Author: Rumolo, G.
Paper Title Page
MOPJE027 Beam-based Impedance Characterization of the ALBA Pinger Magnet 334
 
  • U. Iriso, T.F.G. Günzel
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • H. Bartosik, E. Koukovini-Platia, G. Rumolo
    CERN, Geneva, Switzerland
 
  The ALBA pinger magnet consists on two short kickers (for horizontal and vertical planes) installed in a single Titanium coated ceramic vacuum chamber. Single bunch measurements in the vertical plane were performed in the ALBA Synchrotron Light Source before and after the pinger installation, and by comparing the Transverse Mode Coupling Instability (TMCI) thresholds for zero chromaticity, we infer the pinger impedance and compare it with the model predictions. We also perform measurements for negative chromaticities and results are reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE027  
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MOPJE048 Electron-Cloud Studies for Transversely Split Beams 399
 
  • N. Pradhan, S.S. Gilardoni, M. Giovannozzi, G. Iadarola, G. Rumolo
    CERN, Geneva, Switzerland
  • N. Pradhan
    UMiss, University, Mississippi, USA
 
  Recently, resonance crossing has been proposed as a means of manipulating the transverse beam distribution. This technique has application, among other topics, to injection and extraction schemes. Moreover, the transversely split beams might also be used as a mitigation measure of electron-cloud effects. The results of detailed numerical simulations are discussed in this paper, possibly opening new options for scrubbing of beam pipes in circular accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE048  
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MOPJE049 Benchmarking the CERN-SPS Transverse Impedance Model with Measured Headtail Growth Rates 402
 
  • C. Zannini, H. Bartosik, G. Iadarola, G. Rumolo, B. Salvant
    CERN, Geneva, Switzerland
 
  The latest SPS transverse impedance model includes kicker magnets, wall impedance, transition pieces (e.g. flanges and vacuum chamber discontinuities), beam position monitors and RF cavities. The model has already been successfully benchmarked against coherent tune shift and transverse mode coupling instability measurements. In this paper we present measurements of the headtail growth rates for a wide range of negative chromaticities and for two different configurations of machine optics (nominal and low gamma transition). The measurement results are compared with HEADTAIL simulations using the wake fields obtained from the SPS transverse impedance model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE049  
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MOPJE050 Transverse Impedance Model of the CERN-PSB 406
 
  • C. Zannini, G. Iadarola, K.S.B. Li, T.L. Rijoff, G. Rumolo
    CERN, Geneva, Switzerland
  • B. Jones
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • T.L. Rijoff
    TU Darmstadt, Darmstadt, Germany
 
  In the framework of the PS-Booster upgrade project an accurate impedance model is needed in order to determine the effect on the beam stability and assess the impact of the new devices before installation in the machine. This paper describes the PSB impedance model which includes resistive wall, indirect space charge, flanges, step transitions, ejection kicker including cables, injection kickers and cavities. Each impedance contribution has been computed for different energies in the PSB cycle. Measurements of the coherent tune shifts have been performed and compared to calculations based on the impedance model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE050  
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MOPJE051 Effect of Electron Cloud in Quadrupoles on Beam Instability 409
 
  • G. Iadarola, A.P. Axford, H. Bartosik, K.S.B. Li, G. Rumolo
    CERN, Geneva, Switzerland
 
  Both simulations and machine experience at the CERN-SPS and LHC have shown that the electron cloud has a lower build up threshold in quadrupoles than in dipoles and field free regions. As a consequence, while beam induced scrubbing can efficiently suppress the electron cloud in both dipoles and field free regions, a residual electron cloud can still survive in the quadrupoles and potentially degrade the beam quality. To study this effect, a PyECLOUD module for electron tracking in quadrupole fields including effects of secondary emission at the vacuum chamber has been implemented in PyHEADTAIL. With this module, the effect of the electron cloud in quadrupoles on beam stability and beam quality preservation can be assessed, as well as its impact on future LHC and HL-LHC operation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE051  
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WEPHA002 Electromagnetic Characterization of NEG Properties Above 200 GHz for the CLIC Damping Rings 3097
 
  • E. Koukovini-Platia, G. Iadarola, G. Rumolo, C. Zannini
    CERN, Geneva, Switzerland
 
  Non-Evaporable Getter (NEG) will be used in the CLIC electron damping rings (EDR) to suppress fast beam ion instabilities due to its effective pumping ability. The electromagnetic (EM) characterization of the NEG properties up to high frequencies is required for the correct impedance modeling of the DR components. The properties are determined using WR-3.4 and WR-1.5 rectangular waveguides, based on a combination of experimental measurements of the complex transmission coefficient S21 with a Vector Network Analyzer (VNA) and CST 3D EM simulations, for the frequency range of 220-330 GHz and 500-750 GHz. The results obtained using NEG-coated Aluminum (Al) waveguides are presented in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA002  
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THPF083 Painting Schemes for CERN PS Booster H Injection 3879
 
  • J.L. Abelleira, W. Bartmann, E. Benedetto, C. Bracco, G.P. Di Giovanni, V. Forte, M. Kowalska, M. Meddahi, B. Mikulec, G. Rumolo
    CERN, Geneva, Switzerland
  • V. Forte
    Université Blaise Pascal, Clermont-Ferrand, France
  • M. Kowalska
    EPFL, Lausanne, Switzerland
 
  The present 50-MeV proton injection into the PS Booster will be replaced by a H charge exchange injection at 160 MeV to be provided by Linac 4. The higher energy will allow producing beams at higher brightness. A set of kicker magnets (KSW) will move the beam across the stripping foil to perform phase space painting in the horizontal plane to reduce space charge effects. The PSB must satisfy the different users with very different beams in terms of emittance and intensity. Therefore, the KSW waveforms must be adapted for each case to meet the beam characteristics while minimizing beam losses. Here we present the results of the simulations performed to optimise the injection system. A detailed analysis of the different painting schemes is discussed, including the effect of the working point on the painted beam, and variations in the offset of the injected beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF083  
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THPF087 New Shaving Scheme for Low-Intensity Beams in the CERN PS Booster and Feasibility at 160 MeV 3893
 
  • M. Kowalska, E. Benedetto, V. Forte, B. Mikulec, G. Rumolo
    CERN, Geneva, Switzerland
  • V. Forte
    Université Blaise Pascal, Clermont-Ferrand, France
  • M. Kowalska
    EPFL, Lausanne, Switzerland
 
  The PS Booster is the first synchrotron in the CERN proton accelerator chain, serving all downstream machines. As part of the LHC Injector Upgrade Project, the PSB injection energy will increase from 50 MeV to 160 MeV and a new H charge-exchange injection scheme will be implemented. Beam losses are a concern due to the increased injection energy, and mitigation scenarios are under investigation. On the other hand it is desirable for low-intensity beams to have the possibility to precisely tailor sub-micron beam emittances through controlled scraping (transverse shaving process) towards a suitable aperture restriction. Challenges are the higher activation potential of the beam and the smaller transverse beam sizes around 160 MeV as compared to 63 MeV, at which the shaving is presently done. This paper describes the proposal of a new shaving scheme, more robust with respect to the steering errors and the choice of the working point, which localizes the scraping losses on the main PS Booster aperture restriction. The robustness of the new method, together with the results of simulations and measurements are discussed for the current (50 MeV) and future (160 MeV) situation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF087  
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THPF088 CERN PS Booster Upgrade and LHC Beams Emittance 3897
 
  • E. Benedetto, J.L. Abelleira, C. Bracco, V. Forte, B. Mikulec, G. Rumolo
    CERN, Geneva, Switzerland
  • V. Forte
    Université Blaise Pascal, Clermont-Ferrand, France
 
  By increasing the CERN PS Booster injection energy from 50 MeV to 160 MeV, the LHC Injector Upgrade Project aims at producing twice as brighter beams for the LHC. Previous measurements showed a linear dependence of the transverse emittance with the beam intensity and space-charge simulations confirmed the linear scaling. This paper is discussing in detail the dependence on the longitudinal emittance and on the choice of the working point, with a special attention to the H injection process and to the beam dynamics in the first 5 ms, during the fall of the injection chicane bump.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF088  
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THPF091 Detailed Studies of Beam Induced Scrubbing in the CERN-SPS 3908
 
  • G. Iadarola, H. Bartosik, T. Bohl, B. Goddard, G. Kotzian, K.S.B. Li, L. Mether, G. Rumolo, M. Schenk, E.N. Shaposhnikova, M. Taborelli
    CERN, Geneva, Switzerland
 
  In the framework of the LHC Injectors Upgrade (LIU) program, it is foreseen to take all the necessary measures to avoid electron cloud effects in the CERN-SPS. This can be achieved by either relying on beam induced scrubbing or by coating the vacuum chambers with intrinsically low Secondary Electron Yield (SEY) material over a large fraction of the ring. To clearly establish the potential of beam induced scrubbing, and to eventually decide between the two above options, an extensive scrubbing campaign is taking place at the SPS. Ten days in 2014 and two full weeks in 2015 are devoted to machine scrubbing and scrubbing qualification studies. This paper summarizes the main findings in terms of scrubbing efficiency and reach so far, addressing also the option of using a special doublet beam and its implication for LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF091  
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THPF093 Status of the LHC Injectors Upgrade (LIU) Project at CERN 3915
 
  • M. Meddahi, J. Coupard, H. Damerau, A. Funken, S.S. Gilardoni, B. Goddard, K. Hanke, L. Kobzeva, A.M. Lombardi, D. Manglunki, S. Mataguez, B. Mikulec, G. Rumolo, E.N. Shaposhnikova, M. Vretenar
    CERN, Geneva, Switzerland
 
  CERN is currently carrying out an ambitious improvement programme of the full LHC Injectors chain in order to enable the delivery of beams with the challenging HL-LHC parameters. The LHC Injectors Upgrade project coordinates this massive upgrade program, and covers a new linac (Linac4 project) as well as upgrades to the Proton Synchrotron Booster, the Proton Synchrotron and Super Proton Synchrotron. The heavy ion injector chain is also included, adding the Linac3 and Low Energy Ion Ring to the list of accelerators concerned. The performance objectives and roadmap of the main upgrades will be presented, including the work status and outlook. The machine studies and milestones during LHC Run 2 will be discussed and a preliminary Long Shutdown 2 installation planning given. Finally, for the LHC Run 3, the beam performance across the full injector chain after all the upgrades will be estimated and the required commissioning stages outlined.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF093  
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