A   B   C   D   E   F   G   H   I   K   L   M   O   P   Q   R   S   T   V   W    

dipole

Paper Title Other Keywords Page
IT04 Fast Positional Global Feedback for Storage Rings feedback, closed-orbit, power-supply, damping 7
 
  • E. Plouviez
    ESRF, The European Synchrotron Radiation Facility, Grenoble, France
  Stability of the closed orbit of a storage ring is limited by the stability of the components defining this orbit: magnets position and field values. Measurements of the variation of the stored beam orbit with respect to a nominal orbit and application of orbit correction derived from these measurements can reduce these distortions. The subject of this talk is the implementation of such correction at high frequencies (up to about 100 Hz) using global correction schemes. The basic theoretical aspects of the problem will be presented:
  • Global versus local scheme
  • Feedback loop dynamics.
The technical problems associated with the implementation of such systems will also be addressed:
  • BPM and correctors design
  • Feedback loop electronic design
 
 
CT05 Daresbury SRS Positional Feedback Systems feedback, multipole, wiggler, photon 64
 
  • S.L. Smith, S.F. Hill
    CLRC, Daresbury Laboratory, Warrington, UK
  The Daresbury SRS is a second generation synchrotron radiation source which ramps from its injection energy of 600 MeV to 2.0 GeV. Beam orbit feedback systems have been in routine operation on the SRS since 1994 and are now an essential element in delivering stable photon beams to experimental stations. The most recent enhancements to these systems have included the introduction of a ramp servo system to provide the orbit control demanded by the installation of two new narrow gap insertion device and development of the vertical orbit feedback system to cope with an increasing number of photon beamlines. This paper summaries the current status of these systems and briefly discusses proposed developments.  
 
PS16 The fast head-tail instability suppression in multibunch mode at VEPP-4M feedback, injection, kicker, 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.  
 
PT10 Emittance and dispersion measurements at TTF emittance, quadrupole, linac, acceleration 180
 
  • M. Castellano, A. Cianchi, V.A. Verzilov
    INFN-LNF, Laboratori Nazionali di Frascati dell'INFN, Frascati, Italy
  It is well known that beam dispersion , along with the Twiss parameters and emittance, contributes to the beam spot size. So that, in general, anomalous dispersion is an undesirable event and must be minimized by careful tuning the machine. If not, when the spot size is used to infer beam emittances, as it is the case of the "quadrupole scan" method, basically employed at TTF, the unknown dispersion can lead to overestimated values for the emittance. This paper presents the first attempt to determine the dispersion function at several points of the TTF Linac and to separate its contribution to the local emittance measurement, performed by means of the OTR imaging technique.  
 
PT11 Dipole modes study by means of HOM couplers at SBTF kicker, 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.