A Cyclotron Magnet Case Study: Would Replacing the LTS Coils With HTS Coils Make Sense?

The cyclotron gas-stopper magnet (CGSM) at Michigan State University (MSU) was used as model for a study for whether HTS conductor is feasible for use in cyclotrons. The outside diameter of the CGSM split warm iron magnet yoke is 4 m, with a pole radius of 1.1 m. The desired field shape is obtained by shaping the iron pole profile. Each superconducting coil is in a separate cryostat. The two coils are connected in series through the warm electrical connection. Each coil is wound and potted within an 80 mm × 80 mm cross section and mounted within a 304 stainless steel helium vessel that is designed to carry magnetic forces to the magnet cold mass supports without excessive deflection. The iron is split, so that the cyclotron chamber and RF extraction system can be mounted between the two poles. This magnet has been successfully cooled down and tested at MSU to its 180-A operating current. One can ask the following question, “If one built a cyclotron magnet the size of the MSU cyclotron gas-stopper magnet, would replacing the existing LTS coils with HTS coils using a standard second generation HTS tape make technical sense or economic sense?” The report will explore the technical and economic issues of replacing an existing LTS coil with an HTS coil of the same size and shape, using 2G YBCO tape conductor commercially available in 2015 in place of the Nb-Ti used in the magnet.