HANSEN, WILLIAM WEBSTER

born May 27, 1909, Fresno, Calif., U.S. died May 23, 1949, Palo Alto, Calif. American physicist who contributed to the development of radar and is regarded as the founder of microwave technology. After earning the Ph.D. at Stanford University, Calif., in 1933, Hansen began teaching there the next year. In 1937 he began work on the problem of detecting approaching aircraft. Working with Russell H. Varian and Sigurd F. Varian, he developed the klystrona vacuum tube essential to radar technology (1937). The klystron, which is based on amplitude modulation of an electron beam, rather than on resonant circuits utilizing conventional coils and condensers, permitted the generation of powerful and stable high-frequency oscillations. In 1941 Hansen and his research group moved to the plant of the Sperry Gyroscope Company in Garden City, N.Y., contributing to developments on Doppler radar, aircraft blind-landing systems, electron acceleration, and nuclear magnetic resonance. During World War II Hansen was a scientific consultant on the Manhattan Project. In 1945, as director of Stanford's microwave laboratory, Hansen began the design of a 750-million-volt linear electron accelerator powered by giant klystrons; this accelerator was completed at Stanford after his death.