R&D Of The Canted-Cosine-Theta Superconducting Magnets

At present,the superconducting magnets used in large accelerators usually adopt the cos-theta or racetrack coil structure,which have the disadvantages of winding difficulty,stress accumulation,complex coil winding and forming process and high processing costs.With the rapid development of superconducting magnet technology,it is of great significance to find a coil form with simple structure,good magnetic field distribution and stable operation,as the future superconducting magnets move towards higher magnetic field,more compact structure and lower costs.Canted-Cosin e-Theta coil concept is an innovation configuration which has many advantages,such as superior magnetic field quality,outstanding mechanical properties,simple winding process,lower costs,and many international accelerator laboratories(CERN,LBNL,PSI)have carried out research on this technology.According to the needs of HIAF and CiADS’s magnets and the development of Gantry magnets,a small CCT quadrupole prototype is fabricated based on the experience of previous CCT projects.The electromagnetic and structural aspects of CCT quadrupole magnet are studied in detail,so as to master the key technologies of magnet from design,processing,winding and former assembly.It also provides a new thought for the development of CCT magnet(multipole and combined function).The following researches are carried out around the CCT magnet:(1)Research on magnetic field simulation method of CCT coil.Through the derivation of the parameter equation of CCT coil,the analytical expression between the coil windings and the magnetic field is obtained.The principle of magnetic field generated by CCT dipole,quadrupole and combined-function magnets is introduced respectively.Two methods for CCT coil magnetic field calculation are given: analytical method and finite element method.Combining the advantages of the two methods and professional magnetic field software,a set of efficient and accurate magnetic field design methods for CCT magnets has been developed.(2)Research on parameter optimization and error analysis of CCT coil.By analyzing the magnetic field distribution generated by different coil combinations,an optimal scheme is obtained: RL+LR(LR+RL).The factors that need to be considered in the design process of CCT magnets are expounded,including the minimum tilt angle,magnetic field,field enhancement coefficient and the amount of conductor.By analyzing the relationship between the parameters and the tilt angle,the optimal tilt angle of CCT magnet is determined by the integral field as an optimization objective.Since the magnetic field generated by the CCT coil is directly related to the current path,the influence of winding error and assembly error on magnetic field performance is analyzed based on the Latin hypercube sampling method.(3)Three kinds of CCT coil schemes are presented: cable in grooves,conductor in grooves,and multi-coil in grooves.Through the exploration of different process schemes,the multi-coil technology is determined.A prototype of CCT quadrupole magnet has been developed successfully.A numerical simulation of the CCT magnet is carried out based on the two methods of the quench propagation velocity and the finite element.Finally,CCT quadrupole magnet is tested in the vertical dewar and the performance evaluation is done.As the first CCT superconducting quadrupole magnet prototype in China,we have mastered the design method,technical route and process parameters of the CCT magnet,which lay a solid foundation for the application of CCT superconducting magnet in follow-up large scientific device.