A new accelerator option for driving a sub-critical reactor

A linac and two cyclotrons, of a new type, are considered as a proton driver for an ADSR sub-critical reactor. The cyclotrons use reverse bending, for orbit length adjustments, and harmonic number jumps to achieve a synchronous acceleration. This is a different basis from that of a separated orbit cyclotron (SOC) where accelerating fields must vary over the cavity apertures in a defined manner to maintain synchronism. The new ring is called an orbit separated cyclotron (OSC) as it has the shape of an irregular SOC. An OSC design example is presented, with a six-cell superconducting cavity in each of the eight ring periods. Acceleration, over four turns, of a 10 mA (cw) proton beam from 0.5 to 1.0 GeV relates to input and output beam powers of 5 and 10 MW, respectively. A key design issue is the unusual, spiral magnet system, with all 32 superperiods requiring different combined function magnet designs. One main advantage of an OSC ring over a linac stage is the four times fewer cryogenic and cavity systems, due to the use of the four turn acceleration.