Safe Disposal of the LHC Beam without Beam Dump: Method and Experimental Verification

M Valette,M Zerlauth,D Wollmann,R Schmidt,A Mereghetti,D Valuch,B Lindstrom,J Uythoven,M Solfaroli,J Wenninger

doi:10.1088/1742-6596/1067/2/022007

M Valette, M Zerlauth + Show 8 more

Open Access

https://doi.org/10.1088/1742-6596/1067/2/022007

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Abstract

In the extremely unlikely event of a non-working beam dumping system in the LHC, the 360 MJ of stored beam energy can be dissipated in the collimation system as a last mitigation measure. In such a situation, it is important to reduce the stored beam energy both quickly and at the same time as smoothly as possible in order to limit the risk of trips of critical systems, to avoid quenches of superconducting magnets (which would lead to changes of the beam trajectory and damage to the accelerator) and ultimately damage to the collimators themselves. Detailed steps and parameters have been developed and validated during two dedicated experiments with beam in the LHC. This paper summarizes the key aspects in view of the preparation of such a procedure for operational use, which will allow for the safe disposal of the full LHC beam by the operation crews.

Highlights

The 360 MJ of stored energy in the LHC proton beam [1] and about 700 MJ for its High Luminosity (HL) upgrade [2] require highly reliable machine protection systems, which ensure the controlled and safe disposal of the two proton beams at any time
The Beam Interlock System (BIS) [3] and LHC Beam Dumping System (LBDS) [4], with failure rates in the order of 10−7 failures/hour and an availability of 99.96 %, are the core systems of the machine protection architecture. They ensure that the beam is extracted if a beam dump is requested by an equipment system or the operator. Despite this high level of dependability of the core systems, it is important to prepare an alternative method to dispose of the stored beam energy in case an extraction cannot be executed
The first two methods pose the problem, that the beam core’s projected energy density in the order of 500 kJ/μm requires a sub-μm step size in order not to exceed the damage limit of the primary collimators. Such small step-sizes are neither achievable with the current collimator movement system nor with the existing orbit correctors

Summary

Introduction

The 360 MJ of stored energy in the LHC proton beam [1] and about 700 MJ for its High Luminosity (HL) upgrade [2] require highly reliable machine protection systems, which ensure the controlled and safe disposal of the two proton beams at any time. The results of these tests showed, that the required beam lifetime could be achieved with just a small number of ADT gain changes.

Results

Conclusion