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TUAX04 Test of a prototype active damping system for the e-p instability at the LANL PSR damping, kicker, electron, impedance 94
 
  • R. J. Macek, R. C. McCrady, S. B. Walbridge, J. Zaugg
    LANL, Los Alamos, New Mexico
  • S. Assadi, C. Deibele, S. Henderson, M. A. Plum
    ORNL, Oak Ridge, Tennessee
  • J. M. Byrd
    LBNL, Berkeley, California
  • M. T.F. Pivi
    SLAC, Menlo Park, California
  Our collaboration from LANL, SNS, LBNL and SLAC has developed and successfully tested a prototype of an analog, transverse (vertical) feedback system for active damping of the two-stream (e-p) instability at the Los Alamos Proton Storage Ring (PSR). This system was able to improve the instability threshold (as measured by the RF buncher voltage) by ~30%. Beam leakage into the gap at lower RF buncher voltage and resulting higher growth rates from more trapped electrons is the likely cause of this limitation. We will describe the system configuration and results of several experimental tests of system performance. We will also discuss our studies and analysis of the factors limiting system performance.  
 
TUBX05 Cures for beam instabilities in the CERN SPS and their limitations synchrotron, emittance, beam-loading, injection 153
 
  • E. N. Shaposhnikova
    CERN, Geneva
  The LHC beam in the SPS is unstable with a threshold almost an order of magnitude below the nominal intensity. The cures used to stabilise this beam against coupled bunch instabilities apart from beam feedback, feed-forward and longitudinal damping, include a fourth harmonic RF system and controlled emittance blow-up. The limitations of the two last methods were studied experimentally and are analysed here from the point of view of beam quality requirements at extraction and future intensity increases up to ultimate value.  
 
WEAY03 Experimental studies of stability issues at HIMAC cooler ion, electron, resonance, injection 197
 
  • K. Noda, T. Fujisawa, T. Honma
    NIRS, Chiba-shi
  • M. Aiba, Y. Hashimoto
    KEK, Ibaraki
  • S. Shibuya
    AEC, Chiba
  • E. Syresin
    JINR, Dubna, Moscow Region
  • T. Uesugi
    KURRI, Osaka
  We have investigated coherent transverse instability when high-density circulating-ion beam was obtained with cool-stacking injection in the HIMAC synchrotron. By using a cooled beam and the Oxygen gas-sheet beam profile monitor, further, we have observed a particle trapping in resonance crossing. We will report these experimental studies at the HIMAC synchrotron.  
 
WEBY01 Commisioning of Electron Beam Cooling at S-LSR electron, ion, beam-losses, proton 247
 
  • T. Shirai, S. Fujimoto, M. Ikegami, A. Noda, H. Souda, M. Tanabe, H. Tongu
    Kyoto ICR, Uji, Kyoto
  • H. Fadil, M. Grieser
    MPI-K, Heidelberg
  • T. Fujimoto, S. I. Iwata, S. Shibuya
    AEC, Chiba
  • I. N. Meshkov, I. A. Seleznev, A. V. Smirnov, E. Syresin
    JINR, Dubna, Moscow Region
  • K. Noda
    NIRS, Chiba-shi
  S-LSR is a new compact ion cooler ring at Kyoto University. The circumference is 22.557 m. The commissioning of the electron cooling was started using the 7 MeV proton beam from November, 2005. The total length of the electron cooler is 1.63 m. In order to maximize the effective cooling length in the limited space, the magnetic field of the solenoid and the troid coils was calculated precisely by the 3D code. The electrostatic deflector for the electron and the steering magnet for the ion are placed in the troid. The performances of these devices are evaluated by the cooling measurements. Experiments using the electron cooling are also stared. One is an induction sweep cooling of the proton beam. It is an cooling with the assist of the induction acceleration and possible to reduce the cooling time of the hot ion beams like secondary particles. We also observe the behavior of the cooled ion beam in the small ion number case and the large ion number case. We discuss about the possibility of the phase transition of the proton in the former case and discuss about the coherent instability conditions in the latter case.  
 
WEBZ01 Correction of unevenness in Recycler beam profile beam-loading, synchrotron, impedance, proton 244
 
  • K. Y. Ng, J. L. Crisp, M. Hu
    Fermilab, Batavia, Illinois
  When a beam is confined between two rf barriers in the Fermilab Recycler Ring, it is observed that the longitudinal beam profile between the barriers is in general very uneven (typically about 20% for a beam of intensity 5E11). This leads to the consequence that the momentum-mined antiproton bunches may have an intolerable variation in bunch intensity. It is shown that the observed unevenness in beam profile is the result of a tiny amount (around 2%) of rf potential imperfection and a tiny amount (around 0.5%) of rf beam loading. The beam profile can be made even by feeding back the unevenness of the effective rf potential to the low-level rf.  
 
FRAP01 SUMMARY OF WORKING GROUP A AND A+B+D JOINT SESSION electron, simulation, impedance, emittance 358
 
  • F. Zimmermann
    CERN, Geneva
  • A. V. Burov
    Fermilab, Batavia, Illinois
  We summarize the presentations and discussions of the HB2006 Working Group A, devoted to beam instabilities, and of the joint session of Working Groups A, B (on space charge), and D (beam cooling and experiments). First we review the progress on conventional instabilities and impedances, and then the advances on electron cloud.