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kicker

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PS02 Chromaticity Measurements at HERA-P Using the Head-Tail Technique with Chirp Excitation betatron, synchrotron, proton, pick-up 103
 
  • M. Wendt, F. Willeke
    DESY, Deutsches Elektronen-Synchrotron, Hamburg, Germany
  • A. Boudsko
    TRIUMF, Vancouver, Canada
  • O.R. Jones, H. Schmickler
    CERN, Geneva, Switzerland
  Experiments have been performed in the HERA proton ring (HERA-p) to test a quasi non-destructive method of chromaticity measurements for protons. The method is based on the detection of the head-tail phase shift of coherend betatron oscillations using a broadband beam position pickup and a commercial “fast-frame” oscilloscope. Previous experiments have relied on a single kick for transverse excitation, whereas the results presented here were carried out using swept frequency “chirp” excitation. The tests proved to be successful, and the method seems to be a good candidate for chromaticity measurement in new large hadron accelerators, such as LHC.  
 
PS15 Beam profile measurements at 40 MHz in the PS to SPS transfer channel injection, proton, ion, radiation 135
 
  • G. Ferioli, J.J. Gras, H. Hiller, R. Jung
    CERN, Geneva, Switzerland
  Bunch to bunch beam profile measurements provide a valuable tool to control the injection lines to the SPS. A fast profile monitor based on a 2.5μm Mylar coated with Aluminium Optical Transition Radiation (OTR) radiator, has been developed, installed and tested in the transfer line between the PS and SPS. The OTR beam image is focused onto a fast Linear Multianode Photo Multiplier Tube and the associated electronics sample and store profiles every 25ns. The paper describes the detector design, the electronic processing, and presents the results of different measurements made with bunches of 109-1011 protons at 26 GeV, and bunches of 106 Pb82+ ions at 5.11 GeV/u.  
 
PS16 The fast head-tail instability suppression in multibunch mode at VEPP-4M feedback, injection, dipole, impedance 138
 
  • G. Karpov, V. Kiselev, V. Smaluk, N. Zinvich
    BINP, Budker Institute of Nuclear Physics, Novosibirsk, Russia
  In this paper the bunch-by-bunch transverse feedback system for suppression fast head-tail as well as coupled bunch instabilities is described. The experimental results of the feedback affecting on the current threshold are presented. The effects of reactive and resistive feedback on the current threshold are discussed. Two times as large the bunch current than the threshold current was obtained.  
 
PT11 Dipole modes study by means of HOM couplers at SBTF dipole, coupling, pick-up, damping 183
 
  • N. Baboi, M. Dohlus, A. Jöstingmeier, N. Holtkamp, M. Wendt, M. Nagl, J. Boster, H. Hartwig
    DESY, Deutsches Elektronen Synchrotron, Hamburg, Germany
  High order modes (HOM) are generated by the interaction of a bunched beam with an accelerator environment. They may act destructively on following particle bunches, leading to an increase of the transverse oscillation amplitude and finally to the deterioration of the emittance. Dipole modes have been studied at the S-Band Test Facility at DESY. One accelerating structure, specially designed for this test linac, is equipped with waveguide pick-ups for measuring the HOMs. For one part of the experiments, a modulation of the transverse offset of the bunches at the structure entrance has been induced using a fast broadband kicker and the effect was measured with a precise stripline BPM. No high impedance modes were clearly found in the structure, which has been detuned and damped by both the tapered geometry of the structure and an absorbing stainless steel coating applied on the iris tips.  
 
PT15 High current precision long pulse electron beam position monitor electron, instrumentation, diagnostics, target 193
 
  • S.D. Nelson, Y.J. Chen, T. Fessenden, C. Holmes
    LLNL, Lawrence Livermore National Laboratory, Livermore, CA, USA
  Precision high current long pulse electron beam position monitoring has typically experienced problems with high Q sensors, sensors damped to the point of lack of precision, or sensors that interact substantially with any beam halo thus obscuring the desired signal. As part of the effort to develop a multi-axis electron beam transport system using transverse electromagnetic stripline kicker technology, it is necessary to precisely determine the position and extent of long high energy beams for accurate beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs beam pulse, sub millimeter beam position accuracy.) The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (< 20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt position measurements.