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In a proton therapy system based on cyclotrons, a kicker magnet is an essential equipment to perform fast beam switch within 100 μ s level during energy modulation and spot scanning procedures. This paper gives a systematic view related to the design and technical considerations of a fast kicker applied to HUST-PTF. From the layout and physical requirement of the kicker, a comparative study on the static/dynamic magnetic field with two type of core materials is performed, and a MnZn ferrite core is chosen finally. Technical considerations including the structure design, the topology design of the power supply, and the method for dynamic field measurement are introduced as well.

Purpose: A systematic design procedure for a superconducting gantry is presented. To increase the momentum acceptance of the gantry beamline, alternating-gradient combined-function magnets were used to suppress dispersion. Methods: The main difficulties and challenges occurring in the design procedure, such as the difference between low- and high-order optics and the difference in beam behavior between simplified optics models and realistic magnetic fields, were analyzed. On the basic of these analyses, a step-by-step iterative design approach was proposed. In these steps, a genetic algorithm (GA) was used for multi-objective optimization, and graphics processing unit (GPU) acceleration was adopted for realistic model simulation. Results: The results of the design demonstrated that momentum acceptance of − 7 % ∼ 5 % was achieved for particle tracking in realistic magnetic fields. Conclusions: Using a GA, multi-objective optics fitting up to the fifth order became feasible. The optimization procedure was also more intelligent compared with the traditional one, which depends on experience and manual intervention. The use of GPU acceleration in magnetic field calculation and particle tracking dramatically reduced the overall optimization time. Finally, design optimization for a large momentum acceptance gantry beamline with realistic magnetic fields was achieved.

A proton therapy facility based on spot scanning technique requires a fast ON/OFF beam switch during beam spots and energy modulation procedures. At HUST, a proton therapy facility (HUST-PTF) with multiple treatment rooms is under development. For HUST-PTF, this beam switch function is implemented by a fast kicker magnet and downstream beam dump. This paper introduces the development and measurement of this kicker magnet system, with main topics: (1) the development and measurement of the fast kicker magnet; (2) the corresponding pulsed power supply to implement the kicker function; (3) the dynamic magnetic field measurement system based on printed circuit board (PCB) technique.