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71.
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Simulation of Instability at Transition Energy with a New Impedance Model for CERN PS
/ Wang, Na (Beijing, Inst. High Energy Phys. ; CERN) ; Aumon, Sandra (CERN) ; Biancacci, Nicolo (CERN) ; Migliorati, Mauro (INFN, Rome ; CERN) ; Persichelli, Serena (U. Rome La Sapienza (main)) ; Sterbini, Guido (CERN)
Instabilities driven by the transverse impedance are proven to be one of the limitations for the high intensity reach of the CERN PS. Since several years, fast single bunch vertical instability at transition energy has been observed with the high intensity bunch serving the neu-tron Time-of-Flight facility (n-ToF). [...]
CERN-ACC-2016-233.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-TUPOR010
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.TUPOR010
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72.
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Current Status of Instability Threshold Measurements in the LHC at 6.5 TeV
/ Carver, Lee (CERN) ; Barranco, Javier (Ecole Polytechnique, Lausanne) ; Biancacci, Nicolo (CERN) ; Buffat, Xavier (CERN) ; Höfle, Wolfgang (CERN) ; Kotzian, Gerd (CERN) ; Lefèvre, Thibaut (CERN) ; Levens, Thomas (CERN) ; Métral, Elias (CERN) ; Pieloni, Tatiana (CERN) et al.
Throughout 2015, many measurements of the minimum stabilizing octupole current required to prevent coherent transverse instabilities have been performed. These measurements allow the LHC impedance model at flat top to be verified and give good indicators of future performance and limitations. [...]
CERN-ACC-2016-234.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-TUPMW011
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.TUPMW011
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73.
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Beam Induced RF Heating in LHC in 2015
/ Salvant, Benoit (CERN) ; Aberle, Oliver (CERN) ; Albert, Markus (CERN) ; Alemany-Fernandez, Reyes (CERN) ; Arduini, Gianluigi (CERN) ; Baechler, Joachim (CERN) ; Barnes, Michael (CERN) ; Baudrenghien, Philippe (CERN) ; Berrig, Olav (CERN) ; Biancacci, Nicolo (CERN) et al.
Following the recurrent beam induced RF issues that perturbed LHC operation during LHC Run 1, a series of actions were put in place to minimize the risk that similar issues would occur in LHC Run 2: longitudinal impedance reduction campaign and/or improvement of cooling for equipment that were problematic or at the limit during Run 1, stringent constraints enforced on new equipment that would be installed in the machine, tests to control the bunch length and longitudinal distribution, additional monitoring of temperature, new monitoring tools and warning chains. This contribution reports the outcome of these actions, both successes as well as shortcomings, and details the lessons learnt for the future runs..
CERN-ACC-2016-279.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-MOPOR008
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.MOPOR008
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74.
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Measurements of the CERN PS Longitudinal Resistive Coupling Impedance
/ Migliorati, Mauro (CERN ; Rome U. ; INFN, Rome) ; Persichelli, Serena (Rome U. ; INFN, Rome) ; Ventura, Letizia (Rome U. ; INFN, Rome) ; Biancacci, Nicolo (CERN) ; Damerau, Heiko (CERN) ; Sterbini, Guido (CERN)
The longitudinal coupling impedance of the CERN PS has been studied in the past years in order to better understand collective effects which could produce beam intensity limitations for the LHC Injectors Upgrade project. By measuring the incoherent quadrupole synchrotron frequency vs beam intensity, the inductive impedance was evaluated and compared with the impedance model obtained by taking into account the contribution of the most important machine devices. [...]
IPAC-2016-MOPOR014; CERN-ACC-2016-299.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-MOPOR014
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.MOPOR014
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75.
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Impedance Localization Measurements using AC Dipoles in the LHC
/ Biancacci, Nicolo (CERN) ; Carver, Lee (CERN) ; Papotti, Giulia (CERN) ; Persson, Tobias (CERN) ; Salvant, Benoit (CERN) ; Tomás, Rogelio (CERN)
The knowledge of the LHC impedance is of primary importance to predict the machine performance and allow for the HL-LHC upgrade. The developed impedance model can be benchmarked with beam measurements in order to assess its validity and limit. [...]
CERN-ACC-2016-302.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-MOPOR011
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.MOPOR011
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76.
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Impedance Measurements and Simulations on the TCTP and TDI LHC Collimators
/ Biancacci, Nicolo (CERN) ; Caspers, Fritz (CERN) ; Frasciello, Oscar (LNF, Dafne Light) ; Grudiev, Alexej (CERN) ; Kuczerowski, Joseph (CERN) ; Lamas Garcia, Inigo (CERN) ; Lechner, Anton (CERN) ; Mostacci, Andrea (U. Rome La Sapienza (main)) ; Mounet, Nicolas (EPFL-ISIC, Lausanne) ; Métral, Elias (CERN) et al.
The LHC collimation system is a critical element for the safe operation of the LHC machine and is subject to continuous performance monitoring, hardware upgrade and optimization. In this work we will address the impact on impedance of the upgrades performed on the TDI injection protection collimator, where the absorber material has been changed to mitigate the device heating observed in machine operation, and on selected secondary (TCS) and tertiary (TCT) collimators, where beam position monitors (BPM) have been embedded for faster jaw alignment. [...]
CERN-ACC-2016-310.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-MOPOR010
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.MOPOR010
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77.
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The HL-LHC Impedance Model and Aspects of Beam Stability
/ Biancacci, Nicolo (CERN) ; Li, Kevin (CERN) ; Métral, Elias (CERN) ; Salvant, Benoit (CERN)
The LHC upgrade to the HLLHC foresees new challenging operational scenarios from the beam dynamics point of view. In order to ensure good machine operation and performance, the machine impedance, among other possible sources of instabilities like beam-beam and electron cloud, needs to be carefully quantified profiting also from the current LHC operation. [...]
CERN-ACC-2016-309.-
2016 - 4 p.
- Published in : 10.18429/JACoW-IPAC2016-MOPOR009
Published version from JACoW: PDF;
In : 7th International Particle Accelerator Conference, Busan, Korea, 8 - 13 May 2016, pp.MOPOR009
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78.
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Measurement and interpretation of transverse beam instabilities in the CERN large hadron collider (LHC) and extrapolations to HL-LHC
/ Metral, Elias (CERN) ; Arduini, Gianluigi (CERN) ; Barranco Navarro, Laura (CERN) ; Buffat, Xavier (CERN) ; Carver, Lee Robert (CERN) ; Iadarola, Giovanni (CERN) ; Li, Kevin Shing Bruce (CERN) ; Pieloni, Tatiana (CERN) ; Romano, Annalisa (CERN) ; Rumolo, Giovanni (CERN) et al.
Since the first transverse instability observed in 2010, many studies have been performed on both measurement and simulation sides and several lessons have been learned. In a machine like the LHC, not only all the mechanisms have to be understood separately, but the possible interplays between the different phenomena need to be analysed in detail, including the beam-coupling impedance (with in particular all the necessary collimators to protect the machine but also new equipment such as crab cavities for HL-LHC), linear and nonlinear chromaticity, Landau octupoles (and other intrinsic nonlinearities), transverse damper, space charge, beam-beam (long-range and head-on), electron cloud, linear coupling strength, tune separation between the transverse planes, tune split between the two beams, transverse beam separation between the two beams, etc. [...]
CERN-ACC-2016-0098.-
Geneva : CERN, 2016 - 7 p.
- Published in : 10.18429/JACoW-HB2016-TUAM2X01
Fulltext: PDF; External link: Fulltext
In : 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, Malmö, Sweden, 3 - 8 Jul 2016, pp.TUAM2X01
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79.
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Chromaticity Dependence of the Transverse Effective Impedance in the CERN Proton Synchrotron
/ Persichelli, Serena (CERN) ; Biancacci, Nicolo (CERN) ; Gilardoni, Simone (CERN) ; Huschauer, Alexander (CERN) ; Migliorati, Mauro (U. Rome La Sapienza (main)) ; Métral, Elias (CERN) ; Salvant, Benoit (CERN) ; Wasef, Raymond (CERN)
The current knowledge of the transverse impedance of the Proton Synchrotron (PS) has been established with beam-based measurements at different energies. The transverse coherent tune shift as a function of the beam intensity has been measured in order to evaluate the total effective imaginary part of the transverse impedance and its localization in the accelerator at the energies of 2, 7, 13 and 25 GeV. [...]
CERN-ACC-2015-337.-
2015 - 4 p.
- Published in : (2015) , pp. MOPJE047
Published version from JACoW: PDF; External link: JACOW
In : 6th International Particle Accelerator Conference, Richmond, VA, USA, 3 - 8 May 2015, pp.MOPJE047
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80.
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Injection Protection Upgrade for the HL-LHC
/ Uythoven, Jan (CERN) ; Biancacci, Nicolo (CERN) ; Bracco, Chiara (CERN) ; Frasciello, Oscar (Frascati) ; Gentini, Luca (CERN) ; Goddard, Brennan (CERN) ; Lechner, Anton (CERN) ; Maciariello, Fausto (CERN) ; Perillo Marcone, Antonio (CERN) ; Salvant, Benoit (CERN) et al.
The injector complex of the LHC is undergoing important changes in the light of the LIU project to provide brighter beams to the LHC. For this reason and as part of the High Luminosity LHC project the injection protection system of the LHC will be upgraded in the Long Shutdown 2 (2018 - 2019) to be able to protect downstream elements against injection failures with the high brightness, high intensity HL-LHC beams. [...]
IPAC-2015-TUPTY051; CERN-ACC-2015-359.-
2015 - 4 p.
- Published in : (2015) , pp. TUPTY051
Published version from JACoW: PDF; External link: JACOW
In : 6th International Particle Accelerator Conference, Richmond, VA, USA, 3 - 8 May 2015, pp.TUPTY051
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