I. Introduction
The High Intensity heavy-ion Accelerator Facility (HIAF) is being constructed by the Institute of Modern Physics, Chinese Academy of Sciences (IMP,CAS) [1]. The project aims to provide high-intensity, high-quality and high-energy beams for nuclear physics research. HIAF FRagment Separator (HFRS) is an important beam line featuring high magnetic rigidity (25 Tm) and large ion-optical acceptance (±160 mm) [2]. At present, the magnets installed in A1900 [3], FAIR [4] and other similar projects adopt the superferric design, which is easy to wind and fabricate. However, they will present some inherent problems, such as large cold mass, long cooling-down/recovery time and poor magnetic field quality in high field. A novel Canted-Cosine-Theta (CCT) geometry is desirable for HFRS due to its low weight, compactness and ability to produce arbitrary multipole field [5].