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proton

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OPR02 Recent Experimental Results on Amorphous Carbon Coatings for Electron Cloud Mitigation electron, dipole, vacuum, cathode 6
 
  • C. Yin Vallgren, S. Calatroni, P. Chiggiato, P. Costa Pinto, H. Neupert, M. Taborelli, G. Rumolo, E. Shaposhnikova, W. Vollenberg
    CERN
  Amorphous carbon (a-C) thin films, produced in different coating configurations by using d.c magnetron sputtering, have been investigated in laboratory for low secondary electron yield (SEY) applications. After the coatings had shown a reliable low initial SEY, the a-C thin films have been applied in the SPS and tested with LHC type beams. Currently, we have used a-C thin film coated in so-called liner configuration for the electron cloud monitors as well as for a removable sample. In addition the vacuum chambers of three dipole magnets have been coated and inserted in the machine. After describing the different configurations used for the coatings, results of the tests in the machine and a summary of the analyses after extraction will be presented. Based on comparison between different coating configurations, a new series of coatings has been applied on three further dipole magnet vacuum chambers. They have been installed and will be tested in coming machine development runs.  
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MOD03 Accurate Simulation of the Electron Cloud in the Fermilab Main Injector with VORPAL electron, simulation, dipole, quadrupole 152
 
  • P. Lebrun, P. Spentzouris
    Fermilab
  • J. Cary
    University of Colorado Boulder
  • S. Veitzer, P. Stoltz
    Tech-X Corporation
  We present results from a precision simulation of the electron cloud (EC) problem in the Fermilab Main Injector using the code VORPAL. Fully 3D and self consistent that include both distributions of electrons in 6D phase-space and E. M. field maps. Various configurations of the magnetic fields found around the machine have been studied. Plasma waves associated to the fluctuation density of the cloud have been analyzed. Our results are compaired with those obtained with the POSINST code. It is shown that the 3D effects are important. The response of a Retarding Field Analyzer (RFA) to the EC has been simulated, as well as the more challenging microwave absorption experiment. Definite predictions of their exact response are difficult to compute, mostly because of the uncertainties in the secondary emission yield and, in the case of the RFA, because of the sensitivity of the electron collection efficiency to unknown stray magnetic fields. Nonetheless, our simulations do provide guidance to the experimental program.  
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DIA00 Electron Cloud Studies in the Fermilab Main Injector Using Microwave Transmission electron, lattice, dipole, plasma 173
 
  • J. Thangaraj, N. Eddy, R. Zwaska, K. Seiya, I. Kourbanis, J. Crisp
    Fermilab
  In this paper, we present recent results from our measurement at the Fermilab Main Injector through microwave transmission in a beam pipe. We present three types of measurement techniques. In the first technique, we use time-resolved direct phase shift measurement to measure the e-cloud density. In the second and third techniques, we look for side bands in the frequency spectrum with or without frequency span by collecting turns of data. Finally, we also discuss the resonant BPM method, where a signal below the waveguide cutoff is sent through a one side of the BPM and is collected on the other side of the BPM to look for phase shift due to electron cloud. We present experimental results taken from MI40 and MI52 section of the main injector.  
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DIA02 The Ecloud Measurement Setup in the Main Injector electron, vacuum, simulation, antiproton 177
 
  • C. Tan, R. Zwaska, M. Backfish
    Fermilab
  An ecloud measurement setup was installed in a straight section of the Main Injector in 2009. The goal of the setup was to compare the characteristics of different beam pipe coatings when subjected to proton beam. The setup consists of one coated and one uncoated beam pipe with the same physical dimensions installed at the same location. Four RFAs (retarding field analysers) and two BPMs (used for RF measurements) have been used to measure the ecloud densities. The RFAs have performed very well and have collected both the time evolution and energy distribution of the ecloud for bare and two types of beam pipe coatings.  
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