The Design of a Curved Cryostat for the 90° DCT Superconducting Magnet

Abstract In order to enable the 90° curved Discrete Canted-Cosine-Theta (DCT) superconducting magnet for heavy ion Gantry to operate at low temperature normally, a 90° curved cryostat that can rotate on rotating gantry is developed. For the convenience of welding, the vacuum chamber and thermal shield of the cryostat are both welded by three cylinders. The cryostat uses four high-temperature superconducting current leads, two of which are connected to the superconducting cables for power supply to the magnet, and the other two are connected to the copper wires for quench protection of the magnet. To ensure the stability of the superconducting magnet during rotation, the superconducting magnet is fixed on the vacuum chamber with 12 carbon fiber rods. A heat leakage calculation is conducted on the cryostat, which shows that the first stage heat leakage is 74.6W@50K, and the second stage heat leakage is [email protected]. Therefore, two GM cryocoolers are used for cooling the superconducting magnet. The strength of the rods, vacuum chamber and the base are simulated and checked at different angels (0°, 30°, 60°, 90°, 120°, 150°, 180°). According to the analysis results, the stress at the above structures is less than the corresponding allowable stress, which meets the strength requirements of the system. The cooling process of the cryostat shows it takes 13 days to cool down the whole system with a mass of 900 kg from room temperature until heat balance.