Magnetic field design of combined-function magnets wound with coated conductors

For accelerator magnets, high Tc superconductors (HTS) are a remarkable option comparing with low Tc superconductors (LTS), since they possess several distinctive characteristics, such as good thermal stability and high cooling efficiency. On the other side, HTSs have strong mechanical constraints which make them hard to shape, like bending and winding. In this paper, a method is proposed to solve the mechanical constraint problems of HTSs, and the feasibility of applying HTSs to combined-function accelerator magnets is proved. The detailed method is presented to apply coated conductors into the design of a combined function accelerator magnet containing both dipole and quadrupole magnetic field components, which is named 2+4 pole magnet in this paper. This method takes electromagnetic characteristics of coated conductors into account, and it is capable of solving their mechanical constraint problems. First a 2D cross-sectional design of the straight section was completed, with a layout in the form of multi-layers to generate required magnetic fields. Then a 3D design was carried out to wind coil ends considering flat-wise/edge- wise bending and torsion tolerance. The locations and angles of coated conductors were optimized to improve the efficiency of field generation and minimize the field error. Results show that coil ends can be successfully designed, and electromagnetic analyses show that the designed magnet can properly generate required magnetic field.