ICALEPCS2013 - List of Authors (Branlard, J.)

Paper

Title

Page

Superconducting Cavity Quench Detection and Prevention for the European XFEL

1239

J. Branlard, V. Ayvazyan, O. Hensler, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Cichalewski
TUL-DMCS, Łódź, Poland

Due to its large scale, the European X-ray Free Electron Laser accelerator (XFEL) requires a high level of automation for commissioning and operation. Each of the 800 superconducting RF cavities simultaneously running during normal operation can occasionally quench, potentially tripping the cryogenic system and resulting into machine down-time. A fast and reliable quench detection system is then a necessity to rapidly detect individual cavity quenches and take immediate action, thus avoiding interruption of machine operation. In this paper, the mechanisms implemented in the low level RF system (LLRF) to prevent quenches and the algorithms developed to detect if a cavity quenches anyways are explained. In particular, the different types of cavity quenches and the techniques developed to identify them are shown. Experimental results acquired during the testing of XFEL cryomodules prototypes at DESY are presented, demonstrating the performance and efficiency of this machine operation and cavity protection tool.

THPPC135

From Pulse to Continuous Wave Operation of TESLA Cryomodules – LLRF System Software Modification and Development

1366

W. Cichalewski, W. Jałmużna, A. Piotrowski, K.P. Przygoda
TUL-DMCS, Łódź, Poland
V. Ayvazyan, J. Branlard, H. Schlarb, J.K. Sekutowicz
DESY, Hamburg, Germany
J. Szewiński
NCBJ, Świerk/Otwock, Poland

Funding: We acknowledge the support from National Science Center (Poland) grant no 5593/B/T02/2010/39
Higher efficiency of TESLA based free electron lasers (FLASH, XFEL) by means of increased quantity of photon bursts can be achieved using continuous wave operation mode. In order to maintain constant beam acceleration in superconducting cavities and keep short pulse to CW operation transition costs reasonably low some substantial modification of accelerator subsystems are necessary. Changes in: RF power source, cryo systems, electron beam source, etc. have to be also accompanied by adjustments in LLRF system. In this paper challenges for well established pulsed mode LLRF system are discussed (in case of CW and LP scenarios). Firmware, software modifications needed for maintaining high performance of cavities field parameters regulation (for 1Hz CW and LP cryo-module operation) are described. Results from studies of vector sum amplitude and phase control in case of resonators high Ql factor settings (Ql~1.5e7) are shown. Proposed modifications implemented in VME and microTCA (MTCA.4) based LLRF system has been tested during studies at CryoModule Test Bench (CMTB) in DESY. Results from this tests together with achieved regulation performance data are also presented and discussed.

Poster THPPC135 [1.310 MB]

Paper	Title	Page
THPPC072	Superconducting Cavity Quench Detection and Prevention for the European XFEL	1239
	J. Branlard, V. Ayvazyan, O. Hensler, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Cichalewski TUL-DMCS, Łódź, Poland
	Due to its large scale, the European X-ray Free Electron Laser accelerator (XFEL) requires a high level of automation for commissioning and operation. Each of the 800 superconducting RF cavities simultaneously running during normal operation can occasionally quench, potentially tripping the cryogenic system and resulting into machine down-time. A fast and reliable quench detection system is then a necessity to rapidly detect individual cavity quenches and take immediate action, thus avoiding interruption of machine operation. In this paper, the mechanisms implemented in the low level RF system (LLRF) to prevent quenches and the algorithms developed to detect if a cavity quenches anyways are explained. In particular, the different types of cavity quenches and the techniques developed to identify them are shown. Experimental results acquired during the testing of XFEL cryomodules prototypes at DESY are presented, demonstrating the performance and efficiency of this machine operation and cavity protection tool.

THPPC135	From Pulse to Continuous Wave Operation of TESLA Cryomodules – LLRF System Software Modification and Development	1366
	W. Cichalewski, W. Jałmużna, A. Piotrowski, K.P. Przygoda TUL-DMCS, Łódź, Poland V. Ayvazyan, J. Branlard, H. Schlarb, J.K. Sekutowicz DESY, Hamburg, Germany J. Szewiński NCBJ, Świerk/Otwock, Poland
	Funding: We acknowledge the support from National Science Center (Poland) grant no 5593/B/T02/2010/39 Higher efficiency of TESLA based free electron lasers (FLASH, XFEL) by means of increased quantity of photon bursts can be achieved using continuous wave operation mode. In order to maintain constant beam acceleration in superconducting cavities and keep short pulse to CW operation transition costs reasonably low some substantial modification of accelerator subsystems are necessary. Changes in: RF power source, cryo systems, electron beam source, etc. have to be also accompanied by adjustments in LLRF system. In this paper challenges for well established pulsed mode LLRF system are discussed (in case of CW and LP scenarios). Firmware, software modifications needed for maintaining high performance of cavities field parameters regulation (for 1Hz CW and LP cryo-module operation) are described. Results from studies of vector sum amplitude and phase control in case of resonators high Ql factor settings (Ql~1.5e7) are shown. Proposed modifications implemented in VME and microTCA (MTCA.4) based LLRF system has been tested during studies at CryoModule Test Bench (CMTB) in DESY. Results from this tests together with achieved regulation performance data are also presented and discussed.
	Poster THPPC135 [1.310 MB]