Physics Research Laboratory (PRL) betatron correspondence with Allis-Chalmers, Los Alamos and other laboratories, on experimental work, the operation of the laboratory building and project funding. The series includes copies of patents issued to the betatron group (1944-1954), correspondence with the patent lawyers concerning interference cases and pending applications, betatron financial reports (1943-1947), operating manuals for the PRL (1942-1958), seminar reports of the betatron researchers, Office of Naval Research reports (1946-1947), and correspondence of Donald Kerst with Illinois colleagues and staff at other laboratories while he was at Los Alamos (1943-1945), as the director of the betatron project at the PRL (1945-1953), while working with the Midwest Universities Research Association (1953-1957) and after he left the University of Illinois (1957-1963). The series includes design calculations and drawings, correspondence with suppliers and sub-contractors and betatron installations in other locations (1947-1950); correspondence, photographs, news releases and clippings publications and reports on the history of the betatron (1941-1977, cyclotron (1948-1959, and linear accelerators (1965-1990.