Development of sawtooth waveform beam buncher for medical cyclotron accelerator.

Abstract

A bunching system utilizing a heterodyne combiner is designed to generate a sawtooth waveform with three harmonics to increase the beam current intensity of medical cyclotron accelerators. The design incorporates a low-pass filter, helical bandpass filters, and a broadband matching network, producing a sawtooth waveform exceeding 1200 V, which meets the requirements for efficient bunching. This buncher substitutes the design and manufacturing requirements for high linearity broadband power amplifiers with three narrowband single-frequency power amplifiers for amplification. The digital direct synthesizer achieves coherent amplitude and phase adjustment of these three frequency signals. The broadband matching network is based on transmission line transformers to avoid the design of large-sized coaxial resonant cavities, which satisfy the spatial constraints of the cyclotron injection line.