Accelerators: Microtrons and Synchrotrons

The following introductory remarks are based on lectures given by Schwinger at the Los Alamos laboratory at the end of July 1945, about a week after the first nuclear test, the Trinity experiment at Alamogordo. There he pointed out ideas for a linear accelerator consisting of a succession of microwave cavities driven by a traveling electromagnetic wave of wavelength λ ~ 10 cm, where the length of each cavity was λ/2, so that the phases of the wave, and hence the polarities of the cavities, were reversed in successive cavities. Thus the electron always meets an accelerating field. The total voltage developed by the accelerator