NAL Quadrupole Power Supply Active Filter

A 40 kW active filter is used with each of the main accelerator's 12 quadrupole power supplies to reduce the power supply's voltage ripple. The active filter operates on a voltage-bucking principle with the filter output transformer coupled into the quadrupole magnet bus. The filter electronics is designed to respond to the first three harmonic components of ripple in the power supply output. Voltage ripple attenuation during injection, acceleration, and extraction is approximately 30 dB. Quadrupole magnet current ripple is correspondingly reduced.