Robert J. Van de Graaff
Encyclopedia
Robert Jemison Van de Graaff, (December 20, 1901 – January 16, 1967) was an American
physicist
, noted for his design and construction of high voltage generators
, who taught at Princeton University
and MIT.
in Tuscaloosa, Alabama
, from Dutch descent. In Tuscaloosa, he received his BS and Masters degrees from The University of Alabama where he was a member of The Castle Club (later became Mu Chapter of Theta Tau
). After a year at the Alabama Power Company
, Van de Graaff studied at the Sorbonne
. In 1926 he earned a second BS at Oxford University on a Rhodes Scholarship, completing his PhD in 1928.
Van de Graaff was the designer of the Van de Graaff generator
, a device which produces high voltage
s. In 1929, Van de Graaff developed his first generator (producing 80,000 volts) with help from Nicholas Burke at Princeton University
. By 1931, he had constructed a larger generator, generating 7 million volts. He was a National Research Fellow, and from 1931 to 1934 a research associate at the Massachusetts Institute of Technology
. He became an associate professor in 1934 (staying there until 1960). He was awarded the Elliott Cresson Medal
in 1936.
During WWII, Van de Graaff was director of the High Voltage Radiographic Project. After WWII, he co-founded the High Voltage Engineering Corporation (HVEC). During the 1950s, he invented the insulating-core transformer
(producing high-voltage direct current). He also developed tandem
generator technology. The American Physical Society
awarded him the T. Bonner prize (1965) for the development of electrostatic accelerators.
Van de Graaff died January 16, 1967 in Boston
, Massachusetts
.
The Van de Graaff generator is a simple mechanical device. Small Van de Graaff generators are built by hobbyists and scientific apparatus companies and are used to demonstrate the effects of high DC potentials. Even small hobby machines produce impressive sparks several centimeters long. The largest air insulated Van de Graaff generator in the world, built by Van de Graaff himself, is operational and is on display at the Boston Museum of Science
. Demonstrations throughout the day are a popular attraction. More modern Van de Graaff generators are insulated by pressurized dielectric gas
, usually freon or sulfur hexafluoride
. In recent years, Van de Graaff generators have been slowly replaced by solid-state DC power supplies without moving parts. The energies produced by Van de Graaff atomic particle accelerator
s are limited to about 30 MeV, even with tandem generators accelerating doubly charged (for example alpha) particles. More modern particle accelerators using different technology produce much higher energies, thus Van de Graaff particle accelerators have become largely obsolete. They are still used to some extent for graduate student research at colleges and universities and as ion sources for high energy bursts.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
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...
, noted for his design and construction of high voltage generators
Van de Graaff generator
A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate very high voltages on a hollow metal globe on the top of the stand. It was invented in 1929 by American physicist Robert J. Van de Graaff. The potential differences achieved in modern Van de Graaff...
, who taught at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
and MIT.
Biography
Robert Jemison Van de Graaff was born at the Jemison-Van de Graaff MansionJemison-Van de Graaff Mansion
The Jemison-Van de Graaff Mansion is a historic house in Tuscaloosa, Alabama, United States. The structure remained a private residence until 1955, when it served first as a library, then publishing house offices, and lastly as a historic house museum...
in Tuscaloosa, Alabama
Tuscaloosa, Alabama
Tuscaloosa is a city in and the seat of Tuscaloosa County in west central Alabama . Located on the Black Warrior River, it is the fifth-largest city in Alabama, with a population of 90,468 in 2010...
, from Dutch descent. In Tuscaloosa, he received his BS and Masters degrees from The University of Alabama where he was a member of The Castle Club (later became Mu Chapter of Theta Tau
Theta Tau
ΘΤ Fraternity was founded in 1904 by four engineering students at the University of Minnesota in Minneapolis. As defined by the fraternity, the purpose of Theta Tau is to develop and maintain a high standard of professional interest among its members, and to unite them in a strong bond of...
). After a year at the Alabama Power Company
Alabama Power Company
Alabama Power Company, headquartered in Birmingham, Alabama, is a company in the southern United States that provides electricity service to 1.3 million homes, businesses, and industries in the southern two-thirds of Alabama. It is one of four U.S...
, Van de Graaff studied at the Sorbonne
Sorbonne
The Sorbonne is an edifice of the Latin Quarter, in Paris, France, which has been the historical house of the former University of Paris...
. In 1926 he earned a second BS at Oxford University on a Rhodes Scholarship, completing his PhD in 1928.
Van de Graaff was the designer of the Van de Graaff generator
Van de Graaff generator
A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate very high voltages on a hollow metal globe on the top of the stand. It was invented in 1929 by American physicist Robert J. Van de Graaff. The potential differences achieved in modern Van de Graaff...
, a device which produces high voltage
High voltage
The term high voltage characterizes electrical circuits in which the voltage used is the cause of particular safety concerns and insulation requirements...
s. In 1929, Van de Graaff developed his first generator (producing 80,000 volts) with help from Nicholas Burke at Princeton University
Princeton University
Princeton University is a private research university located in Princeton, New Jersey, United States. The school is one of the eight universities of the Ivy League, and is one of the nine Colonial Colleges founded before the American Revolution....
. By 1931, he had constructed a larger generator, generating 7 million volts. He was a National Research Fellow, and from 1931 to 1934 a research associate at the Massachusetts Institute of Technology
Massachusetts Institute of Technology
The Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological education and research.Founded in 1861 in...
. He became an associate professor in 1934 (staying there until 1960). He was awarded the Elliott Cresson Medal
Elliott Cresson Medal
The Elliott Cresson Medal, also known as the Elliott Cresson Gold Medal, was the highest award given by the Franklin Institute. The award was established by Elliott Cresson, life member of the Franklin Institute, with $1,000 granted in 1848...
in 1936.
During WWII, Van de Graaff was director of the High Voltage Radiographic Project. After WWII, he co-founded the High Voltage Engineering Corporation (HVEC). During the 1950s, he invented the insulating-core transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
(producing high-voltage direct current). He also developed tandem
Tandem
Tandem is an arrangement where a team of machines, animals or people are lined up one behind another, all facing in the same direction....
generator technology. The American Physical Society
American Physical Society
The American Physical Society is the world's second largest organization of physicists, behind the Deutsche Physikalische Gesellschaft. The Society publishes more than a dozen scientific journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than 20...
awarded him the T. Bonner prize (1965) for the development of electrostatic accelerators.
Van de Graaff died January 16, 1967 in Boston
Boston
Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...
, Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
.
Van de Graaff Generator
The Van de Graaff generator uses a motorized insulating belt (usually made of rubber) to conduct electrical charges from a high voltage source on one end of the belt to the inside of a metal sphere on the other end. Since electrical charge resides on the outside of the sphere, it builds up to produce an electrical potential much higher than that of the primary high voltage source. Practical limitations restrict the potential produced by large Van de Graaff generators to about 7 million volts. Van de Graaff generators are used primarily as DC power supplies for linear atomic particle accelerators in nuclear physics experiments. Tandem Van de Graaff generators are essentially two generators in series, and can produce about 15 million volts.The Van de Graaff generator is a simple mechanical device. Small Van de Graaff generators are built by hobbyists and scientific apparatus companies and are used to demonstrate the effects of high DC potentials. Even small hobby machines produce impressive sparks several centimeters long. The largest air insulated Van de Graaff generator in the world, built by Van de Graaff himself, is operational and is on display at the Boston Museum of Science
Museum of Science, Boston
The Museum of Science is a Boston, Massachusetts landmark, located in Science Park, a plot of land spanning the Charles River. Along with over 500 interactive exhibits, the Museum features a number of live presentations throughout the building every day, along with shows at the Charles Hayden...
. Demonstrations throughout the day are a popular attraction. More modern Van de Graaff generators are insulated by pressurized dielectric gas
Dielectric gas
A dielectric gas, or insulating gas, is a dielectric material in gaseous state. Its main purpose is to prevent or rapidly quench electric discharges. Dielectric gases are used as electrical insulators in high voltage applications, e.g...
, usually freon or sulfur hexafluoride
Sulfur hexafluoride
Sulfur hexafluoride is an inorganic, colorless, odorless, and non-flammable greenhouse gas. has an octahedral geometry, consisting of six fluorine atoms attached to a central sulfur atom. It is a hypervalent molecule. Typical for a nonpolar gas, it is poorly soluble in water but soluble in...
. In recent years, Van de Graaff generators have been slowly replaced by solid-state DC power supplies without moving parts. The energies produced by Van de Graaff atomic particle accelerator
Particle accelerator
A particle accelerator is a device that uses electromagnetic fields to propel charged particles to high speeds and to contain them in well-defined beams. An ordinary CRT television set is a simple form of accelerator. There are two basic types: electrostatic and oscillating field accelerators.In...
s are limited to about 30 MeV, even with tandem generators accelerating doubly charged (for example alpha) particles. More modern particle accelerators using different technology produce much higher energies, thus Van de Graaff particle accelerators have become largely obsolete. They are still used to some extent for graduate student research at colleges and universities and as ion sources for high energy bursts.
Education
- B.S. 1922 — University of AlabamaUniversity of AlabamaThe University of Alabama is a public coeducational university located in Tuscaloosa, Alabama, United States....
- Master's degree (Mechanical Engineering, 1923) — University of AlabamaUniversity of AlabamaThe University of Alabama is a public coeducational university located in Tuscaloosa, Alabama, United States....
- Marie Curie lectures (1925) — La Sorbonne
- Doctorate of Philosophy (Physics, 1928) — Oxford University
Patents
-- "Electrostatic Generator" --- US2922905 -- "Apparatus For Reducing Electron Loading In Positive-Ion Accelerators" -- "High Voltage Electromagnetic Apparatus Having An Insulating Magnetic Core" -- "High Voltage Electromagnetic Charged-Particle Accelerator Apparatus Having An Insulating Magnetic Core"
- US3239702 -- "Multi-Disk Electromagnetic Power Machinery" -- "Inclined field High Voltage Vacuum Tubes"
External links
- Short biography at the web-site for the Jemison-Van de Graaff Mansion
- Wiplich, M., "Short Biography Of Robert Jemison Van de Graaff". 2001. [bnl.gov]
- Trump, J.G., Merrill, F.H., and Safford, F.J., "Van de Graaff Generator". Rev. Sci. Instrum., 9 (1938) 398
- "Dr. Van de Graaff's large generator". MIT.
- "VDG for hobbyists and science fairs"
- "History of the Van de Graaff Generator". Museum of Science, Boston. 2004.
- Brenni, Paolo, "The Van de Graaff Generator -- An Electrostatic Machine for the 20th Century". Bulletin of the Scientific Instrument Society No. 63. 1999.
- Photos of Robert J. Van de Graff at the Emilio Segrè Visual Archives, American Institute of Physics
- Build your own VDG