IPAC2015 - List of Authors (Schlarb, H.)

Paper	Title	Page
MOPWA040	Virtual Cavity Probe Generation using Calibrated Forward and Reflected Signals	200
	S. Pfeiffer, V. Ayvazyan, J. Branlard, Ł. Butkowski, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	The European X-ray free electron laser requires a high-precision control of accelerating fields to ensure a stable photon generation. Its low level radio frequency system, based on the MicroTCA.4 standard, detects the probe, forward and reflected signals for each cavity. While the probe signal is used to control the accelerating fields, a combination of the forward and reflected signals can be used to compute a virtual probe, whose accuracy is comparable to the directly sampled probe. This requires the removal of cross-coupling effects between the forward and reflected signals. This paper presents the precise generation of a virtual probe using an extended method of least squares. The virtual probe can then be used for precise field control in case the probe signal is missing or corrupted. It can also be used to detect any deviation from the nominal probe profile.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA040
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MOPHA026	Present and Future Optical-to-Microwave Synchronization Systems at REGAE Facility for Electron Diffraction and Plasma Acceleration Experiments	833
	M. Titberidze, F.J. Grüner, A.R. Maier, B. Zeitler CFEL, Hamburg, Germany S.W. Epp MPSD, Hamburg, Germany M. Felber, K. Flöttmann, T. Lamb, U. Mavrič, J.M. Müller, H. Schlarb, C. Sydlo DESY, Hamburg, Germany F.J. Grüner, A.R. Maier, M. Titberidze Uni HH, Hamburg, Germany E. Janas Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	Relativistic Electron Gun for Atomic Explorations (REGAE) is a Radio Frequency (RF) driven linear accelerator. It uses frequency tripled short photon pulses (~ 35 fs) from the Titanium Sapphire (Ti:Sa.) Laser system in order to generate electron bunches from the photo-cathode. The electron bunches are accelerated up to ~ 5 MeV kinetic energy and compressed down to sub-10 fs using the so called ballistic bunching technique. REGAE currently is used for electron diffraction experiments (by Prof. R.J.D. Miller's Group). In near future within the collaboration of Laboratory for Laser- and beam-driven plasma Acceleration (LAOLA), REGAE will also be employed to externally inject electron bunches into laser driven linear plasma waves. Both experiments require very precise synchronization (sub-50 fs) of the photo-injector laser and RF reference. In this paper we present experimental results of the current and new optical to microwave synchronization systems in comparison. We also address some of the issues related to the current system and give an upper limit in terms of its long-term performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA026
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MOPHA028	Operation of Normal Conducting RF Guns with MicroTCA.4	841
	M. Hoffmann, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, U. Mavrič, M. Omet, S. Pfeiffer, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Fornal, R. Rybaniec Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A. Piotrowski FastLogic Sp. z o.o., Łódź, Poland
	During the last half year, the MicroTCA.4 based single cavity LLRF control system was installed and commissioned at several normal conducting facilities at DESY (FLASH RF gun, REGAE, PITZ RF gun, and XFEL RF gun). First tests during the last year show promising results in optimizing the system for high speed digital LLRF feedbacks, i.e. reducing system latency, increasing the internal controller processing speed, testing new control schemes, and optimizing controller parameters. In this contribution we will present results and gained experience from the commissioning phase and the first time period of real operation.
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MOPHA029	Operation Experiences with the MICROTCA.4-based LLRF Control System at FLASH	844
	M. Omet, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany W. Cichalewski, D.R. Makowski TUL-DMCS, Łódź, Poland K. Czuba, K. Oliwa, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland A. Piotrowski FastLogic Sp. z o.o., Łódź, Poland
	The Free-Electron Laser in Hamburg (FLASH) at Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is a user facility providing ultra-short, femtosecond laser pulses up to the soft X-ray wavelength range. For the precise regulation of the radio frequency (RF) fields within the 60 superconducting cavities, which are organized in 5 RF stations, digital low level RF (LLRF) control systems based on the MTCA.4 standard were implemented in 2013. Until now experiences with failures potentially due to radiation, overheating, and ageing as well as with the general operation of the control systems have been gained. These have a direct impact on the operation and on the performance of FLASH and will allow future improvements. The lessons learned are not only important for FLASH but also in the scope of European X-ray Free-Electron Laser (X-FEL), which will be operated with the same LLRF control system.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA029
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MOPHA030	Commissioning of the Low-Noise MTCA.4-based Local Oscillator and Clock Generation Module	847
	U. Mavrič, J. Branlard, M. Hoffmann, F. Ludwig, H. Schlarb DESY, Hamburg, Germany D.R. Makowski, A. Mielczarek, P. Perek TUL-DMCS, Łódź, Poland A. Rohlev Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Funding: Helmholtz Validation Fund Project "MicroTCA.4 for Industry" Within the Helmholtz Validation Fund Project "MicroTCA.4 for Industry", DESY together with collaboration partners from industry and research developed a compact fully MicroTCA chassis-integrated local RF oscillator module. The local oscillator and clock generation module generates a low noise local oscillator out of the global reference that is distributed over the accelerator. The module includes a splitting section which provides 9 local oscillator signals which are distributed over the RF-Backplane to the rear-transition modules. Similarly, the clock signal is also generated out of a single reference input by means of low-noise dividers. The clock is then fan-out to 22 differential lines that are routed over the RF backplane to the rear-transition modules. The functional block is implemented such that it fits in the rear slots 15 and 14 of a standard MTCA.4 crate. In the paper the commissioning results measured on the L3 low-level RF stations of the European XFEL will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA030
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MOPHA032	All-Optical Synchronization of Pulsed Laser Systems at FLASH and XFEL	854
	J.M. Müller, M.K. Czwalinna, M. Felber, M. Schäfer, H. Schlarb, B. Schmidt, S. Schulz, C. Sydlo, F. Zummack DESY, Hamburg, Germany
	The all-optical laser synchronization at FLASH and XFEL provides femtosecond-stable timing of the FEL X-ray photon pulses and associated optical laser pulses (photo-injector laser, seed laser, pump-probe laser, etc.). Based on a two-color balanced optical cross-correlation scheme a high-precision measure of the laser pulse arrival time is delivered, which is used for diagnostic purposes as well as for the active stabilization of the laser systems. In this paper, we present the latest installations of our all-optical synchronization systems at FLASH and the recent developments for the upcoming European XFEL that will ensure a reliable femtosecond-stable timing of FEL and related pulsed laser systems.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA032
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MOPHA033	Physical Parameter Identification of Cross-Coupled Gun and Buncher Cavity at REGAE	857
	A.S. Nawaz, H. Werner TUHH, Hamburg, Germany M. Hoffmann, S. Pfeiffer, H. Schlarb DESY, Hamburg, Germany
	A reasonable description of the system dynamics is one of the key elements to achieve high performance control for accelerating modules. This paper depicts the system identification of a cross-coupled pair of cavities for the Relativistic Electron Gun for Atomic Exploration - REGAE. Two normal conducting copper cavities driven by a single RF source accelerate and compress a low charge electron bunch with sub 10 fs length at a repetition rate up to 50 Hz. It is shown how the model parameters of the cavities and the attached radio frequency subsystem are identified from data generated at the REGAE facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA033
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MOPHA034	High Voltage RTM Piezo Driver for XFEL Special Diagnostics	860
	K.P. Przygoda, M. Felber, C. Gerth, M. Heuer, E. Janas, U. Mavrič, P. Peier, H. Schlarb, B. Steffen, C. Sydlo DESY, Hamburg, Germany T. Kozak, P. Prędki TUL-DMCS, Łódź, Poland
	High voltage RTM Piezo Driver has been developed to support special diagnostic applications foreseen for XFEL facility. The RTM is capable of driving 4 piezo actuators with voltages up to ±80 V. The solid-state power amplifiers are driven using 18-bit DACs and sampling rates of 1 MSPS. The bandwidth of the driver is remotely tunable using programmable low pass filters. The 4-channel Piezo Driver unit provides the information of piezo output voltage and current. Three independent test setups have been built to test 4-channel Piezo Driver performance. In the paper we are presenting EOD laser lock to 1.3 GHz FLASH master oscillator using bipolar piezo stretcher (fine tuning). The piezo motor based course tuning has been applied for the long term laser stability measurements. The unipolar piezo actuator operation has been demonstrated for the Origami Onefive laser locked to 1.3 GHz LAB MO. The preliminary results of active stabilization of 3 km fiber link laboratory setup are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA034
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TUAD3	LLRF Commissioning of the European XFEL RF Gun and Its First Linac RF Station	1377
	J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, M. Omet, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang DESY, Hamburg, Germany S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, K. Oliwa, J. Piekarski, K.T. Pozniak, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, L.Z. Zembala, M. Żukociński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek TUL-DMCS, Łódź, Poland A. Piotrowski FastLogic Sp. z o.o., Łódź, Poland
	The European X-ray free electron laser (XFEL) at the Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is in its construction phase. Approximately a third of the super-conductive cryomodules have been produced and tested. The RF gun is installed since 2013; periods of commissioning are regularly scheduled between installation phases of the rest of the injector. The first linac, L1, consisting of 4 cryomodules powered by one 10 MW klystron is installed and being commissioned. This contribution reports on the installation and preparation work of the low-level radio frequency system (LLRF) to perform the commissioning of the XFEL first components. The commissioning plans, schedule and first results are presented.
	Slides TUAD3 [14.016 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAD3
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TUPWA029	ARES: Accelerator Research Experiment at SINBAD	1469
	B. Marchetti, R.W. Aßmann, C. Behrens, R. Brinkmann, U. Dorda, K. Flöttmann, J. Grebenyuk, M. Hüning, Y.C. Nie, H. Schlarb, J. Zhu DESY, Hamburg, Germany
	ARES is a planned linear accelerator for R&D for production of ultra-short electron bunches. It will be hosted at the SINBAD facility, at DESY in Hamburg. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with high arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration. The baseline layout of the accelerator foresees an S-band photo-injector which compresses low charge electron bunches via velocity bunching and accelerates them to 100 MeV energy. In the second stage, it is planned to install a third S-band accelerating cavity to reach 200 MeV as well as two X-band cavities: One for the linearization of the longitudinal phase space (subsequently allowing an improved bunch compression) and another one as a transverse deflecting cavity for longitudinal beam diagnostics. Moreover a magnetic bunch compressor is envisaged allowing to cut out the central slice of the beam** or hybrid bunch compression. * R. Assmann et al., TUPME047, Proceedings of IPAC 2014. R. Assmann, J. Grebenyuk, TUOBB01, Proceedings of IPAC 2014. * P. Emma et al., PRL 92 7 (2004).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA029
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TUPWA042	Status of the Accelerator Physics Test Facility FLUTE	1506
	M.J. Nasse, A. Bernhard, I. Birkel, A. Borysenko, A. Böhm, S. Hillenbrand, N. Hiller, S. Höninger, S. Marsching, A.-S. Müller, R. Rossmanith, R. Ruprecht, M. Schuh, M. Schwarz, B. Smit, S. Walther, M. Weber, P. Wesolowski KIT, Karlsruhe, Germany R.W. Aßmann, M. Felber, K. Flöttmann, C. Gerth, M. Hoffmann, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany R. Ischebeck, B. Keil, V. Schlott, L. Stingelin PSI, Villigen PSI, Switzerland
	A new compact versatile linear accelerator named FLUTE (Ferninfrarot Linac Und Test Experiment) is currently under construction at the Karlsruhe Institute of Technology (KIT). It will serve as an accelerator test facility and allow conducting a variety of accelerator physics studies. In addition, it will be used to generate intense, ultra-short THz pulses for photon science experiments. FLUTE consists of a ~7 MeV photo-injector gun, a ~41 MeV S-band linac and a D-shaped chicane to compress bunches to a few femtoseconds. This contribution presents an overview of the project status and the accompanying simulation studies.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA042
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WEPMA029	Design of a Normal Conducting Cavity for Arrival Time Stabilization at FLASH	2818
	M. Fakhari, K. Flöttmann, S. Pfeiffer, H. Schlarb DESY, Hamburg, Germany J. Roßbach Uni HH, Hamburg, Germany
	It has been shown, that beam-based feedback loops stabilize the bunch arrival time in the femtoseconds range. However, further minimizing the bunch arrival time jitter requires a faster actuator that is a normal conducting cavity with higher bandwidth compared to narrow-band superconducting cavities. We present the design of a 4-cell normal conducting cavity that is going to be used in a fast beam-based feedback at free-electron laser FLASH at Hamburg. The input power will be injected to the cavity via a loop coupler from the side of the first cell. The operating frequency of the designed cavity is about 3 GHz with an adjustable bandwidth. The long range longitudinal wakefield calculation results are reported to investigate the cavity performance for multi-beam operation up to 3 MHz bunch repetition rate. The results declare that the influence of the long range wakefield on the arrival time jitter is less than 1 fs.
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WEPMN030	Testing Procedures for Fast Frequency Tuners of XFEL Cavities	2991
	K.P. Przygoda, W. Cichalewski, T. Pożniak TUL-DMCS, Łódź, Poland J. Branlard, O. Hensler, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany K. Kasprzak IFJ-PAN, Kraków, Poland
	The XFEL accelerator will be equipped with 100 accelerating modules. Each accelerating module will host 8 superconducting cavities. Every single cavity will be equipped with a mechanical tuner. Coarse tuning will be supported by a step motor; fine tuning will be handled by double piezoelectric elements installed inside a single mechanical support, providing actuator and sensor functionality or redundancy. Before the main linac installation, all its subcomponents need to be tested and verified. The AMTF (Accelerator Module Test Facility) has been built at DESY to test all XFEL cryomodules. In total 1600 piezos need to be tested. Test procedures for fast frequency tuners have been developed to check their basic performance in cryogenic conditions (tuning range, polarity, acting and sensing abilities). High level applications perform fully automated tests including report generation. After the successful completion of the acceptance tests, the cryomodules will be prepared for tunnel installation.
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WEPMN032	Microphonic Disturbances Prediction and Compensation in Pulsed Superconducting Accelerators	2997
	R. Rybaniec, L.J. Opalski Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland V. Ayvazyan, Ł. Butkowski, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany
	Accelerators are affected by the cavities detuning variation caused by external mechanical disturbances (microphonics). The paper presents microphonics estimation and prediction methods applicable for superconducting accelerators operating in pulsed mode. A mathematical model is built using the estimates of detuning during previous RF pulses. The model can be used for predictions of disturbances for the future time step and setup of the fast tuners accordingly. The proposed method was successfully verified with measurements conducted at the FLASH linac.
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Paper

Title

Page

Virtual Cavity Probe Generation using Calibrated Forward and Reflected Signals

200

S. Pfeiffer, V. Ayvazyan, J. Branlard, Ł. Butkowski, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

The European X-ray free electron laser requires a high-precision control of accelerating fields to ensure a stable photon generation. Its low level radio frequency system, based on the MicroTCA.4 standard, detects the probe, forward and reflected signals for each cavity. While the probe signal is used to control the accelerating fields, a combination of the forward and reflected signals can be used to compute a virtual probe, whose accuracy is comparable to the directly sampled probe. This requires the removal of cross-coupling effects between the forward and reflected signals. This paper presents the precise generation of a virtual probe using an extended method of least squares. The virtual probe can then be used for precise field control in case the probe signal is missing or corrupted. It can also be used to detect any deviation from the nominal probe profile.

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MOPHA026

Present and Future Optical-to-Microwave Synchronization Systems at REGAE Facility for Electron Diffraction and Plasma Acceleration Experiments

833

M. Titberidze, F.J. Grüner, A.R. Maier, B. Zeitler
CFEL, Hamburg, Germany
S.W. Epp
MPSD, Hamburg, Germany
M. Felber, K. Flöttmann, T. Lamb, U. Mavrič, J.M. Müller, H. Schlarb, C. Sydlo
DESY, Hamburg, Germany
F.J. Grüner, A.R. Maier, M. Titberidze
Uni HH, Hamburg, Germany
E. Janas
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

Relativistic Electron Gun for Atomic Explorations (REGAE) is a Radio Frequency (RF) driven linear accelerator. It uses frequency tripled short photon pulses (~ 35 fs) from the Titanium Sapphire (Ti:Sa.) Laser system in order to generate electron bunches from the photo-cathode. The electron bunches are accelerated up to ~ 5 MeV kinetic energy and compressed down to sub-10 fs using the so called ballistic bunching technique. REGAE currently is used for electron diffraction experiments (by Prof. R.J.D. Miller's Group). In near future within the collaboration of Laboratory for Laser- and beam-driven plasma Acceleration (LAOLA), REGAE will also be employed to externally inject electron bunches into laser driven linear plasma waves. Both experiments require very precise synchronization (sub-50 fs) of the photo-injector laser and RF reference. In this paper we present experimental results of the current and new optical to microwave synchronization systems in comparison. We also address some of the issues related to the current system and give an upper limit in terms of its long-term performance.

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MOPHA028

Operation of Normal Conducting RF Guns with MicroTCA.4

841

M. Hoffmann, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, U. Mavrič, M. Omet, S. Pfeiffer, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Fornal, R. Rybaniec
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A. Piotrowski
FastLogic Sp. z o.o., Łódź, Poland

During the last half year, the MicroTCA.4 based single cavity LLRF control system was installed and commissioned at several normal conducting facilities at DESY (FLASH RF gun, REGAE, PITZ RF gun, and XFEL RF gun). First tests during the last year show promising results in optimizing the system for high speed digital LLRF feedbacks, i.e. reducing system latency, increasing the internal controller processing speed, testing new control schemes, and optimizing controller parameters. In this contribution we will present results and gained experience from the commissioning phase and the first time period of real operation.

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MOPHA029

Operation Experiences with the MICROTCA.4-based LLRF Control System at FLASH

844

M. Omet, V. Ayvazyan, J. Branlard, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
W. Cichalewski, D.R. Makowski
TUL-DMCS, Łódź, Poland
K. Czuba, K. Oliwa, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
A. Piotrowski
FastLogic Sp. z o.o., Łódź, Poland

The Free-Electron Laser in Hamburg (FLASH) at Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is a user facility providing ultra-short, femtosecond laser pulses up to the soft X-ray wavelength range. For the precise regulation of the radio frequency (RF) fields within the 60 superconducting cavities, which are organized in 5 RF stations, digital low level RF (LLRF) control systems based on the MTCA.4 standard were implemented in 2013. Until now experiences with failures potentially due to radiation, overheating, and ageing as well as with the general operation of the control systems have been gained. These have a direct impact on the operation and on the performance of FLASH and will allow future improvements. The lessons learned are not only important for FLASH but also in the scope of European X-ray Free-Electron Laser (X-FEL), which will be operated with the same LLRF control system.

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MOPHA030

Commissioning of the Low-Noise MTCA.4-based Local Oscillator and Clock Generation Module

847

U. Mavrič, J. Branlard, M. Hoffmann, F. Ludwig, H. Schlarb
DESY, Hamburg, Germany
D.R. Makowski, A. Mielczarek, P. Perek
TUL-DMCS, Łódź, Poland
A. Rohlev
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

Funding: Helmholtz Validation Fund Project "MicroTCA.4 for Industry"
Within the Helmholtz Validation Fund Project "MicroTCA.4 for Industry", DESY together with collaboration partners from industry and research developed a compact fully MicroTCA chassis-integrated local RF oscillator module. The local oscillator and clock generation module generates a low noise local oscillator out of the global reference that is distributed over the accelerator. The module includes a splitting section which provides 9 local oscillator signals which are distributed over the RF-Backplane to the rear-transition modules. Similarly, the clock signal is also generated out of a single reference input by means of low-noise dividers. The clock is then fan-out to 22 differential lines that are routed over the RF backplane to the rear-transition modules. The functional block is implemented such that it fits in the rear slots 15 and 14 of a standard MTCA.4 crate. In the paper the commissioning results measured on the L3 low-level RF stations of the European XFEL will be presented.

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MOPHA032

All-Optical Synchronization of Pulsed Laser Systems at FLASH and XFEL

854

J.M. Müller, M.K. Czwalinna, M. Felber, M. Schäfer, H. Schlarb, B. Schmidt, S. Schulz, C. Sydlo, F. Zummack
DESY, Hamburg, Germany

The all-optical laser synchronization at FLASH and XFEL provides femtosecond-stable timing of the FEL X-ray photon pulses and associated optical laser pulses (photo-injector laser, seed laser, pump-probe laser, etc.). Based on a two-color balanced optical cross-correlation scheme a high-precision measure of the laser pulse arrival time is delivered, which is used for diagnostic purposes as well as for the active stabilization of the laser systems. In this paper, we present the latest installations of our all-optical synchronization systems at FLASH and the recent developments for the upcoming European XFEL that will ensure a reliable femtosecond-stable timing of FEL and related pulsed laser systems.

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MOPHA033

Physical Parameter Identification of Cross-Coupled Gun and Buncher Cavity at REGAE

857

A.S. Nawaz, H. Werner
TUHH, Hamburg, Germany
M. Hoffmann, S. Pfeiffer, H. Schlarb
DESY, Hamburg, Germany

A reasonable description of the system dynamics is one of the key elements to achieve high performance control for accelerating modules. This paper depicts the system identification of a cross-coupled pair of cavities for the Relativistic Electron Gun for Atomic Exploration - REGAE. Two normal conducting copper cavities driven by a single RF source accelerate and compress a low charge electron bunch with sub 10 fs length at a repetition rate up to 50 Hz. It is shown how the model parameters of the cavities and the attached radio frequency subsystem are identified from data generated at the REGAE facility.

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MOPHA034

High Voltage RTM Piezo Driver for XFEL Special Diagnostics

860

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

High voltage RTM Piezo Driver has been developed to support special diagnostic applications foreseen for XFEL facility. The RTM is capable of driving 4 piezo actuators with voltages up to ±80 V. The solid-state power amplifiers are driven using 18-bit DACs and sampling rates of 1 MSPS. The bandwidth of the driver is remotely tunable using programmable low pass filters. The 4-channel Piezo Driver unit provides the information of piezo output voltage and current. Three independent test setups have been built to test 4-channel Piezo Driver performance. In the paper we are presenting EOD laser lock to 1.3 GHz FLASH master oscillator using bipolar piezo stretcher (fine tuning). The piezo motor based course tuning has been applied for the long term laser stability measurements. The unipolar piezo actuator operation has been demonstrated for the Origami Onefive laser locked to 1.3 GHz LAB MO. The preliminary results of active stabilization of 3 km fiber link laboratory setup are shown.

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TUAD3

LLRF Commissioning of the European XFEL RF Gun and Its First Linac RF Station

1377

J. Branlard, G. Ayvazyan, V. Ayvazyan, Ł. Butkowski, M.K. Grecki, M. Hoffmann, F. Ludwig, U. Mavrič, M. Omet, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt, H.C. Weddig, B.Y. Yang
DESY, Hamburg, Germany
S. Bou Habib, K. Czuba, M. Grzegrzółka, E. Janas, K. Oliwa, J. Piekarski, K.T. Pozniak, I. Rutkowski, R. Rybaniec, D. Sikora, W. Wierba, L.Z. Zembala, M. Żukociński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Cichalewski, D.R. Makowski, A. Mielczarek, P. Perek
TUL-DMCS, Łódź, Poland
A. Piotrowski
FastLogic Sp. z o.o., Łódź, Poland

The European X-ray free electron laser (XFEL) at the Deutsches Elektronen-Synchrotron (DESY), Hamburg Germany is in its construction phase. Approximately a third of the super-conductive cryomodules have been produced and tested. The RF gun is installed since 2013; periods of commissioning are regularly scheduled between installation phases of the rest of the injector. The first linac, L1, consisting of 4 cryomodules powered by one 10 MW klystron is installed and being commissioned. This contribution reports on the installation and preparation work of the low-level radio frequency system (LLRF) to perform the commissioning of the XFEL first components. The commissioning plans, schedule and first results are presented.

Slides TUAD3 [14.016 MB]

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TUPWA029

ARES: Accelerator Research Experiment at SINBAD

1469

B. Marchetti, R.W. Aßmann, C. Behrens, R. Brinkmann, U. Dorda, K. Flöttmann, J. Grebenyuk, M. Hüning, Y.C. Nie, H. Schlarb, J. Zhu
DESY, Hamburg, Germany

ARES is a planned linear accelerator for R&D for production of ultra-short electron bunches. It will be hosted at the SINBAD facility, at DESY in Hamburg*. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with high arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration**. The baseline layout of the accelerator foresees an S-band photo-injector which compresses low charge electron bunches via velocity bunching and accelerates them to 100 MeV energy. In the second stage, it is planned to install a third S-band accelerating cavity to reach 200 MeV as well as two X-band cavities: One for the linearization of the longitudinal phase space (subsequently allowing an improved bunch compression) and another one as a transverse deflecting cavity for longitudinal beam diagnostics. Moreover a magnetic bunch compressor is envisaged allowing to cut out the central slice of the beam*** or hybrid bunch compression.
* R. Assmann et al., TUPME047, Proceedings of IPAC 2014.
** R. Assmann, J. Grebenyuk, TUOBB01, Proceedings of IPAC 2014.
*** P. Emma et al., PRL 92 7 (2004).

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TUPWA042

Status of the Accelerator Physics Test Facility FLUTE

1506

M.J. Nasse, A. Bernhard, I. Birkel, A. Borysenko, A. Böhm, S. Hillenbrand, N. Hiller, S. Höninger, S. Marsching, A.-S. Müller, R. Rossmanith, R. Ruprecht, M. Schuh, M. Schwarz, B. Smit, S. Walther, M. Weber, P. Wesolowski
KIT, Karlsruhe, Germany
R.W. Aßmann, M. Felber, K. Flöttmann, C. Gerth, M. Hoffmann, P. Peier, H. Schlarb, B. Steffen
DESY, Hamburg, Germany
R. Ischebeck, B. Keil, V. Schlott, L. Stingelin
PSI, Villigen PSI, Switzerland

A new compact versatile linear accelerator named FLUTE (Ferninfrarot Linac Und Test Experiment) is currently under construction at the Karlsruhe Institute of Technology (KIT). It will serve as an accelerator test facility and allow conducting a variety of accelerator physics studies. In addition, it will be used to generate intense, ultra-short THz pulses for photon science experiments. FLUTE consists of a ~7 MeV photo-injector gun, a ~41 MeV S-band linac and a D-shaped chicane to compress bunches to a few femtoseconds. This contribution presents an overview of the project status and the accompanying simulation studies.

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WEPMA029

Design of a Normal Conducting Cavity for Arrival Time Stabilization at FLASH

2818

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

It has been shown, that beam-based feedback loops stabilize the bunch arrival time in the femtoseconds range. However, further minimizing the bunch arrival time jitter requires a faster actuator that is a normal conducting cavity with higher bandwidth compared to narrow-band superconducting cavities. We present the design of a 4-cell normal conducting cavity that is going to be used in a fast beam-based feedback at free-electron laser FLASH at Hamburg. The input power will be injected to the cavity via a loop coupler from the side of the first cell. The operating frequency of the designed cavity is about 3 GHz with an adjustable bandwidth. The long range longitudinal wakefield calculation results are reported to investigate the cavity performance for multi-beam operation up to 3 MHz bunch repetition rate. The results declare that the influence of the long range wakefield on the arrival time jitter is less than 1 fs.

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WEPMN030

Testing Procedures for Fast Frequency Tuners of XFEL Cavities

2991

K.P. Przygoda, W. Cichalewski, T. Pożniak
TUL-DMCS, Łódź, Poland
J. Branlard, O. Hensler, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
K. Kasprzak
IFJ-PAN, Kraków, Poland

The XFEL accelerator will be equipped with 100 accelerating modules. Each accelerating module will host 8 superconducting cavities. Every single cavity will be equipped with a mechanical tuner. Coarse tuning will be supported by a step motor; fine tuning will be handled by double piezoelectric elements installed inside a single mechanical support, providing actuator and sensor functionality or redundancy. Before the main linac installation, all its subcomponents need to be tested and verified. The AMTF (Accelerator Module Test Facility) has been built at DESY to test all XFEL cryomodules. In total 1600 piezos need to be tested. Test procedures for fast frequency tuners have been developed to check their basic performance in cryogenic conditions (tuning range, polarity, acting and sensing abilities). High level applications perform fully automated tests including report generation. After the successful completion of the acceptance tests, the cryomodules will be prepared for tunnel installation.

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WEPMN032

Microphonic Disturbances Prediction and Compensation in Pulsed Superconducting Accelerators

2997

R. Rybaniec, L.J. Opalski
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
V. Ayvazyan, Ł. Butkowski, S. Pfeiffer, K.P. Przygoda, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany

Accelerators are affected by the cavities detuning variation caused by external mechanical disturbances (microphonics). The paper presents microphonics estimation and prediction methods applicable for superconducting accelerators operating in pulsed mode. A mathematical model is built using the estimates of detuning during previous RF pulses. The model can be used for predictions of disturbances for the future time step and setup of the fast tuners accordingly. The proposed method was successfully verified with measurements conducted at the FLASH linac.

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