Rotating-coil calibration in a reference quadrupole, considering roll-angle misalignment and higher-order harmonics

摘要

A method is proposed for calibrating the radius of a rotating coil sensor by relaxing the metrological constraints on alignment and field errors of the reference quadrupole. A coil radius calibration considering a roll-angle misalignment of the measurement bench, the magnet, and the motor-drive unit is analyzed. Then, the error arising from higher-order harmonic field imperfections in the reference quadrupole is assessed. The method is validated by numerical field computation for both the higher-order harmonic errors and the roll-angle misalignment. Finally, an experimental proof-of-principle demonstration is carried out in a calibration magnet with sextupole harmonic. (C) 2016 Elsevier Ltd. All rights reserved.