Design Of High Field Nb₃Sn-Nb Ti Hybrid Superconducting Focusing Solenoid

High Intensity Heavy-Ion Accelerator Facility（HIAF） is proposed by Institute of Modern Physics, Chinese Academy of Science,which belongs to a mega scientific infrastructure of Chinese National "12th Five-Year Plan". Serving as the injector of HIAF, Superconducting Ion Linac（i Linac） is responsible for providing BRing（Booster Ring） with H2+ and various other heavy ion beam. The Superconducting Cavity –Superconducting Solenoid- Superconducting Cavity structure is applied to the part of the linac. Since heavy ion beam requires more high focusing force, the heavy ion linac superconducting focusing solenoid has to be longer as well. Because of the requirement of linac physical and space limitation, it is necessary to increase the central magnetic field, and so as to decrease the length of solenoid, and then to reduce the overall length of the cryostat finally,which is on the premise of the requirements from integral field and stray field.The design and manufacture of the superconducting solenoid, which is one of the prototype for the advance research of HIAF, was described in the thesis. And Nb₃Sn-Nb Ti hybrid design has been used to reduce the cost, meantime to get higher field. The magnet is composed of a Nb3 Sn primary coil, a Nb Ti primary coil and two Nb Ti shield coils. Global Particle Swarm Optimization and local SLSQP algorithms are adopted in the design process, a superconducting focusing solenoid’s optimization program was developed with Python, which was then used to conduct the superconducting coils’ optimization. According to the stress analysis results of magnet and framework by ANSYS, a reasonable coil framework’s structure and key technical parameters were obtained. In the meantime, quench simulation has been carried out with QUENCH module of OPERA, some parameters such as hot-spot temperature and quench voltage were obtained as the reference for quench protection circuit design. The cold test of the solenoid has been done in a vertical dewar, and the result verifies the rationality of the magnetic design and the feasibility of the processing technology.Serving as the prototype of HIAF, this prototype is the first Nb₃Sn-Nb Ti hybrid superconducting magnet which would to be applied in an accelerator in IMP. All these research results provide many useful engineering experiences for the development of accelerator superconducting magnet with even stronger magnetic fields in the future.