Donald William Kerst

Donald William Kerst (November 1, 1911 – August 19, 1993) was an American physicist who worked on advanced particle accelerator concepts (accelerator physics) and plasma physics. He is most notable for his development of the betatron, a novel type of particle accelerator used to accelerate electrons.

A graduate of the University of Wisconsin–Madison, Kerst developed the first betatron at the University of Illinois at Urbana Champaign, where it became operational on July 15, 1940. During World War II, Kerst took a leave of absence in 1940 and 1941 to work on it with the engineering staff at General Electric, and he designed a portable betatron for inspecting dud bombs. In 1943 he joined the Manhattan Project's Los Alamos Laboratory, where he was responsible for designing and building the Water Boiler, a nuclear reactor intended to serve as a laboratory instrument.

From 1953 to 1957 Kerst was technical director of the Midwestern Universities Research Association, where he worked on advanced particle accelerator concepts, most notably the FFAG accelerator. He was then employed at General Atomics's John Jay Hopkins Laboratory from 1957 to 1962, where he worked on the problem of plasma physics. With Tihiro Ohkawa he invented toroidal devices for containing the plasma with magnetic fields. Their devices were the first to contain plasma without the instabilities that had plagued previous designs, and the first to contain plasma for lifetimes exceeding the Bohm diffusion limit.

Early life Donald William Kerst was born in Galena, Illinois November 1, 1911, He entered the University of Wisconsin, where he earned a Bachelor of Arts (BA) degree in 1934, and then his Doctor of Philosophy (PhD) in 1937, writing his thesis on "The Development of Electrostatic Generators in Air Pressure and Applications to Excitation Functions of Nuclear Reactions". This involved building and testing a 2.3 MeV generator for experiments with the scattering of protons. When it became operational on July 15, 1940, Kerst became the first person to accelerate electrons using electromagnetic induction, reaching energies of 2.3 MeV. He went on to build more betatrons of increasing energy, a 20 MeV machine in 1941, an 80 MeV in 1948, and a 340 MeV machine, which was completed in 1950. The original 1940 machine was donated to the Smithsonian Institution in 1960.

World War II

During World War II, Kerst took a leave of absence from the University of Illinois to work on the development of the betatron with the engineering staff at General Electric in 1940 and 1941. They designed 20 MeV and 100 MeV versions of the betatron, and he supervised the construction of the former, which he brought back to the University of Illinois with him. He also designed a portable 4 MeV betatron for inspecting dud bombs. He developed the spiral-sector focusing principle, which lies at the heart of many spiral ridge cyclotrons that are now in operation around the world. His team devised and analysed beam stacking, a process of radio frequency acceleration in fixed field machines that led to the development of the colliding beam accelerators.

Kerst was married to Dorothy Birkett Kerst. They had two children, His papers are in the University of Illinois Archives.

Awards and honors Honorary degree, Lawrence College, 1942. Awarded John Scott Award, City of Philadelphia, 1946. Honorary degree, University of São Paulo, 1953. Awarded James Clerk Maxwell Prize in plasma physics, American Physical Society, 1984. Awarded Robert R. Wilson Prize for accelerator physics, 1988. Honorary degree, University of Illinois, 1989.