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Stassen, R.

Paper Title Page
MOPC125 The HESR RF-system and Tests in COSY 361
 
  • R. Stassen, K. Bongardt, F. J. Etzkorn, H. Stockhorst
    FZJ, Jülich
  • A. Schnase
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
 
  Two RF cavities will be installed in the High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt, one “small” cavity for barrier-bucket operation and one “large” cavity to accelerate and decelerate the beam and for bunch rotation. Additionally a barrier bucket with h=1..5 will be formed by this cavity to separate the decelerated beam from the refilled beam in the high luminosity mode (HL). Both prototype cavities have been built and first RF measurements were carried out. The recent results will be presented.  
TUPC138 Development of a New Low-Level RF-Control-System for the S-DALINAC 1389
 
  • A. Araz, U. Bonnes, R. Eichhorn, M. Konrad, M. Platz, A. Richter
    TU Darmstadt, Darmstadt
  • U. Laier
    GSI, Darmstadt
  • R. Stassen
    FZJ, Jülich
 
  The Superconducting DArmstadt electron LINear ACcelerator S-DALINAC has a maximum energy of 130 MeV and beam currents of up to 60 μA. To reach this energy conveniently in cw, superconducting cavities with a high Q at a frequency of 3 GHz are used. In order to achieve minimal energy spread, the amplitude and phase the cavities have to be controlled strictly in order to compensat the impact of microphonic perturbations. The existing analog rf control system based on a self-exited loop, converts the 3 GHz signals down to the base band. This concept will also be followed by the new digital system currently under design. It is based on an FPGA in the low frequency part, giving a great flexibility in the control algorithm and providing additional diagnostics. For example it is possible to change the operational mode between self-exited loop and generator driven resonator within a second. We will report on the design concept, the status and the latest results measured with a prototype, including different control algorithms as well as beam loading effects.  
THPP055 Stochastic Cooling Developments for the HESR at FAIR 3491
 
  • H. Stockhorst, R. Maier, D. Prasuhn, R. Stassen
    FZJ, Jülich
  • T. Katayama
    CNS, Saitama
  • L. Thorndahl
    CERN, Geneva
 
  The High-Energy Storage Ring (HESR) of the future International Facility for Antiproton and Ion Research (FAIR) at the GSI in Darmstadt will be built as an anti-proton cooler ring in the momentum range from 1.5 to 15 GeV/c. An important and challenging feature of the new facility is the combination of phase space cooled beams with internal targets. In addition to electron cooling transverse and longitudinal stochastic cooling are envisaged to accomplish these goals. A detailed numerical analysis of the Fokker-Planck equation for longitudinal filter cooling including an internal target and intrabeam scattering has been carried out to demonstrate the stochastic cooling capability in the newly designed normal conducting ring lattice of the HESR. Theoretical predictions have been compared to experimental cooling results with internal targets at the COSY facility. Recent developments for the HESR stochastic cooling equipment will be discussed. The design of new high sensitive printed loop couplers and ring slot couplers for the (2-4) GHz range as well as prototype measurements with protons in the COSY accelerator will be presented.