James Stark Koehler

James Stark Koehler (10 November 1914 in Oshkosh, Wisconsin – 19 June 2006 in Urbana, Illinois) was an American physicist, specializing in metal defects and their interactions. He is known for the eponymous Peach-Koehler stress formula.

Career Koehler received 1935 his bachelor's degree from Oshkosh State Teachers College (now called the University of Wisconsin, Oshkosh). In 1940 he received from the University of Michigan his Ph.D. under David M. Dennison with a thesis Hindered rotation in methyl-alcohol. After a postdoc fellowship in 1940–1941, supervised by Frederick Seitz, at the University of Pennsylvania, and another fellowship for about six months in 1941–1942 at the Westinghouse Electric Company in Pittsburgh, he became a physics instructor at Carnegie Tech in early 1942.

His original focus was on plastic waves in metals upon impact. By 1944 Koehler joined the Manhattan Engineer District, to study the effects produced in solids by irradiation. One of his many contributions was the measurement of the self-diffusion activation energy of uranium, which was used to calculate the change in the shape of the cylindrical uranium slugs in the Hanford plutonium-producing reactors. After the war, the new Office of Naval Research in 1947 began to support his work on plastic deformation. In 1949, Koehler was invited to join the new Illinois department program in condensed matter physics. Koehler moved his Navy equipment to Urbana, and ONR support continued through 1970. Upon his arrival, substantial support from the Atomic Energy Commission began for a program in radiation damage, which used the Illinois cyclotron. Later his dream was realized to have a dedicated facility for “simple” radiation damage (2 MeV electrons) in the new Illinois Materials Research Laboratory. at the Cavendish Laboratory. the Magnuson-Palmer-Koehler experiment, and the Bauerle-Koehler experiment.

Students Several of Koehler's doctoral students were elected Fellows of the American Physical Society: