Magnet Excitation Circuits for DESY II

In contrast to the existing synchrotron, DESY II will, since it is a separated function machine, have 5 independent magnet circuits: 1 for dipoles, 2 for quadrupoles and 2 for sextupoles. Moreover the repetition frequency will be 12.5 Hz instead of 50 Hz. The present "White circuit" allows the resonance frequency to be changed by a factor of 4 and will be used for the dipoles. The other 4 resonant circuits will be built from new elements and the magnet impedances are chosen such that all the magnets of one circuit can be connected in series. The dipole circuit will be operated with the existing dc-power supply and a new ac-power source of 12 pulse cycloconverter type without circulating current will be installed. The quadrupole and sextupole circuits will be excitated by combined ac-and dc-power supplies of the type used for the FNL booster synchrotron.