Study of eddy current effect in BRing at HIAF

Abstract In the Booster Ring (BRing) of High Intensity heavy ion Accelerator Facility (HIAF), the magnetic field with a ramping speed of 12 T/s will generate non-negligible eddy current in the magnet and the metal vacuum chamber. The eddy current effect will deteriorate the quality of beam. The attenuation and hysteresis effect of magnetic field, eddy loss and eddy-current Lorentz force are analyzed by the code OPERA 3D. Moreover, the effect of eddy-current-induced multi-pole field on the optical parameters is studied by the code MAD. In order to reduce the attenuation and hysteresis effect, the 0.3 mm thick ultra-thin vacuum chamber is selected and the varying curve of magnetic field is corrected. The results show that the maximum temperature of magnet and vacuum chamber caused by eddy loss is below 60.7 °C. The influence of eddy-current Lorentz force on the vacuum chamber is negligible. The chromaticity shift caused by eddy-current-induced sextupole field is large, and the strength of sextupole-correction magnets is modified to fulfill the requirement of chromaticity correction.