Design a Combined Function Curved DCT Superconducting Magnet for the Compact Heavy ION Therapy

Lanzhou Ion Therapy Company Ltd. (Lanith), is developing a new compact heavy ion therapy. The device consists of a superconducting gantry and a 35-meter superconducting synchrotron. A combined function curved Discrete Cosine Theta (DCT) superconducting magnet is the key to miniature heavy ion therapy device. The combined function magnet on the gantry consists of three sets of superconducting magnets with a bending radius of 2 m. The central magnetic field is 3.312 T, and the good field region is not less than 60 mm. In order to reduce the magnet size, DCT coils are used for both the dipole and quadrupole magnets. The quadrupole magnet adopts the closed winding at the end turns, which makes the magnet more compact. This article presents a detailed description of the electromagnetic design and optimization process of the gantry magnet system. In order to achieve the design goal of integral field uniformity, the article applies various new methods, and optimizes the integral field homogeneity for both cases with and without yoke. The first set of magnets is being manufactured and will be completed by the end of the year.