Energy & Power

The Museum's collections on energy and power illuminate the role of fire, steam, wind, water, electricity, and the atom in the nation's history. The artifacts include wood-burning stoves, water turbines, and windmills, as well as steam, gas, and diesel engines. Oil-exploration and coal-mining equipment form part of these collections, along with a computer that controlled a power plant and even bubble chambers—a tool of physicists to study protons, electrons, and other charged particles.

A special strength of the collections lies in objects related to the history of electrical power, including generators, batteries, cables, transformers, and early photovoltaic cells. A group of Thomas Edison's earliest light bulbs are a precious treasure. Hundreds of other objects represent the innumerable uses of electricity, from streetlights and railway signals to microwave ovens and satellite equipment.

Flat fluorescent lamp with green phosphor used to back-light aircraft instrument panels.Currently not on view
Description (Brief)
Flat fluorescent lamp with green phosphor used to back-light aircraft instrument panels.
Location
Currently not on view
date made
ca 1942
Maker
General Electric
ID Number
1997.0388.45
accession number
1997.0388
catalog number
1997.0388.45
Charles Greeley Abbot (1872–1973), the second director of the Smithsonian Astrophysical Observatory and the fifth secretary of the Smithsonian Institution, spent his scientific career measuring the intensity of solar radiation and seeking to correlate solar changes with weather c
Description
Charles Greeley Abbot (1872–1973), the second director of the Smithsonian Astrophysical Observatory and the fifth secretary of the Smithsonian Institution, spent his scientific career measuring the intensity of solar radiation and seeking to correlate solar changes with weather conditions on the earth. He was also interested in the practical use of solar radiation. This cooker, which he built in 1940, uses a cylindrical aluminum mirror that is mounted parallel to the earth's axis to collect solar energy and focus it on a pyrex tube that is filled with a chlorinated benzene ("arochlor"); the energy is then transmitted to a square oven in which cakes and cookies could be baked. Abbot obtained a patent (#2,247,830) on this cooker in 1941.
Location
Currently not on view
Date made
1940
user
Abbot, Charles Greeley
maker
Abbot, Charles Greeley
ID Number
PH.334632
catalog number
334632
patent number
2,247,830
accession number
312088
The discovery of nuclear fission in uranium, announced in 1939, allowed physicists to advance with confidence in the project of creating "trans-uranic" elements - artificial ones that would lie in the periodic table beyond uranium, the last and heaviest nucleus known in nature.
Description
The discovery of nuclear fission in uranium, announced in 1939, allowed physicists to advance with confidence in the project of creating "trans-uranic" elements - artificial ones that would lie in the periodic table beyond uranium, the last and heaviest nucleus known in nature. The technique was simply to bombard uranium with neutrons. Some of the uranium nuclei would undergo fission, newly understood phenomenon, and split violently into two pieces. In other cases, however, a uranium-238 nucleus (atomic number 92) would quietly absorb a neutron, becoming a nucleus of uranium-239, which in turn would soon give off a beta-particle and become what is now called neptunium-239 (atomic number 93). After another beta decay it would become Element 94 (now plutonium-239)
By the end of 1940, theoretical physicists had predicted that this last substance, like uranium, would undergo fission, and therefore might be used to make a nuclear reactor or bomb. Enrico Fermi asked Emilio Segre to use the powerful new 60-inch cyclotron at the University of California at Berkeley to bombard uranium with slow neutrons and create enough plutonium-239 to test it for fission. Segre teamed up with Glenn T. Seaborg, Joseph W. Kennedy, and Arthur C. Wahl in January 1941 and set to work.
They carried out the initial bombardment on March 3-6, then, using careful chemical techniques, isolated the tiny amount (half a microgram) of plutonium generated. They put it on a platinum disc, called "Sample A," and on March 28 bombarded it with slow neutrons to test for fission. As expected, it proved to be fissionable - even more than U-235. To allow for more accurate measurements, they purified Sample A and deposited it on another platinum disc, forming the "Sample B" here preserved. Measurements taken with it were reported in a paper submitted to the Physical Review on May 29, 1941, but kept secret until 1946. (The card in the lid of the box bears notes from a couple of months later.)
After the summer of 1941, this particular sample was put away and almost forgotten, but the research that began with it took off in a big way. Crash programs for the production and purification of plutonium began at Berkeley and Chicago, reactors to make plutonium were built at Hanford, Washington, and by 1945 the Manhattan Project had designed and built a plutonium atomic bomb. The first one was tested on July 16, 1945 in the world's first nuclear explosion, and the next was used in earnest over Nagasaki. (The Hiroshima bomb used U-235.)
Why is our plutonium sample in a cigar box? G.N. Lewis, a Berkeley chemist, was a great cigar smoker, and Seaborg, his assistant, made it a habit to grab his boxes as they became empty, to use for storing things. In this case, it was no doubt important to keep the plutonium undisturbed and uncontaminated, on the one hand, but also, on the other hand, to make it possible for its weak radiations to pass directly into instruments - not through the wall of some closed container. Such considerations, combined probably with an awareness of the historic importance of the sample, brought about the storage arrangement we see.
Location
Currently not on view
Date made
1941-05-21
Associated Date
1941-05-29
referenced
Segre, Emilio
Seaborg, Glenn T.
Kennedy, Joseph W.
Wahl, Arthur C.
Lewis, G. N.
University of California, Berkeley
maker
Segre, Emilio
Seaborg, Glenn
ID Number
EM.N-09384
catalog number
N-09384
accession number
272669
A blue fluorescent “Mazda" lamp. Lamps of this type were used to back-light aircraft instrument panels.Currently not on view
Description (Brief)
A blue fluorescent “Mazda" lamp. Lamps of this type were used to back-light aircraft instrument panels.
Location
Currently not on view
date made
ca 1940
maker
Westinghouse Electric Corporation
ID Number
1997.0387.15
accession number
1997.0387
catalog number
1997.0387.15
Engineer Russell Ohl worked at Bell Labs during the 1930s and made a discovery that contributed to the invention of both solar cells and transistors.
Description (Brief)
Engineer Russell Ohl worked at Bell Labs during the 1930s and made a discovery that contributed to the invention of both solar cells and transistors. While researching semiconductors—materials whose ability to conduct electricity can be manipulated—he found positive (P) and negative (N) regions created by impurities in his silicon sample. The barrier between the regions, called a P-N junction, prevented electrons from moving—until he exposed the silicon to sunlight. Then electrons crossed the junction and generated a current, converting sunlight into electrical energy. The silicon rod mounted in this reflector contains a P-N junction across the center and is drawn as figure eight on U.S. Patent 2,402,662, "Light-Sensitive Electric Device," issued to Ohl on 25 June 1946.
Location
Currently not on view
Date made
1940
associated date
1940
associated user
unknown
associated person
Ohl, Russell S.
maker
Ohl, Russell S.
ID Number
EM.334949
catalog number
334949
accession number
314577
maker number
10
patent number
2402662
A short fluorescent "Mazda" lamp rated at 6 watts. This is a very early fluorescent lamp.Currently not on view
Description (Brief)
A short fluorescent "Mazda" lamp rated at 6 watts. This is a very early fluorescent lamp.
Location
Currently not on view
date made
ca 1945
maker
Westinghouse Electric & Manufacturing Co.
ID Number
1997.0387.16
accession number
1997.0387
catalog number
1997.0387.16
A type DH-1 mercury vapor lamp originally introduced in 1938 for black-light and photochemical applications.Currently not on view
Description (Brief)
A type DH-1 mercury vapor lamp originally introduced in 1938 for black-light and photochemical applications.
Location
Currently not on view
date made
ca 1940
maker
Hanovia Chemical and Manufacturing Company
ID Number
1997.0387.22
accession number
1997.0387
catalog number
1997.0387.22
Type S-4 mercury vapor sunlamp with glass that transmitted both visible light and ultraviolet rays for use in tanning.Currently not on view
Description (Brief)
Type S-4 mercury vapor sunlamp with glass that transmitted both visible light and ultraviolet rays for use in tanning.
Location
Currently not on view
date made
ca 1940
maker
General Electric Company
ID Number
1997.0387.04
accession number
1997.0387
catalog number
1997.0387.04
Production Fluorescent Miniature Christmas-tree lamp, Coral color, 4w. Circa 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (argon?). Tipless G-shape envelope with phosphor coating on inner bulb-wall.
Description (Brief)
Production Fluorescent Miniature Christmas-tree lamp, Coral color, 4w. Circa 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (argon?). Tipless G-shape envelope with phosphor coating on inner bulb-wall. Printed on skirt: "Sylvania Fluorescent 04 4W-120AC Coral [Sylvania Logo]". Unit operates via coronal discharge.
Location
Currently not on view
date made
ca 1946
maker
Sylvania Electric Products Inc.
ID Number
1998.0005.01
catalog number
1998.0005.01
accession number
1998.0005
Laboratory discharge lamp designed to emit the spectrum of the element sodium.Currently not on view
Description (Brief)
Laboratory discharge lamp designed to emit the spectrum of the element sodium.
Location
Currently not on view
date made
1940
maker
Osram
ID Number
2001.0033.06
accession number
2001.0033
catalog number
2001.0033.06
GE Mazda C floodlamp, circa 1943. Steel medium-screw base with glass insulator. C-5BD tungsten filament with 5 upper, 4 lower support hooks set in a glass bead which is affixed to the press with a metal rod, crimp connectors, offset-dumet leads. Tipless G-shape envelope.
Description (Brief)
GE Mazda C floodlamp, circa 1943. Steel medium-screw base with glass insulator. C-5BD tungsten filament with 5 upper, 4 lower support hooks set in a glass bead which is affixed to the press with a metal rod, crimp connectors, offset-dumet leads. Tipless G-shape envelope. Stamped: "Floodlight / Mazda / [GE logo] / 250W 120V / Burn Base Down to Horizontal". The steel base means that this lamp was produced during World War II. Restrictions on brass supplies meant that lamp makers used steel instead.
Location
Currently not on view
date made
ca 1943
maker
General Electric Company
ID Number
EM.320680
catalog number
320680
accession number
242716
Two early transistors in a sample box distributed by Bell Telephone Labs. Each transistor is a steel, cylindrical can with hole in one side, recessed top, two leads at right angles emerge from the bottom. Printed on top of box: “Bell Telephone Labs.
Description (Brief)
Two early transistors in a sample box distributed by Bell Telephone Labs. Each transistor is a steel, cylindrical can with hole in one side, recessed top, two leads at right angles emerge from the bottom. Printed on top of box: “Bell Telephone Labs. / Transistors / Complimentary Sample / For Experimental Use Only”. One transistor marked: “AP1198”, the other is marked “AP1274”.
John Bardeen, Walter Brattain and William Shockley at Bell Telephone Laboratories developed a revolutionary device in 1947: the transistor. Using a semiconductor like germanium, transistors could transmit or amplify electrical currents more reliably and using far less power than vacuum tubes. The Bell Telephone Company provided most of the telephone service in the U.S. at that time but worried about anti-trust regulations should they try to monopolize the transistor invention. So for a licensing fee or $25,000 any company could gain access to transistor technology. This 1948 sample case contains two germanium point-contact transistors “for experimental use only.”
date made
ca 1948
maker
Bell Telephone Laboratories
ID Number
2003.0231.17
accession number
2003.0231
catalog number
2003.0231.17
An incandescent lamp made to provide a minimum level of lighting for safety inside homes during air-raid alerts. Red light is emitted from the top, although lamp envelope gets very hot. Characteristics: Brass medium-screw base with glass insulator. Tungsten filament (intact).
Description (Brief)
An incandescent lamp made to provide a minimum level of lighting for safety inside homes during air-raid alerts. Red light is emitted from the top, although lamp envelope gets very hot. Characteristics: Brass medium-screw base with glass insulator. Tungsten filament (intact). BT-style envelope with black coating around sides, and red coating on top. Note overspray around base-collar. Lamp purchased by donor at a Shrewsbury, PA antique shop in 1997. Printed on label: "Wabash / Blackout Bulb / For Blackout Lighting / Mf'd. By / Wabash Appliance Corp. / * Brooklyn, N.Y. / Patent Pending".
Location
Currently not on view
date made
ca 1943
maker
Wabash Appliance Corporation
ID Number
2003.0030.02
accession number
2003.0030
catalog number
2003.0030.02
Introduced in the early 19th century, snag boats were designed to clear trees, stumps, and other obstructions from navigable rivers and channels.
Description
Introduced in the early 19th century, snag boats were designed to clear trees, stumps, and other obstructions from navigable rivers and channels. Most were in the form of a catamaran, with two parallel hulls between which trees were hauled in, cut up, and disposed of on land.
Designed by the Army Corps of Engineers, the federal agency responsible for maintaining the national waterways, Charles H. West was built at Nashville, Tenn., in 1933-34 by the Nashville Bridge Co. at a cost of $227,260.48. It measured 170’ in length and 38’ in beam but only drew 4’-6” of water. Instead of a catamaran design, the West had a normal, shallow sternwheeler hull. At the flat or scow bow, two A-frames hauled snags up a ramp for disposal. It cleared snags along the lower Mississippi River for many years.
In 1969, the West was sold to a private party and converted to the restaurant boat Lt. Robert E. Lee in St. Louis, Mo. the following year. The name was fitting. Although best known as a Confederate general, in the late 1830s, Lee had been an officer in the Corps of Engineers. His work installing pilings and wing dams had helped the Mississippi currents to clear silt and keep open the main St. Louis landing.
Moored on the Mississippi near the St. Louis Arch, the Lee was a successful restaurant until a 1993 flood devastated the waterfront. After several failed attempts to reopen, the vessel was auctioned on December 19, 2008, for $200,000. Its new owners plan to renovate and reopen the famous ship once again as a restaurant and nightclub in St. Louis.
Date made
1966
ID Number
TR.326538
catalog number
326538
accession number
265606
Flat fluorescent lamp with green phosphor used to back-light aircraft instrument panels.Currently not on view
Description (Brief)
Flat fluorescent lamp with green phosphor used to back-light aircraft instrument panels.
Location
Currently not on view
date made
ca 1942
Maker
General Electric
ID Number
1997.0388.46
accession number
1997.0388
catalog number
1997.0388.46
As knowledge of materials and experience making electric lamps grew in the early 20th century, more efficient light sources began to reach the market.
Description
As knowledge of materials and experience making electric lamps grew in the early 20th century, more efficient light sources began to reach the market. In 1932 a collaboration of General Electric Company of England (GEC), Philips in the Netherlands, and Osram in Germany introduced a discharge lamp that used low-pressure sodium vapor. The key to a workable sodium lamp lay in a special glass (called borate glass) that could withstand the very corrosive nature of sodium. Arthur Compton in the U.S. described such a glass in 1926. But it took five more years to learn how to actually produce it so that a lamp could be made.
Discharge lamps make light by passing an electrical current through a gas, in this case sodium vapor. The current energizes the gas which then emits light. In this lamp, the sodium is contained by the bulb, which is lined with the borate glass. The lamp in turn is mounted inside a larger, double-walled glass jacket (part of the light fixture, not shown) to keep the temperature around the lamp stable during operation. Sodium light is a stark yellow suitable only for use in applications like street lighting, but the energy efficiency is very high. Early models gave 40 lumens per watt (lpw), a figure that reached about 100 lpw by 1960. Today's low-pressure sodium lamps give close to 200 lpw, the most energy efficient light source commercially available.
This lamp was made for street-lighting use by (U.S.) General Electric around 1940.
Lamp characteristics: Plastic, four-post base. Re-coiled tungsten electrodes mounted inside metal shields. The small brown cylinder mounted near the stem press is a starting resistance. Six asbestos insulator rings mount on the lamp's neck and are secured by the brass collar. (The rings have been removed and stored while the lamp is on display and are not in this picture.) Tipless, T-shaped envelope with about 70% of the inner wall coated by condensed sodium.
date made
ca. 1940
Date made
ca 1940
Associated Name
Sero, Charles M.
maker
General Electric Vapor Lamp Company
ID Number
1997.0387.14
accession number
1997.0387
catalog number
1997.0387.14
Object N-08216 is the assembly of the first Kerst Betatron as it appeared in the Atom Smashers exhibition at the NMAH.
Description
Object N-08216 is the assembly of the first Kerst Betatron as it appeared in the Atom Smashers exhibition at the NMAH. mounted horizontally, a toroidal vacuum chamber made of white ceramic with two cylindrical ports, each joined to fused-on glass extensions; circular magnet coils mounted above and below plane of vacuum chamber; rectangular laminated iron yoke surrounding the coils on top, bottom and two sides; enclosing the yoke, a rectangular metal frame of four horizontal angle strips joined by four welded vertical straps, two on each side, and by four bolts, two on each end. Between the yoke laminations and each coil is a thin sheet of slightly flexible, warped, black material, like plastic or impregnated cardboard; each is in two pieces to fit around the central axis. Two circular gray plates are positioned at the top and bottom of the vacuum chamber, separating it from the upper and lower coils, respectively.
It is presumed that the left-hand cylindrical port contains the electron source, and the right-hand port contains the beam of x-rays from the internal target. Wires protrude from both cylindrical ports.
History and basic principles
Among the many investigators who attempted to accelerate electrons by magnetic induction, none were successful until Donald Kerst produced 2.3-MeV electrons in a betatron at the University of Illinois in 1940. He later constructed a number of betatrons of successively higher energies, culminating in the 300-MeV betatron at the University of Illinois. Kerst’s success was due to a very careful theoretical analysis of the orbit dynamics in accelerators (including a study of the requirements for injection); to a preliminary analysis of all conceivable effects relevant to the operation of a betatron; and to a careful and detailed design of the magnet structure, vacuum system, and power supply. This was the first new accelerator to be constructed on the basis of a careful scientific analysis and a completely engineered design. Its success represented a turning point in the technology of particle accelerators from cut and try methods to scientifically engineered designs. All later accelerators, including the newest high energy synchrotrons, have been influenced by this early work of Kerst. It is only in the light of these later developments that we see the importance of the betatron not merely as a valuable instrument in itself but as a milestone in the development of particle accelerators generally. For example, the radial and vertical oscillations of the beam in all particle accelerators are now universally called betatron oscillations after the pioneering work of Kerst and Robert Serber, who together in 1941 published the first theoretical analysis of such oscillations as they occur in the betatron.
The betatron was quickly put to use in industry, medicine, and nuclear physics research. It was the first accelerator to provide gamma rays for photo-nuclear studies. In the late 1940s and early 1950s the betatron was used for much of the experimental research on photo disintegration of the deuteron, on photo-nuclear reactions (including the discovery of the giant dipole resonances), and important early work on nuclear structure from electron scattering. Of great importance was the pioneering use of megavolt electron beams for the production of energetic X rays for the therapeutic treatment of cancer. His fascinating depiction of this treatment included a description of the first use of phantoms and the intense activity precipitated by a student afflicted with brain tumor, heroic efforts that achieved much, but were unable to save the student. Kerst took a one-year leave of absence from the University of Illinois (1940-41), designed a 20-MeV betatron and a 100-MeV betatron working with the engineering staff at General Electric. He oversaw the construction and operation of the 20-MeV betatron, which he brought back to Urbana. During World War II days, Kerst built a 4-MeV portable betatron for inspecting bomb duds in situ and, most importantly, built a 20-MeV betatron at Los Alamos for study of bomb assembly implosions. His work was described in the official history of Los Alamos as: “The technical achievements are amongst the most impressive at Los Alamos.” After World War II Kerst built a 300-MeV betatron at the University of Illinois that was brought into operation in 1950 and provided a facility for studying high energy physics until it was superseded by synchrotrons and then by electron linacs.
(Above text excerpted from Donald William Kerst, 1911—1993, a Biographical Memoir by Andrew M. Sessler and Keith R. Symon, Copyright 1997, National Academies Press, Washington DC.)
It is no accident that the magnetic induction accelerator was so late to be realized. The concept had been advanced repeatedly in the preceding twenty years, but the problems of establishing and maintaining a particle beam were far greater than those encountered with several other accelerator types that were reduced to practice in the 1930’s.
Electrons, due to their relatively small mass, are much more “skittish” than the much more massive protons, and in the betatron must make a thousand times more circuits to reach the same energy as protons accelerated in a cyclotron. Where the cyclotron runs continuously, allowing the protons to find their own orbit, the betatron is pulsed: electrons must be injected at the right velocity to be captured into stable orbits, and held in them by a balance between the magnetic fields responsible for their acceleration and their orbit guidance, respectively. Kerst’s success depended decisively upon close mathematical analysis of these orbits, especially those immediately after injection into the vacuum chamber. This analysis was performed in collaboration with theoretical physicist, Robert Serber.
The principle of operation of the betatron is similar to that of a high voltage transformer. Alternating currents in the upper coils produce an increasing magnetic field, thus inducing an electromotive force around the electron’s circular orbit. This force, which Kerst calculated to be only 17 volts maximum acts on the electrons during each of their 200,000 circuits of the vacuum chamber, imparting a total energy of over two million electron volts (MeV).
The electrons are introduced into the vacuum chamber by an injector; they are not brought out of the vacuum chamber, but strike an internal target, converting their energy into x-rays which emerge through a second port.
Kerst, like E.O. Lawrence at the University of California, Berkeley, saw no intrinsic limits to his device. From the moment Kerst’s first device operated successfully in July 1940, he and his University looked forward to one more powerful (300 MeV) even than the cyclotrons being developed at Berkeley. Begun in 1945, immediately after World War II, with a special appropriation from the Illinois State Legislature, it was soon to be outmoded by newer methods of particle acceleration (e.g., the synchrotron).
Location
Currently not on view
date made
early 1940's
maker
Kerst, Donald
ID Number
EM.N-08216
accession number
233629
Background on Nier Mass Spectrograph; object id no. 1990.0446.01; catalog no. N-09567This object consists of the following three components: ion source with oven and acceleration electrode; semicircular glass vacuum chamber; ion collector with two plates.
Description
Background on Nier Mass Spectrograph; object id no. 1990.0446.01; catalog no. N-09567
This object consists of the following three components: ion source with oven and acceleration electrode; semicircular glass vacuum chamber; ion collector with two plates. The original device included an electromagnet, which is not part of this accession.
In 1939, as political tensions in Europe increased, American physicists learned of an astonishing discovery: the nucleus of the uranium atom can be split, causing the release of an immense amount of energy. Given the prospects of war, the discovery was just as worrying as it was intellectually exciting. Could the Germans use it to develop an atomic bomb?
The Americans realized that they had to determine whether a bomb was physically possible. Uranium consists mostly of the isotope U-238, with less than 1% of U-235. Theoreticians predicted that it was the nuclei of the rare U-235 isotope that undergo fission, the U-238 being inactive. To test this prediction, it was necessary to separate the two isotopes, but it would be difficult to do this since they are chemically identical.
Alfred Nier, a young physicist at the University of Minnesota, was one of the few people in the world with the expertise to carry out the separation. He used a physical technique that took advantage of the small difference in mass of the two isotopes. To separate and collect small quantities of them, he employed a mass spectrometer technique that he first developed starting in about 1937 for measurement of relative abundance of isotopes throughout the periodic table. (The basic principles of the mass spectrometer are described below.)
As a measure of the great importance of his work, in October 1939, Nier received a letter from eminent physicist Enrico Fermi, then at Columbia University, expressing great interest in whether, and how, the separation was progressing. Motivated by such urging, by late February 1940, Nier was able to produce two tiny samples of separated U-235 and U-238, which he provided to his collaborators at Columbia University, a team headed by John R. Dunning of Columbia. The Dunning team was using the cyclotron at the University in numerous studies to follow up on the news from Europe the year before on the fission of the uranium atom. In March 1940, with the samples provided by Nier, the team used neutrons produced by a proton beam from the cyclotron to show that it was the comparatively rare uranium-235 isotope that was the most readily fissile component, and not the abundant uranium-238.
The fission prediction was verified. The Nier-Dunning group remarked, "These experiments emphasize the importance of uranium isotope separation on a larger scale for the investigation of chain reaction possibilities in uranium" (reference: A.O. Nier et. al., Phys. Rev. 57, 546 (1940)). This proof that U-235 was the fissile uranium isotope opened the way to the intense U.S. efforts under the Manhattan Project to develop an atomic bomb. (For details, see Nier’s reminiscences of mass spectrometry and The Manhattan Project at: http://pubs.acs.org/doi/pdf/10.1021/ed066p385).
The Dunning cyclotron is also in the Modern Physics Collection (object id no. 1978.1074.01; catalog no. N-09130), and it will be presented on the SI collections website in 2015. (Search for “Dunning Cyclotron” at http://collections.si.edu/search/)
The Nier mass spectrometer used to collect samples of U-235 and U-238 (object id no. 1990.0446.01)
Nier designed an apparatus based on the principle of the mass spectrometer, an instrument that he had been using to measure isotopic abundance ratios throughout the entire periodic table. As in most mass spectrometers of the time, his apparatus produced positive ions by the controlled bombardment of a gas (UBr˅4, generated in a tiny oven) by an electron beam. The ions were drawn from the ionizing region and moved into an analyzer, which used an electromagnet for the separation of the various masses. Usually, the ion currents of the separated masses were measured by means of an electrometer tube amplifier, but in this case the ions simply accumulated on two small metal plates set at the appropriate positions. Nier’s mass spectrometer required that the ions move in a semicircular path in a uniform magnetic field. The mass analyzer tube was accordingly mounted between the poles of an electromagnet that weighed two tons, and required a 5 kW generator with a stabilized output voltage to power it. (The magnet and generator were not collected by the Smithsonian.) The ion source oven, 180-degree analyzer tube, and isotope collection plates are seen in the photos of the Nier apparatus (see accompanying media file images for this object).
Basic principles of the mass spectrometer
When a charged particle, such as an ion, moves in a plane perpendicular to a magnetic field, it follows a circular path. The radius of the particle’s path is proportional to the product of its mass and velocity, and is inversely proportional to the product of its electrical charge and the magnetic field strength. A mass spectrometer consists of three components: an ion source, a mass analyzer, and a detector. The ion source converts a portion of the sample into ions. There is a wide variety of ionization techniques, depending on the phase (solid, liquid, gas) of the sample and the efficiency of various ionization mechanisms for the unknown species. An extraction system removes ions from the sample and gives them a selected velocity. They then pass through the magnetic field (created by an electromagnet) of the mass analyzer. For a given magnetic field strength, the differences in mass-to-charge ratio of the ions result in corresponding differences in the curvature of their circular paths through the mass analyzer. This results in a spatial sorting of the ions exiting the analyzer. The detector records either the charge induced or the current produced when an ion passes by or hits a surface, thus providing data for calculating the abundance and mass of each isotope present in the sample. For a full description with a schematic diagram of a typical mass spectrometer, go to: http://www.chemguide.co.uk/analysis/masspec/howitworks.html
The Nier sector magnet mass spectrometer (not in Smithsonian Modern Physics Collection)
In 1940, during the time that Nier separated the uranium isotopes, he developed a mass spectrometer for routine isotope and gas analysis. An instrument was needed that did not use a 2-ton magnet, or required a 5 kW voltage-stabilized generator for providing the current in the magnet coils. Nier therefore developed the sector magnet spectrometer, in which a 60-degree sector magnet took the place of the much larger one needed to give a 180-degree deflection. The result was that a magnet weighing a few hundred pounds, and powered by several automobile storage batteries, took the place of the significantly larger and heavier magnet which required a multi-kW generator. Quoting Nier, “The analyzer makes use of the well-known theorem that if ions are sent into a homogeneous magnetic field between two V-shaped poles there is a focusing action, provided the source, apex of the V, and the collector lie along a straight line” (reference: A.O. Nier, Rev. Sci. Instr., 11, 212, (1940)). This design was to become the prototype for all subsequent magnetic deflection instruments, including hundreds used in the Manhattan Project.
Location
Currently not on view
Date made
ca 1940-02
associated person
Nier, Alfred O.
maker
Nier, Alfred O.
ID Number
1990.0446.01
accession number
1990.0446
catalog number
1990.0446.01
Object 1978.1073.01.1 is the first seven feet of the 40-ft. long Alvarez proton linear accelerator (linac), with two of the total of 9 oscillators.
Description
Object 1978.1073.01.1 is the first seven feet of the 40-ft. long Alvarez proton linear accelerator (linac), with two of the total of 9 oscillators. The Alvarez linac became operational in 1947-48.
The accelerator assembly .01.1 consists of the following major components: horizontal cylindrical vacuum tank enclosing a cylindrical copper cavity and central beam tube, (.01.1.01), connected externally to two vertical cylindrical oscillators (.01.1.02 and 01.1.09) and their associated power systems. The vacuum chamber is open at one end to show the internal cavity and linear array of drift tubes at the center. From its open end, five feet (approx.) of top half of the vacuum chamber has been cutaway to show the outer surface of the copper cavity. As displayed in Atom Smashers exhibition, a flange-type support attached under the vacuum tank is mounted on two pyramidal-shaped, vertical supports, which rest on a low platform surface. With the exception of oscillator .01.1.09, the other components numbered from .01.1.03 to .01.1.17 are minor (e.g., bolts, pipe, cables, electrical fittings, etc. - see curator's notes for details).
History and basic principles
The linear resonance accelerator, developed by E.O. Lawrence and colleagues during the 1930’s, was one of the earliest designs for attaining high particle energy without the requirement of correspondingly high voltage. Numerous attempts to realize it were made before World War II, but all proved disappointing, largely due to the limitations of technology for generating high-frequency electric fields.
As the name implies, linear resonance accelerators are straight machines in which, as in circular cyclotrons, the accelerated motion of charged particles is synchronized with an oscillating electric field. They were first made practical by the radar technology developed during World War II. Pulsed radio transmitters of extremely high peak power at ultra-high frequency made it possible to think about adding a million volts to the energy of protons and electrons for each linear foot of the accelerator. The opportunity was recognized by many physicists developing radar in Britain and the U.S. The boldest in exploiting it was Luis W. Alvarez, one of the scientists in Lawrence’s cyclotron group at University of California, Berkeley. In the Alvarez accelerator, an intense 200 MHz electric field is produced within the copper cavity by powerful oscillators - - originally surplus radar transmitters - - for 400 microseconds, 15 times per second. Protons injected into the end of the cavity from a Van de Graaff (electrostatic) accelerator with an energy of 4 MeV are accelerated further by the oscillating electric field when crossing the gaps between the drift tubes, but are shielded by the tubes when the electric field is in the opposite, retarding, phase. Along the length of the cavity, the individual drift tubes (see object ID no. 1978.1073.01.4-.5) lengthen in proportion to the increasing particle velocity, so that the protons always take the same time to travel from gap to gap, thus remaining in step with the oscillating electric field. The proton bunches are longitudinally stable as in a synchrotron, and are stabilized transversely by the action of converging fields produced by focusing grids (see object ID no. 1978.1073.01.3.01-.03). In 1947, the linac’s 40-ft. long cavity accelerated protons to 31.5 MeV, which, until that time was the highest energy to which protons had ever been accelerated. (Berkeley’s synchrocyclotron leap-frogged the energy to 350 MeV the next year.)
By 1947 the synchrotron emerged as the most practical concept for a high-energy particle accelerator, and the linac was subsequently used as the proton injector into the synchrotron. A smaller version of the Alvarez linac was used to inject 10 MeV protons into Berkeley’s “Bevatron”, a billion electron volt (BeV) synchrotron. Present injector linacs are hundreds of feet in length and produce particle beams of hundreds of MeV. For basic principles and history of synchrotrons, see McMillian synchrotron, Object ID no. N-09621.01 in the Modern Physics Collection.
Principle of strong focusing
Until 1952 designers of circular accelerators - - cyclotrons, betatrons, synchrotrons - - relied on the relatively “weak” focusing action of the magnetic field guiding ion or electron beams to hold these charged particles in stable circular orbits during acceleration. In 1952 the principle of alternating, or “strong”, focusing of particle beams was discovered at Brookhaven National Laboratory, and immediately found wide application in all types of accelerators.
Focusing forces on a particle deviating vertically are stronger the more the lines of magnetic force bulged outward, and focusing forces on a particle deviating from the orbit circle are much stronger if the magnet gap narrowed, so that the lines of magnetic force bulged inward. These two conditions, incompatible simultaneously, do not completely cancel their effects if applied successively. Thus, a sequence of magnets whose radial field gradients are directed alternatively outward and inward can have a powerful net focusing action on the particles passing through them. This approach is known as alternating-gradient focusing. The same principle applies to the action of electric fields on charged particles. After learning of the possibility and value of applying alternating-gradient focusing to proton linear accelerators, Alvarez’s group demonstrated strong radial focusing of the proton beam with electrostatic quadrupole lenses. In autumn of 1952, they immediately removed the original focusing grids and installed one such electrostatic quadrupole lens inside each drift tube (see object ID no. 1978.1073.01.5.2). The intensity of the proton beam doubled, and would have quadrupled had the insulation of the electrical leads held the required voltage. Thus the first proton linac was also the first strong-focusing accelerator. (The first accelerator to use magnetic alternating-gradient focusing was the 1 GeV synchrotron at Cornell University in 1953.) Before the prototype 32-MeV linac was shipped from Berkeley to its final location for operations at the University of Southern California, all of its drift tubes had been fitted with electrostatic strong-focusing electrodes.
Location
Currently not on view
date made
1945-48
ID Number
1978.1073.01.1
catalog number
1978.1073.01.1
accession number
1978.1073
Sylvania Fluorescent Christmas lamp, green, 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (neon?), wire resistance in stem. Tipless G-shape envelope with phosphor coating on inner bulb-wall.
Description (Brief)
Sylvania Fluorescent Christmas lamp, green, 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (neon?), wire resistance in stem. Tipless G-shape envelope with phosphor coating on inner bulb-wall. Printed on skirt: "Sylvania Fluorescent 08 4W-120AC Green [Sylvania "flashing S" logo] Made in U.S.A." Stamped under neutral-contact solder joint: "...[USA]...". Label found in box with lamp reads: "fluorescent Christmas Bulbs 1940's".
Location
Currently not on view
date made
1946
maker
Sylvania Electric Products Inc.
ID Number
2000.0224.10
catalog number
2000.0224.10
accession number
2000.0224
Sylvania Fluorescent Christmas lamp, coral, 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (neon?), wire resistance in stem. Tipless G-shape envelope with phosphor coating on inner bulb-wall.
Description (Brief)
Sylvania Fluorescent Christmas lamp, coral, 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (neon?), wire resistance in stem. Tipless G-shape envelope with phosphor coating on inner bulb-wall. Printed on skirt: "Sylvania Fluorescent 10 4W-120AC Coral [Sylvania "flashing S" logo] Made in U.S.A." Stamped under neutral-contact solder joint: "...U.[S.A..]..". Note found with lamp reads: "Flashing 'S' c1948 Christmas bulb - appeared in Spotlight Winter '92".
Location
Currently not on view
date made
1946
maker
Sylvania Electric Products Inc.
ID Number
2000.0224.14
catalog number
2000.0224.14
accession number
2000.0224
Production Fluorescent Miniature Christmas-tree lamp, blue color, 5w. Circa 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (argon?), wire resistance in stem.
Description (Brief)
Production Fluorescent Miniature Christmas-tree lamp, blue color, 5w. Circa 1946. Brass candelabra screw-base with glass insulator, plastic skirt. Two electrodes inside lamp, gas fill (argon?), wire resistance in stem. Tipless G-shape envelope with phosphor coating on inner bulb-wall. Printed on skirt: "Sylvania Fluorescent .. 5W-120AC Blue . [Sylvania "flashing S" logo]". Stamped on base shell: "[U.S.]A." Display label accompanying object reads: "1945 Christmas Tree Glow lamp." Second label reads: "Christmas tree glow lamp, 1945". Unit operates via coronal discharge.
Location
Currently not on view
date made
1946
maker
Sylvania Electric Products Inc.
ID Number
2000.0224.09
catalog number
2000.0224.09
accession number
2000.0224

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.