Simulation study of HIRFL-SFC using flattop acceleration system

It is planned to upgrade the HIRFL-SFC system for improving the quality of extracting beam and making it matched with the separated sector cyclotron (SSC) of the downstream accelerator. The methods mainly include increasing the accelerating voltage of Dee, equipping phase slit or using flattop acceleration system. The flattop acceleration system is a key method to reduce the energy spread and enhance the transmission efficiency. This paper calculates the beam quality of sector-focused cyclotron (SFC) using the cyclotron beam simulation program AGORA and compares the results obtained with and without flattop acceleration system. The results show that the energy spread reduces sharply with flattop system. The beam width in the radial direction and the turn separation meet the requirements of single turn extraction at the entrance of extraction deflector.