In-situ calibration of rotating coil magnetic measurement systems: a case study on Linac4 magnets at CERN

Abstrac tAn in-situ procedure for calibrating the equivalent radius and width of the coil transducer in rotating mode measurements for magnetic field quality analysis is proposed. The standard calibration procedure is not suitable when the coil is longer than the magnet under test, because an average value of the radius and of the width along the length as a whole is obtained. This problem increases for small coils used in small-aperture magnets, such as quadrupoles of new-generation linear accelerators. In the paper, the problem of the coil parameter calibration is highlighted and then the proposed calibration method and the corresponding measurement station are illustrated. Experimental results of a case study on the magnet series of the new linear particle accelerator LINAC4, designed to intensify the proton flux currently available in the accelerator chain at the European Organization for Nuclear Research (CERN), are reported.