the beam of light as it exits the parabolic primary reflector of the lamp. A secondary reflector can have a complex geometry which allows it to break up the light and direct it to where it is desired. It can spotlight an object or spread out the light for general illumination.At Sundsvall-Härnösand Airport
Sundsvall-Härnösand Airport
Sundsvall-Härnösand Airport or Midlanda Airport is located about 21 km north of Sundsvall and 32 km south of Härnösand, Sweden....
near Sundsvall
Sundsvall
-External links:* - Official site from Nordisk Familjebok - Sundsvalls tourist information bureau. - The alternative guide to Sundsvall. - Blog with photos from Sundsvall....
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, airfield lighting is provided by sulfur lamps mounted on towers 30 metres tall. The lamps are directed upward and shine their light onto wing-shaped secondary reflectors that spread the light out and direct it downward. In this way, one lamp can illuminate an area 30 by.
At the headquarters of DONG Energy
DONG Energy
-History:The Danish state company Dansk Naturgas A/S was founded in 1972 to manage resources in the Danish sector of the North Sea. After some years, the company was renamed to Dansk Olie og Naturgas A/S . At the beginning of 2000s, DONG started to extend itself into the electricity market by...
, an energy company in Denmark, a single sulfur lamp directs its light onto numerous specular reflectors and diffusers to illuminate the entrance hall as well as several sculptures outside of the building.
At the entrance to University Hospital in Lund
Lund
-Main sights:During the 12th and 13th centuries, when the town was the seat of the archbishop, many churches and monasteries were built. At its peak, Lund had 27 churches, but most of them were demolished as result of the Reformation in 1536. Several medieval buildings remain, including Lund...
, Sweden
Sweden
Sweden , officially the Kingdom of Sweden , is a Nordic country on the Scandinavian Peninsula in Northern Europe. Sweden borders with Norway and Finland and is connected to Denmark by a bridge-tunnel across the Öresund....
, secondary reflectors on the ceiling are clad with highly reflective films, but shaped so as to avoid any glare. Moreover, since these films have a microprismatic surface
Prismatic surface
A prismatic surface is a surface generated by all the lines that are parallel to a given line and intersect a broken line that is not in the same plane as the given line. The broken line is the directrix of the surface; the parallel lines are its generators . If the broken line is closed A...
structure that splits up the beams, the risk of glare problems is further reduced. 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.
Indirect lighting
Indirect fixtures direct most of their luminous flux upward toward a ceiling. A highly reflective ceiling can then serve as a secondary source of diffusive, low luminance, high visual quality lighting for interior spaces. The primary advantages of indirect lighting are the opportunity to significantly reduce indirect glare potential and to completely eliminate direct source viewing.At the Sacramento Municipal Utility District (SMUD) headquarters building, two sulfur lamps were installed in the tops of free-standing kiosk
Kiosk
Kiosk is a small, separated garden pavilion open on some or all sides. Kiosks were common in Persia, India, Pakistan, and in the Ottoman Empire from the 13th century onward...
s. The 4.2 metre high ceiling was retrofit with high reflectance (90%), white acoustic ceiling tile
Dropped ceiling
A dropped ceiling is a secondary ceiling, hung below the main ceiling. They may also be referred to as a drop ceiling, false ceiling, or suspended ceiling, and are a staple of modern construction and architecture. The area above the dropped ceiling is called the plenum space, as it is sometimes...
. The lamps direct their light upward, and it is reflected off the ceiling providing indirect light. Narrow, medium, or wide beam patterns can be created by choosing various reflector elements.
Direct lighting
Stadium
A modern stadium is a place or venue for outdoor sports, concerts, or other events and consists of a field or stage either partly or completely surrounded by a structure designed to allow spectators to stand or sit and view the event.)Pausanias noted that for about half a century the only event...
lighting, where a plain fixture can be mounted high enough so that the light can spread over a large area. The installation at Hill Air Force Base
Hill Air Force Base
Hill Air Force Base is a major U.S. Air Force Base located in northern Utah, just south of the city of Ogden, and near the towns of Clearfield, Riverdale, Roy, Sunset, and Layton. It is about north of Salt Lake City. The base was named in honor of Major Ployer Peter Hill of the U.S. Army Air...
contains lamps with light pipes as well as downlight fixtures mounted high in an aircraft hangar
Hangar
A hangar is a closed structure to hold aircraft or spacecraft in protective storage. Most hangars are built of metal, but other materials such as wood and concrete are also sometimes used...
.
Optical fibers
Optical fiberOptical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
s have been studied as a distribution system for sulfur lamps, but no practical system has ever been marketed.
Future prospects
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. Because most sulfur lamp have moving parts, reliability remains a critical issue, and system maintenance may impede market adoption, however newer design lamps which no longer require active cooling are commercially available.Researchers have had some success at eliminating the need to rotate the bulb by using circularly polarized
Circular polarization
In electrodynamics, circular polarization of an electromagnetic wave is a polarization in which the electric field of the passing wave does not change strength but only changes direction in a rotary type manner....
microwaves to spin the plasma discharge instead. Other experiments have used sodium iodide
Sodium iodide
Sodium iodide is a white, crystalline salt with chemical formula NaI used in radiation detection, treatment of iodine deficiency, and as a reactant in the Finkelstein reaction.-Uses:Sodium iodide is commonly used to treat and prevent iodine deficiency....
, scandium
Scandium
Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanoids...
iodide
Iodide
An iodide ion is the ion I−. Compounds with iodine in formal oxidation state −1 are called iodides. This page is for the iodide ion and its salts. For information on organoiodides, see organohalides. In everyday life, iodide is most commonly encountered as a component of iodized salt,...
, indium monobromide (InBr), or tellurium as the light-generating medium.
A patent #20070075617 is pending since 2006 for a sulfur lamp with electrodes — in fact, a more traditional gas–discharge lamp where a magnetron is not required. Various electrode coatings are suggested to combat high chemical activity of sulfur. As usual with patents, though, only commercial applications will reveal whether this design is viable.
Prominent installations
Atrium (architecture)
In modern architecture, an atrium is a large open space, often several stories high and having a glazed roof and/or large windows, often situated within a larger multistory building and often located immediately beyond the main entrance doors...
in the National Air and Space Museum
National Air and Space Museum
The National Air and Space Museum of the Smithsonian Institution holds the largest collection of historic aircraft and spacecraft in the world. It was established in 1976. Located in Washington, D.C., United States, it is a center for research into the history and science of aviation and...
.
See also
- Electrodeless lampElectrodeless lampAn electrodeless lamp is a light source in which the power required to generate light is transferred from outside the lamp envelope to inside via electromagnetic fields, in contrast with a typical electrical lamp that uses electrical connections through the lamp envelope to transfer power...
- Plasma lampPlasma lampPlasma globes, or plasma lamps , are novelty items that were most popular in the 1980s...
- List of light sources
- Timeline of lighting technologyTimeline of lighting technologyTimeline of lighting technology- Antiquity :* 70,000 BCE A hollow rock, shell, or other natural found object was filled with moss or a similar material that was soaked in animal fat and then ignited.* c. 4500 BCE oil lamps...
External links
- General information
- Sulphur lamp information
- "Lighting a Revolution: Lee Anderson and Michael Ury"
- "Sun on Earth", International Association for Energy-Efficient Lighting Newsletter, March 1994
- Radio frequency lamps overview
- Sulphur Plasma Light manufacturer
- Sulphur Plasma Videos
- Technical papers
- An artificial solar spectrum substantially alters plant development compared with usual climate room irradiance spectra
- Transport and equilibrium in molecular plasmas: the sulfur lamp
- General treatment of the interplay between fluid and radiative transport phenomena in symmetric plasmas: the sulphur lamp as a case study
- Investigation of the IR Radiation Losses in Microwave Operated Sulfur Lamps
- Environmental Friendly High Efficient Light Source
- Spectral Properties of Microwave-powered Sulfur Lamps in Comparison to Sunlight and High Pressure Sodium/Metal Halide Lamps
- The electrodeless discharge lamp: a prospective tool for photochemistry
- Sulfur Light Sources with Minimal Microwave Power
- Courret, Gilles, Environmental Friendly High Efficient Light Source, La Haute École d'Ingénierie et de Gestion du Canton de Vaud
- Environmental Friendly High Efficient Light Source
- Radio interference
- Criticism
- Criticism of sulfur lamps at SlashdotSlashdotSlashdot is a technology-related news website owned by Geeknet, Inc. The site, which bills itself as "News for Nerds. Stuff that Matters", features user-submitted and ‑evaluated current affairs news stories about science- and technology-related topics. Each story has a comments section...
- First-hand experience with sulfur lamps at Slashdot
- More first-hand experience with sulfur lamps at Slashdot
- Criticism of sulfur lamps at Slashdot
Offline sources
- Suplee, Curt, "Energy Dept. Brings Dazzling Bulb to Light", The Washington PostThe Washington PostThe Washington Post is Washington, D.C.'s largest newspaper and its oldest still-existing paper, founded in 1877. Located in the capital of the United States, The Post has a particular emphasis on national politics. D.C., Maryland, and Virginia editions are printed for daily circulation...
, October 21, 1994 - Suplee, Curt, "A New Kind of Illumination That Burns Brightly, but Not Out", The Washington Post, October 24, 1994
- Holusha, John, "Light Source To Replace Many Bulbs", The New York TimesThe New York TimesThe New York Times is an American daily newspaper founded and continuously published in New York City since 1851. The New York Times has won 106 Pulitzer Prizes, the most of any news organization...
, October 26, 1994 - "Sulfur Lighting on Track", Environmental Building News, July 1995
- Schroeder, Michael, and Dreazen, YochiYochi DreazenYochi J. Dreazen is an American reporter for the National Journal. His area of expertise is military affairs and national security. He is a frequent guest on radio and television programs, including The Diane Rehm Show and Washington Week with Gwen Ifill .Dreazen was born in Chicago, Illinois, US...
, "Energy-Saving Light Bulbs Mar Satellite Radio", The Wall Street JournalThe Wall Street JournalThe Wall Street Journal is an American English-language international daily newspaper. It is published in New York City by Dow Jones & Company, a division of News Corporation, along with the Asian and European editions of the Journal....
, August 6, 2001 - "Sulfur Lighting No Longer on Track", Environmental Building News, August 2005