Injection septum magnets for the Loma Linda medical accelerator

Experience obtained from operation of the pulsed septum magnets in the Fermilab Antiproton Source was used to design injection septum magnets in the proton accelerator of the Loma Linda University Proton Therapy Facility. A detailed description is given of the septum magnets, which produce a peak field of 3.4 kG at a current of 28 kA within a 0.1-ms long pulse. Each magnet has a single-turn copper coil bonded to a stainless-steel plate for reinforcement. This eliminates insulating material, which could be subject to radiation damage, at the septum. The stainless steel plate is welded to the magnet laminations. The current is confined to the septum by the insulation between the laminations, which are of a standard core material. The total septum thickness with shield is 1.27 cm. Pulsing the magnet eliminates the need for water cooling.