Pulsed Wire Magnetic-Field Measurement System on Permanent Magnet Quadrupoles

The adjustable strength permanent magnet quadrupoles used in this study were designed and manufactured at the National Synchrotron Radiation Research Center (NSRRC). The permanent magnet quadrupole had a bore radius of 3.5 mm and an effective length of 50 mm. It was based on SmCo blocks and provided an effective gradient field from 325 T/m to 355 T/m. Typical methods for measuring the magnetic-field performance of quadrupole magnets are the stretched-wire and rotating coil measurement systems. A pulsed-wire measurement (PWM) system was used to measure the magnetic fields of an in-vacuum undulator at the NSRRC. The PWM system provides quick measurements of the magnetic fields and is easy to install on any permanent accelerator magnet. In this work, a PWM system was used to measure the magnetic-field integrals and the multipole errors of quadrupole magnets. Comparison was made of the magnetic field results obtained with PWM and stretched-wire measurement methods.