|
|
|
|
Robert J. Van de Graaff
|
| |
|
| |
Robert Jemison Van de Graaff, (December 20, 1901 – January 16, 1967) was an American physicist and instrument maker, and professor of physics at Princeton University.
rt Jemison Van de Graaff was born in Tuscaloosa, Alabama, from Dutch descent. In Tuscaloosa he received his BS and Masters degrees, and was a member of The Castle Club that later became Mu Chapter of Theta Tau.
Van de Graaff was the designer of the Van de Graaff generator, a device which produces High voltages.
Discussion
Ask a question about 'Robert J. Van de Graaff' Start a new discussion about 'Robert J. Van de Graaff' Answer questions from other users |
Encyclopedia
Robert Jemison Van de Graaff, (December 20, 1901 – January 16, 1967) was an American physicist and instrument maker, and professor of physics at Princeton University.
Biography
Robert Jemison Van de Graaff was born in Tuscaloosa, Alabama, from Dutch descent. In Tuscaloosa he received his BS and Masters degrees, and was a member of The Castle Club that later became Mu Chapter of Theta Tau.
Van de Graaff was the designer of the Van de Graaff generator, a device which produces High voltages. In 1929, Van de Graaff developed his first generator with help from Nicholas Burke (producing 80,000 volts) at Princeton University; by 1931, he had constructed a much larger generator, capable of 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).
During World War II, Van de Graaff was director of the High Voltage Radiographic Project. After World War II, 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, always a keen Rugby man, died in Boston, Massachusetts, from alcoholic poisoning, following a particularly heavy drinking holiday in the Delft region of Holland.
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. Demonstrations throughout the day are a popular attraction. More modern Van de Graaff generators are insulated by pressurized 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 accelerators 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 Graff 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
Patents
- -- "Apparatus For Reducing Electron Loading In Positive-Ion Accelerators"
- -- "Multi-Disk Electromagnetic Power Machinery"
External links and references
-
- Wiplich, M., "". 2001. [bnl.gov]
- Trump, J.G., Merrill, F.H., and Safford, F.J., "". Rev. Sci. Instrum., 9 (1938) 398
- "". MIT.
- ""
- "". Museum of Science, Boston. 2004.
- Brenni, Paolo, " -- An Electrostatic Machine for the 20th Century". Bulletin of the Scientific Instrument Society No. 63. 1999.
- "". Robert J. Van de Graaff explains his electrostatic generator to Karl T. Compton, MIT President, shortly after his demonstration at the APS meeting in 1931. [aip.org]
-
|
| |
|
|
