Eddy current effect in a booster ring of Korea-4GSR

Since the field strength of magnets in a booster synchrotron changes during the energy ramping process, it induces the inevitable eddy currents in a metallic vacuum chamber. Specifically, the eddy currents induced by a dipole magnet lead to the formation of a relatively weak sextupole field component. Nevertheless, this field exerts noticeable effects as a result of the considerable physical length of the bending magnet. These sextupole components result in chromatic aberrations, indicating a momentum-dependent tune shift. The alteration in chromaticity can lead to a reduction of the dynamic aperture, potentially causing crucial beam loss. Therefore, it is necessary to assess its impact. This study evaluates the sextupole magnetic field component originating from eddy currents in a dipole magnet chamber, along with the associated chromaticity variations and beam dynamics, for the Korea-4GSR booster synchrotron.