Magnetic field leakage of HTS medical accelerators

A high temperature superconducting (HTS) magnet used in medical accelerators was designed with combined function for bending and focusing/defocusing, through a layer-by-layer design process. The six-layer combined function magnet produced by the layer-by-layer design process reduces the total volume of HTS material required compared to existing designs, in addition to achieving a precise field. The magnetic field distribution and leakage from the coil ends of the designed combined function magnet were studied, and the effects of changing the length of the coil ends as well as the radius of the layers were compared to the original design, to determine what influence this would have. Results show that shorter coil ends have the smallest leakage magnetic field, and is thus preferred, however due to mechanical constraints of HTS tape there will be a minimum length requirement depending on the design.