Low Energy Beam Transport of High Current Proton Beam with Quality Analysis System

High current proton source and the low energy beam transport(LEBT) are the key front-end systems for CIADS injector:high current proton linac accelerator. CIADS injector's LEBT adopts double solenoid matching structure, using a limit cone which can partially avoid H₂⁺ and H₃⁺ which injecting into the back-end linac accelerator may impact the long-term stability and reliability of the whole system. It will be an effective method to separate the hybrid ions (H⁺, H₂⁺, H₃⁺) by adding a dipole magnet at LEBT. In this article, we simulated and mesasured the high current proton beam quality behind the LEBT with a 30 degree dipole. The results show that the the proton beam quality is significantly effected by high-order magnetic fields of the dipole magnet, and the effect increases with the increase of the beam envelope. The achieved result is useful for the LEBT design of CIADS injector.