A computer simulation of injection into a superconducting synchrotron

Persistent currents circulating in the windings of a superconducting synchrotron produce strong sextupole field imperfections. Apart from the chromaticity which results, and which may be corrected with other sextupoles, stop-bands are excited which limit the region of the working diagram in which the beam will survive at injection when the effect of persistent currents is most felt. In the computer simulation the authors studied how small closed orbit distortions and a residual chromaticity aggravate this situation using as a model a machine of 6.5 km circumference and including synchrotron motion. (6 refs).