Magnetic field measurements of printed-circuit quadrupoles and dipoles

Printed-Circuit (PC) quadrupoles and dipoles have been designed and developed for focusing and bending a space-charge dominated electron beam in the University of Maryland Electron Ring (UMER), currently under development. Due to the rather small aspect ratio (length/diameter <1) of the magnets, the field quality, especially the nonlinear fringe field, has been a concern for the success of the UMER project. Extensive theoretical and experimental studies of the field structure of the magnets have been performed. Simple and precise methods for the magnetic field measurements of the PC magnets have been developed. In this paper, we present the various techniques and results of the measurements. The magnetic multipole components of quadrupoles and dipoles are determined from measurements with a long rotating coil. In addition, the integrated field of quadrupoles is obtained with the pulsed, taut-wire method. A comparison between the experimental results, theoretical analysis and calculation with a magnetics code, MAG-PC, is presented