Dynamic vacuum simulation for the Booster Ring in the high-intensity heavy ion accelerator facility

摘要

The High-Intensity Heavy Ion Accelerator Facility (HIAF) will provide intermediate charge state ion U-238(35+) with intensity up to 2 x 10(11) particle per pulse (ppp) to different experiments. However, large dynamic vacuum pressure rises of orders of magnitude, caused by lost heavy ions can seriously limit the maximum ion intensity and beam lifetime. Therefore, in order to predict the dynamic vacuum effects induced by the ionization beam loss for the BRing in the HIAF project, a new simulation program (ColBeam) has been developed together with GSI's simulation code StrahlSim are both conducted. The calculation algorithm for dynamic vacuum effect is introduced in this paper. According to the simulation result, up to 3 x 10(11) ppp U-238(35+) particles can be extracted for the current designed BRing vacuum and collimation system, which testifies the rationality of the system design and achieves the requirements of the physics experiments. Higher beam intensity can reach to 5 x 10(11) ppp if the Non-Evaporable Getter (NEG) coating technology is implemented on the dipole and quad-rupole chamber to further suppress the dynamic vacuum effect. The total vacuum pressure evolution with time in the BRing is shown in three-dimensional figure to explain the dynamic vacuum effect induced by the charge exchanged beam loss. The self-developed simulation program was implemented at 320 kV high voltage platform in IMP to simulate the dynamic vacuum evolution and compared with the measured vacuum pressure. Based on the simulation and benchmark results with the experimental data, it is concluded that the software can be used to confirm that dynamic vacuum effect can be suppressed by the collimation system and high speed pump distribution in the BRing.