Performance of a Multicavity Racetrack Microtron

Measured characteristics of both the extracted beam and the beam within the accelerator are given for a racetrack microtron with a three-cavity accelerating structure. Final beam energies of 9 to 15 MeV with currents up to 30 mA have been achieved by passing the beam six times through the cavities and beam energies of 4.5 to 7.5 MeV with currents up to 60 mA have been obtained after three traversals of the cavities. An improved injection system and magnetic guide field design are described, and the suitability of this type of machine for radiation therapy is considered.