X-band crab cavities for the CLIC beam delivery system

TL;DR

This paper discusses the design and proposed testing of X-band crab cavities for the CLIC beam delivery system, focusing on minimizing beam loading and wake-field effects to improve collision efficiency.

Contribution

It introduces a novel HE11 mode travelling wave structure for the crab cavity and proposes a damping scheme to suppress wake-fields, enhancing performance.

Findings

Design considerations for the crab cavity are outlined.

A damping scheme for wake-field suppression is proposed.

Plans for high power testing at SLAC are discussed.

Abstract

The CLIC machine incorporates a 20 mrad crossing angle at the IP to aid the extraction of spent beams. In order to recover the luminosity lost through the crossing angle a crab cavity is proposed to rotate the bunches prior to collision. The crab cavity is chosen to have the same frequency as the main linac (11.9942 GHz) as a compromise between size, phase stability requirements and beam loading. It is proposed to use a HE11 mode travelling wave structure as the CLIC crab cavity in order to minimise beam loading and mode separation. The position of the crab cavity close to the final focus enhances the effect of transverse wake-fields so effective wake-field damping is required. A damped detuned structure is proposed to suppress and de-cohere the wake-field hence reducing their effect. Design considerations for the CLIC crab cavity will be discussed as well as the proposed high power testing of these structures at SLAC.