摘要： The purpose of this study was to design a rapid cycling synchrotron, making it capable of proton beam ultra-high dose rate irradiation, inspired by laser accelerators. The design had to be cheap and simple. We consider our design from six aspects: the lattice, injection, extraction, space charge effects, eddy current effects and energy switching. Efficiency and particle quantity must be addressed when injected. The space charge effects at the injection could affect particles’ number. The eddy current effects in the vacuum chambers would affect the magnetic field itself and generate heat, all of which need to be taken into account. Fast extraction can obtain 1010 protons/pulse, equal to instantaneous dose rate up to 107 Gy/s in a very short time, while changing various extraction energies rapidly and easily to various deposition depths. In the further research we expect to combine a delivery system with this accelerator to realize the FLASH irradiation.