FEL Experiments and Projects
Paper Title Page
MOOA2 First Lasing of the ALICE IR-FEL at Daresbury Laboratory 1
 
  • D.J. Dunning, S. Leonard, A.D. Smith
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.A. Clarke, Y.M. Saveliev, N. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Surman
    STFC/DL/SRD, Daresbury, Warrington, Cheshire, United Kingdom
  
  We report the first lasing of the ALICE IR-FEL, an oscillator FEL at the UK’s STFC Daresbury Laboratory. The ALICE (Accelerators and Lasers In Combined Experiments) facility is a testbed for advanced accelerator technologies and experiments, based on an Energy Recovery Linac (ERL) accelerator. First lasing of the ALICE IR-FEL was achieved on October 23rd 2010, making it the first FEL to operate in the UK, and the first FEL based on an ERL accelerator in Europe. First lasing was achieved at 27.5 MeV electron beam energy and 8 μm radiation wavelength. This report describes the steps taken in commissioning the FEL, and the characterisation of the FEL performance and output. Continuous wavelength tuning between 5.7-8 μm (through varying the undulator gap) has been demonstrated.  
slides icon Slides MOOA2 [3.435 MB]  
 
MOOA3
 First Lasing of the FERMI@elettra seeded FEL  
 
  • G. Penco
    ELETTRA, Basovizza, Italy
  
  Commissioning of the FERMI@elettra FEL-1 line started in August 2009. A challenging program of installations and machine commissioning has been carried out until the end of 2010. Efforts have been spent to optimize the photo-injector performance, to implement the one-stage magnetic compresssion of the electron bunch length and to accelerate the electron beam to the design energy of 1.2 GeV. In the fourth trimester of 2010 seven undulator segments have been installed. The first seeded FEL light was generated at the fundamental wavelength of 43 nm in December 2010. Further FEL optimization has been performed in the first half of 2011: the FEL peak power and stability have been improved. FEL output in the wavelength range 52 nm to 32 nm has been provided to the beam lines and experimental stations for preliminary tests.  
slides icon Slides MOOA3 [4.066 MB]  
 
MOOA4
 Fist Lasing of SACLA  
 
  • T. Shintake
    RIKEN Spring-8 Harima, Hyogo, Japan
  
  On June 7 2011, we observed the first lasing X-ray at 1.2 Angstrom in our new X-ray FEL (SACLA) in Japan. The construction project, previously called XFEL/Japan, started in 2006 at SPring-8, spending four and half years for civil construction, fabrication of hardware components, installation and another half year for high power processing and debugging, then completed in March 2011. After three-month beam commissioning and tuning, we tried lasing at 7.1 GeV, by sending beam into the undulator line. We slowly closed undulator gaps from upstream, when we came to 8th undulator, we firstly observed a bright spot on YAG-screen in a middle of spontaneous radiation. Using whole undulators (sixteen of 5 m each), the power reached to 20 μJ/pulse at 30 fsec with 3 kA beam. The FEL power has not yet reached to its saturation level. We currently tuning whole machine, and preparing for X-ray experiments from this autumn run. The accelerator construction itself was a big project and tremendous effort was made by Joint Construction Team (JASRI+RIKEN) and a large number of industry people. We would like to thank all contributors and all friends in FEL community.  
slides icon Slides MOOA4 [3.858 MB]  
 
MOOA5 Coherent Harmonic Generation at the DELTA Storage Ring 5
 
  • H. Huck, M. Bakr, M. Höner, S. Khan, R. Molo, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh
    DELTA, Dortmund, Germany
  
  Funding: Supported by DFG, BMBF, and the Federal State NRW
First commissioning results from a new Coherent Harmonic Generation (CHG) source, recently installed at the DELTA storage ring, are presented. DELTA, a university-operated synchrotron light source in Dortmund, has successfully operated an optical klystron as storage-ring FEL. After installing a Ti:sapphire laser system and new undulator power supplies earlier this year, the optical klystron can be seeded using ultrashort pulses at 800 nm wavelength and harmonics thereof during standard operation of the storage ring at 1.5 GeV. The energy modulation induced within a short slice of an electron bunch is converted to a density modulation and the micro-bunched electrons emit ultrashort pulses coherently at harmonics of the initial wavelength. Several meters downstream of the optical klystron, path length differences of the energy-modulated electrons cause a dip in the charge distribution, giving rise to coherent ultrashort THz pulses which are extracted using a dedicated beamline. 		 
slides icon Slides MOOA5 [2.605 MB]  
 
TUOBI1
 SACLA (XFEL/SPring-8) Project -Status of Beam Commissioning-  
 
  • H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  
  The Japanese XFEL at SPring-8, which was named SACLA (Spring-8 Angstrom Compact free electron LAser), was completed in FY2010. After RF full-power aging the beam commissioning of SACLA has been started since 21 February 2011. About one month later, in 23 March a design beam energy of 8 GeV was achieved and a spontaneous undulator radiation of 0.8 Angstrom was observed. The beam commissioning has proceeded smoothly and since the middle of April we have entered to a tuning phase towards SASE lasing. We have already achieved critical beam performances, a peak current of 3 kA and project normalized emittance of a few mm mrad. In the end of May we started fine tuning of the undulator beamline, which is expected as a final hurdle before SASE lasing. This talk will report the beam commissioning overview of SACLA including SASE XFEL performance, key tuning-processes and critical issues for achieving SASE XFEL.  
slides icon Slides TUOBI1 [2.536 MB]  
 
TUOBI2 First Lasing in the Water Window with 4.1nm at FLASH 164
 
  • S. Schreiber
    DESY, Hamburg, Germany
  
  The free-electron laser facility FLASH at DESY, Germany has been upgraded. The electron beam energy has been increased from 1 to 1.25 GeV by adding a 7th superconducting accelerating module. In September 2010, for the first time, lasing in the water window at a fundamental wavelength of 4.1 nm has been achieved. The water window is a wavelength region between 2.3 and 4.4 nm in which water is transparent for light. This remarkable achievement opens the possibility for new class of experiments, especially for biological samples in aqueous solution.  
slides icon Slides TUOBI2 [6.481 MB]  
 
TUOBI3 Operational Experience at LCLS 166
 
  • H. Loos
    SLAC, Menlo Park, California, USA
  
  Funding: *Work supported by DOE contract DE-AC02-76SF00515
The Linac Coherent Light Source (LCLS) X-ray FEL has been operational since 2009 and is delivering soft and hard x-rays to users now in the 4th user run. Reliable operation to deliver x-rays to users, quick machine turn on after shutdowns, and fast configuration changes for the wide range of user requests are particularly important for a facility serving a single user at a time. This talk will discuss procedures to set-up and optimize the accelerator and FEL x-ray beam for user operation. The emphasis will be on the most relevant diagnostics and tuning elements as well as the experience with feedback systems and high level support software to automate FEL operation. 		 
slides icon Slides TUOBI3 [3.074 MB]  
 
TUPA01 Tunable THz-pulse-train Photoinjector 187
 
  • Y.-C. Huang, F.H. Chao, C.H. Chen, H.H. Chen, K.Y. Huang
    NTHU, Hsinchu, Taiwan
  
  Funding: This work is jointly supported by the National Science Council, under Contract NSC97-2112-M-007-018-MY2; the National Synchrotron Radiation Research Center,under Project 955LRF01N.
A THz-pulse-train photoinjector is under construction at the High-energy OPtics and Electronics (HOPE) Laboratory at National Tsinghua University, Taiwan. This photoinjector is believed to be useful for generating high-power THz radiation, as well as for driving or loading a plasma-wave accelerator. A THz laser beat wave with full tunability in its beat frequency is employed to induce the emission of the THz electron pulses from the photoinjector. We show in our study that such a photoinjector is capable of generating periodically bunched MeV electrons with a bunching factor larger than 0.1 at THz frequencies for a total amount of 1 nC charges in a 10-ps time duration. We will also present a driver laser technology that can tune the electron bunch frequency with ease and help the growth of the high harmonics in the bunching spectrum of accelerated electrons. Experimental progress on this photoinjector will be reported in the conference. 		 
 
TUPA02 Development of Material Analysis Facility in KU-FEL 190
 
  • K. Yoshida, M. A. Bakr, Y.W. Choi, H. Imon, K. Ishida, T. Kii, N. Kimura, R. Kinjo, K. Komai, K. Masuda, H. Ohgaki, M. Omer, S. Shibata, K. Shimahashi, T. Sonobe, H. Zen
    Kyoto University, Institute for Advanced Energy, Kyoto, Japan
  
  A mid infrared-free electron laser (MIR-FEL) (5-20 μm) facility (KU-FEL: Kyoto University Free Electron Laser) has been constructed for contributing to researches on energy science at Institute of Advanced Energy, Kyoto University. Up to now 12-14 μm FEL beam has been generated. When MIR-FEL with the wavelength matched to the molecular vibration mode is irradiated to the material, a particular chemical bond in the material will be selectively excited, or dissociated [1]. The selective photochemical reaction can be applied for surface modification and the evaluation of material in biochemistry, chemistry, and solid physics. Therefore, material analysis facility in combination with MIR-FEL is constructed. In the material analysis facility, advanced analysis systems such as photoluminescence measurement system, photoelectron spectroscopy, super centrifuge and high performance liquids chromatography, ICP emission spectroscopy, and high speed atomic force spectroscopy are installed. In this meeting, the development of material analysis facility will be introduced.
[1] Jhon C.Tully, Science, 312(2006) 1004 		 
 
TUPA04 sFLASH - Present Status and Commisioning Results 194
 
  • V. Miltchev, S. Ackermann, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, E. Hass, Th. Maltezopoulos, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach, R. Tarkeshian
    Uni HH, Hamburg, Germany
  • H. Delsim-Hashemi, K. Honkavaara, T. Laarmann, H. Schlarb, S. Schreiber, M. Tischer
    DESY, Hamburg, Germany
  • R. Ischebeck
    Paul Scherrer Institut, Villigen, Switzerland
  
  The free-electron laser in Hamburg (FLASH) was previously being operated in the self-amplified spontaneous emission (SASE) mode, producing photons in the XUV wavelength range. Due to the start-up from noise the SASE-radiation consists of a number of uncorrelated modes, which results in a reduced coherence. One option to simultaneously improve both the coherence and the synchronisation between the FEL-pulse and an external laser is to operate FLASH as an amplifier of a seed produced using high harmonics generation (HHG). An experimental set-up - sFLASH, has been installed to test this concept for the wavelengths below 40 nm. The sFLASH installation took place during the planed FLASH shutdown in the winter of 2009/2010. The technical commissioning, which began in the spring of 2010, has been followed by FEL-characterization and seeded-FEL commissioning in 2011. In this contribution the present status and the sFLASH commissioning results will be discussed.  
 
TUPA06 Seeding Schemes on the French FEL Project LUNEX5 198
 
  • C. Evain, F. Briquez, M.-E. Couprie, M. Labat, A. Loulergue
    SOLEIL, Gif-sur-Yvette, France
  • V. Malka
    LOA, Palaiseau, France
  
  LUNEX5 is a single pass FEL project producing coherent synchrotron radiation with, in a first step, an electron bunch accelerated in conventional RF cavities up to 300 MeV. It is planned to work in a seeded configuration where the longitudinal coherence of the emitted light is improved and the gain length reduced, compared to the SASE configuration (Self-Amplified Spontaneous Emission). Two seeding schemes are considered: High order Harmonic in Gas seeding and EEHG scheme (Echo Enabled Harmonic Generation). Preliminary simulation results indicate that these two schemes permit to reach the saturation below a wavelength of 7 nm, and with less undulator periods for the EEHG scheme. Finally, the feasibility of plasma acceleration based FEL will also be investigated on this facility.  
 
TUPA07 Study of a Silicon Based XFELO for the European XFEL 202
 
  • J. Zemella, D. Novikov, M. Tolkiehn
    DESY, Hamburg, Germany
  • J. Roßbach
    Uni HH, Hamburg, Germany
  • H. Sinn
    European XFEL GmbH, Hamburg, Germany
  
  For the European XFEL in Hamburg three different SASE undulators are planed whose radiation output have a high peak brilliance up to 5.4·1033 photon/s/mm2/mrad2/0.1% BW at wavelengths down to below 5·10-11 m. The radiation pulses are nearly fully coherent in transverse direction but have a poor longitudinal coherence of about 0.3 fs. Several schemes were developed to get a better longitudinal coherence. In this paper an X-ray Free Electron Laser Oscillator is presented whose radiation output is nearly fully coherent in all directions. In contrast to previous schemes it is based on Silicon crystals rather than Diamond. The use of Silicon has the advantage of the availability of perfect crystals in nearly any size and crystal geometry but with a lower reflectivity and heat conduction than Diamond. To overcome the lower round-trip reflectivity of a Silicon cavity a longer undulator has to be used to get a sufficiently large gain. To reduce the heat load an extremely asymmetric crystal geometry has to be used to enlarge the beam spot on the crystal.  
 
TUPA08 The Control System for CAEP FEL 206
 
  • D. Zhang, M. Li, H.B. Wang, X. Yang
    CAEP/IAE, Mianyang, Sichuan, People's Republic of China
  
  It describes a control system of CAEP Free Electron Laser (FEL), which is a distributed control system based on EPICS and Visual C++6.0. EPICS is popular in large accelerator laboratories in the world. It is a software toolkit for building process control system for a wide variety of experiment and industrial applications. The software tools in the kit provide independent and expandable modules for system configuration, distributed process control, run-time database, alarm manager, etc. It gives detailed description of the magnet power supply system , beam diagnostic system, including the hardware structure and software design. Other subsystems are also described in the paper. The control system has standard module, interoperability, and repeatability are available. The control system is simple direct, and stable.  
 
TUPA09 LUNEX5: A FEL Project Towards the Fifth Generation in France 208
 
  • M.-E. Couprie, C. Benabderrahmane, F. Briquez, J. Daillant, J.-C. Denard, C. Evain, P. Eymard, F. Ferrari, J.-M. Filhol, M. Labat, A. Loulergue, P. Marchand, C. Miron, P. Morin, F. Polack
    SOLEIL, Gif-sur-Yvette, France
  • S. Bielawski, C. Szwaj
    PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
  • B. Carré
    CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
  • N. Delerue, R. Roux, A. Variola
    LAL, Orsay, France
  • G. Lambert, V. Malka, A. Rousse
    LOA, Palaiseau, France
  • J. Lüning
    CCPMR, Paris, France
  
  LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short intense and coherent pulses in the soft X rays region (down to 7 nm on the fifth harmonic). It comprises a free electron laser in the seeded configuration (High order Harmonic in Gas seeding and Echo Enable Harmonic Generation) using a conventional linear accelerator of 300 MeV. The FEL beamline including 15 m of in vacuum (potentially cryogenic undulators) of 15 and 30 mm period is designed so as to also accommodate a Laser Wake Field Accelerator (LWFA) ranging from 0.3 to 1 GeV, relying on electron beam parameters produced and accelerated by either the 60 TW laser of LOA or by the 10 PW APOLLON laser of ILE. After the completion and testing of the FEL with the conventional accelerator installed inside the SOLEIL booster inner area, the FEL line can be transported to a LWFA. A laser could alternatively be implemented at SOLEIL for starting testing the principles of a fifth generation light source.  
 
TUPA11 Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II 212
 
  • T. Tanikawa
    PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
  • M. Adachi, M. Katoh, J. Yamazaki, H. Zen
    UVSOR, Okazaki, Japan
  • M. Hosaka, Y. Taira, N. Yamamoto
    Nagoya University, Nagoya, Japan
  
  Light source by using a laser seeding technique are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region, and also in generating CH with variable polarizations in deep UV [1]. In previous conferences, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependencies, and injection laser power dependencies on VUV CHs [2]. This time we have successfully observed saturation on CHs intensities and have found some interesting phenomena, which are the necessary power of injection laser to achieve the saturation of CHG is different in different harmonic orders, and the CH intensity is oscillated in deep saturated regime. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations.
[1] M. Labat, et al., Phys. Rev. Lett. 101 (2008) 164803
[2] T. Tanikawa, et al., Prc. 1st Int. Particle Accelerator Conf., Kyoto, 2010.
[3] T. Tanikawa, et al., Appl. Phys. Express 3 (2010) 122702 		 
 
TUPA13 Present Status and Future Prospects of Project on Utilizing Coherent Light Sources for User Experiments at UVSOR-II 215
 
  • H. Zen, K. Hayashi, S.I. Kimura, E. Nakamura, J. Yamazaki
    UVSOR, Okazaki, Japan
  • M. Adachi, M. Katoh
    Sokendai - Okazaki, Okazaki, Aichi, Japan
  • M. Hosaka, Y. Takashima, N. Yamamoto
    Nagoya University, Nagoya, Japan
  • T. Takahashi
    Kyoto University, Research Reactor Institute, Osaka, Japan
  
  Funding: Quantum Beam Technology Program supported by JST/MEXT (Japan)
We have been intensively developing coherent light sources utilizing electron bunches in the storage ring, UVSOR-II, by adding some external components to the ring. After successful generation of coherent synchrotron radiation (CSR) in THz range* and coherent harmonic generation (CHG) in DUV range** by using an intense driving laser, a 5-year new research project named as Quantum Beam Technology Program has been started from FY2008. The project includes introduction of new driving laser system, dedicated undulators and beamlines, and aims at utilizing those coherent radiations for user experiments. The new driving laser system has been installed last year. The undulators and beamlines are now under construction. Installation of those components will be finished before the conference. In the conference, we will report on the present status of system development and future plan of application experiments.
*M. Shimada et al., Japanese Journal of Applied Physics, vol. 46, pp. 7939-7944 (2007).
**M. Labat et al., European Physical Journal D, vol. 44, pp. 187-200 (2007). 		 
 
TUPA14 Conceptual Layout of a New Short-Pulse Radiation Source at DELTA Based on Echo-Enabled Harmonic Generation 219
 
  • R. Molo, M. Bakr, H. Huck, M. Höner, S. Khan, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh
    DELTA, Dortmund, Germany
  
  As an upgrade of the present coherent harmonic generation (CHG) source at the DELTA storage ring, the installation of an additional undulator to implement and study the echo-enabled harmonic generation (EEHG) scheme [1] is planned. Compared to the CHG scheme, EEHG allows to produce radiation of shorter wavelengths, thus reaching more relevant absorption edges. In order to avoid dispersive distortions, all undulators should be placed along a straight line. This requires to increase the length of the present straight section by rearranging several magnets and vacuum components as well as a significant modification of the storage ring optics.
[1] G. Stupakov, PRL 102, 074801 (2009) 		 
 
TUPA15 Status of the SwissFEL Facility at the Paul Scherrer Institute 223
 
  • S. Reiche
    Paul Scherrer Institut, Villigen, Switzerland
  
  SwissFEL is a X-ray Free-electron Laser facility with a soft and hard X-ray beamline, planned to be built at the Paul Scherrer Institute and to be finished in 2016. It covers the wavelength range from 1 Angstrom to 7 nm. In addition to the SASE operation at the entire wavelength, seeding is foreseen down to a wavelength of 1 nm. We report in this presentation the status of the SwissFEL facility, including the layout, the timeline of the project, the different operation modes and the expected performance of the FEL beamlines.  
 
TUPA16 A Simple Spectral Calibration Technique for Terahertz Free Electron Laser Radiation 227
 
  • G. Berden
    FOM Rijnhuizen, Nieuwegein, The Netherlands
  • R.T. Jongma, F.J.P. Wijnen, H.J.F.M. van der Pluijm
    Radboud University, Nijmegen, The Netherlands
  
  Upconversion of terahertz FEL radiation to the optical spectral region allows the use of highly efficient optical detection techniques (such as photo-diodes, spectrometers, array detectors) for sensitive characterization of the THz radiation. For online monitoring of the FEL radiation, a small fraction of the radiation is upconverted to the near-infrared region using a ZnTe crystal and a narrow bandwidth continuous wave (cw) laser operating at 780 nm. The ZnTe crystal does not need any angle tuning, and allows the efficient conversion of all wavelengths longer than 100 μm. Because the upconversion laser is cw, the FEL radiation is automatically temporally synchronized. Furthermore, its narrow bandwidth ensures that the spectral properties of the upconverted light can be directly related to the FEL radiation. In this contribution we demonstrate the upconversion technique for the spectral characterization of THz pulses of FELIX. In the near future, the upconversion spectrometer will be used as online wavelength spectrometer for FLARE, the THz FEL under construction at the Radboud University in Nijmegen which will operate in the 100-1500 μm spectral range.  
 
TUPA18 Considerations about Optics-Based Phase-Space Measurements at Linac-Based FEL Facilities 231
 
  • B. Beutner, E. Prat
    Paul Scherrer Institut, Villigen, Switzerland
  
  Transverse phase-space measurements are an essential issue for FEL facilities. After acceleration in the injector the energy is sufficiently high to bring the beam out of the space-charge dominated regime, thus optics based techniques are favored. The beam moments at a given point in the machine are fitted to beam size values downstream with different phase advances between the reconstruction and the measurement point. Two principle methods are possible. Beam sizes can be measured at different positions in the beam line keeping the lattice unchanged. The other possibility is to actively change quadrupoles and use only one screen. These two techniques are compared in this paper including monte-carlo studies on systematic errors using the SwissFEL Injector Test Facility as an example. On the other hand beam size measurements, which are done with OTR screens at SwissFEL Injector Test Facility, are critical for such measurements. An analysis of these images can be an issue, especially if the signal-to-noise is compromised for example by low bunch charges. This study on the phase-space measurement techniques will be completed by a discussion of the image post-processing procedures.  
 
TUPA19 Operation Modes and Longitudinal Layout for the SwissFEL Hard X-Ray Facility 235
 
  • B. Beutner, S. Reiche
    Paul Scherrer Institut, Villigen, Switzerland
  
  The SwissFEL facility will produce coherent, ultrabright, and ultra-short photon pulses covering a wavelength range from 0.1 nm to 7 nm, requiring an emittance between 0.18 to 0.43 mm mrad at bunch charges between 10pC and 200pC. In nominal operation continous changes between these two bunch charges will be offered to the users in order to allow them an individual tradeoff between photon power and pulse length depending on thier requirements. The facility consists of an S-band rf-gun and booster and a C-band main linac, which accelerates the beam up to 5.8 GeV. Two compression chicanes will provide a nominal peak current of about 1-3 kA depending on the charge. In addition special operation setups for ultra short single mode photon pulses and large bandwidth will be availiable to users. In this paper different operation modes including nominal operation as well as special modes are presented and discussed in terms of photon performance and machine stability requiremnts.  
 
TUPA20 Third Harmonic Lasing in the NIJI-IV Storage Ring Free-Electron Lasers 239
 
  • N. Sei, H. Ogawa, K. Yamada
    AIST, Tsukuba, Ibaraki, Japan
  
  Funding: This study was financially supported by the Budget for Nuclear Research of the Ministry of Education, Culture, Sports, Science and Technology.
Studies of the storage ring free electron lasers (SRFELs) and their application experiments have progressed with the compact storage ring NIJI-IV at the National Institute of Advanced Industrial Science and Technology. We achieved SRFEL oscillations on the third harmonic in the near-infrared region*. The measured gain and power of the third-harmonic FEL were consistent with those obtained by the storage ring FEL theory. The measured linewidth of the third-harmonic FEL was less than that of the fundamental FEL, and its pulse width was wider than that of the fundamental FEL. Our studies would be useful for a study of x-ray FEL oscillations with a resonator. In this presentation, characteristics of the higher-harmonic FELs with the NIJI-IV will be discussed in detail.
*: N. Sei et al., J. Phys. Soc. Jpn. 79 (2010) 093501. 		 
 
TUPA21 Optical Synchronization of the SwissFEL 250 Mev Test Injector Gun Laser With the Optical Master Oscillator 243
 
  • V.R. Arsov, S. Hunziker, M.G. Kaiser, V. Schlott
    Paul Scherrer Institut, Villigen, Switzerland
  • F. Löhl
    CLASSE, Ithaca, New York, USA
  
  Funding: This work is partly supported by IRUVX-PP, an EU co-funded project under FP7 (Grant Agreement 211285)
The SwissFEL gun laser stability is crucial for stable SASE operation in the hard X-ray regime. In 10 pC mode in which sub-10 fs photon pulses will be delivered for the users, the gun laser arrival time jitter at the cathode shouldn't exceed 30 fs (rms). In the present design it is foreseen that the gun oscillator is optically stabilized. It is also necessary to check the stability of the combination laser oscillator and transfer line with an optical reference. For this, the Ti:Sa oscillator was used as a master laser and its pulses were delivered through a ca. 5 m long free space transfer line to optically synchronize an Er-fiber oscillator via two color balanced optical cross correlator with a BBO crystal. The two lasers were placed on different optical tables, which didn't have a mechanical connection through the transfer line. Stable optical lock for at least 60 minutes was demonstrated with an in-loop stability in the range 3.7-17.6 fs. In the range 10 Hz-1 kHz the phase noise stability of the optically locked Er-fiber oscillator varied between 76.5 fs and 118.5 fs rms, 76 fs of which was the contribution of the 1.5 GHz PLO, to which the Ti:Sa oscillator was RF-locked. 		 
 
TUPA22 FLASH II: A Project Update 247
 
  • B. Faatz, V. Ayvazyan, N. Baboi, V. Balandin, W. Decking, S. Düsterer, H.-J. Eckoldt, M. Felber, J. Feldhaus, N. Golubeva, K. Honkavaara, M. Körfer, T. Laarmann, A. Leuschner, L. Lilje, T. Limberg, D. Nölle, F. Obier, A. Petrov, E. Plönjes, K. Rehlich, H. Schlarb, B. Schmidt, M. Schmitz, S. Schreiber, H. Schulte-Schrepping, J. Spengler, M. Staack, K.I. Tiedtke, M. Tischer, R. Treusch, M. Vogt, H.C. Weddig
    DESY, Hamburg, Germany
  • J. Bahrdt, R. Follath, K. Holldack, A. Meseck, R. Mitzner
    HZB, Berlin, Germany
  • J. Chen, H.X. Deng, B. Liu
    SINAP, Shanghai, People's Republic of China
  • M. Drescher, A. Hage, V. Miltchev, R. Riedel, J. Rönsch-Schulenburg, J. Roßbach, M. Schulz, A. Willner
    Uni HH, Hamburg, Germany
  • M. Gensch
    HZDR, Dresden, Germany
  • F. Tavella
    HIJ, Jena, Germany
  
  FLASH II is an extension of the existing FLASH facility by an undulator line and an experimental Hall of which the construction will start before the end of the year. Aims are to increase beamtime for users and implement HHG seeding for the longer wavelength range from 10 to 40 nm at a reduced repetition rate of 100 kHz. Additional seeding schemes are under discussion as a future option. We will present a progress report of FLASH II.  
 
TUPA25 EEHG Seeding Design for SwissFEL 251
 
  • E. Prat, S. Reiche
    Paul Scherrer Institut, Villigen, Switzerland
  
  The SwissFEL facility, planned at the Paul Scherrer Institute, is based on the SASE operation of a hard (1-7 Å) and a soft (7-70 Å) X-ray FEL beamline. In addition, seeding is foreseen for the soft X-ray beamline, down to a wavelength of 1 nm. The Echo-Enabled Harmonic Generation (EEHG) scheme, which utilizes a rather complex manipulation of the longitudinal phase space distribution of the electron beam to generate high harmonic density modulation, is presently considered the first choice for seeding at SwissFEL. However, EEHG is highly demanding and complex at 1 nm, therefore other strategies like High-Harmonic Generation (HHG) and self-seeding are also evaluated. This paper presents the current status of the seeding design for SwissFEL based on EEHG.  
 
TUPA26 Beam Commissioning of the SACLA Accelerator 255
 
  • T. Hara, H. Tanaka, K. Togawa
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • T. Hasegawa, Y. Kano, T. Morinaga, Y. Tajiri, S. Tanaka, R. Yamamoto
    SES, Hyogo-pref., Japan
  
  The commissioning of the X-ray FEL facility of SPring-8, which is named SACLA (SPring-8 Angstrom Compact free-electron LAser), has been started since February 2011. During the beam commissioning, beam diagnostic system and control system are also tested and improved to enable fine tuning of the machine. The position and energy of the electron beam shows excellent stability and the fault rate of the RF system per hour is currently decreased to less than one. Since coherent OTR hinders the beam profile measurement after full bunch compression, several OTR screens are changed to YAG screens with a partial mask installed in its optics. So far the electron beam is successfully accelerated up to 8 GeV and spontaneous emission was observed with weak bunch compression. For the lasing, the RF parameters are first set so that a 0.1 nC bunch is compressed to 30 fs to obtain 3 kA beam current. Then the transverse beam profile is adjusted to match the focusing condition of the undulator section. In the conference, we will report the beam commissioning of the SACLA accelerator.  
 
TUPA30 Multi-stage Bunch Compression at the Japanese X-ray Free Electron Laser SACLA 259
 
  • K. Togawa, T. Hara, H. Tanaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  
  The Japanese x-ray free electron laser facility, named as SACLA (Spring-8 Angstrom Compact free electron LAser), was constructed at SPring-8 site. After finishing installation of all accelerator components, beam commissioning started on February 21, 2011. In order to produce a high-quality electron beam with extremely low-emittance and high-peak current, SACLA adopts multi-stage bunch compression scheme that uses an injector velocity bunching system and following three magnetic bunch compressors. A design bunch compression factor reaches to 3000, namely the peak current of 1 A at the CeB6 thermionic gun increases up to 3 kA at the exit of the final bunch compressor at 1.4 GeV. A longitudinal bunch profile was measured using a transverse beam deflector cavity that was located at the exit of the final bunch compressor. After step-by-step beam commissioning from the injector, we have accomplished a peak current of 3 kA and a short bunch length less than 100 fs. In this conference, we will report the commissioning of the multi-stage bunch compression system at SACLA.  
 
TUPA31 Transverse Phase-space Studies for the Electron Optics at the Direct XUV-seeding Experiment at FLASH (DESY) 263
 
  • S. Ackermann, V. Miltchev, J. Roßbach
    Uni HH, Hamburg, Germany
  
  Funding: BMBF under contract No. 05 ES7GU1 - DFG GrK 1355 - Joachim Herz Stiftung
During the shutdown in 2009/2010 the Free-Electron Laser in Hamburg (FLASH) was upgraded with an experiment to study the high-gain-FEL amplification of a laser ‘‘seed'' from a high harmonic generation (HHG) source in the XUV wavelength range-sFLASH. For an optimal FEL-performance knowledge of the electron bunch transverse phase-space as well as control on the electron optics parameters is required. In this contribution the technical design, the present status and the commissioning results of the sFLASH diagnostic stations will be presented. The possible options for transverse phase space characterization will be discussed. An emphasis will be put on the error analysis and the tolerance estimations. Analysis of experimental data from both OTR-screens and wire scanners will be presented and discussed. 		 
 
TUPB04 Status of the FEL User Facility FLASH 267
 
  • S. Schreiber, B. Faatz, J. Feldhaus, K. Honkavaara, R. Treusch, M. Vogt
    DESY, Hamburg, Germany
  
  The free-electron laser FLASH at DESY, Germany has been upgraded in 2010 and extended its wavelength range down to 4.1 nm. Beside the increased electron beam energy to 1.25 GeV, an other important upgrade is the installation of 3.9 GHz superconducting RF cavities in the injector. They are used to shape the longitudinal electron beam phase space. Now, significantly more FEL radiation energy per pulse of up to several hundreds of microjoules are achieved. Moreover, the system allows to adjust the FEL pulse length, from long pulses of more than 200 fs to short pulses well below 50 fs. The upgraded FLASH facility shows an excellent performance in terms of FEL radiation quality and stability as well as in reliability of operation. The 3rd user period started as scheduled in September 2010.  
 
TUPB06 Design of Shanghai High Power THz -FEL Source 271
 
  • J.H. Dai, Z.M. Dai, H.X. Deng
    SINAP, Shanghai, People's Republic of China
  
  Funding: This work was supported by the CAS (29Y029011) and Shanghai NSF (09JC1416900).
An ERL-based THz source with kW average power is proposed in Shanghai, which will serve as an effective tool in material and biological sciences. In this paper, the physical design of two FEL oscillators, in the frequency range of 2~10THz and 0.5~2THz respectively, are given. In the design strategy, three dimensional, time-dependent numerical modelling of GENESIS and paraxial optical propagation code (OPC) are used. The performances of THz oscillator, the detuning effects and the influence of the THz radiation to the electron beam are presented. 		 
 
TUPB09 Free Electron Lasers in 2011 274
 
  • J. Blau, K. R. Cohn, W.B. Colson, C.M. Pogue, M. Stanton, A.I. Yilmaz
    NPS, Monterey, California, USA
  
  Funding: This work has been supported by the Office of Naval Research.
Thirty-five years after the first operation of the short wavelength free electron laser (FEL) at Stanford University, there continue to be many important experiments, proposed experiments, and user facilities around the world. Properties of FELs in the infrared, visible, UV, and x-ray wavelength regimes are tabulated and discussed. 		 
 
TUPB10 Echo Seeding Experiment at FLASH 279
 
  • K.E. Hacker, S. Khan
    DELTA, Dortmund, Germany
  • G. Angelova Hamberg, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
  • A. Azima
    Uni HH, Hamburg, Germany
  • P. Salén, P. van der Meulen
    FYSIKUM, AlbaNova, Stockholm University, Stockholm, Sweden
  • H. Schlarb
    DESY, Hamburg, Germany
  
  Using the two perpendicularly oriented undulators and chicanes developed for an optical replica synthesizer (ORS) experiment together with the sFLASH 800 nm seed laser, radiator undulators and diagnostics, an echo seeding experiment will be conducted at FLASH in January 2012. For this experiment, the 800 nm laser pulse will be transported with a new, 12 meter long, in-vacuum laser transport line. On an in-vacuum optical breadboard, the 800 nm pulse will then be tripled in beta-BBO nonlinear crystals. The laser pulse will then be split longitudinally using a birefringent alpha BBO crystal into two pulses with orthogonal polarization states corresponding to the orthogonal orientations of the ORS undulators. These pulses will be focused to a 400 μm waist between the undulators with a Galileo telescope and steered with 4 motorized mirrors onto the electron beam axis in the ORS undulator section. The hardware layout and simulations of the echo seeding parameters will be described.  
 
TUPB12 Combined Optimization of a Linac-based FEL Light Source Using a Multiobjective Genetic Algorithm 283
 
  • C. F. Papadopoulos, D. Filippetto, G. Penn, J. Qiang, F. Sannibale, M. Venturini
    LBNL, Berkeley, California, USA
  
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
We report on the development status and preliminary results of a combined optimization scheme for a linac-based, high repetition rate, soft X-ray FEL. The underlying model includes the injector and linac parts of the machine, and the scheme will integrate the design process of these components toward the optimization of the FEL performance. For this, a parallel, multi-objective genetic algorithm is used. We also discuss the beam dynamics considerations that lead to the choices of objectives, or figure-of-merit beam parameters, and describe numerical solutions compatible with the requirements of a high repetition rate user facility. 		 
 
TUPB13 Beam Dynamics Considerations for APEX a High Repetition Rate Photoinjector 287
 
  • C. F. Papadopoulos, D. Filippetto, F. Sannibale, R.P. Wells
    LBNL, Berkeley, California, USA
  
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
The Advanced Photoinjector EXperiment is a photo-injector project at Lawrence Berkeley National Lab, designed to test the performance of a high repetition rate (>1 MHz) VHF normal conducting electron gun. The requirements of high beam brightness, as well as significant compression at low energy determine the base setup for the injector transport line. The beam dynamics considerations for a high repetition rate injector are discussed and the potential to use multiple bunch charges that require different tunings of the base setup is explored. 		 
 
TUPB14 Design Studies for Cascaded HGHG and EESHG Experiments Based on SDUV-FEL 291
 
  • C. Feng, J.H. Chen, H.X. Deng, Q. Gu, D. Wang, M. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  
  Funding: This work was supported by the National Natural Science Foundation of China (Grant No. 10935011).
As a test facility for modern FEL R&D, The Shanghai deep ultra-violent FEL (SDUV-FEL) is now under upgrading for the cascading two stage of HGHG experiment. It is found that this upgraded facility will be also well suited for the echo-enabled staged harmonic generation (EESHG) scheme demonstration. With help of 3D simulation codes, design studies on the FEL physics for both these two schemes based on the upgraded SDUV-FEL is presented in this paper. 		 
 
TUPB18 Preliminary Studies of a Possible Normal-conducting Linac Option for the UK's New Light Sourc 295
 
  • R.P. Walker, C. Christou, J.H. Han
    Diamond, Oxfordshire, United Kingdom
  • R. Bartolini
    JAI, Oxford, United Kingdom
  
  A Conceptual Design Report for a major new soft-Xray light source facility for the UK, the New Light Source (NLS), based on high repetition rate free-electron lasers driven by a cw superconducting L-band linac was completed in May 2010. While the science case for such a facility was considered very strong, due to funding restrictions the NLS design project, supported by STFC and Diamond Light Source, was terminated after completion of the CDR. Since then we have been giving some preliminary considerations to a possible alternative option for the NLS which could provide similar performance but at reduced repetition rate, and potentially reduced cost, based on normal conducting technology. In this report we summarise the work done so far, including possible operating parameters and performance, as well as an assessment of relative costs of different frequency options.  
 
TUPB19 Design and Beam Dynamics Simulation for the Photoinjector of Shanghai Soft X-ray Free Electron Laser Test Facility 299
 
  • W.-H. Huang, Q. Du, Y.-C. Du, H.J. Qian, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
  
  The Shanghai soft X-ray free electron laser test facility (SXFEL) aims to radiate at 9 nm based on the cascaded high-gain harmonic-generation (HGHG) scheme. The photoinjector of SXFEL consists of Ti-sapphire driving laser system, S-band photocathode RF gun, booster linacs, laser heater, beam diagnostics and matching section. It will produce ~130 MeV electron beam in high charge regime (~0.5 nC) with a baseline transverse emittance of 1.5 mm-mrad. This paper will present basic designs and beam dynamics simulations of SXFEL photoinjector.  
 
TUPB21 Conceptual Design of a High Brightness and Fully Coherent Free Electron Laser in VUV Regime 302
 
  • D. Wang, T. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • X.M. Yang
    DICP, Dalian, People's Republic of China
  
  In this paper we propose a new generation light source based on the High Gain Harmonic Generation (HGHG) Free Electron Laser (FEL) for scientific researches. This facility is designed to cover wavelength range from 50 nm to 150 nm with high brightness and full coherence by using the continuously tuning Optical Parametric Amplifier (OPA) seed laser system and variable gap undulators.  
 
TUPB22 THz Pump and X-Ray Probe Development at LCLS 304
 
  • A.S. Fisher, H.A. Durr, J.C. Frisch, M. Fuchs, S. Ghimire, J.J. Goodfellow, A. Lindenberg, H. Loos, M. Petree, D.A. Reis
    SLAC, Menlo Park, California, USA
  • D.R. Daranciang
    Stanford University, Stanford, California, USA
  
  Funding: This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under contract DE-AC02-76SF00515.
We report on measurements of broadband, intense, coherent transition radiation at terahertz frequencies, generated as the highly compressed electron bunches in LCLS pass through a thin metal foil. The foil is inserted at 45 degrees to the electron beam, 30 m downstream of the undulator. The THz emission passes downward through a diamond window to an optical table below the beamline. A fully compressed 350-pC bunch produces over 0.5 mJ in a nearly half-cycle pulse of 50 fs FWHM with a spectrum peaking at 10 THz. We estimate a peak field at the focus of over 2.5 GV/m. Electro-optic measurements using a newly installed 20-fs Ti:sapphire oscillator will be presented. We will discuss plans to add a THz pump and x-ray probe setup, in which a thin silicon crystal diffracts FEL light onto the table with adjustable time delay from the THz. This will provide a rapid start to user studies of materials excited by intense single-cycle pulses and will serve as a step toward a THz transport line for LCLS-II. 		 
 
TUPB28 Considerations for a Light Source Test Facility at Daresbury Laboratory 308
 
  • N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.A. Clarke, D.J. Dunning, J.W. McKenzie
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  This paper considers design options for a dedicated light source test facility at Daresbury Laboratory in the United Kingdom. The facility layout should be easily configurable to enable exploration of many research themes including: ultrashort pulse generation; seeding and harmonic generation; direct laser/electron beam interactions; compact FELs; high brightness photoinjectors. The strategy is to develop and demonstrate novel concepts and expertise relevant to future generations of FEL-based light sources, significantly shortening the R&D phase of any future light source in the UK.  
 
TUPB29 Status of the FERMI@Elettra Project 312
 
  • M. Svandrlik, E. Allaria, E. Busetto, C. Callegari, D. Cocco, P. Craievich, I. Cudin, G. D'Auria, M.B. Danailov, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, M. Ferianis, R. Gobessi, E. Karantzoulis, M. Kiskinova, M. Lonza, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, M. Trovò, A. Vascotto, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando
    ELETTRA, Basovizza, Italy
  
  FERMI@Elettra is a seeded FEL user-facility covering the wavelength range from 100 nm (12 eV) to 4 nm (310 eV) located next to the third-generation synchrotron light source Elettra in Trieste, Italy. The facility is based on a normal conducting linac and covers the wavelength range with two FEL lines, FEL-1 and FEL-2. A photon distribution and diagnostic system transports the photons from the end of the two FEL lines to three experimental stations. Beneficial occupancy of the new undulator hall and experimental hall was given end of Summer 2010 when also all auxiliary systems were made available. The installation of the machine is now almost completed; commissioning of the linac has started in parallel to the installation activities and now commissioning of FEL-1 is in a well advanced status. The first seeded lasing from FEL-1 was actually observed in December 2010 and first experiments are starting in 2011. In this paper an overview of the facility will be given as well as the general status of installation and commissioning and a perspective into future developments and user programs.  
 
TUPB30 Status of the Fritz Haber Institute THz FEL 315
 
  • W. Schöllkopf, W. Erlebach, S. Gewinner, H. Junkes, A. Liedke, G. Meijer, W.Q. Zhang, G. von Helden
    FHI, Berlin, Germany
  • H. Bluem, V. Christina, M.D. Cole, J. Ditta, D. Dowell, R. Lange, J.H. Park, J. Rathke, T. Schultheiss, A.M.M. Todd, L.M. Young
    AES, Princeton, New Jersey, USA
  • S.C. Gottschalk
    STI, Washington, USA
  • K. Jordan
    Kevin Jordan PE, Newport News, Virginia, USA
  • U. Lehnert, P. Michel, W. Seidel, R. Wünsch
    FZD, Dresden, Germany
  
  The THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4 m long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2 m long cavity with a 1-d waveguide for the optical mode is used for the far-IR. A key aspect of the accelerator performance is low longitudinal emittance, < 50 keV-psec, at 200 pC bunch charge and 50 MeV from a gridded thermionic electron source. We utilize twin accelerating structures separated by a chicane to deliver the required performance over the < 20 - 50 MeV energy range. The first structure operates at near fixed field while the second structure controls the output energy, which, under some conditions, requires running in a decelerating mode. "First Light" is targeted for the centennial of the FHI in October 2011 and we will describe progress in the commissioning of this device. Specifically, the measured performance of the accelerated electron beam will be compared to design simulations and the observed matching of the beam to the mid-IR wiggler will be described.  
 
WEOBI1
 FEL Commissioning at FERMI@Elettra  
 
  • E. Allaria, P. Craievich, S. Di Mitri, W.M. Fawley, L. Fröhlich, G. Penco, C. Spezzani, M. Trovò
    ELETTRA, Basovizza, Italy
  • G. De Ninno, S. Spampinati
    University of Nova Gorica, Nova Gorica, Slovenia
  • L. Giannessi
    ENEA C.R. Frascati, Frascati (Roma), Italy
  
  The FERMI@Elettra Free Electron Laser (FEL) produced the first coherent photons in December 2010 at the end of the first commissioning phase. Starting from February 2011 the commissioning has continued, leading to an improvement of the FEL performance. In agreement with to the design, FEL-1, the first of the two FERMI free electron lasers, has been producing coherent FEL pulses in the 60 to 20 nm wavelength range. Benefits of the seeded scheme adopted for FERMI have been immediately evident also in the case of a non-optimized electron beam.  
slides icon Slides WEOBI1 [4.528 MB]  
 
WEOB3
 Seeding Experiments at SPARC  
 
  • M. Labat, F. Briquez, M.-E. Couprie
    SOLEIL, Gif-sur-Yvette, France
  • D. Alesini, M. Bellaveglia, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, L. Ficcadenti, A. Gallo, G. Gatti, A. Ghigo, E. Pace, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
  • A. Bacci, V. Petrillo, A.R. Rossi, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • M. Bougeard, B. Carré, D. Garzella
    CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • F. Ciocci, G. Dattoli, M. Del Franco, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia, I.P. Spassovsky, V. Surrenti
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • L. Cultrera
    CLASSE, Ithaca, New York, USA
  • D. Filippetto
    LBNL, Berkeley, California, USA
  • F. Frassetto, L. P. Poletto
    LUXOR, Padova, Italy
  • G. Lambert
    LOA, Palaiseau, France
  • G. Marcus, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • M. Migliorati, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma, Italy
  • J.V. Rau
    ISM-CNR, Rome, Italy
  • M. Serluca
    INFN-Roma, Roma, Italy
  • C. Vicario
    PSI, Villigen PSI, Switzerland
  
  The SPARC FEL amplifier has been configured as a single stage HGHG FEL with a modulator and a radiator operating at the second harmonic. The HGHG cascade has been seeded with harmonics generated in a gas cell where a Ti:Sa laser pulse of 120 fs of duration is converted into higher harmonics. The cascaded FEL configuration obtained by tuning the undulator gaps has been studied by varying the number of modulators and radiators to optimize the conversion efficiency. The process of harmonic generation in a free electron laser operating in superradiant regime has been also analysed. Harmonic generation is expected to be efficient because of the quasi steady-state distribution of the e-beam phase space predicted in this regime. Harmonics up to the 11th have been experimentally observed.  
slides icon Slides WEOB3 [5.198 MB]  
 
WEOB4
 Demonstration of High Harmonics from Echo-enabled Harmonic Generation with Small Energy Modulation  
 
  • D. Xiang
    SLAC, Menlo Park, California, USA
  
  Funding: This work was supported by the US DOE under Contract No. DE-AC02-76SF00515.
5th harmonic from EEHG has been observed at SLAC's NLCTA [1], yet with energy modulation amplitudes about 80 times larger than beam slice energy spread. While the experiment demonstrated that long-term memory of phase space correlations could be preserved, it was incapable of providing insight into the underlying physics of EEHG that high harmonics can be generated with small energy modulation. Here we report generation of the 7th harmonic from EEHG technique in realistic scenarios where the laser energy modulation is comparable to the beam slice energy spread. The experiment demonstrates the supreme up-frequency conversion efficiency of EEHG technique and indicates that scaling to X-ray wavelength may be possible.
[1] D. Xiang et al., Phys. Rev. Lett, 105, 114801 (2010). 		 
slides icon Slides WEOB4 [0.981 MB]  
 
WEOCI1 Beam Line Commissioning of a UV/VUV FEL at Jefferson Lab 326
 
  • S.V. Benson, G.H. Biallas, K. Blackburn, D.B. Bullard, J.L. Coleman, C. Dickover, D. Douglas, F.K. Ellingsworth, P. Evtushenko, C.W. Gould, J.G. Gubeli, D. Hardy, C. Hernandez-Garcia, K. Jordan, J.M. Klopf, J. Kortze, R.A. Legg, M. Marchlik, S.W. Moore, G. Neil, T. Powers, D.W. Sexton, M.D. Shinn, C. Tennant, R.L. Walker, G.P. Williams, F.G. Wilson, S. Zhang
    JLAB, Newport News, Virginia, USA
  • C. Clavero
    The College of William and Mary, Williamsburg, USA
  
  Funding: Work supported by U.S. DOE Contract DE-AC05-84-ER40150, Air Force Office of Scientific Research, DOE Basic Energy Sciences, Office of Naval Research, and the Joint Technology Office.
Many novel applications in photon sciences require very high source brightness and/or short pulses in the vacuum ultra-violet (VUV). Jefferson Lab has commissioned a UV oscillator with high gain and has transported the third harmonic of the UV to a user lab. The experimental performance of the UV FEL is much better than simulated performance in both gain and efficiency. This success is important for efforts to push towards higher gain FELs at short wavelengths where mirrors absorb strongly. We will report on efforts to characterize the UV laser and the VUV coherent harmonics as well as designs to lase directly in the VUV wavelength range. 		 
slides icon Slides WEOCI1 [3.331 MB]  
 
WEOCI2
 Ultrashort Single Spike Pulse Generation at the SPARC Test Facility  
 
  • D. Filippetto
    LBNL, Berkeley, California, USA
  • A. Bacci, M. Bellaveglia, M. Castellano, E. Chiadroni, L. Cultrera, G. Di Pirro, M. Ferrario, L. Ficcadenti, A. Gallo, G. Gatti, E. Pace, B. Spataro, C. Vaccarezza, C. Vicario
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • F. Ciocci, G. Dattoli, M. Del Franco, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia, I.P. Spassovsky, V. Surrenti
    ENEA C.R. Frascati, Frascati (Roma), Italy
  • F. Frassetto, L. P. Poletto
    LUXOR, Padova, Italy
  • M. Moreno, M. Serluca
    INFN-Roma, Roma, Italy
  • A. Mostacci
    Rome University La Sapienza, Roma, Italy
  • V. Petrillo, A.R. Rossi
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • J.V. Rau, V. Rossi Albertini
    ISM-CNR, Rome, Italy
  
  We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a Self Amplified Spontaneous Emission mode Free Electron Laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. Longitudinal phase space rotation via velocity bunching is used to generate the energy chirp, which also increases the peak current and the FEL performances. An increase of more than one order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.  
slides icon Slides WEOCI2 [16.008 MB]  
 
WEOC3
 Experimental Study of FEL Power Scaling in the Storage Ring FEL  
 
  • Y.K. Wu, B. Jia, J.Y. Li, S.F. Mikhailov, V. Popov, W. Wu
    FEL/Duke University, Durham, North Carolina, USA
  • S. Huang
    PKU/IHIP, Beijing, People's Republic of China
  
  Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
It is well known that the optical power of a storage ring FEL (SRFEL) is limited by the FEL induced e-beam energy spread (the Renieri's limit). This power limit can be derived using a 1D model under certain assumptions. However, systematic, experimental studies of SRFEL power as a function of operation parameters are lacking. In fact, it is difficulty to directly measure the e-beam energy spread over a wide range. In this work, we report our work on measuring e-beam energy spread in a wide range using optical klystron radiation [1]. A novel numerical method has been developed to treat spectral broadening and modulation on an equal footing. Using this new technique, we have conducted a systematic study of the SRFEL power as a function of various parameters. Our results show for the first time that for in a wide range of operation conditions, the storage ring FEL power only directly depends on the induced electron beam energy spread. Means of tuning of the FEL power, including changing the synchronization between electron and FEL beams, RF voltage, FEL cavity loss, etc, are possible though a change of the induced energy spread.
[1] Phys. Rev. STAB, 13, 080702 (2010) 		 
slides icon Slides WEOC3 [1.158 MB]  
 
WEOC4
 Intense Coherent THz Synchrotron Radiation Induced by a Storage Ring FEL Seeded with a Femtosecond Laser  
 
  • M. Hosaka, Y. Taira, Y. Takashima, N. Yamamoto
    Nagoya University, Nagoya, Japan
  • M. Adachi, M. Katoh, T. Tanikawa, H. Zen
    UVSOR, Okazaki, Japan
  • S. Bielawski, C. Szwaj
    PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
  • C. Evain
    SOLEIL, Gif-sur-Yvette, France
  
  Very recently, we have succeeded in seeding a resonator FEL by injecting an external femtosecond laser at the UVSOR-II storage ring [1]. Intense coherent synchrotron radiation (CSR) in the THz region from a bending magnet was observed when the seeded FEL was operated in the pulsed Q-switch mode [2]. We have also found that the CSR intensity depends on the pulse duration of the seed laser. The CSR intensity is enhanced with short pulse ~200 fsec and suppressed with longer pulse ~200 psec. Simultaneous measurement of the terahertz radiation and the FEL pulse reveals that the radiation is emitted in the growing phase of the Q-switch FEL pulse. We think that the CSR comes from repetitive interactions between the laser pulse and the electron bunch as the short pulse laser growth in the optical cavity. In the presentation, we will also discuss the production mechanism of the CSR.
[1] C. Szwaj et al., FEL2011, TUPB05, in this conference.
[2] H. Zen et al., FEL2011, TUPA13, in this conference.
 		 
slides icon Slides WEOC4 [2.715 MB]  
 
THOBI1
 Polarization Control Experiences in Single-pass Seeded FELs  
 
  • C. Spezzani
    ELETTRA, Basovizza, Italy
  
  The design of FERMI@Elettra, being based on APPLE type undulators, allows a straightforward tuning of the polarization of the emitted radiation. The possibility to perform polarization-dependent experiments has been confirmed from the very first phases of FERMI’s commissioning. Moreover, at the seeded storage-ring FEL test facility installed at Elettra, which also relies on an APPLE-based optical klystron, we have measured the Stokes' parameters of coherent harmonic emission and demonstrated that the polarization tunability can be maintained also in the so-called non-linear harmonic generation regime. This result definitely extends the scientific opportunities offered by FERMI@Elettra and concretize the idea of reducing the minimum accessible wavelength at which polarization can be controlled down to the spectral range that matters for transition metal magnetism studies. After a brief discussion about the importance of polarization tunability on FEL light sources, we will review the present status of FEL projects aiming to achieve polarization control and we will present the most recent results obtained at FERMI@Elettra and at the storage-ring FEL of Elettra.  
slides icon Slides THOBI1 [8.326 MB]  
 
THOB3 First Demonstration of a Slippage-dominant Superradiant Free-electron Laser Amplifier 455
 
  • X. Yang, Y. Hidaka, B. Podobedov, S. Seletskiy, Y. Shen, X.J. Wang
    BNL, Upton, Long Island, New York, USA
  
  We report the first experimental demonstration of a slippage-dominant superradiant free-electron laser (FEL) using an ultrafast seed-laser pulse. We measured the evolution of the longitudinal phase space in the slippage-dominant superradiant regime, and also the output spectrum and pulse energy versus the electron beam energy. With a ±1% variation in the electron beam energy, we observed a seed-like fully longitudinal coherence, and ±2% spectral tuning range. The temporal and spectral evolution of the slippage-dominant FEL radiation as predicted by a numerical simulation was experimentally verified for the first time.  
slides icon Slides THOB3 [0.374 MB]  
 
THOB5 FEL Spectral Measurements at LCLS 461
 
  • J.J. Welch, F.-J. Decker, Y.T. Ding, P. Emma, A.S. Fisher, J.C. Frisch, Z. Huang, R.H. Iverson, H. Loos, M. Messerschmidt, H.-D. Nuhn, D.F. Ratner, J.L. Turner, J. Wu
    SLAC, Menlo Park, California, USA
  
  Funding: Work supported in part by the DOE Contract DE-AC02-76SF00515.
Control and knowledge of the spectrum of FEL X-ray radiation at the LCLS is important to the quality and interpretation of experimental results. Narrow bandwidth is useful in experiments requiring high-brightness beams. Wide bandwidth is particularly useful for photon energy calibration using absorption spectra. Since LCLS was commissioned in 2009 measurements have been made of average and single shot spectra of X-ray FEL radiation at the LCLS over a range of 800 to 8000 eV, for fundamental and harmonic radiation. These include correlations with chirp, bunch current, undulator K-taper, electron beam energy, and charge as well as some specialized machine configurations. In this paper we present results and discuss the relationship of the electron beam energy distribution to the observed X-ray spectrum. 		 
slides icon Slides THOB5 [0.442 MB]  
 
THOC3
 Few-fs X-ray Pulse Length Measurement at LCLS  
 
  • A.R. Maier, F. Grüner
    LMU, Garching, Germany
  • J.D. Bozek, R.N. Coffee
    SLAC, Menlo Park, California, USA
  • A.L. Cavalieri, I. Grguras
    CFEL, Hamburg, Germany
  • J.T. Costello
    DCU, Dublin, Republic of Ireland
  • G. Doumy
    ANL, Argonne, USA
  • S. Düsterer
    DESY, Hamburg, Germany
  • J. Gagnon, W. Helml, R. Kienberger, W. Schweinberger, V.S. Yakovlev
    MPQ, Garching, Munich, Germany
  • M. Meyer, P. Radcliffe, T. Tschentscher
    European XFEL GmbH, Hamburg, Germany
  • C. Roedig
    Ohio State University, USA
  
  The Linac Coherent Light Source (LCLS) has an unique operating mode, delivering X-ray pulses of only a few femtoseconds (fs) length, though so far the precise X-ray pulse length has been experimentally inaccessible. In a recent experiment we measured the LCLS pulse length in this regime to be 4 fs fwhm by overlapping the FEL pulse with an optical infrared laser in a Neon gas jet. The IR laser maps the temporal X-ray pulse profile into the energy spectrum of the generated photolectrons. By measuring the photoelectron spectrum a direct characterization of the FEL pulse is possible. In the experiment we were able to directly access the temporal substructure of the X-ray pulses, measured the typical pulse length in the LCLS low charge mode to be 4 fs fwhm and showed single-spike, single-fs X-ray pulses.  
slides icon Slides THOC3 [2.818 MB]  
 
FROA4 Response Matrix of Longitudinal Instrumentation in SwissFEL 652
 
  • R. Ischebeck, B. Beutner, R. Kalt, P. Peier, S. Reiche, T. Schilcher, V. Schlott
    Paul Scherrer Institut, Villigen, Switzerland
  
  Several sources of jitter and drift affect the longitudinal phase space dynamics of SwissFEL. To evaluate how drifts can be identified and corrected through appropriate diagnostics and beam-based feedbacks, the response matrix of possible longitudinal diagnostics on laser and RF stability is modeled. To this intent, photocathode laser intensity, laser arrival time, RF phases and RF amplitudes are individually varied in an ELEGANT model, and the expected response of on-line diagnostics on the simulated bunches is evaluated. By comparing the slope of the response to the expected resolution of the instrumentation, suitable monitors can be selected for a feedback.  
slides icon Slides FROA4 [2.837 MB]