Abstract:
Background High-power proton beams extracted from cyclotrons usually have small transverse dimensions and nonuniform intensity distributions, which may lead to localized power deposition, excessive thermal load, and reduced target lifetime when directly delivered to the target.
Purpose To improve the target beam distribution, this study proposes and verifies an automatic beam tuning method for the nonlinear-magnet-based beam transport line of the 18 MeV/1 mA high-current proton cyclotron at the China Institute of Atomic Energy (CIAE), aiming to realize beam centering, beam expansion, and beam uniformization. The beamline consists of steering magnets, quadrupole magnets, and nonlinear magnets for beam orbit correction, envelope control, and transverse distribution shaping.
Methods During the tuning process, the beam spot image on the fluorescent screen installed at the end of the beamline is acquired and analyzed in real time. The beam center, spot size, and transverse uniformity are extracted from the image, and the excitation currents of the steering magnets, quadrupole magnets, and nonlinear magnets are adjusted accordingly.
Results After automatic tuning, a square beam spot with a size of 60 mm × 60 mm was obtained on the fluorescent screen. The measured horizontal and vertical uniformities reached 92.4% and 90.7%, respectively.
Conclusions The proposed automatic beam tuning method based on real-time beam image analysis can effectively control the beam position, expand the beam spot, and improve the transverse beam uniformity, demonstrating its applicability to compact high-current proton beam transport lines using nonlinear magnets.
下载: