Author: Auchmann, B.
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MOOCB01 Beam-induced Quench Tests of LHC Magnets 52
 
  • M. Sapinski, B. Auchmann, T. Bär, W. Bartmann, M. Bednarek, S. Bozyigit, C. Bracco, R. Bruce, F. Cerutti, V. Chetvertkova, K. Dahlerup-Petersen, B. Dehning, E. Effinger, J. Emery, A. Guerrero, E.B. Holzer, W. Höfle, A. Lechner, A. Priebe, S. Redaelli, B. Salvachua, R. Schmidt, N.V. Shetty, A.P. Siemko, E. Skordis, M. Solfaroli Camillocci, J. Steckert, J.A. Uythoven, D. Valuch, A.P. Verweij, J. Wenninger, D. Wollmann, M. Zerlauth, E.N. del Busto
    CERN, Geneva, Switzerland
 
  At the end of the LHC Run1 a 48-hour quench-test campaign took place to investigate the quench levels of superconducting magnets for loss durations from nanoseconds to tens of seconds. The longitudinal losses produced extended from one meter to hundreds of meters and the number of lost protons varied from 108 to 1013. The results of these and other, previously conducted quench experiments, allow the quench levels of several types of LHC magnets under various loss conditions to be assessed. The quench levels are expected to limit LHC performance in the case of steady-state losses in the interaction regions and also in the case of fast losses initiated by dust particles all around the ring. It is therefore required to accurately adjust beam loss abort thresholds in order to maximize the operation time. A detailed discussion of these quench test results and a proposal for additional tests after the LHC restart is presented.  
slides icon Slides MOOCB01 [2.737 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCB01  
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MOPRO019 Energy Deposition and Quench Level Calculations for Millisecond and Steady-state Quench Tests of LHC Arc Quadrupoles at 4 TeV 105
 
  • N.V. Shetty, B. Auchmann, V. Chetvertkova, A. Lechner, A. Priebe, M. Sapinski, A.P. Verweij, D. Wollmann
    CERN, Geneva, Switzerland
 
  In 2013, beam-induced quench tests with 4 TeV protons were performed to probe the quench level of LHC arc quadrupole magnets at timescales corresponding to millisecond beam losses and steady-state losses. As the energy deposition in magnet coils cannot be measured directly, this study presents corresponding FLUKA simulations as well as estimates of quench levels derived with the QP3 code. Furthermore, beam loss monitor (BLM) signals were simulated and benchmarked against the measurements. Simulated and measured BLM signals are generally found to agree within 30 percent.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO019  
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MOPRO021 Power Deposition in LHC Magnets With and Without Dispersion Suppressor Collimators Downstream of the Betatron Cleaning Insertion 112
 
  • A. Lechner, B. Auchmann, R. Bruce, F. Cerutti, P.P. Granieri, A. Marsili, S. Redaelli, N.V. Shetty, E. Skordis, G.E. Steele, A.P. Verweij
    CERN, Geneva, Switzerland
 
  The power deposited in dispersion suppressor (DS) magnets downstream of the LHC betatron cleaning insertion is governed by off-momentum protons which predominantly originate from single-diffractive interactions in primary collimators. With higher beam energy and intensities anticipated in future operation, these clustered proton losses could possibly induce magnet quenches during periods of short beam lifetime. In this paper, we present FLUKA simulations for nominal 7 TeV operation, comparing the existing layout with alternative layouts where selected DS dipoles are substituted by pairs of shorter higher-field magnets and a collimator. Power densities predicted for different collimator settings are compared against present estimates of quench limits. Further, the expected reduction factor due to DS collimators is evaluated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO021  
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WEPRI092 Test and Simulation Results for Quenches Induced by Fast Losses on a LHC Quadrupole 2706
 
  • C. Bracco, B. Auchmann, W. Bartmann, M. Bednarek, A. Lechner, M. Sapinski, R. Schmidt, N.V. Shetty, M. Solfaroli Camillocci, A.P. Verweij
    CERN, Geneva, Switzerland
 
  A test program for beam induced quenches was started in the LHC in 2011 in order to reduce as much as possible BLM-triggered beam dumps, without jeopardizing the safety of the superconducting magnets. A first measurement was performed to assess the quench level of a quadrupole located in the LHC injection region in case of fast (ns) losses. It consisted in dumping single bunches onto an injection protection collimator located right upstream of the quadrupole, varying the bunch intensity up to 3·1010 protons and ramping the quadrupole current up to 2200 A. No quench was recorded at that time. The test was repeated in 2013 with increased bunch intensity (6·1010 protons); a quench occurred when powering the magnet at 2500 A. The comparison between measurements during beam induced and quench heaters induced quenches is shown. Results of FLUKA simulations on energy deposition, calculations on quench behaviour using QP3 and the respective estimates of quench levels are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI092  
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WEPRI097 STATUS OF 11 T 2-IN-1 Nb3Sn DIPOLE DEVELOPMENT FOR LHC 2722
 
  • A.V. Zlobin, N. Andreev, G. Apollinari, E.Z. Barzi, R. Bossert, M. Buehler, G. Chlachidze, J. DiMarco, A. Nobrega, I. Novitski, D. Turrioni, G. Velev
    Fermilab, Batavia, Illinois, USA
  • B. Auchmann, M. Karppinen, L. Rossi, D. Smekens
    CERN, Geneva, Switzerland
 
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and European Commission under FP7 project HiLumi LHC, GA no.284404
The LHC upgrade plans foresee installation of additional collimators in the LHC lattice. To provide the necessary longitudinal space for these collimators, shorter and stronger Nb3Sn dipoles compatible with the LHC lattice and main systems could be used. This paper describes the design and status of the twin-aperture Nb3Sn dipole being developed by FNAL and CERN for the LHC, and reports test results of two collared coils to be used in the first 1 m long twin-aperture dipole model.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPRI097  
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THPRI093 CSCM: EXPERIMENTAL AND SIMULATION RESULTS 3988
 
  • S. Rowan, B. Auchmann, K. Brodzinski, Z. Charifoulline, R. Denz, V. Roger, I. Romera, R. Schmidt, A.P. Siemko, J. Steckert, H. Thiesen, A.P. Verweij, G.P. Willering, D. Wollmann, M. Zerlauth
    CERN, Geneva, Switzerland
  • H. Pfeffer
    Fermilab, Batavia, Illinois, USA
 
  The copper-stabilizer continuity measurement - or CSCM - was devised to obtain a direct and complete qualification of the continuity in the 13 kA bypass circuits of the LHC, especially in the copper-stabilizer of the busbar joints and the bolted connections in the diode-leads. The circuit under test is brought to ~20 K, a voltage is applied to open the diodes, and the low-inductance circuit is powered with a pre-defined series of current profiles. The profiles are designed to successively increase the thermal load on the busbar joints up to a level that corresponds to worst-case operating conditions at nominal energy. In this way, the circuit is tested for thermal runaways in the joints - the very process that could prove catastrophic if it occurred under nominal conditions with the full circuit energy. Surveillance software and a numerical model were devised to carry out the analysis and ensure complete protection of the circuit from over-heating. A type test of the CSCM was successfully carried out in April 2013 on one main dipole and one main quadrupole circuit of the LHC. This paper describes the analysis procedure, the numerical model, and results of this first type test.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI093  
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THPRI094 MadX Tracking Simulations to Determine the Beam loss Distributions for the LHC Quench Tests with ADT Excitation 3991
 
  • V. Chetvertkova, B. Auchmann, T. Bär, W. Höfle, A. Priebe, M. Sapinski, R. Schmidt, A.P. Verweij, D. Wollmann
    CERN, Geneva, Switzerland
 
  Quench tests with stored beam were performed in 2013 with one of the LHC main focusing quadrupoles to experimentally verify the quench levels for beam losses in the time scales from a few milliseconds to several seconds. A novel technique combining a 3-corrector orbital bump and transverse-damper kicks was used for inducing the beam losses. MadX tracking simulations were an essential step for determining the spatial and angular beam loss distributions during the experiment. These were then used as input for further energy-deposition and quench-level calculations. In this paper the simulated beam-loss distributions for the respective time scales and experimental parameters are presented. Furthermore the sensitivity of the obtained loss-distributions to the variation of key input parameters, which were measured during the experiment, is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPRI094  
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