Study on multi-fold bunch splitting in a high-intensity medium-energy proton synchrotron

TL;DR

This paper introduces a generalized multi-fold bunch splitting method using multi-harmonic RF systems, demonstrating its feasibility and acceptable impact on bunch quality for high-intensity proton synchrotrons, with potential applications in collider injectors.

Contribution

It presents a new multi-fold bunch splitting technique with specially designed RF systems, extending previous two- and three-fold methods, and applies it to the SPPC injector chain.

Findings

Five-fold bunch splitting is feasible with acceptable bunch distribution.

The method results in less than 10% emittance growth.

Population deviation remains within a few percent.

Abstract

Bunch splitting is an RF manipulation method of changing the bunch structure, bunch numbers and bunch intensity in the high-intensity synchrotrons that serve as the injector for a particle collider. An efficient way to realize bunch splitting is to use the combination of different harmonic RF systems, such as the two-fold bunch splitting of a bunch with a combination of fundamental harmonic and doubled harmonic RF systems. The two-fold bunch splitting and three-fold bunch splitting methods have been experimentally verified and successfully applied to the LHC/PS. In this paper, a generalized multi-fold bunch splitting method is given. The five-fold bunch splitting method using specially designed multi-harmonic RF systems was studied and tentatively applied to the medium-stage synchrotron (MSS), the third accelerator of the injector chain of the Super Proton-Proton Collider (SPPC), to mitigate the pileup effects and collective instabilities of a single bunch in the SPPC. The results show that the five-fold bunch splitting is feasible and both the bunch population distribution and longitudinal emittance growth after the splitting are acceptable, e.g., a few percent in the population deviation and less than 10% in the total emittance growth.