| Paper |
Title |
Page |
| MOPLS008 |
Beam Halo on the LHC TCDQ Diluter System and Thermal Load on the Downstream Superconducting Magnets
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547 |
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- B. Goddard, R.W. Assmann, A. Presland, S. Redaelli, G. Robert-Demolaize, L. Sarchiapone, Th. Weiler, W.J.M. Weterings
CERN, Geneva
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The moveable single-jawed graphite TCDQ diluter must be positioned very close to the circulating LHC beam in order to prevent damage to downstream components in the event of an unsynchronised beam abort. A two-jawed graphite TCS collimator forms part of the TCDQ system. The requirement to place the TCDQ and TCS jaws close to the beam means that the system can intercept a substantial beam halo load. Initial investigations indicated a worryingly high heat load on the Q4 coils. This paper presents the updated load cases, shielding and simulation geometry, and the results of simulations of the energy deposition in the TCDQ system and in the downstream superconducting Q4 magnet. The implications for the operation of the LHC are discussed.
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| TUPLS012 |
Dynamic Stresses in the LHC TCDS Diluter from 7 TeV Beam Loading
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1511 |
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- B. Goddard, A. Presland, W.J.M. Weterings
CERN, Geneva
- L. Massidda
CRS4, PULA
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In the event of an unsynchronised beam abort, the MSD extraction septum of the LHC beam dumping system is protected from damage by the TCDS diluter. The simultaneous constraints of obtaining sufficient beam dilution while ensuring the survival of the TCDS make the design difficult, with high thermally induced dynamic stresses occurring in the material needed to attenuate the particle showers induced by the primary beam impact. In this paper, full 3D simulations are described where the worst-case beam loading has been used to generate the local temperature rise and to follow the resulting time evolution of the mechanical stresses. The results and the accompanying design changes for the TCDS, to provide an adequate performance margin, are detailed.
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| TUPLS013 |
Protection of the LHC against Unsynchronised Beam Aborts
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1514 |
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- B. Goddard, R.W. Assmann, E. Carlier, J.A. Uythoven, J. Wenninger, W.J.M. Weterings
CERN, Geneva
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An unsynchronised beam abort in the LHC could cause major damage to other downstream accelerator components, in particular the extraction septum magnets, the experimental low-beta triplet magnet apertures and the tertiary collimators. Although the LHC beam dumping system includes design features to minimise their frequency, such unsynchronised aborts can arise from several sources and cannot be excluded. A system of protection devices comprising fixed and moveable passive diluters and collimators will be built to safely protect the downstream LHC aperture from the mis-directed bunches in case of such a failure. The sources of unsynchronised abort events are described, together with the requirements and design of the protection devices and their expected performance. The accompanying operational requirements and envisaged solutions are discussed, in particular the problem of ensuring the local orbit at the protection devices.
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