Machine Protection Experience from Beam Tests with Crab Cavity Prototypes in the CERN SPS

M Zerlauth,D Wollmann,J Uythoven,G Papotti,L R Carver,A Butterworth,J Wenninger,G Vandoni,B Lindstrom,V Kain,R Secondo,T Bohl,H Bartosik,R Calaga,T E Levens,M Valette

doi:10.1088/1742-6596/1350/1/012004

M Zerlauth, D Wollmann + Show 14 more

Open Access

https://doi.org/10.1088/1742-6596/1350/1/012004

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Abstract

Crab cavities (CCs) constitute a key component of the High Luminosity LHC (HL-LHC) project. In case of a failure, they can induce significant transverse beam offsets within tens of microseconds, necessitating a fast removal of the circulating beam to avoid damage to accelerator components due to losses from the displaced beam halo. In preparation for the final design to be employed in the LHC, a series of tests were conducted on prototype crab cavities installed in the Super Proton Synchrotron (SPS) at CERN. This paper summarizes the machine protection requirements and observations during the first tests of crab cavities with proton beams in the SPS. In addition, the machine protection implications for future SPS tests and for the use of such equipment in the HL-LHC are discussed.

Highlights

Crab cavities will be used in the HL-LHC to counteract the loss of luminosity due to the increase of the crossing angle [1] by providing a longitudinally dependent transverse kick to the beam
This paper summarizes the machine protection requirements and observations during the first tests of crab cavities with proton beams in the Super Proton Synchrotron (SPS)
The SPS beam is still capable of causing damage when uncontrolled beam losses occur [6], and it is necessary for the Crab cavities (CCs) tests to be conducted either at safe beam intensities/energies, or with appropriate fast hardware interlocks in place

Summary

INTRODUCTION

Crab cavities will be used in the HL-LHC to counteract the loss of luminosity due to the increase of the crossing angle [1] by providing a longitudinally dependent transverse kick to the beam. In preparation for the series production, tests on prototype CCs were conducted in the SPS, the last accelerator in the injector chain before the LHC [4, 5]. Less beam intensity and being non-superconducting with short cycles, it provides a flexible and relatively safe base for the prototype tests. The SPS beam is still capable of causing damage when uncontrolled beam losses occur [6], and it is necessary for the CC tests to be conducted either at safe beam intensities/energies, or with appropriate fast hardware interlocks in place. The implementation and testing of these interlocks provides important experience for the HL-LHC and for further use of CCs in the SPS.

Crab Cavities in the SPS

Beam interlocking

Observed Failures

Findings

Conclusions