Author: Domont-Yankulova, D.
Paper Title Page
TUPIK048 Longitudinal Beam Stabilization at FAIR by Means of a Derivative Estimation 1795
 
  • B.R. Reichardt, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  Funding: Supported by the GSI
During acceleration in SIS18/SIS100 at GSI/FAIR longitudinal beam-oscillations are expected to occur. To reduce emittance blow-up, dedicated LLRF beam feedback systems are planned. To date longitudinal beam oscillations have been damped in machine experiments with a finite-impulse-response (FIR) filter controller with 3 filter taps[1]. An alternative approach implementing the FIR filter as a derivative estimator controller is simulated and tested. This approach shares the same controller topology and can therefore be easily integrated in the system. It exploits the fact that the sampling rate of the feedback hardware is considerably higher than the frequency of the beam oscillations. It is therefore capable of damping oscillations without overshoot within one oscillation period.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK048  
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THPAB100 On the Impact of Empty Buckets on the Ferrite Cavity Control Loop Dynamics in High Intensity Hadron Synchrotrons 3954
 
  • D. Mihailescu Stoica, D. Domont-Yankulova
    Technische Universität Darmstadt (TU Darmstadt, RMR), Darmstadt, Germany
  • D. Domont-Yankulova, H. Klingbeil
    TEMF, TU Darmstadt, Darmstadt, Germany
  • H. Klingbeil, D.E.M. Lens
    GSI, Darmstadt, Germany
 
  Funding: Supported by the Helmholtz Graduate School for Hadron and Ion Research
Due to technical reasons two of ten buckets have to stay empty in the planned SIS100 synchrotron at the GSI Helmholtzzentrum für Schwerionenforschung. The planned low level RF control systems consist of linear P and PI type controllers. These are responsible to maintain a desired phase and amplitude of the gap voltage. In addition the cavity is controlled to follow a prescribed resonance frequency ramp. In SIS100 the acceleration will be performed by ferrite cavities with comparatively small quality factors. Therefore, effects resulting from transient beam loading have to be expected. Influences due to empty buckets are analysed in the frequency domain and particle tracking simulations are carried out to estimate the effect on the overall system with particular consideration of emittance growth and particle loss.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB100  
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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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