High Precision Temperature Control of Normal-conducting RF GUN for a High Duty Cycle Free-Electron Laser

Kai Kruppa, Sven Pfeiffer, Gerwald Lichtenberg, Frank Brinker, Winfried Decking, Klaus Flöttmann, Olaf Krebs, Holger Schlarb, Siegfried Schreiber

Abstract

High precision temperature control of the RF GUN is necessary to optimally accelerate thousands of electrons within the injection part of the European X-ray free-electron laser XFEL and the Free Electron Laser FLASH. A difference of the RF GUN temperature from the reference value of only 0.01 K leads to detuning of the cavity and thus limits the performance of the whole facility. Especially in steady-state operation there are some undesired temperature oscillations when using classical standard control techniques like PID control. That is why a model based approach is applied here to design the RF GUN temperature controller for the free-electron lasers. A thermal model of the RF GUN and the cooling facility is derived based on heat balances, considering the heat dissipation of the Low-Level RF power. This results in a nonlinear model of the plant. The parameters are identified by fitting the model to data of temperature, pressure and control signal measurements of the FLASH facility, a pilot test facility for the European XFEL. The derived model is used for controller design. A linear model predictive controller was implemented in MATLAB/Simulink and tuned to stabilize the temperature of the RF GUN in steady-state operation. A test of the controller in simulation shows promising results.

References

  1. FLASH (2013). Free-electron laser FLASH.
  2. Flöttmann, K., Paramonov, V., Skasyrskaya, A., and Stephan, F. (2008). Rf gun cavities cooling regime study. Desy report, TESLA-FEL 2008-02.
  3. Hoffmann, M., Ayvazyan, V., Branlard, J., Butkowski, L., Grecki, M. K., Mavric, U., Omet, M., Pfeiffer, S., Schlarb, H., Schmidt, C., Piotrowski, A., Fornal, W., and Rybaniec, R. (2015). Operation of normal conducting rf guns with mtca.4. In IPAC - 6th International Particle Accelerator Conference, Richmond, USA. DESY Hamburg, FastLogic Sp. z o.o., Lodz, Warsaw University of Technology.
  4. Kuchling, H. (1991). Taschenbuch der Physik. Fachbuchverlag Leipzig, 13. edition.
  5. Ljung, L. (1987). System identification: Theory for the User. Englewood Cleffs, Prentice-Hall.
  6. Ljung, L. (2001). System Identification Toolbox. The Math Works.
  7. Maciejowski, J. (2002). Predictive Control with Constraints. Pearson Education Limited.
  8. Mathworks, I. (2014a). Simulink Design Optmization User's Guide. The Mathworks Inc.
  9. Mathworks, I. (2014b). Simulink User's Guide. The Mathworks Inc.
  10. Schilcher, T. (1998). Vector Sum Control of Pulsed Accelerating Fields in Lorentz Force Detuned Superconducting Cavities. PhD thesis, Hamburg University.
  11. Stephan, F. (2015). private communication. DESY.
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Paper Citation


in Harvard Style

Kruppa K., Pfeiffer S., Lichtenberg G., Brinker F., Decking W., Flöttmann K., Krebs O., Schlarb H. and Schreiber S. (2015). High Precision Temperature Control of Normal-conducting RF GUN for a High Duty Cycle Free-Electron Laser . In Proceedings of the 5th International Conference on Simulation and Modeling Methodologies, Technologies and Applications - Volume 1: SIMULTECH, ISBN 978-989-758-120-5, pages 307-317. DOI: 10.5220/0005567503070317


in Bibtex Style

@conference{simultech15,
author={Kai Kruppa and Sven Pfeiffer and Gerwald Lichtenberg and Frank Brinker and Winfried Decking and Klaus Flöttmann and Olaf Krebs and Holger Schlarb and Siegfried Schreiber},
title={High Precision Temperature Control of Normal-conducting RF GUN for a High Duty Cycle Free-Electron Laser},
booktitle={Proceedings of the 5th International Conference on Simulation and Modeling Methodologies, Technologies and Applications - Volume 1: SIMULTECH,},
year={2015},
pages={307-317},
publisher={SciTePress},
organization={INSTICC},
doi={10.5220/0005567503070317},
isbn={978-989-758-120-5},
}


in EndNote Style

TY - CONF
JO - Proceedings of the 5th International Conference on Simulation and Modeling Methodologies, Technologies and Applications - Volume 1: SIMULTECH,
TI - High Precision Temperature Control of Normal-conducting RF GUN for a High Duty Cycle Free-Electron Laser
SN - 978-989-758-120-5
AU - Kruppa K.
AU - Pfeiffer S.
AU - Lichtenberg G.
AU - Brinker F.
AU - Decking W.
AU - Flöttmann K.
AU - Krebs O.
AU - Schlarb H.
AU - Schreiber S.
PY - 2015
SP - 307
EP - 317
DO - 10.5220/0005567503070317