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