Continuous electron-energy variation of the Eindhoven racetrack microtron

For the Eindhoven racetrack microtron, which has been designed as a fixed-energy accelerator at 75 MeV, continuous electron-energy variation between 45 and 90 MeV can be obtained by taking the microtron's orbit pattern as constant and varying certain parameters. The microtron injector is a linac producing electrons between 6 and 12 MeV. The microtron cavity potential and the magnetic guide fields must be adapted to the injection energy in order to fulfil the synchronism condition. The racetrack microtron's transversal and longitudinal acceptance are effected by electron-velocity deviations from the speed of light, which are different for each extraction energy. An account of these effects is presented together with the energy-setting measurements by using one of the microtron magnets as a spectrometer