A Multi-Orbit Recirculation System for a Superconducting Linear Accelerator - The Recyclotron

The energy available from a superconducting linear electron accelerator (SCA) may be increased many times by means of an economical multi-orbit recirculation system, which preserves the most desirable characteristics of the SCA: good energy resolution (~10-4), high current and unity duty cycle. Furthermore, these properties of the SCA and its excellent emittance considerably simplify the design of the transport system and minimize aperture requirements. In order to maintain energy resolution each orbit of the recirculation system must be isochronous with respect to all phase space variables and beams must be reinjected into the linac precisely at the correct phase. These conditions have been achieved in a compact separated orbit design which uses multi-channel uniform field bending magnets. It is suggested that such a device be called a recyclotron. At HEPL a prototype 4 orbit recirculation system is being planned as part of the SCA program. Cost estimates for machines of this type have been made and show considerable advantage over other types of accelerator, especially at very high energies. The configuration also shows promise as an intermediate energy, high current accelerator, which could provide a source for a medical pion therapy facility.