End Chamfer Study and Field Measurements of the BEPCII Dipoles

The new BEPCII double ring will be added in the existing BEPC tunnel. There are more then 40 bending magnets named 67B in the new ring. The 67B is conventional ‘C’-type dipole magnet. The magnetic field properties are improved by the magnet end effect. The end effect have been studied and minimized by a proper end chamfer. Magnetic measurements of the prototype and productions are carried out using the translating integral long coil. The developing process of pole end chamfers and the measurement results of the 67B prototype and batch production are described in the paper.