185-MeV Injector Design for the ANL 4-GeV Microtron Project

The injector starts with a 5 MeV preinjector followed by an-18 MeV S-band linac. The 23 MeV electrons are transported and injected into a Racetrack Microtron via a 10° achromatic bend system. Twenty-seven turns are used to boost the energy to 185 MeV. Reverse-field stripes on the 180° end magnets and quadrupole focussing on the return paths maintain a matched-dispersion free beam with transverse ß* = 5.0 m in the center of the 4.6 m long linac. The beam is recirculated outside of the RTM linac to shear the longitudinal phase-space ellipse before extraction. The extracted beam is transported and injected into the six-sided microtron at 185 MeV.