AND MEANS FOR LONG, MAGNETICALLY CONTROLLED BEAM SPILLS*

Summary Ripple frequencies in the ring magnet guide field of the Zero Gradient Synchrotron (ZGS) range from less than 1 Hz to several kHz. Filter systems which reduce the ripple components to negligible magnitudes are described, as 1s the use of these systems for long, magnetically controlled beam spills. High frequency ripple is attenuated by an improved LCR filter. Low frequency ripple is reduced by a feedback loop from g to the rectifier phase control of the ring magnet power supply (RMPS). The attenuation of the mid-frequency compovents is accomplished with a feedback loop from B to a ripple bucking coil in each octant of the ZGS. Two modes of operation for magnetically controlled beam spills without RF structure are discussed. In one mode the feedback to the low frequency loop is a signal from a spilled beam lmonitor. In the secondmode the spilled beam monitor drives both the low frequency and the mid-frequency loops.