IPAC2014 - List of Authors (Schlarb, H.)

Paper	Title	Page
MOPRO066	Status of FLUTE	231
	M. Schuh, I. Birkel, A. Borysenko, A. Böhm, N. Hiller, E. Huttel, S. Höninger, V. Judin, S. Marsching, A.-S. Müller, A.-S. Müller, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schwarz, M. Weber, P. Wesolowski KIT, Eggenstein-Leopoldshafen, Germany R.W. Aßmann, M. Felber, K. Flöttmann, M. Hoffmann, H. Schlarb DESY, Hamburg, Germany H.-H. Braun, R. Ganter, V. Schlott, L. Stingelin PSI, Villigen PSI, Switzerland
	FLUTE, a new linac-based test facility and THz source is currently being built at the Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It consists of an RF photo gun and a traveling wave linac accelerating electrons to beam energies of ~41 MeV in the charge range from a few pC up to 3 nC. The electron bunch will then be compressed in a magnetic chicane in the range of 1 - 300 fs, depending on the charge, in order to generate coherent THz radiation with high peak power. An overview of the simulation and hardware status is given in this contribution.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-MOPRO066
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TUZA02	THz Facility at ELBE: A Versatile Test Facility for Electron Bunch Diagnostics on Quasi-CW Electron Beams	933
	M. Gensch, B.W. Green, J. Hauser, S. Kovalev, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig HZDR, Dresden, Germany A. Al-Shemmary, V. B. Asgekar, T. Golz, H. Schlarb, N. Stojanovic, S. Vilcins DESY, Hamburg, Germany A.S. Fisher SLAC, Menlo Park, California, USA G. Geloni XFEL. EU, Hamburg, Germany A.-S. Müller, M. Schwarz KIT, Karlsruhe, Germany N.E. Neumann, D. Plettemeier TU Dresden, Dresden, Germany
	At the Helmholtz-Zentrum Dresden-Rossendorf near Dresden a quasi-cw low-energy electron linear accelerator based on superconducting radiofrequency technology is operated successfully for more than 10 years. The ELBE accelerator is driving several secondary radiation sources including 2 infrared free electron lasers. A new addition will be a THz facility that aims to make use of super-radiant THz radiation. In its final form the THz facility shall consist of one coherent diffraction radiator and one undulator source which provide high-field THz pulses at unprecedented repetition rates. While the medium term goal is to establish a unique user facility for nonlinear THz science, the THz sources are already used as a test facility for novel diagnostic techniques on quasi-cw electron beams. The progress of the developments is reported and an outlook into future challenges and opportunities is given.
	Slides TUZA02 [3.041 MB]
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TUPME047	SINBAD - A Proposal for a Dedicated Accelerator Research Facility at DESY	1466
	R.W. Aßmann, C. Behrens, R. Brinkmann, U. Dorda, K. Flöttmann, B. Foster, J. Grebenyuk, I. Hartl, M. Hüning, Y.C. Nie, J. Osterhoff, A. Rühl, H. Schlarb, B. Schmidt DESY, Hamburg, Germany M. Groß, B. Marchetti, F. Stephan DESY Zeuthen, Zeuthen, Germany F.J. Grüner, B. Hidding, A.R. Maier Uni HH, Hamburg, Germany F.X. Kärtner, B. Zeitler CFEL, Hamburg, Germany A.-S. Müller, M. Schuh KIT, Karlsruhe, Germany
	A new, dedicated accelerator research facility SINBAD (Short INnovative Bunches and Accelerators at DESY) is proposed. This facility is aimed at promoting two major goals: (1) Short electron bunches for ultra-fast science. (2) Construction of a plasma accelerator module with useable beam quality. Research and development on these topics is presently ongoing at various places at DESY, as add-on experiments at operational facilities. The two research goals are intimately connected: short bunches and precise femtosecond timing are requirements for developing a plasma accelerator module. The scientific case of a dedicated facility for accelerator research at DESY is discussed. Further options are mentioned, like the use of a 1 GeV beam from Linac2 for FEL studies and the setup of an attosecond radiation source with advanced technology. The presently planned conversion of the DORIS storage ring and its central halls into the SINBAD facility is described. The available space will allow setting up several independent experiments with a cost-effective use of the same infrastructure. National and international contributions and proposals can be envisaged.
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TUPRI104	A Beam Arrival Time Cavity for REGAE at DESY	1820
	M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke TU Darmstadt, Darmstadt, Germany K. Flöttmann, D. Lipka, H. Schlarb, S. Vilcins DESY, Hamburg, Germany F.J. Grüner, B. Zeitler CFEL, Hamburg, Germany
	Funding: Kindly funded by BMBF within FSP302. REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY in Hamburg is a linear accelerator for electron diffraction experiments. It is upgraded to allow for laser driven wake field accelerator experiments. The bunch length is around 10 fs and the wakefield structure is about 100 fs and the synchronization of the laser and the electron bunch needs to be in order of the bunch length. To achieve this, a RFbased scheme will be used, comparing the phase of a beam induced signal with the reference clock. To improve the performance for the operation with charges well below 1 pC a beam arrival time cavity (BAC) at 3.025 GHz is foreseen as a highly sensitive pickup. To provide the maximum energy to the measurement electronics, the cavity needs a high R=Qvalue and an optimized coupling. An over-coupled setting might be beneficial as it provides a higher signal-to-noise ratio for the first samples. In this paper the concept of the beam arrival time cavity, the influence of the dark current on the measurement and parameter studies and optimization of the cavity itself are presented.
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TUPRI107	Compact MTCA.4 Based Laser Synchronization	1823
	M. Felber, Ł. Butkowski, H.T. Duhme, M. Fenner, C. Gerth, U. Mavrič, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany T. Kozak, P. Prędki, K.P. Przygoda TUL-DMCS, Łódź, Poland
	In this paper we present a compact and efficient approach for laser synchronization based on MTCA.4 platform. Laser pulses are converted to the RF signals using a photo-diode detector. The RF section performs filtering, amplification and down-conversion of a narrowband, CW signal. The resulting IF signal is sampled by a high resolution digitizer on the AMC (Advanced Mezzanine Card) side and transported via point-to-point links to an adjacent AMC board. The processing electronics on this board drives a digital-to-analog converter on the rear-side. The analog signal is then filtered and amplified by a high voltage power amplifier which drives the piezo stretcher in the laser. Some preliminary results of laser to RF locking with such a scheme are presented.
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WEPME065	European XFEL RF Gun Commissioning and LLRF Linac Installation	2427
	J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, R. Rybaniec, D. Sikora, L.Z. Zembala, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek, A. Piotrowski, T. Pożniak TUL-DMCS, Łódź, Poland S. Korolczuk, I.M. Kudla, J. Szewiński NCBJ, Świerk/Otwock, Poland K. Oliwa, W. Wierba IFJ-PAN, Kraków, Poland
	The European x-ray free electron laser (XFEL) is based on a 17.5 GeV super conducting pulsed linac and is scheduled to deliver its first beam in 2016. The first component of its accelerator chain, the RF gun, was installed in fall of 2013 and its commissioning is underway. This contribution gives an update on the low level radio frequency (LLRF) system development and installation for the XFEL. In particular, the installation, performance and conditioning results of the RF gun are presented. The subsequent steps toward LLRF components mass-production, testing and installation for the XFEL linac are also explained.
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WEPME066	High Speed Digitial LLRF Feedbacks for Normal Conducting Cavity Operation	2430
	M. Hoffmann, Ł. Butkowski, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Köhler DESY Zeuthen, Zeuthen, Germany A. Piotrowski TUL-DMCS, Łódź, Poland I. Rutkowski, R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	In the first half of the year 2014, the MTCA.4 based LLRF control system will be installed at several facilities (FLASH RF Gun, REGAE, PITZ, FLUTE/KIT). First tests during the last year show promising results in optimizing the system for high speed digital llrf feedbacks (reducing system latency, increase internal controller processing speed). In this contribution we will present further improvements in latency and performance optimization of the system, results and gained experience from the commisioning of the system at the metioned facilities.
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WEPME067	Performance of the MTCA.4 Based LLRF System at FLASH	2433
	Ch. Schmidt, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, K.P. Przygoda, H. Schlarb, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany W. Cichalewski, D.R. Makowski, A. Piotrowski TUL-DMCS, Łódź, Poland K. Czuba, I. Rutkowski, D. Sikora, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland I.M. Kudla NCBJ, Świerk/Otwock, Poland K. Oliwa, W. Wierba IFJ-PAN, Kraków, Poland
	The Free Electron Laser in Hamburg (FLASH) is the first linac which is equipped with a MTCA.4 based low level RF control system. Precise regulation of RF fields is essential for stable and and reproducible photon generation. Flash benefits from the performance increase using the new developments like, accurate and precise field detection devices. Further enourmous increase of processing capabilities allow for more sophisticated controller applications which better the overall performance of the regulation.
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WEPME068	Mitigating Noise Sources in MTCA.4 Electronics for High Precision Measurements	2436
	U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb DESY, Hamburg, Germany
	The RF field detection instrumentation plays a crucial role in modern accelerator performance. The most critical section is the transition from the analog signal processing to the digitalization. In this paper we present state of the art performance of COTS components and limitations imposed by crate-oriented solutions. We give recipes on how to optimize performance and present some of the recent results.
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WEPME069	Performance of a Compact LLRF System using Analog RF Backplane in MTCA.4 Crates	2438
	U. Mavrič, M. Fenner, M. Hoffmann, F. Ludwig, A.T. Rosner, H. Schlarb DESY, Hamburg, Germany K. Czuba, T.P. Leśniak Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A. Rohlev Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	In order to increase system compactness, mitigate cabling problems, increase rack space, minimize points of failure in the system and reduce digital distortion leakage into the sensitive analog signals, the concept of the RF backplane located in the rear section of the MTCA.4 crate has been introduced. Besides signal distribution, the concept includes a signal generation module and backplane management module. The generation and splitting of the analog signals is taking place in slots 15 and 14 on the rear side in theμLO generation module (uLOG). This module generates the local oscillator signal, the clocks and feeds through the master reference signal over the RF backplane to the slots. In this paper we present the recent results of such system.
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WEPME075	Real-time Estimation of Superconducting Cavities Parameters	2456
	R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland V. Ayvazyan, J. Branlard, Ł. Butkowski, S. Pfeiffer, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Cichalewski, K.P. Przygoda TUL-DMCS, Łódź, Poland
	Performance of accelerators based on the superconductive cavities including FLASH and XFEL facilities at DESY is affected by cavity parameters variation over time. High gradient electromagnetic field inside cavities causes detuning due to the Lorentz force. In addition the quality factor of cavities can change during the RF field pulse. Currently used method for estimation of those parameters is based on the post-processing of the data recorded during operation of the RF. External servers calculate cavity parameters using cavity equation, forward power and probe signals collected during previous pulse. A novel approach* based on the component implemented in FPGA is presented. In the new method loaded quality factor and detuning are estimated in real-time during the RF pulse for increased reliability and better exception handling. Modified firmware of the LLRF control system based on the Micro Telecommunications Computing Architecture (MTCA) platform has been used for the method verification. *”Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments”, K. Przygoda, PhD thesis, Technical University of Łódź, Poland, 2010.
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WEPRI115	Design and Integration of the Optical Reference Module at 1.3 GHz for FLASH and the European XFEL	2768
	E. Janas, K. Czuba, P. Kownacki, D. Sikora Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland M.K. Czwalinna, M. Felber, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack DESY, Hamburg, Germany J. Szewiński NCBJ, Świerk/Otwock, Poland
	In this paper we present recent progress on the integration and implementation of the optical reference module (REFM-OPT) for the free-electron lasers FLASH and European XFEL. In order to achieve high energy stability and low arrival time jitter of the electron beam, the accelerator requires an accurate low-level RF (LLRF) field regulation and a sophisticated synchronization scheme for various devices along the facility. The REFM-OPT is a 19” module which is responsible for resynchronizing the 1.3 GHz reference signal for the LLRF distributed by coaxial cables to a phase-stable signal of the optical synchronization system. The module provides a 1.3 GHz output signal with low phase noise and high long-term stability. Several sub-components of the REFM-OPT designed specifically for this module are described in detail. The readout electronics of the high-precision Laser-to-RF phase detector are presented as well as the integration of this key component into the 19” module. Additionally, we focus on design solutions which assure phase stability and synchronization of the 1.3 GHz signal at several high power outputs of the module.
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WEPRI116	Master Oscillator for the European XFEL	2771
	L.Z. Zembala, K. Czuba, B. Gąsowski, D. Sikora Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland J. Branlard, H. Schlarb, H.C. Weddig DESY, Hamburg, Germany
	The reference signal outage causes breakdown of the synchronisation in the entire accelerator, which could result in a multi-day break in the operation. Therefore, the Master Oscillator (MO) for the European XFEL has to be redundant, in order to achieve extremely high reliability. The redundancy concept, which provides no interruption in the reference signal, requires phase coherence, fast RF switching and sustaining the RF power with a high-Q filter. These features allow to keep possible signal transitions smooth. Furthermore, the MO has to generate a 1.3 GHz signal of exceptionally good phase noise performance – jitter < 35 fs RMS integrated from 10 Hz to1 MHz. One of the problems in the way are vibrations, which have to be properly isolated to avoid microphonics effects in oscillators. The proposed MO architecture and connection with the RF distribution system is described. A basic prototype is tested and results are presented.
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THPRO105	MTCA.4 Module for Cavity and Laser Piezo Operation	3140
	K.P. Przygoda, J. Branlard, M. Felber, C. Gerth, M. Heuer, U. Mavrič, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany T. Kozak, P. Prędki TUL-DMCS, Łódź, Poland
	A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4)* has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for superconducting cavities fine tuning, synchronization of pulsed lasers and stabilization of fiber links. This paper briefly presents the designed system requirements and discusses the main hardware issues. The Piezo Driver performance measurements are also discussed. The first results of the prototype hardware usage for laser locking** to an external RF source and fiber link stabilization are summarized. K. Przygoda et all.,“MTCA.4 Compilant Piezo Driver RTM for Laser Synchronization”,MIXDES'13*U. Mavric et. all, "Precision Synchronization of Optical Lasers based on MTCA.4 Electronics", IBIC'13
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THPRI033	Design of New Buncher Cavity for Relativistic Electron Gun for Atomic Exploration – REGAE	3840
	M. Fakhari, H. Delsim-Hashemi, K. Flöttmann, M. Hüning, S. Pfeiffer, H. Schlarb DESY, Hamburg, Germany J. Roßbach Uni HH, Hamburg, Germany
	The Relativistic Electron Gun for Atomic Exploration, REGAE, is a small electron accelerator build and operated at DESY. Its main application is to provide high quality electron bunches for time resolved diffraction experiments. The RF system of REGAE contains different parts such as low level RF, preamplifier, modulator, phase shifter, and cavities. A photocathode gun cavity to produce the electrons and a buncher cavity to compress the electron bunches in the following drift tube. Since the difference between the operating mode of the existing buncher and its adjacent mode is too small, the input power excites the other modes in addition to the operating mode which affects the beam parameters. A new buncher cavity is designed in order to improve the mode separation. Furthermore the whole cavity is modeled by a circuit which can be useful especially during the tuning process. Beam dynamics simulations have been performed in order to compare the new designed cavity with the old one which declare that the effects of the adjacent modes on the beam parameters are decreased.
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Paper

Title

Page

Status of FLUTE

231

M. Schuh, I. Birkel, A. Borysenko, A. Böhm, N. Hiller, E. Huttel, S. Höninger, V. Judin, S. Marsching, A.-S. Müller, A.-S. Müller, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schwarz, M. Weber, P. Wesolowski
KIT, Eggenstein-Leopoldshafen, Germany
R.W. Aßmann, M. Felber, K. Flöttmann, M. Hoffmann, H. Schlarb
DESY, Hamburg, Germany
H.-H. Braun, R. Ganter, V. Schlott, L. Stingelin
PSI, Villigen PSI, Switzerland

FLUTE, a new linac-based test facility and THz source is currently being built at the Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. It consists of an RF photo gun and a traveling wave linac accelerating electrons to beam energies of ~41 MeV in the charge range from a few pC up to 3 nC. The electron bunch will then be compressed in a magnetic chicane in the range of 1 - 300 fs, depending on the charge, in order to generate coherent THz radiation with high peak power. An overview of the simulation and hardware status is given in this contribution.

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TUZA02

THz Facility at ELBE: A Versatile Test Facility for Electron Bunch Diagnostics on Quasi-CW Electron Beams

933

M. Gensch, B.W. Green, J. Hauser, S. Kovalev, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig
HZDR, Dresden, Germany
A. Al-Shemmary, V. B. Asgekar, T. Golz, H. Schlarb, N. Stojanovic, S. Vilcins
DESY, Hamburg, Germany
A.S. Fisher
SLAC, Menlo Park, California, USA
G. Geloni
XFEL. EU, Hamburg, Germany
A.-S. Müller, M. Schwarz
KIT, Karlsruhe, Germany
N.E. Neumann, D. Plettemeier
TU Dresden, Dresden, Germany

At the Helmholtz-Zentrum Dresden-Rossendorf near Dresden a quasi-cw low-energy electron linear accelerator based on superconducting radiofrequency technology is operated successfully for more than 10 years. The ELBE accelerator is driving several secondary radiation sources including 2 infrared free electron lasers. A new addition will be a THz facility that aims to make use of super-radiant THz radiation. In its final form the THz facility shall consist of one coherent diffraction radiator and one undulator source which provide high-field THz pulses at unprecedented repetition rates. While the medium term goal is to establish a unique user facility for nonlinear THz science, the THz sources are already used as a test facility for novel diagnostic techniques on quasi-cw electron beams. The progress of the developments is reported and an outlook into future challenges and opportunities is given.

Slides TUZA02 [3.041 MB]

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TUPME047

SINBAD - A Proposal for a Dedicated Accelerator Research Facility at DESY

1466

R.W. Aßmann, C. Behrens, R. Brinkmann, U. Dorda, K. Flöttmann, B. Foster, J. Grebenyuk, I. Hartl, M. Hüning, Y.C. Nie, J. Osterhoff, A. Rühl, H. Schlarb, B. Schmidt
DESY, Hamburg, Germany
M. Groß, B. Marchetti, F. Stephan
DESY Zeuthen, Zeuthen, Germany
F.J. Grüner, B. Hidding, A.R. Maier
Uni HH, Hamburg, Germany
F.X. Kärtner, B. Zeitler
CFEL, Hamburg, Germany
A.-S. Müller, M. Schuh
KIT, Karlsruhe, Germany

A new, dedicated accelerator research facility SINBAD (Short INnovative Bunches and Accelerators at DESY) is proposed. This facility is aimed at promoting two major goals: (1) Short electron bunches for ultra-fast science. (2) Construction of a plasma accelerator module with useable beam quality. Research and development on these topics is presently ongoing at various places at DESY, as add-on experiments at operational facilities. The two research goals are intimately connected: short bunches and precise femtosecond timing are requirements for developing a plasma accelerator module. The scientific case of a dedicated facility for accelerator research at DESY is discussed. Further options are mentioned, like the use of a 1 GeV beam from Linac2 for FEL studies and the setup of an attosecond radiation source with advanced technology. The presently planned conversion of the DORIS storage ring and its central halls into the SINBAD facility is described. The available space will allow setting up several independent experiments with a cost-effective use of the same infrastructure. National and international contributions and proposals can be envisaged.

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TUPRI104

A Beam Arrival Time Cavity for REGAE at DESY

1820

M. Hansli, A. Angelovski, R. Jakoby, A. Penirschke
TU Darmstadt, Darmstadt, Germany
K. Flöttmann, D. Lipka, H. Schlarb, S. Vilcins
DESY, Hamburg, Germany
F.J. Grüner, B. Zeitler
CFEL, Hamburg, Germany

Funding: Kindly funded by BMBF within FSP302.
REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY in Hamburg is a linear accelerator for electron diffraction experiments. It is upgraded to allow for laser driven wake field accelerator experiments. The bunch length is around 10 fs and the wakefield structure is about 100 fs and the synchronization of the laser and the electron bunch needs to be in order of the bunch length. To achieve this, a RFbased scheme will be used, comparing the phase of a beam induced signal with the reference clock. To improve the performance for the operation with charges well below 1 pC a beam arrival time cavity (BAC) at 3.025 GHz is foreseen as a highly sensitive pickup. To provide the maximum energy to the measurement electronics, the cavity needs a high R=Qvalue and an optimized coupling. An over-coupled setting might be beneficial as it provides a higher signal-to-noise ratio for the first samples. In this paper the concept of the beam arrival time cavity, the influence of the dark current on the measurement and parameter studies and optimization of the cavity itself are presented.

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TUPRI107

Compact MTCA.4 Based Laser Synchronization

1823

M. Felber, Ł. Butkowski, H.T. Duhme, M. Fenner, C. Gerth, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
T. Kozak, P. Prędki, K.P. Przygoda
TUL-DMCS, Łódź, Poland

In this paper we present a compact and efficient approach for laser synchronization based on MTCA.4 platform. Laser pulses are converted to the RF signals using a photo-diode detector. The RF section performs filtering, amplification and down-conversion of a narrowband, CW signal. The resulting IF signal is sampled by a high resolution digitizer on the AMC (Advanced Mezzanine Card) side and transported via point-to-point links to an adjacent AMC board. The processing electronics on this board drives a digital-to-analog converter on the rear-side. The analog signal is then filtered and amplified by a high voltage power amplifier which drives the piezo stretcher in the laser. Some preliminary results of laser to RF locking with such a scheme are presented.

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WEPME065

European XFEL RF Gun Commissioning and LLRF Linac Installation

2427

J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, J. Piekarski, I. Rutkowski, R. Rybaniec, D. Sikora, L.Z. Zembala, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek, A. Piotrowski, T. Pożniak
TUL-DMCS, Łódź, Poland
S. Korolczuk, I.M. Kudla, J. Szewiński
NCBJ, Świerk/Otwock, Poland
K. Oliwa, W. Wierba
IFJ-PAN, Kraków, Poland

The European x-ray free electron laser (XFEL) is based on a 17.5 GeV super conducting pulsed linac and is scheduled to deliver its first beam in 2016. The first component of its accelerator chain, the RF gun, was installed in fall of 2013 and its commissioning is underway. This contribution gives an update on the low level radio frequency (LLRF) system development and installation for the XFEL. In particular, the installation, performance and conditioning results of the RF gun are presented. The subsequent steps toward LLRF components mass-production, testing and installation for the XFEL linac are also explained.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME065

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WEPME066

High Speed Digitial LLRF Feedbacks for Normal Conducting Cavity Operation

2430

M. Hoffmann, Ł. Butkowski, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Köhler
DESY Zeuthen, Zeuthen, Germany
A. Piotrowski
TUL-DMCS, Łódź, Poland
I. Rutkowski, R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

In the first half of the year 2014, the MTCA.4 based LLRF control system will be installed at several facilities (FLASH RF Gun, REGAE, PITZ, FLUTE/KIT). First tests during the last year show promising results in optimizing the system for high speed digital llrf feedbacks (reducing system latency, increase internal controller processing speed). In this contribution we will present further improvements in latency and performance optimization of the system, results and gained experience from the commisioning of the system at the metioned facilities.

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WEPME067

Performance of the MTCA.4 Based LLRF System at FLASH

2433

Ch. Schmidt, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, K.P. Przygoda, H. Schlarb, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
W. Cichalewski, D.R. Makowski, A. Piotrowski
TUL-DMCS, Łódź, Poland
K. Czuba, I. Rutkowski, D. Sikora, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
I.M. Kudla
NCBJ, Świerk/Otwock, Poland
K. Oliwa, W. Wierba
IFJ-PAN, Kraków, Poland

The Free Electron Laser in Hamburg (FLASH) is the first linac which is equipped with a MTCA.4 based low level RF control system. Precise regulation of RF fields is essential for stable and and reproducible photon generation. Flash benefits from the performance increase using the new developments like, accurate and precise field detection devices. Further enourmous increase of processing capabilities allow for more sophisticated controller applications which better the overall performance of the regulation.

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WEPME068

Mitigating Noise Sources in MTCA.4 Electronics for High Precision Measurements

2436

U. Mavrič, M. Hoffmann, F. Ludwig, H. Schlarb
DESY, Hamburg, Germany

The RF field detection instrumentation plays a crucial role in modern accelerator performance. The most critical section is the transition from the analog signal processing to the digitalization. In this paper we present state of the art performance of COTS components and limitations imposed by crate-oriented solutions. We give recipes on how to optimize performance and present some of the recent results.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2014-WEPME068

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WEPME069

Performance of a Compact LLRF System using Analog RF Backplane in MTCA.4 Crates

2438

U. Mavrič, M. Fenner, M. Hoffmann, F. Ludwig, A.T. Rosner, H. Schlarb
DESY, Hamburg, Germany
K. Czuba, T.P. Leśniak
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A. Rohlev
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

In order to increase system compactness, mitigate cabling problems, increase rack space, minimize points of failure in the system and reduce digital distortion leakage into the sensitive analog signals, the concept of the RF backplane located in the rear section of the MTCA.4 crate has been introduced. Besides signal distribution, the concept includes a signal generation module and backplane management module. The generation and splitting of the analog signals is taking place in slots 15 and 14 on the rear side in theμLO generation module (uLOG). This module generates the local oscillator signal, the clocks and feeds through the master reference signal over the RF backplane to the slots. In this paper we present the recent results of such system.

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WEPME075

Real-time Estimation of Superconducting Cavities Parameters

2456

R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
V. Ayvazyan, J. Branlard, Ł. Butkowski, S. Pfeiffer, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Cichalewski, K.P. Przygoda
TUL-DMCS, Łódź, Poland

Performance of accelerators based on the superconductive cavities including FLASH and XFEL facilities at DESY is affected by cavity parameters variation over time. High gradient electromagnetic field inside cavities causes detuning due to the Lorentz force. In addition the quality factor of cavities can change during the RF field pulse. Currently used method for estimation of those parameters is based on the post-processing of the data recorded during operation of the RF. External servers calculate cavity parameters using cavity equation, forward power and probe signals collected during previous pulse. A novel approach* based on the component implemented in FPGA is presented. In the new method loaded quality factor and detuning are estimated in real-time during the RF pulse for increased reliability and better exception handling. Modified firmware of the LLRF control system based on the Micro Telecommunications Computing Architecture (MTCA) platform has been used for the method verification.
*”Development of Control System for Fast Frequency Tuners of Superconducting Resonant Cavities for FLASH and XFEL Experiments”, K. Przygoda, PhD thesis, Technical University of Łódź, Poland, 2010.

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WEPRI115

Design and Integration of the Optical Reference Module at 1.3 GHz for FLASH and the European XFEL

2768

E. Janas, K. Czuba, P. Kownacki, D. Sikora
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
M.K. Czwalinna, M. Felber, T. Lamb, H. Schlarb, S. Schulz, C. Sydlo, M. Titberidze, F. Zummack
DESY, Hamburg, Germany
J. Szewiński
NCBJ, Świerk/Otwock, Poland

In this paper we present recent progress on the integration and implementation of the optical reference module (REFM-OPT) for the free-electron lasers FLASH and European XFEL. In order to achieve high energy stability and low arrival time jitter of the electron beam, the accelerator requires an accurate low-level RF (LLRF) field regulation and a sophisticated synchronization scheme for various devices along the facility. The REFM-OPT is a 19” module which is responsible for resynchronizing the 1.3 GHz reference signal for the LLRF distributed by coaxial cables to a phase-stable signal of the optical synchronization system. The module provides a 1.3 GHz output signal with low phase noise and high long-term stability. Several sub-components of the REFM-OPT designed specifically for this module are described in detail. The readout electronics of the high-precision Laser-to-RF phase detector are presented as well as the integration of this key component into the 19” module. Additionally, we focus on design solutions which assure phase stability and synchronization of the 1.3 GHz signal at several high power outputs of the module.

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WEPRI116

Master Oscillator for the European XFEL

2771

L.Z. Zembala, K. Czuba, B. Gąsowski, D. Sikora
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
J. Branlard, H. Schlarb, H.C. Weddig
DESY, Hamburg, Germany

The reference signal outage causes breakdown of the synchronisation in the entire accelerator, which could result in a multi-day break in the operation. Therefore, the Master Oscillator (MO) for the European XFEL has to be redundant, in order to achieve extremely high reliability. The redundancy concept, which provides no interruption in the reference signal, requires phase coherence, fast RF switching and sustaining the RF power with a high-Q filter. These features allow to keep possible signal transitions smooth. Furthermore, the MO has to generate a 1.3 GHz signal of exceptionally good phase noise performance – jitter < 35 fs RMS integrated from 10 Hz to1 MHz. One of the problems in the way are vibrations, which have to be properly isolated to avoid microphonics effects in oscillators. The proposed MO architecture and connection with the RF distribution system is described. A basic prototype is tested and results are presented.

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THPRO105

MTCA.4 Module for Cavity and Laser Piezo Operation

3140

K.P. Przygoda, J. Branlard, M. Felber, C. Gerth, M. Heuer, U. Mavrič, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
T. Kozak, P. Prędki
TUL-DMCS, Łódź, Poland

A MicroTCA.4 (MTCA.4) compliant Piezo Driver (DRTM-PZT4)* has been developed to drive piezoelectric-based actuators used in accelerator instrumentation applications. More specifically, it is used for superconducting cavities fine tuning, synchronization of pulsed lasers and stabilization of fiber links. This paper briefly presents the designed system requirements and discusses the main hardware issues. The Piezo Driver performance measurements are also discussed. The first results of the prototype hardware usage for laser locking** to an external RF source and fiber link stabilization are summarized.
*K. Przygoda et all.,“MTCA.4 Compilant Piezo Driver RTM for Laser Synchronization”,MIXDES'13**U. Mavric et. all, "Precision Synchronization of Optical Lasers based on MTCA.4 Electronics", IBIC'13

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THPRI033

Design of New Buncher Cavity for Relativistic Electron Gun for Atomic Exploration – REGAE

3840

M. Fakhari, H. Delsim-Hashemi, K. Flöttmann, M. Hüning, S. Pfeiffer, H. Schlarb
DESY, Hamburg, Germany
J. Roßbach
Uni HH, Hamburg, Germany

The Relativistic Electron Gun for Atomic Exploration, REGAE, is a small electron accelerator build and operated at DESY. Its main application is to provide high quality electron bunches for time resolved diffraction experiments. The RF system of REGAE contains different parts such as low level RF, preamplifier, modulator, phase shifter, and cavities. A photocathode gun cavity to produce the electrons and a buncher cavity to compress the electron bunches in the following drift tube. Since the difference between the operating mode of the existing buncher and its adjacent mode is too small, the input power excites the other modes in addition to the operating mode which affects the beam parameters. A new buncher cavity is designed in order to improve the mode separation. Furthermore the whole cavity is modeled by a circuit which can be useful especially during the tuning process. Beam dynamics simulations have been performed in order to compare the new designed cavity with the old one which declare that the effects of the adjacent modes on the beam parameters are decreased.

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