Author: Frey, M.
Paper Title Page
WEPVA047 Input Signal Generation for Barrier Bucket RF Systems at GSI 3359
 
  • J. Harzheim, D. Domont-Yankulova, K. Groß, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Frey, H. Klingbeil
    GSI, Darmstadt, Germany
 
  At the GSI facility in Darmstadt, Germany, Barrier Bucket RF systems are currently designed for the SIS 100 synchrotron (part of the future FAIR facility) and the Experimental Storage Ring (ESR). The purpose of these systems is to provide single sine voltage pulses at the cavity gap. Due to the high requirements regarding the gap signal quality, the calculation of the pre-distorted input signal plays a major role in the system development. A procedure to generate the input signal based on the dynamic properties in the linear region of the system has been developed and tested at a prototype system. It was shown that this method is able to generate single sine gap signals of high quality in a wide voltage range. As linearity can only be assumed up to a certain magnitude, nonlinear effects limit the quality of the output signal at very high input levels. An approach to overcome this limit is to extend the input signal calculation to a nonlinear model of the system. In this contribution, the current method to calculate the required input signal is presented and experimental results at a prototype system are shown. Additionally, first results in the nonlinear region are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA047  
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THPAB098 Test Setup for Automated Barrier Bucket Signal Generation 3948
 
  • K. Groß, D. Domont-Yankulova, J. Harzheim, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Frey, H. Klingbeil
    GSI, Darmstadt, Germany
 
  Funding: Work supported by the German Federal Ministry of Education and Research (BMBF) under the project 05P15RDRBA.
For sophisticated beam manipulation several ring accelerators at FAIR and GSI like the main synchrotron SIS100 and the ESR will be equipped with barrier bucket systems. Hence, the associated LLRF has to be applicable to different RF systems, with respect to the cavity layout and the power amplifier used, as well as to variable repetition rates and amplitudes. Since already the first barrier bucket pulse of a long sequence has to meet certain minimum demands, an open-loop control on the basis of calibration data is foreseen. Closed-loop control is required to improve the signal quality during a sequence of pulses and to adapt to changing conditions like temperature drifts. A test setup was realized that allows controlling the signal generator, reading out the oscilloscope as well as processing the collected data. Frequency and time domain methods can be implemented to approach the dynamics of the RF system successively and under operating conditions, i.e. generating single sine pulses. The setup and first results from measurements are presented as a step towards automated acquisition of calibration data and iterative improvement of the same.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB098  
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THPIK015 Prototype Results of the ESR Barrier-Bucket System 4133
 
  • M. Frey, P. Hülsmann, H. Klingbeil
    GSI, Darmstadt, Germany
  • D. Domont-Yankulova, K. Groß, J. Harzheim, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  The experimental storage ring (ESR), operated at the GSI facility in Darmstadt, Germany, allows experiments with a variety of ion species. In combination with the existing electron cooler, its RF cavities have been used to demonstrate longitudinal beam accumulation in order to increase the beam intensity. Limitations of the existing narrow-band cavities led to the development of a magnetic alloy (MA) based broad-band cavity for the generation of Barrier-Bucket signals. The application of a pre-distortion method demands high linearity of the driver amplifier and highlights the importance of its selection process. In this contribution, the cavity and amplifier system design is described and data measured at a prototype system are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK015  
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THPIK016 Status of the SIS100 RF Systems 4136
 
  • H. Klingbeil, R. Balß, M. Frey, P. Hülsmann, A. Klaus, H.G. König, U. Laier, D.E.M. Lens, K.-P. Ningel
    GSI, Darmstadt, Germany
 
  Four different types of RF cavities are realized for the heavy-ion synchrotron SIS100 which is built in the scope of the FAIR (Facility for Antiproton and Ion Research) project. The standard acceleration is performed by ferrite cavities. Barrier bucket cavities will allow a pre-compression of the beam by means of moving barriers. Bunch compressor cavities are used to realize a rotation in longitudinal phase space by 90 degrees, thereby reducing the bunch length. Finally, a longitudinal feedback system reduces undesired beam oscillations. In contrast to the ferrite-loaded accelerating cavities, the last-mentioned three cavity types are based on magnetic alloy (MA) material. Depending on the type of the cavity system, the realization is done by - or in close collaboration with - different industrial companies and institutions. In this contribution, the realization status of all these synchrotron RF systems is summarized.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK016  
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