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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. Events 69 - Vespasian, formerly a general under Nero, enters Rome to claim the title of Emperor. Year 1901 ( MCMI) was a Common year starting on Tuesday (link will display calendar of the Gregorian calendar (or a Common year starting Events 27 BC - The title Augustus is bestowed upon Gaius Julius Caesar Octavian by the Roman Senate. Year 1967 ( MCMLXVII) was a Common year starting on Sunday (link will display full calendar of the 1967 Gregorian calendar. The United States of America —commonly referred to as the A physicist is a Scientist who studies or practices Physics. Physicists study a wide range of physical phenomena in many branches of physics spanning Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. Princeton University is a private Coeducational research university located in Princeton, New Jersey.

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Biography

Robert Jemison Van de Graaff, born in Tuscaloosa, Alabama. Tuscaloosa is a city in west central Alabama in the southern United States. 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. A Van de Graaff generator is an electrostatic machine which uses a moving belt to accumulate very high electrostatically stable Voltages on a hollow metal globe The term high voltage characterizes electrical circuits in which the voltage used is the cause of particular safety concerns and insulation requirements 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. Princeton University is a private Coeducational research university located in Princeton, New Jersey. 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). A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors He also developed tandem generator technology. Tandem is a Latin Adverb meaning "at length" or "finally" The American Physical Society awarded him the T. The American Physical Society was founded in 1899 and is the World 's second largest organization of physicists behind the Deutsche Physikalische Gesellschaft. Bonner prize (1965) for the development of electrostatic accelerators.

Van de Graaff died in Boston, Massachusetts.

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 Robert Van de Graaff himself, is operational and is on display at the Boston Museum of Science. The Museum of Science ( MoS) is a Boston Massachusetts landmark located in Science Park a plot of land spanning the Charles River. Frequent demonstrations throughout the day are one of the most popular exhibits. 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 with no 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 (e. g. 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 buts.

Education

Patents

External links and references


Persondata
NAMEGraaff, Robert J. Van de
ALTERNATIVE NAMESGraaff, Robert Jemison Van de
SHORT DESCRIPTIONphysicist, inventor of Van de Graaff generator
DATE OF BIRTH20 December 1901
PLACE OF BIRTHTuscaloosa, Alabama
DATE OF DEATH16 January 1967
PLACE OF DEATHBoston, Massachusetts
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