Keyword: flattop
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MOPG05 Transient Studies of the Stripline Kicker for Beam Extraction from CLIC Damping Rings impedance, extraction, kicker, simulation 35
  • C. Belver-Aguilar, M.J. Barnes
    CERN, Geneva, Switzerland
  Stripline kickers are generally assumed to have equal contributions from the electric and magnetic field to the total deflection angle, for ultra-relativistic beams. Hence parameters of the striplines, such as the characteristic impedance, the field homogeneity and the deflection angle are typically determined by simulating the striplines from an electrostatic perspective. However recent studies show that, when exciting the striplines with a trapezoidal current pulse, the magnetic field changes during the flat-top of the pulse, and this can have a significant effect upon the striplines performances. The transient solver of Opera2D has been used to study the magnetic field, for the striplines to be used for beam extraction from the CLIC damping rings, when exciting the electrodes with a pulse of 1 us flat-top and 100 ns rise and fall times. The time dependence of the characteristic impedance, field homogeneity and deflection angle are presented in this paper. In addition, two solutions are proposed to improve the flatness of the magnitude of the magnetic field throughout the flat-top of the pulse, and the predicted results are reported.  
poster icon Poster MOPG05 [1.557 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG05  
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MOPG47 Beta Function Measurement for the AGS IPM emittance, dipole, betatron, proton 157
  • H. Huang, L. Ahrens, C.E. Harper, F. Méot, V. Schoefer
    BNL, Upton, Long Island, New York, USA
  Emittance control is important for polarization preservation of proton beam in the Alternative Gradient Synchrotron (AGS). For polarization preservation, two helical dipole partial snake magnets are inserted into the AGS lattice. In addition, the vertical tune has to run very high, in the vicinity of integer. These helical dipole magnets greatly distort the optics, especially near injection. The beta functions along the energy ramp have been modeled and measured at the locations of the Ion Profile Monitor (IPM). For the measurements to be valid, the betatron tune, dipole current and orbit responses have to be carefully measured. This paper summarize the experiment results and comparison with the model. These results will lead to understanding of emittance evolution in the AGS.  
poster icon Poster MOPG47 [2.033 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG47  
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MOPG48 Optimized Cryogenic Current Comparator for CERN's Low-Energy Antiproton Facilities antiproton, cryogenics, injection, controls 161
  • M.F. Fernandes, D. Alves, T. Koettig, A. Lees, E. Oponowicz, J. Tan
    CERN, Geneva, Switzerland
  • M.F. Fernandes, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • R. Geithner, R. Neubert, T. Stöhlker
    HIJ, Jena, Germany
  • R. Geithner, R. Neubert, T. Stöhlker
    IOQ, Jena, Germany
  • M. Schwickert
    GSI, Darmstadt, Germany
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  Funding: This project has received funding from the European Unions Seventh Framework Programme for research, technological development and demonstration under grant agreement number 289485.
Non-perturbative measurement of low-intensity charged particle beams is particularly challenging for beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy Antiproton Decelerator (AD) and the future Extra Low ENergy Antiproton (ELENA) rings at CERN, an absolute measurement of the beam intensity is essential to monitor operational efficiency and provide important calibration data for all AD experiments. Cryogenic Current Comparators (CCC) based on Superconducting QUantum Interference Device (SQUID) have in the past been used for the measurement of beams in the nA range, showing a very good current resolution. However these were unable to provide a measurement of short bunched beams, due to the slew-rate limitation of SQUID devices and their strong susceptibility to external perturbations. Here, we present the measurements and results obtained during 2016 with a CCC system developed for the Antiproton Decelerator, which has been optimized to overcome these earlier limitations in terms of current resolution, system stability, the ability to cope with short bunched beams, and immunity to mechanical vibrations.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IBIC2016-MOPG48  
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