Beam collimator of electrostatic septum for high-intensity heavy-ion accelerator facility booster

The dynamic vacuum effect is the primary limitation of beam intensity in high-intensity heavy-ion synchrotrons. Although the dynamic vacuum effect in the arc section is mitigated effectively by the beam collimators, the gas desorption induced by injection beam loss occurring in the injection electrostatic septum (ESi) is still an unresolved issue. In addition, the gas desorption is enhanced due to some special mechanisms, including the ultrafast beam loss process, multiple traversals of wire surfaces, and high-voltage breakdown. Mitigating the dynamic vacuum effect in the ESi is a critical approach to achieve a higher beam intensity. Therefore, a novel ES collimator is proposed to reduce beam deposition on the septum. Dynamic simulation of the dual-plane painting injection of BRing reveals the excellent performance of this scheme by a tenfold reduction in beam loss. The features associated with collimation efficiency and structure optimization are analyzed in detail.