IPAC2014 - List of Authors (Valuch, D.)

Paper	Title	Page
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 MOOCB01 [2.737 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCB01
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MOPRO031	Abort Gap Cleaning for LHC Run 2	138
	J.A. Uythoven, A. Boccardi, E. Bravin, B. Goddard, G.H. Hemelsoet, W. Höfle, D. Jacquet, V. Kain, S. Mazzoni, M. Meddahi, D. Valuch CERN, Geneva, Switzerland E. Gianfelice-Wendt Fermilab, Batavia, Illinois, USA
	To minimize the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO031
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MOPRO043	Handling 1 MW Losses with the LHC Collimation System	174
	B. Salvachua, R. Bruce, F. Carra, M. Cauchi, E.B. Holzer, W. Höfle, D. Jacquet, L. Lari, D. Mirarchi, E. Nebot Del Busto, S. Redaelli, A. Rossi, M. Sapinski, R. Schmidt, G. Valentino, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland M. Cauchi UoM, Msida, Malta L. Lari IFIC, Valencia, Spain
	Funding: Research supported by EU FP7 HiLumi LHC (Grant agree. 284404) The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO043
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THPME174	High-accuracy Diagnostic Tool for Electron Cloud Observation in the LHC based on Synchronous Phase Measurements	3677
SUSPSNE068	use link to see paper's listing under its alternate paper code
	J.F. Esteban Müller, P. Baudrenghien, T. Mastoridis, E.N. Shaposhnikova, D. Valuch CERN, Geneva, Switzerland
	Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results show clearly the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system. The plan to use this method in the LHC operation is also presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME174
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Paper

Title

Page

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 MOOCB01 [2.737 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOOCB01

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRO031

Abort Gap Cleaning for LHC Run 2

138

J.A. Uythoven, A. Boccardi, E. Bravin, B. Goddard, G.H. Hemelsoet, W. Höfle, D. Jacquet, V. Kain, S. Mazzoni, M. Meddahi, D. Valuch
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA

To minimize the beam losses at the moment of an LHC beam dump the 3 μs long abort gap should contain as few particles as possible. Its population can be minimised by abort gap cleaning using the LHC transverse damper system. The LHC Run 1 experience is briefly recalled; changes foreseen for the LHC Run 2 are presented. They include improvements in the observation of the abort gap population and the mechanism to decide if cleaning is required, changes to the hardware of the transverse dampers to reduce the detrimental effect on the luminosity lifetime and proposed changes to the applied cleaning algorithms.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO031

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

MOPRO043

Handling 1 MW Losses with the LHC Collimation System

174

B. Salvachua, R. Bruce, F. Carra, M. Cauchi, E.B. Holzer, W. Höfle, D. Jacquet, L. Lari, D. Mirarchi, E. Nebot Del Busto, S. Redaelli, A. Rossi, M. Sapinski, R. Schmidt, G. Valentino, D. Valuch, J. Wenninger, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland
M. Cauchi
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain

Funding: Research supported by EU FP7 HiLumi LHC (Grant agree. 284404)
The LHC superconducting magnets in the dispersion suppressor of IR7 are the most exposed to beam losses leaking from the betatron collimation system and represent the main limitation for the halo cleaning. In 2013, quench tests were performed at 4 TeV to improve the quench limit estimates, which determine the maximum allowed beam loss rate for a given collimation cleaning. The main goal of the collimation quench test was to try to quench the magnets by increasing losses at the collimators. Losses of up to 1 MW over a few seconds were generated by blowing up the beam, achieving total losses of about 5.8 MJ. These controlled losses exceeded by a factor 2 the collimation design value, and the magnets did not quench.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO043

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reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

THPME174

High-accuracy Diagnostic Tool for Electron Cloud Observation in the LHC based on Synchronous Phase Measurements

3677

SUSPSNE068

use link to see paper's listing under its alternate paper code

J.F. Esteban Müller, P. Baudrenghien, T. Mastoridis, E.N. Shaposhnikova, D. Valuch
CERN, Geneva, Switzerland

Electron cloud effects such as heat load in the cryogenic system, pressure rise and beam instabilities are among the main limitations for the LHC operation with 25 ns spaced bunches. A new observation tool was developed to monitor the e-cloud activity and has been successfully used in the LHC during Run 1 (2010-2012). The power loss of each bunch due to the e-cloud can be estimated using very precise bunch-by-bunch measurement of the synchronous phase shift. In order to achieve the required accuracy, corrections for reflection in the cables and some systematic errors need to be applied followed by a post-processing of the measurements. Results show clearly the e-cloud build-up along the bunch trains and its evolution during each LHC fill as well as from fill to fill. Measurements during the 2012 LHC scrubbing run reveal a progressive reduction in the e-cloud activity and therefore a decrease in the secondary electron yield (SEY). The total beam power loss can be computed as a sum of the contributions from all bunches and compared with the heat load deposited in the cryogenic system. The plan to use this method in the LHC operation is also presented.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-THPME174

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)