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An arc lamp or arc light is a lamp that produces light by an
electric arc An electric arc, or arc discharge, is an electrical breakdown of a gas that produces a prolonged electrical discharge. The electric current, current through a normally Electrical conductance, nonconductive medium such as air produces a plasma (p ...
(also called a voltaic arc). The carbon arc light, which consists of an arc between carbon electrodes in air, invented by
Humphry Davy Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for t ...
in the first decade of the 1800s, was the first practical
electric light An electric light, lamp, or light bulb is an electrical component that produces light. It is the most common form of artificial lighting. Lamps usually have a base made of ceramic, metal, glass, or plastic, which secures the lamp in the soc ...
. It was widely used starting in the 1870s for street and large building lighting until it was superseded by the
incandescent light An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxidat ...
in the early 20th century. It continued in use in more specialized applications where a high intensity point light source was needed, such as
searchlight A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direc ...
s and
movie projector A movie projector is an optics, opto-mechanics, mechanical device for displaying Film, motion picture film by projecting it onto a movie screen, screen. Most of the optical and mechanical elements, except for the illumination and sound devices ...
s until after
World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...
. The carbon arc lamp is now obsolete for most of these purposes, but it is still used as a source of high intensity
ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than ...
light. The term is now used for
gas discharge lamp Gas-discharge lamps are a family of artificial light sources that generate light by sending an electric discharge through an ionized gas, a plasma. Typically, such lamps use a noble gas (argon, neon, krypton, and xenon) or a mixture of these ...
s, which produce light by an arc between metal electrodes through a gas in a glass bulb. The common
fluorescent lamp A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet lig ...
is a low-pressure mercury arc lamp. The
xenon arc lamp A xenon arc lamp is a highly specialized type of gas discharge lamp, an electric light that produces light by passing electricity through ionized xenon gas at high pressure. It produces a bright white light to simulate sunlight, with application ...
, which produces a high intensity white light, is now used in many of the applications which formerly used the carbon arc, such as movie projectors and searchlights.


Operation

An ''arc'' is the discharge that occurs when a gas is
ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...
ized. A high voltage is pulsed across the lamp to "ignite" or "strike" the arc, after which the discharge can be maintained at a lower voltage. The "strike" requires an electrical circuit with an ''igniter'' and a
ballast Ballast is material that is used to provide stability to a vehicle or structure. Ballast, other than cargo, may be placed in a vehicle, often a ship or the gondola of a balloon or airship, to provide stability. A compartment within a boat, ship ...
. The ballast is wired in series with the lamp and performs two functions. First, when the power is first switched on, the igniter/starter (which is wired in parallel across the lamp) sets up a small current through the ballast and starter. This creates a small magnetic field within the ballast windings. A moment later the starter interrupts the current flow from the ballast, which has a high inductance and therefore tries to maintain the current flow (the ballast opposes any change in current through it); it cannot, as there is no longer a 'circuit'. As a result, a high voltage appears across the ballast momentarily, to which the lamp is connected; therefore the lamp receives this high voltage across it which 'strikes' the arc within the tube/lamp. The circuit will repeat this action until the lamp is ionized enough to sustain the arc. When the lamp sustains the arc, the ballast performs its second function, to limit the current to that needed to operate the lamp. The lamp, ballast and igniter are rating-matched to each other; these parts must be replaced with the same rating as the failed component or the lamp will not work. The colour of the light emitted by the lamp changes as its electrical characteristics change with temperature and time.
Lightning Lightning is a naturally occurring electrostatic discharge during which two electric charge, electrically charged regions, both in the atmosphere or with one on the land, ground, temporarily neutralize themselves, causing the instantaneous ...
is a similar principle where the atmosphere is ionized by the high potential difference (voltage) between earth and storm clouds. The temperature of the arc in an arc lamp can reach several thousand degrees Celsius. The outer glass envelope can reach 500 degrees Celsius, therefore before servicing one must ensure the bulb has cooled sufficiently to handle. Often, if these types of lamps are turned off or lose their power supply, one cannot restrike the lamp again for several minutes (called cold restrike lamps). However, some lamps (mainly fluorescent tubes/energy saving lamps) can be restruck as soon as they are turned off (called hot restrike lamps). The Vortek water-wall plasma arc lamp, invented in 1975 by David Camm and Roy Nodwell at the
University of British Columbia The University of British Columbia (UBC) is a public university, public research university with campuses near Vancouver and in Kelowna, British Columbia. Established in 1908, it is British Columbia's oldest university. The university ranks a ...
, Vancouver, Canada, made the Guinness Book of World Records in 1986 and 1993 as the most powerful continuously burning light source at over 300 kW or 1.2 million candle power.


Carbon arc lamp

In popular use, the term ''arc lamp'' means ''
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent In chemistry, the valence (US spelling) or valency (British spelling) of an element is the measure of its combining capacity with o ...
arc lamp'' only. In a carbon arc lamp, the electrodes are carbon rods in free air. To ignite the lamp, the rods are touched together, thus allowing a relatively low voltage to strike the arc. The rods are then slowly drawn apart, and electric current heats and maintains an arc across the gap. The tips of the carbon rods are heated and the carbon vaporizes. The carbon vapor in the arc is highly luminous, which is what produces the bright light. The rods are slowly burnt away in use, and the distance between them needs to be regularly adjusted in order to maintain the arc. Many ingenious mechanisms were invented to control the distance automatically, mostly based on
solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whose ...
s. In one of the simplest mechanically-regulated forms (which was soon superseded by more smoothly acting devices) the electrodes are mounted vertically. The current supplying the arc is passed in
series Series may refer to: People with the name * Caroline Series (born 1951), English mathematician, daughter of George Series * George Series (1920–1995), English physicist Arts, entertainment, and media Music * Series, the ordered sets used in ...
through a solenoid attached to the top electrode. If the points of the electrodes are touching (as in start up) the resistance falls, the current increases and the increased pull from the solenoid draws the points apart. If the arc starts to fail the current drops and the points close up again. The
Yablochkov candle A Yablochkov candle (sometimes electric candle) is a type of electric carbon arc lamp, invented in 1876 by the Russian electrical engineer Pavel Yablochkov. Design A Yablochkov candle consists of a sandwich of two electrodes, which are long car ...
is a simple arc lamp without a regulator, but it has the drawbacks that the arc cannot be restarted (single use) and a limited lifetime of only a few hours.


History

The concept of carbon-arc lighting was first demonstrated by
Humphry Davy Sir Humphry Davy, 1st Baronet, (17 December 177829 May 1829) was a British chemist and inventor who invented the Davy lamp and a very early form of arc lamp. He is also remembered for isolating, by using electricity, several elements for t ...
in the early 19th century, but sources disagree about the year he first demonstrated it; 1802, 1805, 1807 and 1809 are all mentioned. Davy used charcoal sticks and a two-thousand-
cell Cell most often refers to: * Cell (biology), the functional basic unit of life Cell may also refer to: Locations * Monastic cell, a small room, hut, or cave in which a religious recluse lives, alternatively the small precursor of a monastery ...
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
to create an arc across a gap. He mounted his electrodes horizontally and noted that, because of the strong convection flow of air, the arc formed the shape of an arch. He coined the term "arch lamp", which was contracted to "arc lamp" when the devices came into common usage. In the late nineteenth century, electric arc lighting was in wide use for public lighting. The tendency of electric arcs to flicker and hiss was a major problem. In 1895,
Hertha Ayrton Phoebe Sarah Hertha Ayrton (28 April 1854 – 26 August 1923) was a British engineer, mathematician, physicist and inventor, and suffragette. Known in adult life as Hertha Ayrton, born Phoebe Sarah Marks, she was awarded the Hughes Medal by the ...
wrote a series of articles for ''
The Electrician ''The Electrician'', published in London from 1861–1863 and 1878–1952, was the one of the earliest and foremost electrical engineering periodicals and scientific journals. It was published in two series: The original ''Electrician'' was publi ...
'', explaining that these phenomena were the result of oxygen coming into contact with the carbon rods used to create the arc. In 1899, she was the first woman ever to read her own paper before the
Institution of Electrical Engineers The Institution of Electrical Engineers (IEE) was a British professional organisation of electronics, electrical, manufacturing, and Information Technology professionals, especially electrical engineers. It began in 1871 as the Society of Te ...
(IEE). Her paper was "The Hissing of the Electric Arc". The arc lamp provided one of the first commercial uses for electricity, a phenomenon previously confined to experiment, the telegraph, and entertainment.


Carbon-arc lighting in the U.S.

In the United States, there were attempts to produce arc lamps commercially after 1850, but the lack of a constant electricity supply thwarted efforts. Thus electrical engineers began focusing on the problem of improving Faraday's
dynamo file:DynamoElectricMachinesEndViewPartlySection USP284110.png, "Dynamo Electric Machine" (end view, partly section, ) A dynamo is an electrical generator that creates direct current using a commutator (electric), commutator. Dynamos were the f ...
. The concept was improved upon by a number of people including and Charles F. Brush. It was not until the 1870s that lamps such as the
Yablochkov candle A Yablochkov candle (sometimes electric candle) is a type of electric carbon arc lamp, invented in 1876 by the Russian electrical engineer Pavel Yablochkov. Design A Yablochkov candle consists of a sandwich of two electrodes, which are long car ...
were more commonly seen. In 1877, the
Franklin Institute The Franklin Institute is a science museum and the center of science education and research in Philadelphia, Pennsylvania. It is named after the American scientist and statesman Benjamin Franklin. It houses the Benjamin Franklin National Memori ...
conducted a comparative test of dynamo systems. The one developed by Brush performed best, and Brush immediately applied his improved dynamo to arc-lighting, an early application being
Public Square A town square (or square, plaza, public square, city square, urban square, or ''piazza'') is an open public space, commonly found in the heart of a traditional town but not necessarily a true square, geometric square, used for community gathe ...
in
Cleveland, Ohio Cleveland ( ), officially the City of Cleveland, is a city in the U.S. state of Ohio and the county seat of Cuyahoga County. Located in the northeastern part of the state, it is situated along the southern shore of Lake Erie, across the U.S. ...
, on April 29, 1879. Despite this, Wabash, Indiana claims to be the first city ever to be lit with "Brush Lights". Four of these lights became active there on March 31, 1880
Wabash, IN
Wabash was a small enough city to be lit entirely by 4 lights, whereas the installation at Cleveland's Public Square only lit a portion of that larger city
Brush Lights, Cleveland
In 1880, Brush established the
Brush Electric Company Brush Electrical Machines is a manufacturer of electrical generators typically for gas turbine and steam turbine driven applications. The main office is based at Loughborough in Leicestershire, UK. History Charles Francis Brush, born in Eucli ...
. The harsh and brilliant light was found most suitable for public areas, such as Cleveland's Public Square, being around 200 times more powerful than contemporary filament lamps. The usage of Brush electric arc lights spread quickly. ''
Scientific American ''Scientific American'', informally abbreviated ''SciAm'' or sometimes ''SA'', is an American popular science magazine. Many famous scientists, including Albert Einstein and Nikola Tesla, have contributed articles to it. In print since 1845, it i ...
'' reported in 1881 that the system was being used in: 800 lights in rolling mills, steel works, shops, 1,240 lights in woolen, cotton, linen, silk, and other factories, 425 lights in large stores, hotels, churches, 250 lights in parks, docks, and summer resorts, 275 lights in railroad depots and shops, 130 lights in mines, smelting works, 380 lights in factories and establishments of various kinds, 1,500 lights in lighting stations, for city lighting, 1,200 lights in England and other foreign countries. A total of over 6,000 lights which are actually sold. There were three major advances in the 1880s:
František Křižík František Křižík (; July 8, 1847 – January 22, 1941) was a Czech inventor, electrical engineer, and entrepreneur. Biography Křižík was born into a family in Plánice. In spite of his background, Křižík managed in 1866 to study engin ...
invented in 1880 a mechanism to allow the automatic adjustment of the electrodes. The arcs were enclosed in a small tube to slow the carbon consumption (increasing the life span to around 100 hours). ''Flame arc lamps'' were introduced where the carbon rods had metal salts (usually magnesium, strontium, barium, or calcium fluorides) added to increase light output and produce different colours. In the U.S., patent protection of arc-lighting systems and improved dynamos proved difficult and as a result the arc-lighting industry became highly competitive. Brush's principal competition was from the team of
Elihu Thomson Elihu Thomson (March 29, 1853 – March 13, 1937) was an English-born American engineer and inventor who was instrumental in the founding of major electrical companies in the United States, the United Kingdom and France. Early life He was bor ...
and
Edwin J. Houston Edwin James Houston (July 9, 1847 – March 1, 1914) was an American electrical engineer, academic, businessman, inventor and writer. Biography Houston was born July 9, 1847, to John Mason and Mary (Lamour) Houston in Alexandria, Virginia. He gr ...
. These two had formed the American Electric Corporation in 1880, but it was soon bought up by Charles A. Coffin, moved to
Lynn, Massachusetts Lynn is the eighth-largest municipality in Massachusetts and the largest city in Essex County. Situated on the Atlantic Ocean, north of the Boston city line at Suffolk Downs, Lynn is part of Greater Boston's urban inner core. Settled by E ...
, and renamed the
Thomson-Houston Electric Company The Thomson-Houston Electric Company was a manufacturing company which was one of the precursors of the General Electric company. History The Thomson-Houston Electric Company was formed in 1882 in the United States when a group of Lynn, Massa ...
. Thomson remained, though, the principal inventive genius behind the company patenting improvements to the lighting system. Under the leadership of Thomson-Houston's patent attorney,
Frederick P. Fish Frederick Perry Fish (13 January 1855 – 6 November 1930) was an American lawyer and executive who served as president of American Telephone & Telegraph Corporation from 1901 to 1907. One of the leading patent attorneys of his age, representin ...
, the company protected its new patent rights. Coffin's management also led the company towards an aggressive policy of buy-outs and mergers with competitors. Both strategies reduced competition in the electrical lighting manufacturing industry. By 1890, the Thomson-Houston company was the dominant electrical manufacturing company in the U.S.
David F. Noble David Franklin Noble (July 22, 1945 – December 27, 2010Morrow, Adria"David Noble, academic and activist, dies at 65" ''The Globe and Mail'', December 28, 2010, accessed December 30, 2010.) was a historian and critic of technology, science ...
, ''America By Design: Science, Technology, and the Rise of Corporate Capitalism'' (New York: Oxford University Press, 1977), 6-10.
Nikola Tesla Nikola Tesla ( ; ,"Tesla"
''
Thomas Edison Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventio ...
's
Edison General Electric Company Thomas Alva Edison (February 11, 1847October 18, 1931) was an American inventor and businessman. He developed many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventio ...
. Conversely, Edison's control of direct current distribution and generating machinery patents blocked further expansion of Thomson-Houston. The roadblock to expansion was removed when the two companies merged in 1892 to form the
General Electric Company The General Electric Company (GEC) was a major British industrial conglomerate involved in consumer and defence electronics, communications, and engineering. The company was founded in 1886, was Britain's largest private employer with over 250 ...
. Arc lamps were used in some early motion-picture studios to illuminate interior shots. One problem was that they produce such a high level of
ultra-violet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30  PHz) to 400 nm (750  THz), shorter than that of visible light, but longer than X-rays. UV radiatio ...
light that many actors needed to wear
sunglasses Sunglasses or sun glasses (informally called shades or sunnies; more names below) are a form of protective eyewear designed primarily to prevent bright sunlight and high-energy visible light from damaging or discomforting the eyes. They can s ...
when off camera to relieve sore eyes resulting from the ultra-violet light. The problem was solved by adding a sheet of ordinary window glass in front of the lamp, blocking the ultra-violet. By the dawn of the "talkies", arc lamps had been replaced in film studios with other types of lights. In 1915,
Elmer Ambrose Sperry Elmer Ambrose Sperry Sr. (October 12, 1860 – June 16, 1930) was an American inventor and entrepreneur, most famous for construction, two years after Hermann Anschütz-Kaempfe, of the gyrocompass and as founder of the Sperry Gyroscope Company. ...
began manufacturing his invention of a high-intensity carbon arc
searchlight A searchlight (or spotlight) is an apparatus that combines an extremely bright source (traditionally a carbon arc lamp) with a mirrored parabolic reflector to project a powerful beam of light of approximately parallel rays in a particular direc ...
. These were used aboard warships of all navies during the 20th century for signaling and illuminating enemies. In the 1920s, carbon arc lamps were sold as family health products, a substitute for natural sunlight. Arc lamps were superseded by filament lamps in most roles, remaining in only certain niche applications such as
cinema Cinema may refer to: Film * Cinematography, the art of motion-picture photography * Film or movie, a series of still images that create the illusion of a moving image ** Film industry, the technological and commercial institutions of filmmaking ...
projection Projection, projections or projective may refer to: Physics * Projection (physics), the action/process of light, heat, or sound reflecting from a surface to another in a different direction * The display of images by a projector Optics, graphic ...
, spotlights, and searchlights. Even in these applications conventional carbon arc lamps are being pushed into obsolescence by
xenon arc lamp A xenon arc lamp is a highly specialized type of gas discharge lamp, an electric light that produces light by passing electricity through ionized xenon gas at high pressure. It produces a bright white light to simulate sunlight, with application ...
s, but were still being manufactured as spotlights at least as late as 1982 and are still manufactured for at least one purpose – simulating sunlight in "accelerated aging" machines intended to estimate how fast a material is likely to be degraded by environmental exposure. The practice of shipping and projecting motion pictures on 2,000-foot reels, and employing "changeovers" between two projectors, was due to the carbon rods used in projector lamphouses having a lifespan of roughly 22 minutes (which corresponds to the amount of film in said reels when projected at 24 frames/second). The projectionist would replace the carbon rod when changing film reels. The two-projector changeover setup largely disappeared in the 1970s with the advent of xenon projector lamps, being replaced with single-projector platter systems, though films would continue to be shipped to cinemas on 2,000-foot reels.


See also

*
Graphite Graphite () is a crystalline form of the element carbon. It consists of stacked layers of graphene. Graphite occurs naturally and is the most stable form of carbon under standard conditions. Synthetic and natural graphite are consumed on large ...
*
High-intensity discharge lamp High-intensity discharge lamps (HID lamps) are a type of electrical gas-discharge 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 tu ...
*
Large-format slide projector A large-format slide projector (also often called large-format projector or large-image projector) is a kind of slide projector for large image projection which has a very powerful light source (up to 12 thousand watts using arc lamps). Therefor ...
*
Léon Foucault Jean Bernard Léon Foucault (, ; ; 18 September 1819 – 11 February 1868) was a French physicist best known for his demonstration of the Foucault pendulum, a device demonstrating the effect of Earth's rotation. He also made an early measurement ...
*
List of light sources This is a list of sources of light, the visible part of the electromagnetic spectrum. Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic ener ...
*
List of Nikola Tesla patents Nikola Tesla was an inventor who obtained around 300 patents worldwide for his inventions. Some of Tesla's patents are not accounted for, and various sources have discovered some that have lain hidden in patent archives. There are a minimum of 27 ...
*
Moonlight tower A moonlight tower or moontower is a lighting structure designed to illuminate areas of a town or city at night. The towers were popular in the late 19th century in cities across the United States and Europe; they were most common in the 1880s and ...
*
Pavel Yablochkov Pavel Nikolayevich Yablochkov (also transliterated as Jablochkoff; russian: Павел Николаевич Яблочков) ( – ) was a Russian electrical engineer, businessman and the inventor of the Yablochkov candle (a type of electric ...
and
Yablochkov candle A Yablochkov candle (sometimes electric candle) is a type of electric carbon arc lamp, invented in 1876 by the Russian electrical engineer Pavel Yablochkov. Design A Yablochkov candle consists of a sandwich of two electrodes, which are long car ...
*
Photolithography In integrated circuit manufacturing, photolithography or optical lithography is a general term used for techniques that use light to produce minutely patterned thin films of suitable materials over a substrate, such as a silicon wafer, to protect ...
*
Praseodymium Praseodymium is a chemical element with the symbol Pr and the atomic number 59. It is the third member of the lanthanide series and is considered to be one of the rare-earth metals. It is a soft, silvery, malleable and ductile metal, valued for i ...
*
Shielded metal arc welding Shielded metal arc welding (SMAW), also known as manual metal arc welding (MMA or MMAW), flux shielded arc welding or informally as stick welding, is a manual arc welding process that uses a consumable electrode covered with a flux to lay the we ...
*
Stage lighting Stage lighting is the craft of lighting as it applies to the production of theater, dance, opera, and other performance arts.
* Timeline of lighting technology * Walther Nernst


References


Bibliography

* * * *


External links


"UNILAM Super High Pressure Short Arc Lamp"


article in Low-tech Magazine {{Authority control Gas discharge lamps Types of lamp