FEL2014 - List of Keywords (timing)

Paper	Title	Other Keywords	Page
MOP021	Commissioning of a Dual-sweep Streak Camera with Applications to the ASTA Photoinjector Drive Laser	laser, controls, cavity, gun	66
	A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci Fermilab, Batavia, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The high-power electron beams for the Advanced Superconducting Test Accelerator (ASTA) facility will be generated in a photoinjector based on a UV drive laser and the L-band rf photocathode (PC) gun cavity. The initial objectives of these studies were: 1) the evaluation of the amplified UV component’s bunch length and phase stability and 2) the commissioning of the laser room Hamamatsu C5680 streak camera system. We used a new readout camera based on the Prosilica GC1380 digital CCD with Gig-E readout that was compatible with our image processing tools. We observed a longer than expected UV bunch length of 4 ps σ and an unexpected peak multiplicity (with spacing of about 70 ps) in the synchronous sum of 5 UV micropulses. We have now systematically investigated the issues of whether the multiplicity was with each micropulse of the 3-MHz pulse train. We describe our extensive investigations that indicated both issues originated in the multi-pass amplifier. We have replaced the MPA with three single-pass devices, measured 3.5-ps bunch lengths without the multiplicity, and generated photoelectrons from the gun successfully.

THB03	Femtosecond-Stability Delivery of Synchronized RF-Signals to the Klystron Gallery over 1-km Optical Fibers	laser, klystron, detector, experiment	663
	J. Kim, K. Jung, J. Lim, J. Shin, H. Yang KAIST, Daejeon, Republic of Korea H.-S. Kang, C.-K. Min PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This work was supported by the PAL-XFEL Project and the National Research Foundation (Grant number 2012R1A2A2A01005544) of South Korea. We present our recent progress in optical frequency comb-based remote optical and RF distribution system at PAL-XFEL. A 238 MHz mode-locked Er-laser is used as an optical master oscillator (OMO), which is stabilized to a 2.856 GHz RF master oscillator (RMO) using a fiber- loop optical-microwave phase detector (FLOM-PD). We partly installed a pair of 1.15 km long fiber links through a cable duct to connect and OMO room to a klystron gallery in the PAL-XFEL Injector Test Facility (ITF). The fiber links are stabilized using balanced optical cross- correlators (BOC). A voltage controlled RF oscillator (VCO) is locked to the delivered optical pulse train using the second FLOM-PD. Residual timing jitter and drift between the two independently distributed optical pulse train and RF signal is measured at the klystron gallery. The results are 6.6 fs rms and 31 fs rms over 7 hours and 62 hours, respectively. This is the first comb-based optical/RF distribution and phase comparison in the klystron gallery environment.
	Slides THB03 [7.478 MB]

THP004	Start-to-End Error Studies for FLUTE	laser, simulation, linac, gun	682
	M. Weber, A.-S. Müller, S. Naknaimueang, M. Schuh, M. Schwarz, P. Wesolowski KIT, Karlsruhe, Germany
	FLUTE, a new linac based test facility and THz source, is currently under construction at the Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. With a repetition rate of 10 Hz, electron bunches with charges from 1 pC to 3 nC will be accelerated up to 40-50 MeV and then compressed longitudinally in a magnetic chicane to generate intense coherent THz radiation. Since the stability and repeatability of longitudinal bunch profiles are essential for optimum compression and THz radiation properties, simulation-based start-to-end error studies using the tracking code ASTRA have been performed to determine the influence of the machine elements on the bunches. Thus, critical parameters are identified and their respective tolerance ranges defined. In this contribution a summary of the error studies will be given.

THP010	Analysis of Beam Stability in the KAERI Ultrashort Pulse Accelerator	electron, kicker, septum, linac	697
	H.W. Kim, S. Bae, B.A. Gudkov, K.H. Jang, Y.U. Jeong, Y. Kim, K. Lee, S.V. Miginsky, J. Mun, S. H. Park, S. Park, N. Vinokurov KAERI, Daejon, Republic of Korea K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, S. H. Park, N. Vinokurov UST, Daejeon City, Republic of Korea S.V. Miginsky, N. Vinokurov BINP SB RAS, Novosibirsk, Russia
	An RF-photogun-based linear accelerator for the Korea Atomic Energy Research Institute (KAERI) ultrashort pulse facility is under construction. It has a symmetry structure with four different beamlines. The UED beamlines will generate ultrashort electron pulses with over 10⁶ electrons per pulse for the single-shot measurements on femtoseconds dynamics of atomic or molecular structures. Electron bunches with an energy of ~3 MeV from the RF photogun can be compressed up to less than 50 fs by achromatic and isochronous bends. The intrinsic r.m.s. timing jitter of the pulses through the bends is estimated to be less than 30 fs with the r.m.s. energy fluctuation of 0.1%. In the THz pump and X-ray probe beamline, two successive laser pulses with a time interval of ~10 ns are used to generate two electron bunches having bunch charges more than 100 pC. Two electron bunches are accelerated by a linac up to ~25 MeV and separated into individual beamlines by a fast kicker. We will present on estimated timing jitter and effects of magnet errors to the beam dynamics in the accelerator by considering beam dilution effects.

THP040	Status of Pump-probe Laser Development for the European XFEL	laser, controls, software, hardware	807
	L.-G. Wißmann, M. Emons, M. Kellert, K. Kruse, M. Lederer, G. Palmer, M. Pergament, G. Priebe, J. Wang, U. Wegner XFEL. EU, Hamburg, Germany
	The European XFEL is under construction and is designed to become a multi-user facility. Three SASE beam lines with two experimental areas each are foreseen to guarantee a high user throughput. In order to enable the full scientific potential of the facility, optical laser pulses for either pumping or probing samples will be deployed regularly. We are presenting the pump-probe laser concept and the current status of the development, showing some experimental results of the prototype laser, achieved to date. The main emphasis of the presentation lies on the integration of the laser system into Karabo, the emerging control system of the European XFEL.

THP075	Design of TDS-based Multi-screen Electron Beam Diagnostics for the European XFEL	kicker, emittance, electron, operation	909
	J. Wychowaniak TUL-DMCS, Łódź, Poland C. Gerth, M. Yan DESY, Hamburg, Germany
	Dedicated longitudinal electron beam diagnostics is essential for successful operation of modern free-electron lasers. Demand for diagnostic data includes the longitudinal bunch profile, bunch length and slice emittance of the electron bunches. Experimental setups based on transverse deflecting structures (TDS) are excellent candidates for this purpose. At the Free-Electron Laser in Hamburg (FLASH), such a longitudinal bunch profile monitor utilizing a TDS, a fast kicker magnet and an off-axis imaging screen, has been put into operation. It enables the measurement of a single bunch out of a bunch train without affecting the remaining bunches. At the European X-ray Free-Electron Laser (XFEL) multiscreen stations in combination with TDS are planned to be installed. In order to allow for flexible measurements of longitudinal bunch profile and slice emittance, a configurable timing and trigger distribution to the fast kicker magnets and screen stations is required. In this paper, we discuss various operation patterns and the corresponding realization based on MTCA.4 technology.

THP076	Measurements of the Timing Stability at the FLASH1 Seeding Experiment	laser, electron, experiment, FEL	913
	C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach, M. Wieland Uni HH, Hamburg, Germany S. Ackermann, J. Bödewadt, H. Dachraoui, N. Ekanayake, B. Faatz, M. Felber, K. Honkavaara, T. Laarmann, J.M. Mueller, H. Schlarb, S. Schreiber, S. Schulz DESY, Hamburg, Germany G. Angelova Hamberg Uppsala University, Uppsala, Sweden K.E. Hacker, S. Khan, R. Molo DELTA, Dortmund, Germany P.M. Salen, P. van der Meulen FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
	Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4 and 05K13PE3 and the German Research Foundation programme graduate school 1355. For seeding of a free-electron laser, the spatial and temporal overlap of the seed laser pulse and the electron bunch in the modulator is critical. To establish the temporal overlap, the time difference between pulses from the seed laser and spontaneous undulator radiation is reduced to a few pico-seconds with a combination of a photomultiplier tube and a streak camera. Finally, for the precise overlap the impact of the seed laser pulses on the electron bunches is observed. In this contribution, we describe the current experimental setup, discuss the techniques applied to establish the temporal overlap and analyze its stability.

THP080	A Low-Cost, High-Reliability Femtosecond Laser Timing System for LCLS	laser, controls, software, cavity	917
	K. Gumerlock, J.C. Frisch, B.L. Hill, J. May, D.J. Nelson, S.R. Smith SLAC, Menlo Park, California, USA
	Funding: Work supported by DOE Contract DE-AC02-76-SF00515 LCLS has developed a low-cost, high-reliability radio-frequency-based locking system which provides phase locking with sub-25-femtosecond jitter for the injector and experiment laser systems. This system does not add significantly to the X-ray timing jitter from the accelerator RF distribution. The system uses heterodyne RF locking at 3808 MHz with an I/Q vector phase shifter and variable event receiver triggers to control the timing of the emission of the amplified laser pulse. Controls software provides full automation with a single process variable to control the laser timing over a 600 microsecond range with up to 4 femtosecond resolution, as well as online diagnostics and automatic error correction and recovery. The performance of this new locking system is sufficient for experiments with higher-precision timing needs that use an X-ray/optical cross-correlator to record relative photon arrival times.

THP085	Commissioning and Results from the Bunch Arrival-time Monitor Downstream the Bunch Compressor at the SwissFEL Test Injector	pick-up, cavity, diagnostics, laser	933
	V.R. Arsov, M. Aiba, M.M. Dehler, F. Frei, S. Hunziker, M.G. Kaiser, A. Romann, V. Schlott PSI, Villigen PSI, Switzerland
	A high bandwidth Bunch Arrival-Time Monitor has been commissioned at the Swiss FEL test injector. A new acquisition front end allowing utilization of the ADC full dynamic range has been implemented. The resolution is measured as a function of the charge for different EOM front-ends. Downstream the magnetic chicane the bunch arrival time is sensitive to the amplitude and phases of the RF structures, responsible for creation of an energy chirp, used for bunch compression, as well as the ones of the harmonic cavity, used for phase space linearization. The time of flight as a function of the angle of the magnetic chicane has also been measured.

THP090	Femtosecond Timing Distribution for the European XFEL	laser, status, operation, FEL	945
	C. Sydlo, M.K. Czwalinna, M. Felber, C. Gerth, T. Lamb, H. Schlarb, S. Schulz, F. Zummack DESY, Hamburg, Germany S. Jabłoński Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
	Accurate timing synchronization on the femtosecond timescale is an essential installation for time-resolved experiments at free-electron lasers (FELs) such as FLASH and the upcoming European XFEL. To date the required precision levels can only be achieved by a laser-based synchronization system. Such a system has been successfully deployed at FLASH and is based on the distribution of femtosecond laser pulses over actively stabilized optical fibers. Albeit its maturity and proven performance this system had to undergo a major redesign for the upcoming European XFEL due to the enlarged number of stabilized optical fibers and an increase by a factor of up to 10 in length. The experience and knowledge gathered from the operation of the optical synchronization system at FLASH has led to an elaborate and modular precision instrument which can stabilize polarization maintaining fibers for highest accuracy as well as economic single mode fibers for shorter lengths. This paper reports on the laser-based synchronization system focusing on the active fiber stabilization units for the European XFEL, discusses major complications, their solutions and and the most recent performance results.

Paper

Title

Other Keywords

Page

MOP021

Commissioning of a Dual-sweep Streak Camera with Applications to the ASTA Photoinjector Drive Laser

laser, controls, cavity, gun

66

A.H. Lumpkin, D.R. Edstrom, J. Ruan, J.K. Santucci
Fermilab, Batavia, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The high-power electron beams for the Advanced Superconducting Test Accelerator (ASTA) facility will be generated in a photoinjector based on a UV drive laser and the L-band rf photocathode (PC) gun cavity. The initial objectives of these studies were: 1) the evaluation of the amplified UV component’s bunch length and phase stability and 2) the commissioning of the laser room Hamamatsu C5680 streak camera system. We used a new readout camera based on the Prosilica GC1380 digital CCD with Gig-E readout that was compatible with our image processing tools. We observed a longer than expected UV bunch length of 4 ps σ and an unexpected peak multiplicity (with spacing of about 70 ps) in the synchronous sum of 5 UV micropulses. We have now systematically investigated the issues of whether the multiplicity was with each micropulse of the 3-MHz pulse train. We describe our extensive investigations that indicated both issues originated in the multi-pass amplifier. We have replaced the MPA with three single-pass devices, measured 3.5-ps bunch lengths without the multiplicity, and generated photoelectrons from the gun successfully.

THB03

Femtosecond-Stability Delivery of Synchronized RF-Signals to the Klystron Gallery over 1-km Optical Fibers

laser, klystron, detector, experiment

663

J. Kim, K. Jung, J. Lim, J. Shin, H. Yang
KAIST, Daejeon, Republic of Korea
H.-S. Kang, C.-K. Min
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This work was supported by the PAL-XFEL Project and the National Research Foundation (Grant number 2012R1A2A2A01005544) of South Korea.
We present our recent progress in optical frequency comb-based remote optical and RF distribution system at PAL-XFEL. A 238 MHz mode-locked Er-laser is used as an optical master oscillator (OMO), which is stabilized to a 2.856 GHz RF master oscillator (RMO) using a fiber- loop optical-microwave phase detector (FLOM-PD). We partly installed a pair of 1.15 km long fiber links through a cable duct to connect and OMO room to a klystron gallery in the PAL-XFEL Injector Test Facility (ITF). The fiber links are stabilized using balanced optical cross- correlators (BOC). A voltage controlled RF oscillator (VCO) is locked to the delivered optical pulse train using the second FLOM-PD. Residual timing jitter and drift between the two independently distributed optical pulse train and RF signal is measured at the klystron gallery. The results are 6.6 fs rms and 31 fs rms over 7 hours and 62 hours, respectively. This is the first comb-based optical/RF distribution and phase comparison in the klystron gallery environment.

Slides THB03 [7.478 MB]

THP004

Start-to-End Error Studies for FLUTE

laser, simulation, linac, gun

682

M. Weber, A.-S. Müller, S. Naknaimueang, M. Schuh, M. Schwarz, P. Wesolowski
KIT, Karlsruhe, Germany

FLUTE, a new linac based test facility and THz source, is currently under construction at the Karlsruhe Institute of Technology (KIT) in collaboration with DESY and PSI. With a repetition rate of 10 Hz, electron bunches with charges from 1 pC to 3 nC will be accelerated up to 40-50 MeV and then compressed longitudinally in a magnetic chicane to generate intense coherent THz radiation. Since the stability and repeatability of longitudinal bunch profiles are essential for optimum compression and THz radiation properties, simulation-based start-to-end error studies using the tracking code ASTRA have been performed to determine the influence of the machine elements on the bunches. Thus, critical parameters are identified and their respective tolerance ranges defined. In this contribution a summary of the error studies will be given.

THP010

Analysis of Beam Stability in the KAERI Ultrashort Pulse Accelerator

electron, kicker, septum, linac

697

H.W. Kim, S. Bae, B.A. Gudkov, K.H. Jang, Y.U. Jeong, Y. Kim, K. Lee, S.V. Miginsky, J. Mun, S. H. Park, S. Park, N. Vinokurov
KAERI, Daejon, Republic of Korea
K.H. Jang, Y.U. Jeong, H.W. Kim, K. Lee, S.V. Miginsky, S. H. Park, N. Vinokurov
UST, Daejeon City, Republic of Korea
S.V. Miginsky, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia

An RF-photogun-based linear accelerator for the Korea Atomic Energy Research Institute (KAERI) ultrashort pulse facility is under construction. It has a symmetry structure with four different beamlines. The UED beamlines will generate ultrashort electron pulses with over 10⁶ electrons per pulse for the single-shot measurements on femtoseconds dynamics of atomic or molecular structures. Electron bunches with an energy of ~3 MeV from the RF photogun can be compressed up to less than 50 fs by achromatic and isochronous bends. The intrinsic r.m.s. timing jitter of the pulses through the bends is estimated to be less than 30 fs with the r.m.s. energy fluctuation of 0.1%. In the THz pump and X-ray probe beamline, two successive laser pulses with a time interval of ~10 ns are used to generate two electron bunches having bunch charges more than 100 pC. Two electron bunches are accelerated by a linac up to ~25 MeV and separated into individual beamlines by a fast kicker. We will present on estimated timing jitter and effects of magnet errors to the beam dynamics in the accelerator by considering beam dilution effects.

THP040

Status of Pump-probe Laser Development for the European XFEL

laser, controls, software, hardware

807

L.-G. Wißmann, M. Emons, M. Kellert, K. Kruse, M. Lederer, G. Palmer, M. Pergament, G. Priebe, J. Wang, U. Wegner
XFEL. EU, Hamburg, Germany

The European XFEL is under construction and is designed to become a multi-user facility. Three SASE beam lines with two experimental areas each are foreseen to guarantee a high user throughput. In order to enable the full scientific potential of the facility, optical laser pulses for either pumping or probing samples will be deployed regularly. We are presenting the pump-probe laser concept and the current status of the development, showing some experimental results of the prototype laser, achieved to date. The main emphasis of the presentation lies on the integration of the laser system into Karabo, the emerging control system of the European XFEL.

THP075

Design of TDS-based Multi-screen Electron Beam Diagnostics for the European XFEL

kicker, emittance, electron, operation

909

J. Wychowaniak
TUL-DMCS, Łódź, Poland
C. Gerth, M. Yan
DESY, Hamburg, Germany

Dedicated longitudinal electron beam diagnostics is essential for successful operation of modern free-electron lasers. Demand for diagnostic data includes the longitudinal bunch profile, bunch length and slice emittance of the electron bunches. Experimental setups based on transverse deflecting structures (TDS) are excellent candidates for this purpose. At the Free-Electron Laser in Hamburg (FLASH), such a longitudinal bunch profile monitor utilizing a TDS, a fast kicker magnet and an off-axis imaging screen, has been put into operation. It enables the measurement of a single bunch out of a bunch train without affecting the remaining bunches. At the European X-ray Free-Electron Laser (XFEL) multiscreen stations in combination with TDS are planned to be installed. In order to allow for flexible measurements of longitudinal bunch profile and slice emittance, a configurable timing and trigger distribution to the fast kicker magnets and screen stations is required. In this paper, we discuss various operation patterns and the corresponding realization based on MTCA.4 technology.

THP076

Measurements of the Timing Stability at the FLASH1 Seeding Experiment

laser, electron, experiment, FEL

913

C. Lechner, A. Azima, M. Drescher, L.L. Lazzarino, Th. Maltezopoulos, V. Miltchev, T. Plath, J. Rönsch-Schulenburg, J. Roßbach, M. Wieland
Uni HH, Hamburg, Germany
S. Ackermann, J. Bödewadt, H. Dachraoui, N. Ekanayake, B. Faatz, M. Felber, K. Honkavaara, T. Laarmann, J.M. Mueller, H. Schlarb, S. Schreiber, S. Schulz
DESY, Hamburg, Germany
G. Angelova Hamberg
Uppsala University, Uppsala, Sweden
K.E. Hacker, S. Khan, R. Molo
DELTA, Dortmund, Germany
P.M. Salen, P. van der Meulen
FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden

Funding: Supported by Federal Ministry of Education and Research of Germany under contract No. 05K10PE1, 05K10PE3, 05K13GU4 and 05K13PE3 and the German Research Foundation programme graduate school 1355.
For seeding of a free-electron laser, the spatial and temporal overlap of the seed laser pulse and the electron bunch in the modulator is critical. To establish the temporal overlap, the time difference between pulses from the seed laser and spontaneous undulator radiation is reduced to a few pico-seconds with a combination of a photomultiplier tube and a streak camera. Finally, for the precise overlap the impact of the seed laser pulses on the electron bunches is observed. In this contribution, we describe the current experimental setup, discuss the techniques applied to establish the temporal overlap and analyze its stability.

THP080

A Low-Cost, High-Reliability Femtosecond Laser Timing System for LCLS

laser, controls, software, cavity

917

K. Gumerlock, J.C. Frisch, B.L. Hill, J. May, D.J. Nelson, S.R. Smith
SLAC, Menlo Park, California, USA

Funding: Work supported by DOE Contract DE-AC02-76-SF00515
LCLS has developed a low-cost, high-reliability radio-frequency-based locking system which provides phase locking with sub-25-femtosecond jitter for the injector and experiment laser systems. This system does not add significantly to the X-ray timing jitter from the accelerator RF distribution. The system uses heterodyne RF locking at 3808 MHz with an I/Q vector phase shifter and variable event receiver triggers to control the timing of the emission of the amplified laser pulse. Controls software provides full automation with a single process variable to control the laser timing over a 600 microsecond range with up to 4 femtosecond resolution, as well as online diagnostics and automatic error correction and recovery. The performance of this new locking system is sufficient for experiments with higher-precision timing needs that use an X-ray/optical cross-correlator to record relative photon arrival times.

THP085

Commissioning and Results from the Bunch Arrival-time Monitor Downstream the Bunch Compressor at the SwissFEL Test Injector

pick-up, cavity, diagnostics, laser

933

V.R. Arsov, M. Aiba, M.M. Dehler, F. Frei, S. Hunziker, M.G. Kaiser, A. Romann, V. Schlott
PSI, Villigen PSI, Switzerland

A high bandwidth Bunch Arrival-Time Monitor has been commissioned at the Swiss FEL test injector. A new acquisition front end allowing utilization of the ADC full dynamic range has been implemented. The resolution is measured as a function of the charge for different EOM front-ends. Downstream the magnetic chicane the bunch arrival time is sensitive to the amplitude and phases of the RF structures, responsible for creation of an energy chirp, used for bunch compression, as well as the ones of the harmonic cavity, used for phase space linearization. The time of flight as a function of the angle of the magnetic chicane has also been measured.

THP090

Femtosecond Timing Distribution for the European XFEL

laser, status, operation, FEL

945

C. Sydlo, M.K. Czwalinna, M. Felber, C. Gerth, T. Lamb, H. Schlarb, S. Schulz, F. Zummack
DESY, Hamburg, Germany
S. Jabłoński
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland

Accurate timing synchronization on the femtosecond timescale is an essential installation for time-resolved experiments at free-electron lasers (FELs) such as FLASH and the upcoming European XFEL. To date the required precision levels can only be achieved by a laser-based synchronization system. Such a system has been successfully deployed at FLASH and is based on the distribution of femtosecond laser pulses over actively stabilized optical fibers. Albeit its maturity and proven performance this system had to undergo a major redesign for the upcoming European XFEL due to the enlarged number of stabilized optical fibers and an increase by a factor of up to 10 in length. The experience and knowledge gathered from the operation of the optical synchronization system at FLASH has led to an elaborate and modular precision instrument which can stabilize polarization maintaining fibers for highest accuracy as well as economic single mode fibers for shorter lengths. This paper reports on the laser-based synchronization system focusing on the active fiber stabilization units for the European XFEL, discusses major complications, their solutions and and the most recent performance results.