Design of the New Trim Coils at the Karlsruhe Isochronous Cyclotron

After the decision in 1975 to build a new set of trim coils, the conception for designing the coils was that they should permit acceleration of 3He2+-ions and protons in addition to the e/m = 1/2-particles already available. Numerical calculations were done and led to a trim coil configuration consisting of six coils per plate with summing fields. The desired field strength (1.2 KG) and a small installation height (13.5 mm) led to a high current density (12 A/mm2). The coil conductor is indirectly cooled by 3 mm copper plates which are pasted on each side of the coil, after which the coil is completely filled with special epoxy resin. To get a high accuracy in the overall height, the coil was pressed during the hardening process in a special set-up which can be heated up to 90°C. The basic design of the coil and first results will be reported.