Cryogenic design of an isodynamic magnetic separator

A superconducting isodynamic open gradient magnetic separator has been designed in order to test the separation of various slurries at high magnetic field. The system will be used as a measuring device in order to determine the conditions for the separation process at different applications. The magnet system consists of two racetrack coils. The separator system will be tested with two types of magnets: a pair of NbTi coils and a pair of Nb₃Sn coils. Both magnets are operated at 4.2 K. The coils are designed to create a volume with a nearly constant magnetic force density distribution. The slurry flows through this volume at room temperature. The distance between the magnet and the working volume is 15 mm, which sets stringent constraints to the cryostat design. A thermal network model combined with numerical optimization is exploited in order to compute the heat load to the cryogenic environment. The computational model is used to determine the sensitivity of the total heat load with respect to the design parameters of the cryostat. Finally, the quench behavior and protection scheme of NbTi and Nb₃Sn magnets is discussed.