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Winter, A.

    
Paper Title Page
TUPCH081 Technical Aspects of the Integration of the Optical Replica Synthesizer for the Diagnostics of Ultra-short Bunches in FLASH at DESY 1199
 
  • V.G. Ziemann
    UU/ISV, Uppsala
  • N.X. Javahiraly, P. van der Meulen
    FYSIKUM, AlbaNova, Stockholm University, Stockholm
  • M. Larsson
    Stockholm University, Department of Physics, Stockholm
  • E. Saldin, H. Schlarb, E. Schneidmiller, A. Winter, M.V. Yurkov
    DESY, Hamburg
 
  In this paper we present an overview of current status of the Optical Replica synthesizer at DESY. The method is based on producing an "optical copy" of the electron bunch with its subsequent analysis with optical techniques*. To this end, a near-IR laser beam is superimposed on the electron beam in the first undulator of an optical klystron. In the following dispersive section the laser-induced energy modulation is transformed into a density modulation . The modulated electron bunch then produces a strong optical pulse in the second undulator. Analysis of this near-IR pulse (the optical copy) then provides information about the profile, the slice emittance and the slice energy spread of the electron bunch. We discuss the implementation of such a measurement set-up at the FLASH facility at DESY and investigate the influence of various parameters on the performance of the device. Topics we address include the dispersive chicane, as well as the requirements for the seed laser pulses and the detection and analysis of the near-IR pulse.

*E. Saldin, et al. "A simple method for the determination of the structure of ultrashort relativistic electron bunches," Nucl. Inst. and Methods A 539 (2005) 499.

 
THOPA03 An Integrated Femtosecond Timing Distribution System for XFELs 2744
 
  • J. Kim, J. Burnham, dc. Cheever, J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • M. Ferianis
    ELETTRA, Basovizza, Trieste
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb, A. Winter
    DESY, Hamburg
 
  Tightly synchronized lasers and rf-systems with timing jitter in the few femtoseconds range are an important component of future x-ray free electron laser facilities. In this paper, we present an optical-rf phase detector that is capable of extracting an rf-signal from an optical pulse stream without amplitude-to-phase conversion. Extraction of a microwave signal with less than 10 fs timing jitter (from 1 Hz to 10 MHz) from an optical pulse stream is demonstrated. Scaling of this component to sub-femtosecond resolution is discussed. Together with low noise mode-locked lasers, timing-stabilized optical fiber links and compact optical cross-correlators, a flexible femtosecond timing distribution system with potentially sub-10 fs precision over distances of a few kilometres can be constructed. Experimental results on both synchronized rf and laser sources will be presented.

*A. Winter et al. "Synchronization of Femtosecond Pulses", Proceedings of FEL 2005.**J. Kim et al. "Large-Scale Timing Distribution and RF-Synchronization for FEL Facilities", Proc. of FEL 2004.

 
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TUPCH028 Layout of the Optical Synchronization System for FLASH 1061
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • F. Loehl, F. Ludwig, H. Schlarb, B. Schmidt
    DESY, Hamburg
 
  The present RF synchronization system of the VUV-FEL can typically stabilize the arrival time of the electron bunches at the undulator to about 200 fs on a timescale of minutes and to several picoseconds on a timescale of hours. To improve the machine stability and to ensure optimal performance for the VUV-FEL user facility, a new ultra-precise timing system is mandatory. The optical synchronization system under construction will satisfy three goals: Firstly, it provides a local oscillator frequency with the same stability as the existing low-level RF regulation, secondly, it can synchronize the experimental lasers of the FEL users with a precision in the order of 30 fs, thirdly, it provides an ultra-stable reference for beam arrival time measurements and enables a feedback on the electron beam to compensate residual drifts and timing jitter. The optical synchronization system is based on an optical pulse train from a mode-locked laser with a highly stabilized repetition rate. This paper describes the proposed layout of the optical synchronization system, the integration into the machine layout and the diagnostic experiments to monitor the performance of the system.  
TUPCH028 Layout of the Optical Synchronization System for FLASH 1061
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • F. Loehl, F. Ludwig, H. Schlarb, B. Schmidt
    DESY, Hamburg
 
  The present RF synchronization system of the VUV-FEL can typically stabilize the arrival time of the electron bunches at the undulator to about 200 fs on a timescale of minutes and to several picoseconds on a timescale of hours. To improve the machine stability and to ensure optimal performance for the VUV-FEL user facility, a new ultra-precise timing system is mandatory. The optical synchronization system under construction will satisfy three goals: Firstly, it provides a local oscillator frequency with the same stability as the existing low-level RF regulation, secondly, it can synchronize the experimental lasers of the FEL users with a precision in the order of 30 fs, thirdly, it provides an ultra-stable reference for beam arrival time measurements and enables a feedback on the electron beam to compensate residual drifts and timing jitter. The optical synchronization system is based on an optical pulse train from a mode-locked laser with a highly stabilized repetition rate. This paper describes the proposed layout of the optical synchronization system, the integration into the machine layout and the diagnostic experiments to monitor the performance of the system.  
TUPCH029 High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources 1064
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb
    DESY, Hamburg
 
  X-ray pulses with a pulse duration in the 10 fs regime or even less are needed for numerous experiments planned at next generation free electron lasers. A synchronization of probe laser pulses to the x-ray pulses with a stability on the order of the pulse width is highly desirable for these experiments. This requirement can be fulfilled by distributing an ultra-stable timing signal to various subsystems of the machine and to the experimental area to provide synchronization at the fs level over distances of several kilometers. Mode-locked fiber lasers serve as laser master oscillators (LMO), generating the frequencies required in the machine. The pulse train is distributed through length-stabilized fiber links. This paper focuses on the LMO, devoting special attention to the phase noise properties of the frequencies to be generated, its reliability to operate in an accelerator environment, and the residual timing jitter and drifts of the RF feedback for the fiber links. A prototype experimental system has been constructed and tested in an accelerator environment and its performance characteristics will be evaluated.  
TUPCH029 High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources 1064
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb
    DESY, Hamburg
 
  X-ray pulses with a pulse duration in the 10 fs regime or even less are needed for numerous experiments planned at next generation free electron lasers. A synchronization of probe laser pulses to the x-ray pulses with a stability on the order of the pulse width is highly desirable for these experiments. This requirement can be fulfilled by distributing an ultra-stable timing signal to various subsystems of the machine and to the experimental area to provide synchronization at the fs level over distances of several kilometers. Mode-locked fiber lasers serve as laser master oscillators (LMO), generating the frequencies required in the machine. The pulse train is distributed through length-stabilized fiber links. This paper focuses on the LMO, devoting special attention to the phase noise properties of the frequencies to be generated, its reliability to operate in an accelerator environment, and the residual timing jitter and drifts of the RF feedback for the fiber links. A prototype experimental system has been constructed and tested in an accelerator environment and its performance characteristics will be evaluated.  
THPPA01 High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources 2747
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb
    DESY, Hamburg
 
  Abstract to be supplied  
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THPPA01 High-precision Laser Master Oscillators for Optical Timing Distribution Systems in Future Light Sources 2747
 
  • A. Winter, P. Schmüser, A. Winter
    Uni HH, Hamburg
  • J. Chen, F.X. Kaertner
    MIT, Cambridge, Massachusetts
  • F.O. Ilday
    Bilkent University, Bilkent, Ankara
  • F. Ludwig, H. Schlarb
    DESY, Hamburg
 
  Abstract to be supplied  
slides icon Transparencies
THOBFI01 A Sub 100 fs Electron Bunch Arrival-time Monitor System for FLASH 2781
 
  • F. Loehl, K.E. Hacker, F. Ludwig, H. Schlarb, B. Schmidt
    DESY, Hamburg
  • A. Winter
    Uni HH, Hamburg
 
  The stability of free-electron lasers and experiments carried out in pump-probe configurations depends sensitively on precise synchronization between the photo-injector laser, low-level RF-systems, probe lasers, and other components in the FEL. A measurement of the jitter in the arrival-time of the electron bunch with respect to the clock signal of a master oscillator is, therefore, of special importance. For this task, we propose an arrival-time monitor based on a beam pick-up with more than 10GHz bandwidth which permits measurements in the sub 100 fs regime. The RF-signal from the beam pick-up is sampled by an ultra-short laser pulse using a broad-band electro-optical modulator. The modulator converts the electron bunch arrival-time jitter into an amplitude modulation of the laser pulse. This modulation is detected by a photo detector and sampled by a fast ADC. By directly using the laser pulses from the master laser oscillator of the machine, any additional timing jitter is avoided. In this paper we present the layout of the system and first experimental results.  
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TUPCH024 Comparative Study of Bunch Length and Arrival Time Measurements at FLASH 1049
 
  • H. Schlarb, A. Azima, S. Düsterer, M. Huening, E.-A. Knabbe, M. Roehrs, R. Rybnikov, B. Schmidt, B. Steffen
    DESY, Hamburg
  • M.C. Ross
    SLAC, Menlo Park, California
  • P. Schmüser, A. Winter
    Uni HH, Hamburg
 
  Diagnostic devices to precisely measure the longitudinal electron beam profile and the bunch arrival time require elaborate new instrumentation techniques. At the VUV-FEL, two entirely different methods are used. The bunch profile can be determined with high precision by a transverse deflecting RF structure. The method is disruptive and does not allow to monitor multiple bunches in a macro-pulse train. Therefore, it is augmented by two non-disruptive electro-optical devices, called EO and TEO. The EO setup uses a dedicated diagnostic laser synchronized to the machine RF. The longitudinal electron beam profile is encoded in the intensity profile of a chirped laser pulse and analyzed by looking at the spectral composition of the pulse. The second setup, TEO, utilizes the TiSa-based laser system used for pump-probe experiments. Here, the temporal electron shape is encoded into a spatial dimension of laser pulse by an intersection angle between the laser and the electron beam at the EO-crystal. In this paper, we present a comparative study of bunch length and arrival time measurements performed simultaneously with all three experimental techniques.