Energy Multiplication by Beam Recycling in an Isochronous Cyclotron

We have made an initial computer study of a recycling method for increasing the final energy of heavy-ion beams from ORIC. The system involves simultaneous acceleration of two beams. A first beam originating either in an ion source or external injector is accelerated, extracted, and reinjected in a higher charge state obtained by means of a foil located between the turns of the first-pass beam. For example, with a 20 MV tandem injecting into ORIC the energy for 208Pb after the first pass would be 1.9 or 2.3 MeV/u and after the second pass 5.2 or 6.3 MeV/u depending on the injection charge. The requirements of this scheme are 1) sufficient dee voltage to override the differing mass increase factors of the 2 beams; 2) good beam quality and accelerator stability to insure spatial separation of orbits; 3) an allmagnetic extraction system to assure identical paths for the 2 beams; and 4) relatively standard external beam separation and reinjection equipment.