Robert Jemison Van de Graaff
Van de Graaff, Robert Jemison (1901-1967), an American physicist, invented a particle accelerator. The Van de Graaff accelerator is used worldwide in nuclear research, medicine, and industry.
Van de Graaff studied mechanical engineering at the University of Alabama. He received his bachelor's degree in 1922 and his master's degree in 1923. In 1924, he studied at the Sorbonne in Paris, and in 1925 he was awarded a Rhodes scholarship to Oxford University in England, where he earned a Ph.D. degree in physics and began researching how particles might be accelerated to energies high enough to disintegrate atomic nuclei.
In 1929, Van de Graaff became a National Research Fellow at Princeton University, New Jersey. There he developed a device that utilized static electricity. A belt carrying electric charges moved through a vertical column to an insulated spherical metal terminal. Charges were swept off the belt and accumulated on the sphere. The high voltage was then discharged into an acceleration tube. Van de Graaff built his first working accelerator, which could generate 50,000 volts, in 1929, and demonstrated a more sophisticated one, which could generate up to 1 million volts, in September 1931.
In 1931, Van de Graaff became a research associate at the Massachusetts Institute of Technology (MIT), and in 1933 he unveiled his first large generator, which sent out 7 million volts of electricity. The simplicity of design of the accelerator, which Van de Graaff patented in 1935, gave it an advantage over earlier generators, and it achieved significantly higher energies. In 1946, he and John G. Trump, an electrical engineering professor at MIT, established a corporation for its commercial production. Later it was greatly enhanced and adapted for medical and scientific uses.