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

CBM

Paper Title Other Keywords Page
TUPCH018 Fast Beam Dynamics Investigation Based on an ADC Filling Pattern Measurement synchrotron, controls, diagnostics, storage-ring 1034
 
  • J. Kettler, P. Hartmann, R.G. Heine, T. Weis
    DELTA, Dortmund
  A diagnostic tool to determine the longitudinal particle filling pattern has been installed at the 1.5 GeV electron storage ring DELTA. The instrument is PC-based using an ADC-conversion at a sampling rate of 2 GS/s and a nominal bandwidth of 1 GHz which is applied to the sumsignal of a single storage ring beam position monitor. By sampling over successive turns the resolution is enhanced by one order of magnitude allowing an easy access to the longitudinal particle distribution inside the ring. The data obtained turn-by-turn over hundreds of revolutions can be further analysed by FFT-techniques allowing a very fast detection (~ 1 s) of longitudinal coupled bunch mode (CBM) instabilities from the phase modulated spectrum. The application of the FFT to the amplitude modulated particle distribution moreover allows a "post mortem"-investigation of CBM induced beam loss. The paper will present the layout of the diagnostic system and will report on filling pattern measurements as well as on investigations of longitudinal CBM-instabilities.  
 
TUPCH129 Conceptual Design of a 3rd Harmonic Cavity System for the LNLS Electron Storage Ring electron, storage-ring, damping, synchrotron 1316
 
  • N.P. Abreu, O.R. Bagnato, R.H.A. Farias, M.J. Ferreira, C. Pardine, P.F. Tavares
    LNLS, Campinas
  The installation of a second RF cavity in the UVX electron storage ring at the Brazilian Synchrotron Light Laboratory (LNLS) at the end of 2003 brought about longitudinal instabilities driven by one of the HOMs of the new cavity. Even though the operational difficulties related to these unstable modes were successfully overcome by means of a combination of cavity tuning (using temperature and plunger adjustments) with phase modulation of the RF fields at the second harmonic of the synchrotron frequency, a more appropriate technique to avoid those problems is the use of higher harmonic cavities, which have the important advantage of providing damping of the longitudinal modes without increasing the energy spread, i.e., without compromising the longitudinal emittance. In this work we present the design of a passive higher harmonic cavity system optimized for operation at the LNLS storage ring. The parameters for a set of cavities as well as the analysis of some of the effects that they may introduce in the beam dynamics are presented. An overview of the technical aspects related to the project, construction and installation of the cavities in the storage ring is also presented.  
 
THPCH035 Characterisation of the EU-HOM-damped Normal Conducting 500 MHz Cavity from the Beam Power Spectrum at DELTA impedance, synchrotron, single-bunch, storage-ring 2856
 
  • R.G. Heine, P. Hartmann, T. Weis
    DELTA, Dortmund
  A HOM-damped prototype cavity developed in the framework of an EC collaboration has been installed into the Dortmund synchrotron light source DELTA. This paper reports on beam studies performed at beam energies of 1.5 GeV and 542 MeV in an attempt to get information on coupled bunch instability thresholds. In addition an evaluation of the longitudinal cavity impedance is presented, based on beam power spectra up to 3 GHz for different filling patterns of the storage ring by analysing the RF signal from the HOM-dampers.