Optimization of Design Parameters for SPPC Longitudinal Dynamics

TL;DR

This paper systematically studies the longitudinal beam dynamics of the SPPC collider complex, optimizing RF schemes and bunch filling to achieve high luminosity and stability for the future proton-proton collider.

Contribution

It introduces a comprehensive design and optimization of RF systems and bunch filling schemes for the SPPC complex, addressing stability and luminosity enhancement.

Findings

Optimized dual-harmonic RF system for instability mitigation.

Designed bunch filling scheme considering technical constraints.

Established self-consistent beam and RF parameters for SPPC.

Abstract

As the second stage of the CEPC-SPPC project, SPPC (Super Proton-Proton Collider) aims at exploring new physics beyond the Standard Model. The key design goal for the SPPC accelerator complex is to reach 75 TeV in center of mass energy with a circumference of 100 km for the collider and an injector chain of four accelerators in cascade to support the collider. As an important part of the SPPC conceptual study, the longitudinal beam dynamics was studied systematically, which includes the dynamics in the collider and its complex injector chain. First, the bunch filling scheme of the SPPC complex was designed on the basis of various constraints such as the technical challenges of the kicker magnets, limited extraction energy per injection and so on. Next, the study on the longitudinal dynamics in the collider focused on the RF scheme to meet the requirements for luminosity and mitigate relevant instabilities. A higher harmonic RF system (800 MHz) together with the basic RF system (400 MHz) to form a dual-harmonic RF system was employed to mitigate collective instabilities and increase the luminosity by producing shorter bunches. In addition, the longitudinal matchings between the bunches in the different accelerator stages were studied, with special attention to the space charge effects and the beam loading effect in the two lower energy rings (p-RCS and MSS), which result in an optimization of the RF schemes. A set of self-consistent beam and RF parameters for the SPPC complex was obtained. The collider and the three proton synchrotrons of the injector chain have unprecedented features, thus this study demonstrates how a future proton-proton collider complex looks like.