Carbon coating of the SPS dipole chambers

TL;DR

This paper discusses the development and testing of carbon thin film coatings with low secondary electron yield to mitigate electron multipacting in CERN's SPS dipole chambers, aiming to enhance accelerator performance.

Contribution

It introduces a new carbon coating technology with improved SEY properties and outlines a scalable production strategy for accelerator applications.

Findings

Carbon coatings significantly reduce secondary electron yield.

Coating performance meets the requirements for SPS upgrade.

A scalable process for large-scale coating production is developed.

Abstract

The Electron Multipacting (EM) phenomenon is a limiting factor for the achievement of high luminosity in accelerators for positively charged particles and for the performance of RF devices. At CERN, the Super Proton Synchrotron (SPS) must be upgraded in order to feed the Large Hadron Collider (LHC) with 25 ns bunch spaced beams. At such small bunch spacing, EM may limit the performance of the SPS and consequently that of the LHC. To mitigate this phenomenon CERN is developing a carbon thin film coating with low Secondary Electron Yield (SEY) to coat the internal walls of the SPS dipoles beam pipes. This paper presents the progresses in the coating technology, the performance of the carbon coatings and the strategy for a large scale production.