Dynamic fringe field effects of the rapid ramping quadrupole magnets at the Rapid Cycling Synchrotron of China Spallation Neutron Source

The dynamic fringe field of the quadruple magnets at the Rapid Cycling Synchrotron (RCS) of China Spallation Neutron Source (CSNS) was measured and studied using a small flip coil measurement system. For DC quadruple magnets, the normalized magnetic field distribution along the beam trajectory, which is determined by the mechanical structure of the magnet, is independent of the exciting current. However, the magnetic field measurement results at CSNS-RCS showed that the normalized magnetic field distribution along the beam trajectory varies during the exciting current ramping process for quadruple magnets. The variation of the normalized magnetic field distribution can induce a time-dependent tune during the ramping process. Therefore, in this paper, we analyzed and studied the dynamic fringe field effects of the rapid ramping quadrupole magnets at CSNS-RCS.