FEL2013 - List of Keywords (free-electron-laser)

Paper	Title	Other Keywords	Page
MOOBNO01	First Lasing of FERMI FEL-2	FEL, laser, injection, electron	1
	L. Giannessi, E. Allaria, D. Castronovo, P. Cinquegrana, G. D'Auria, M. Dal Forno, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, G. Gaio, R. Ivanov, B. Mahieu, N. Mahne, I. Nikolov, F. Parmigiani, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, M. Veronese, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy M. Dal Forno DEEI, Trieste, Italy G. De Ninno, D. Gauthier University of Nova Gorica, Nova Gorica, Slovenia E. Ferrari, F. Parmigiani Università degli Studi di Trieste, Trieste, Italy L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy B. Mahieu CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France M. Zangrando IOM-CNR, Trieste, Italy
	During the month of October 2012 the commissioning of the light source FEL-2 at FERMI was successfully concluded. Fermi FEL-2 is the first seeded FEL operating with a double stage cascade in the "fresh bunch injection" mode. The two stages are two high gain harmonic generation FELs where the first stage is seeded by the 3rd harmonic of a Ti:Sa laser system, which is up converted to the 4th-6th harmonic. The output of the first stage is then used to seed the second stage. A final wavelengths of 10.8 nm was obtained as the 24th harmonic of the seed wavelength at the end of the two frequency conversion processes, demonstrating that the FEL is capable of producing single mode narrow bandwidth pulses with an energy of several tens of microjoules. I. Ben-Zvi, K. M. Yang, L. H. Yu, ”The ”fresh-bunch” technique in FELs”, NIM A 318 (1992), p 726-729
	Slides MOOBNO01 [25.265 MB]

MOPSO57	Measurement of Wigner Distribution Function for Beam Characterization of FELs	laser, electron, FEL, focusing	92
	T. Mey, K. Mann, B. Schäfer LLG, Goettingen, Germany B. Keitel, S. Kreis, M. Kuhlmann, E. Plönjes, K.I. Tiedtke DESY, Hamburg, Germany
	Free-electron lasers deliver VUV and soft x-ray pulses with the highest brilliance available and high spatial coherence. Users of such facilities have high demands on phase and coherence properties of the beam, for instance when working with coherent diffractive imaging (CDI). To gain highly resolved spatial coherence information, we have performed a caustic scan at BL2 of FLASH using the ellipsoidal beam line focusing mirror and a movable XUV sensitive CCD detector. This measurement allows for retrieving the Wigner distribution function, being the two-dimensional Fourier transform of the mutual intensity of the beam. Computing the reconstruction on a four-dimensional grid, this yields the Wigner distribution which describes the beam propagation completely. Hence, we are able to provide comprehensive information about spatial coherence properties of the FLASH beam including the mutual coherence function and the global degree of coherence. Additionally, we derive the beam propagation parameters such as Rayleigh length, waist diameter and the beam quality factor M².

MOPSO81	Broad-band Amplifier Based on Two-stream Instability	electron, FEL, plasma, space-charge	144
	G. Wang, Y.C. Jing, V. Litvinenko BNL, Upton, Long Island, New York, USA
	A broadband FEL amplifier is of great interests for short-pulse generation in FEL technology as well as for novel hadron beam cooling technique, such as CeC. We present our founding of a broadband amplification in 1D FEL based on electron beam with two energy peaks and a strong space charge forces. We present the optimization of such amplifier and connect its origin to the two-stream instability in electron plasma. In this work, we study how the two-stream instability affects the FEL process and consider various applications in amplifying short spikes of electron current modulation.

TUPSO49	Electric Field Dependence of Photoemission From n- and p- Type SI Crystals	FEL, cathode, lattice, laser	339
	S. Mingels, B. Bornmann, D. Lützenkirchen-Hecht, G. Müller Bergische Universität Wuppertal, Wuppertal, Germany C. Langer, C. Prommesberger, R. Schreiner Regensburg University of Applied Sciences, Regensburg, Germany
	Funding: Funding Agency: German Federal Ministry of Education and Research BMBF (contract number 05K10PXA) The performance of free electron lasers depends on the brilliance of the electron source. Nowadays photocathodes (e.g. Cs2Te) are used despite of their high emittance. To develop robust and more brilliant cathodes we have built up an UHV system which enables systematic photoemission (PE) measurements with a tunable pulsed laser (W=0.5-5.9 eV) at high electric fields (E<400 MV/m). First results on Au and Ag crystals revealed only low quantum efficiency (QE) due to fast electron relaxation. Hence, we have started QE(W,E) investigations on n- and p-Si wafers. Resonant PE was observed above as well as below the work function F, which can be allocated to optical transitions in the band structure of Si or explained by thermally excited states at the bottom of the conduction band. As expected, only low QE values were achieved even for n-Si probably due to surface oxide. Moreover, a significant rise of the QE peaks above F were obtained for n-Si already at E=8-9 MV/m, which was limited by discharges due to surface pollution. Detailed results and a discussion on the potential of semiconductors as highly brilliant photo-induced field emission cathodes will be presented at the conference. D.H. Dowell et al., Nucl. Instr. And Meth. Phys. A 622, 685-697 (2010) **B. Bornmann et al., Rev. Sci. Instrum. 83, 013302 (2012)

TUPSO64	Short SASE-FEL Pulses at FLASH	laser, FEL, electron, radiation	379
	J. Rönsch-Schulenburg, E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Roßbach Uni HH, Hamburg, Germany G. Brenner, C. Gerth, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov DESY, Hamburg, Germany
	Funding: This project has been supported by BMBF under contract 05K10GU2 & FS FLASH 301 FLASH is a high-gain free-electron laser (FEL) in the soft x-ray range. This paper discusses the production of very short FEL pulses in the SASE-mode without an external seeding signal at FLASH in the optimal case the single-spike operation. A new photo-injector laser has been commissioned, which allows the generation of shorter bunches with low bunch charge directly at the photo-cathode. This shorter injector laser reduces the required bunch compression for short pulses and thus allows a stable SASE performance with shorter pulses. First SASE performance using the new injector laser has been demonstrated and electron bunch and FEL radiation properties have been measured. Beam dynamics as well as the optimization of bunch diagnostics for low charge and short bunches are discussed.

WEPSO01	Free Electron Lasers in 2013	FEL, electron, undulator, laser	486
	J. Blau, K. R. Cohn, W.B. Colson, R. Vigil NPS, Monterey, California, USA
	Funding: This work has been supported by the Office of Naval Research. Thirty-seven 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.

WEPSO04	The Conceptual Design of CLARA, a Novel FEL Test Facility for Ultra-short Pulse Generation	FEL, electron, laser, undulator	496
	J.A. Clarke, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, P.A. Corlett, L.S. Cowie, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.P. Jamison, J.K. Jones, A. Kalinin, B.P.M. Liggins, L. Ma, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, H.L. Owen, R.N.C. Santer, Y.M. Saveliev, R.J. Smith, S.L. Smith, E.W. Snedden, M. Surman, T.T. Thakker, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Appleby, R.J. Barlow, H.L. Owen, M. Serluca, G.X. Xia UMAN, Manchester, United Kingdom R. Appleby, G. Burt, S. Chattopadhyay, D. Newton, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom R. Bartolini, S.T. Boogert, A. Lyapin JAI, Oxford, United Kingdom N. Bliss, R.J. Cash, G. Cox, G.P. Diakun, A. Gallagher, D.M.P. Holland, B.G. Martlew, M.D. Roper STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom S.T. Boogert Royal Holloway, University of London, Surrey, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom L.T. Campbell, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom A.M. Kolano University of Huddersfield, Huddersfield, United Kingdom I.P.S. Martin Diamond, Oxfordshire, United Kingdom D. Newton, A. Wolski The University of Liverpool, Liverpool, United Kingdom V.V. Paramonov RAS/INR, Moscow, Russia
	The conceptual design of CLARA, a novel FEL test facility focussed on the generation of ultra-short photon pulses with extreme levels of stability and synchronisation is described. The ultimate aim of CLARA is to experimentally demonstrate that sub-coherence length pulse generation with FELs is viable, and to compare the various schemes being championed. The results will translate directly to existing and future X-ray FELs, enabling them to generate attosecond pulses, thereby extending the science capabilities of these intense light sources. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven.

WEPSO05	Progress of the LUNEX5 Project	laser, FEL, electron, undulator	502
	M.-E. Couprie, C. Benabderrahmane, L. Cassinari, J. Daillant, C. Evain, N. Hubert, M. Labat, A. Loulergue, J. Lüning, P. Marchand, O. Marcouillé, C. Miron, P. Morin, A. Nadji, P. Roy, T. Tanikawa SOLEIL, Gif-sur-Yvette, France S. Bielawski, M. Le Parquier, E. Roussel, C. Szwaj PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré, D. Garzella CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France N. Delerue LAL, Orsay, France G. Devanz CEA/IRFU, Gif-sur-Yvette, France A. Dubois CCPMR, Paris, France G. Lambert, R. Lehé, V. Malka, C. Thaury LOA, Palaiseau, France G. Le Bec ESRF, Grenoble, France M. Luong CEA/DSM/IRFU, 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-ray region, with a 400 MeV superconducting linear accelerator and a laser wakefield accelerator (LWFA), feeding a single Free Electron Laser line with seeding with High order Harmonic in Gas and Echo Enable Harmonic Generation. After the Conceptual Design Report (CDR), R&D has been launched on specific magnetic elements (cryo-ready 3 m long in-vacuum undulator, a variable strong permanent magnet quadrupoles), on diagnostics (Smith-Purcell, electro-optics). In recent transport studies from a LWFA with more realistic beam parameters (1 % energy spread, 1 μm size and 1 mrad divergence) than the ones taken in the CDR, a longitudinal and transverse manipulation enables to provide theoretical amplification. A test experiment is under preparation. The French scientific community is increasing its participation to the use of operating FELs.

WEPSO09	Two-Color Self-seeding and Scanning the Energy of Seeded Beams at LCLS	FEL, photon, electron, background	514
	F.-J. Decker, Y. Ding, Y. Feng, M. Gibbs, J.B. Hastings, Z. Huang, H. Lemke, A.A. Lutman, A. Marinelli, A. Robert, J.L. Turner, J.J. Welch, D.H. Zhang, D. Zhu SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. The Linac Coherent Light Source (LCLS) produces typically SASE FEL pulses with an intensity of up to 5 mJ and at high photon energy a spread of 0.2% (FWHM). Self seeding with a diamond crystal reduces the energy spread by a factor of 10 to 40. The range depends on which Bragg reflection is used, or the special setup of the electron beam like over-compression. The peak intensity level is lower by a factor of about five, giving the seeded beam an advantage of about 2.5 in average intensity over the use of a monochromator with SASE. Some experiments want to scan the photon energy, which requires that the crystal angle be carefully tracked. At certain energies and crystal angles different lines are crossing which allows seeding at two or even three different colors inside the bandwidth of the SASE pulse. Out-off plane lines come in pairs, like [1 -1 1] and [-1 1 1], which can be split by using the yaw angle adjustments of the crystal, allowing a two-color seeding for all energies above 4.83 keV.

WEPSO22	FERMI@Elettra Status Report	FEL, electron, laser, linac	546
	L. Giannessi, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, M. Kiskinova, M. Lonza, B. Mahieu, N. Mahne, C. Masciovecchio, F. Parmigiani, G. Penco, M. Predonzani, E. Principi, L. Raimondi, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy P. Craievich PSI, Villigen PSI, Switzerland L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy B. Mahieu CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
	Funding: Work supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3 In this paper we report about the status of FERMI, the seeded Free Electron Laser located at the Elettra laboratory in Trieste, Italy. The facility welcomed the first external users on FEL-1 between December 2012 and March 2013, operating at wavelengths between 65 and 20 nm. Variable polarization and tunability of the radiation wavelength were widely used. Photon energies attained up to 200 microJoule, depending on the grade of spectral purity requested and on the selected wavelength. Pump-probe experiments were performed, both by double FEL pulses obtained via double pulse seeding of the electron beam and by providing part of the seed laser to the experimental stations as user laser. The FEL-2 line, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, operating in the "fresh bunch injection” mode, generated its first coherent photons in October 2012 and has seen further progress during the commissioning phases in 2013, at higher electron beam energy. In fact we will also report on the linac energy increase to 1.5 GeV and on the repetition rate upgrade from 10 to 50 Hz and eventually comment on the FEL operability and uptime.

WEPSO33	Remote RF Synchronization With Femtosecond Drift at PAL	laser, electron, photon, radio-frequency	570
	J. Kim, K. Jung, J. Lim KAIST, Daejeon, Republic of Korea L. Chen Idesta Quantum Electronics, New Jersey, USA S. Hunziker PSI, Villigen PSI, Switzerland F.X. Kaertner CFEL, Hamburg, Germany H.-S. Kang, C.-K. Min PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: This research was supported by the PAL-XFEL Project, South Korea. We present our recent progress in remote RF synchronization using an optical way at PAL. A 79.33-MHz, low-jitter fiber laser is used as an optical master oscillator (OMO), which is locked to the 2.856-GHz RF master oscillator (RMO) using a balanced optical-microwave phase detector (BOM-PD). The locked optical pulse train is then transferred via a timing-stabilized 610-m long optical fiber link. The output is locked to the 2.856 GHz voltage controlled oscillator (VCO) using the second BOM-PD, which results in remote synchronization between the RMO and the VCO. We measured the long-term phase drift between the input optical pulse train and the remote RF signals using an out-of-loop BOM-PD, which results in 2.7 fs (rms) drift maintained over 7 hours. We are currently working to measure the phase drift between the two RF signals and reduce the phase drift over longer measurement time.

WEPSO37	Femtosecond Fiber Timing Distribution System for the Linac Coherent Light Source	laser, electron, linac, background	583
	H. Li, P.H. Bucksbaum, J.C. Frisch, A.R. Fry, J. May, K. Muehlig, S.R. Smith SLAC, Menlo Park, California, USA L. Chen, H.P.H. Cheng Idesta Quantum Electronics, New Jersey, USA F.X. Kaertner CFEL, Hamburg, Germany F.X. Kaertner MIT, Cambridge, Massachusetts, USA A. Uttamadoss PU, Princeton, New Jersey, USA
	Funding: This work is supported by Department of Energy under STTR grant DE-C0004702. We present the design and progress of a femtosecond fiber timing distribution system for the Linac Coherent Light Source (LCLS) at SLAC to enable the machine diagnostic at the 10 fs level. The LCLS at the SLAC is the world’s first hard x-ray free-electron laser (FEL) with unprecedented peak brightness and pulse duration. The time-resolved optical/x-ray pump-probe experiments on this facility open the era of exploring the ultrafast dynamics of atoms, molecules, proteins, and condensed matter. However, the temporal resolution of current experiments is limited by the time jitter between the optical and x-ray pulses. Recently, sub-25 fs rms jitter is achieved from an x-ray/optical cross-correlator at the LCLS, and external seeding is expected to reduce the intrinsic timing jitter, which would enable full synchronization of the optical and x-ray pulses with sub-10 fs precision. Of such a technique, synchronization between seed and pump lasers would be implemented. Preliminary test results of the major components for a 4 link system will be presented. Currently, the system is geared towards diagnostics to study the various sources of jitter at the LCLS. P. Emma et al.,Nat. Photonics 4,641-647(2010). J. Kim et al.,Opt. Lett,, 31,3659(2006). J. Kim et al.,Opt. Lett,, 32,1044(2007). J.Kim et al.,Nat. Photonics 2,733-736(2008).

WEPSO62	The IR and THz Free Electron Laser at the Fritz-Haber-Institut	FEL, laser, electron	657
	W. Schöllkopf, W. Erlebach, S. Gewinner, G. Heyne, H. Junkes, A. Liedke, G. Meijer, V. Platschkowski, G. von Helden FHI, Berlin, Germany H. Bluem, D. Dowell, K. Jordan, R. Lange, J. Rathke, A.M.M. Todd, L.M. Young AES, Princeton, New Jersey, USA M.A. Davidsaver BNL, Upton, New York, USA S.C. Gottschalk STI, Washington, USA U. Lehnert, P. Michel, W. Seidel, R. Wünsch HZDR, Dresden, Germany H. Loos SLAC, Menlo Park, California, USA
	A mid-infrared oscillator FEL with a design wavelength range from 4 to 50 μm has been commissioned at the Fritz-Haber-Institut in Berlin, Germany, for applications in molecular and cluster spectroscopy as well as surface science. The accelerator consists of a thermionic gridded electron gun, a subharmonic buncher and two S-band standing-wave copper structures. The device was designed to meet challenging specifications, including a final energy adjustable in the range of 15 to 50 MeV, low longitudinal emittance (< 50 keV-psec) and transverse emittance (< 20 π mm-mrad), at more than 200 pC bunch charge with aμpulse repetition rate of 1 GHz and a macro pulse length of up to 15 μs. Two isochronous achromatic 180 degree bends deliver the beam to the undulators, only one of which is presently installed, and to the beam dumps. Calculations of the FEL gain and IR-cavity losses predict that lasing will be possible in the wavelength range from less than 4 to more than 50 μm. First lasing was achieved at a wavelength of 16 μm in 2012. We will describe the FEL system design and performance, provide examples of lasing, and touch on the first anticipated user experiments. W. Schöllkopf et al., MOOB01, Proc. FEL 2012.

WEPSO70	Fully Phase Matched High Harmonics Generation in a Hollow Waveguide for Free Electron Laser Seeding	laser, FEL, photon, electron	693
	C. Vicario INFN/LNF, Frascati (Roma), Italy F. Ardana-Lamas, C.P. Hauri, A. Trisorio PSI, Villigen PSI, Switzerland C.P. Hauri EPFL, Lausanne, Switzerland G. Lambert, V. Malka, B. Vodungbo, P. Zeitoun LOA, Palaiseau, France
	Funding: LASERLAB-EUROPE, grant n◦ 228334 PARIS ERC project (Contract No. 226424) Swiss National Science Foundation under grant PP00P2_128493 A bright high harmonic source is presented delivering up to 10¹¹ photons per second around a central photon energy of 120 eV. Fully phase matched harmonics are generated in an elongated capillary reaching a cut-off energy of 160 eV. The high HHG fluence opens new perspectives towards seeding FELs at shorter wavelengths than the state of the art. Characterization of the phase matching conditions in the capillary is presented.

Paper

Title

Other Keywords

Page

MOOBNO01

First Lasing of FERMI FEL-2

FEL, laser, injection, electron

1

L. Giannessi, E. Allaria, D. Castronovo, P. Cinquegrana, G. D'Auria, M. Dal Forno, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, G. Gaio, R. Ivanov, B. Mahieu, N. Mahne, I. Nikolov, F. Parmigiani, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, M. Veronese, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
M. Dal Forno
DEEI, Trieste, Italy
G. De Ninno, D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia
E. Ferrari, F. Parmigiani
Università degli Studi di Trieste, Trieste, Italy
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
B. Mahieu
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
M. Zangrando
IOM-CNR, Trieste, Italy

During the month of October 2012 the commissioning of the light source FEL-2 at FERMI was successfully concluded. Fermi FEL-2 is the first seeded FEL operating with a double stage cascade in the "fresh bunch injection" mode*. The two stages are two high gain harmonic generation FELs where the first stage is seeded by the 3rd harmonic of a Ti:Sa laser system, which is up converted to the 4th-6th harmonic. The output of the first stage is then used to seed the second stage. A final wavelengths of 10.8 nm was obtained as the 24th harmonic of the seed wavelength at the end of the two frequency conversion processes, demonstrating that the FEL is capable of producing single mode narrow bandwidth pulses with an energy of several tens of microjoules.
*I. Ben-Zvi, K. M. Yang, L. H. Yu, ”The ”fresh-bunch” technique in FELs”, NIM A 318 (1992), p 726-729

Slides MOOBNO01 [25.265 MB]

MOPSO57

Measurement of Wigner Distribution Function for Beam Characterization of FELs

laser, electron, FEL, focusing

92

T. Mey, K. Mann, B. Schäfer
LLG, Goettingen, Germany
B. Keitel, S. Kreis, M. Kuhlmann, E. Plönjes, K.I. Tiedtke
DESY, Hamburg, Germany

Free-electron lasers deliver VUV and soft x-ray pulses with the highest brilliance available and high spatial coherence. Users of such facilities have high demands on phase and coherence properties of the beam, for instance when working with coherent diffractive imaging (CDI). To gain highly resolved spatial coherence information, we have performed a caustic scan at BL2 of FLASH using the ellipsoidal beam line focusing mirror and a movable XUV sensitive CCD detector. This measurement allows for retrieving the Wigner distribution function, being the two-dimensional Fourier transform of the mutual intensity of the beam. Computing the reconstruction on a four-dimensional grid, this yields the Wigner distribution which describes the beam propagation completely. Hence, we are able to provide comprehensive information about spatial coherence properties of the FLASH beam including the mutual coherence function and the global degree of coherence. Additionally, we derive the beam propagation parameters such as Rayleigh length, waist diameter and the beam quality factor M².

MOPSO81

Broad-band Amplifier Based on Two-stream Instability

electron, FEL, plasma, space-charge

144

G. Wang, Y.C. Jing, V. Litvinenko
BNL, Upton, Long Island, New York, USA

A broadband FEL amplifier is of great interests for short-pulse generation in FEL technology as well as for novel hadron beam cooling technique, such as CeC. We present our founding of a broadband amplification in 1D FEL based on electron beam with two energy peaks and a strong space charge forces. We present the optimization of such amplifier and connect its origin to the two-stream instability in electron plasma. In this work, we study how the two-stream instability affects the FEL process and consider various applications in amplifying short spikes of electron current modulation.

TUPSO49

Electric Field Dependence of Photoemission From n- and p- Type SI Crystals

FEL, cathode, lattice, laser

339

S. Mingels, B. Bornmann, D. Lützenkirchen-Hecht, G. Müller
Bergische Universität Wuppertal, Wuppertal, Germany
C. Langer, C. Prommesberger, R. Schreiner
Regensburg University of Applied Sciences, Regensburg, Germany

Funding: Funding Agency: German Federal Ministry of Education and Research BMBF (contract number 05K10PXA)
The performance of free electron lasers depends on the brilliance of the electron source*. Nowadays photocathodes (e.g. Cs2Te) are used despite of their high emittance. To develop robust and more brilliant cathodes we have built up an UHV system which enables systematic photoemission (PE) measurements with a tunable pulsed laser (W=0.5-5.9 eV) at high electric fields (E<400 MV/m)**. First results on Au and Ag crystals revealed only low quantum efficiency (QE) due to fast electron relaxation. Hence, we have started QE(W,E) investigations on n- and p-Si wafers. Resonant PE was observed above as well as below the work function F, which can be allocated to optical transitions in the band structure of Si or explained by thermally excited states at the bottom of the conduction band. As expected, only low QE values were achieved even for n-Si probably due to surface oxide. Moreover, a significant rise of the QE peaks above F were obtained for n-Si already at E=8-9 MV/m, which was limited by discharges due to surface pollution. Detailed results and a discussion on the potential of semiconductors as highly brilliant photo-induced field emission cathodes will be presented at the conference.
*D.H. Dowell et al., Nucl. Instr. And Meth. Phys. A 622, 685-697 (2010)
**B. Bornmann et al., Rev. Sci. Instrum. 83, 013302 (2012)

TUPSO64

Short SASE-FEL Pulses at FLASH

laser, FEL, electron, radiation

379

J. Rönsch-Schulenburg, E. Hass, A. Kuhl, T. Plath, M. Rehders, J. Roßbach
Uni HH, Hamburg, Germany
G. Brenner, C. Gerth, U. Mavrič, H. Schlarb, E. Schneidmiller, S. Schreiber, B. Steffen, M. Yan, M.V. Yurkov
DESY, Hamburg, Germany

Funding: This project has been supported by BMBF under contract 05K10GU2 & FS FLASH 301
FLASH is a high-gain free-electron laser (FEL) in the soft x-ray range. This paper discusses the production of very short FEL pulses in the SASE-mode without an external seeding signal at FLASH in the optimal case the single-spike operation. A new photo-injector laser has been commissioned, which allows the generation of shorter bunches with low bunch charge directly at the photo-cathode. This shorter injector laser reduces the required bunch compression for short pulses and thus allows a stable SASE performance with shorter pulses. First SASE performance using the new injector laser has been demonstrated and electron bunch and FEL radiation properties have been measured. Beam dynamics as well as the optimization of bunch diagnostics for low charge and short bunches are discussed.

WEPSO01

Free Electron Lasers in 2013

FEL, electron, undulator, laser

486

J. Blau, K. R. Cohn, W.B. Colson, R. Vigil
NPS, Monterey, California, USA

Funding: This work has been supported by the Office of Naval Research.
Thirty-seven 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.

WEPSO04

The Conceptual Design of CLARA, a Novel FEL Test Facility for Ultra-short Pulse Generation

FEL, electron, laser, undulator

496

J.A. Clarke, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, P.A. Corlett, L.S. Cowie, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.P. Jamison, J.K. Jones, A. Kalinin, B.P.M. Liggins, L. Ma, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, H.L. Owen, R.N.C. Santer, Y.M. Saveliev, R.J. Smith, S.L. Smith, E.W. Snedden, M. Surman, T.T. Thakker, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Appleby, R.J. Barlow, H.L. Owen, M. Serluca, G.X. Xia
UMAN, Manchester, United Kingdom
R. Appleby, G. Burt, S. Chattopadhyay, D. Newton, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Bartolini, S.T. Boogert, A. Lyapin
JAI, Oxford, United Kingdom
N. Bliss, R.J. Cash, G. Cox, G.P. Diakun, A. Gallagher, D.M.P. Holland, B.G. Martlew, M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
A.M. Kolano
University of Huddersfield, Huddersfield, United Kingdom
I.P.S. Martin
Diamond, Oxfordshire, United Kingdom
D. Newton, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia

The conceptual design of CLARA, a novel FEL test facility focussed on the generation of ultra-short photon pulses with extreme levels of stability and synchronisation is described. The ultimate aim of CLARA is to experimentally demonstrate that sub-coherence length pulse generation with FELs is viable, and to compare the various schemes being championed. The results will translate directly to existing and future X-ray FELs, enabling them to generate attosecond pulses, thereby extending the science capabilities of these intense light sources. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven.

WEPSO05

Progress of the LUNEX5 Project

laser, FEL, electron, undulator

502

M.-E. Couprie, C. Benabderrahmane, L. Cassinari, J. Daillant, C. Evain, N. Hubert, M. Labat, A. Loulergue, J. Lüning, P. Marchand, O. Marcouillé, C. Miron, P. Morin, A. Nadji, P. Roy, T. Tanikawa
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, M. Le Parquier, E. Roussel, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré, D. Garzella
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
N. Delerue
LAL, Orsay, France
G. Devanz
CEA/IRFU, Gif-sur-Yvette, France
A. Dubois
CCPMR, Paris, France
G. Lambert, R. Lehé, V. Malka, C. Thaury
LOA, Palaiseau, France
G. Le Bec
ESRF, Grenoble, France
M. Luong
CEA/DSM/IRFU, 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-ray region, with a 400 MeV superconducting linear accelerator and a laser wakefield accelerator (LWFA), feeding a single Free Electron Laser line with seeding with High order Harmonic in Gas and Echo Enable Harmonic Generation. After the Conceptual Design Report (CDR), R&D has been launched on specific magnetic elements (cryo-ready 3 m long in-vacuum undulator, a variable strong permanent magnet quadrupoles), on diagnostics (Smith-Purcell, electro-optics). In recent transport studies from a LWFA with more realistic beam parameters (1 % energy spread, 1 μm size and 1 mrad divergence) than the ones taken in the CDR, a longitudinal and transverse manipulation enables to provide theoretical amplification. A test experiment is under preparation. The French scientific community is increasing its participation to the use of operating FELs.

WEPSO09

Two-Color Self-seeding and Scanning the Energy of Seeded Beams at LCLS

FEL, photon, electron, background

514

F.-J. Decker, Y. Ding, Y. Feng, M. Gibbs, J.B. Hastings, Z. Huang, H. Lemke, A.A. Lutman, A. Marinelli, A. Robert, J.L. Turner, J.J. Welch, D.H. Zhang, D. Zhu
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
The Linac Coherent Light Source (LCLS) produces typically SASE FEL pulses with an intensity of up to 5 mJ and at high photon energy a spread of 0.2% (FWHM). Self seeding with a diamond crystal reduces the energy spread by a factor of 10 to 40. The range depends on which Bragg reflection is used, or the special setup of the electron beam like over-compression. The peak intensity level is lower by a factor of about five, giving the seeded beam an advantage of about 2.5 in average intensity over the use of a monochromator with SASE. Some experiments want to scan the photon energy, which requires that the crystal angle be carefully tracked. At certain energies and crystal angles different lines are crossing which allows seeding at two or even three different colors inside the bandwidth of the SASE pulse. Out-off plane lines come in pairs, like [1 -1 1] and [-1 1 1], which can be split by using the yaw angle adjustments of the crystal, allowing a two-color seeding for all energies above 4.83 keV.

WEPSO22

FERMI@Elettra Status Report

FEL, electron, laser, linac

546

L. Giannessi, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, M. Kiskinova, M. Lonza, B. Mahieu, N. Mahne, C. Masciovecchio, F. Parmigiani, G. Penco, M. Predonzani, E. Principi, L. Raimondi, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
P. Craievich
PSI, Villigen PSI, Switzerland
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
B. Mahieu
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France

Funding: Work supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
In this paper we report about the status of FERMI, the seeded Free Electron Laser located at the Elettra laboratory in Trieste, Italy. The facility welcomed the first external users on FEL-1 between December 2012 and March 2013, operating at wavelengths between 65 and 20 nm. Variable polarization and tunability of the radiation wavelength were widely used. Photon energies attained up to 200 microJoule, depending on the grade of spectral purity requested and on the selected wavelength. Pump-probe experiments were performed, both by double FEL pulses obtained via double pulse seeding of the electron beam and by providing part of the seed laser to the experimental stations as user laser. The FEL-2 line, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, operating in the "fresh bunch injection” mode, generated its first coherent photons in October 2012 and has seen further progress during the commissioning phases in 2013, at higher electron beam energy. In fact we will also report on the linac energy increase to 1.5 GeV and on the repetition rate upgrade from 10 to 50 Hz and eventually comment on the FEL operability and uptime.

WEPSO33

Remote RF Synchronization With Femtosecond Drift at PAL

laser, electron, photon, radio-frequency

570

J. Kim, K. Jung, J. Lim
KAIST, Daejeon, Republic of Korea
L. Chen
Idesta Quantum Electronics, New Jersey, USA
S. Hunziker
PSI, Villigen PSI, Switzerland
F.X. Kaertner
CFEL, Hamburg, Germany
H.-S. Kang, C.-K. Min
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: This research was supported by the PAL-XFEL Project, South Korea.
We present our recent progress in remote RF synchronization using an optical way at PAL. A 79.33-MHz, low-jitter fiber laser is used as an optical master oscillator (OMO), which is locked to the 2.856-GHz RF master oscillator (RMO) using a balanced optical-microwave phase detector (BOM-PD). The locked optical pulse train is then transferred via a timing-stabilized 610-m long optical fiber link. The output is locked to the 2.856 GHz voltage controlled oscillator (VCO) using the second BOM-PD, which results in remote synchronization between the RMO and the VCO. We measured the long-term phase drift between the input optical pulse train and the remote RF signals using an out-of-loop BOM-PD, which results in 2.7 fs (rms) drift maintained over 7 hours. We are currently working to measure the phase drift between the two RF signals and reduce the phase drift over longer measurement time.

WEPSO37

Femtosecond Fiber Timing Distribution System for the Linac Coherent Light Source

laser, electron, linac, background

583

H. Li, P.H. Bucksbaum, J.C. Frisch, A.R. Fry, J. May, K. Muehlig, S.R. Smith
SLAC, Menlo Park, California, USA
L. Chen, H.P.H. Cheng
Idesta Quantum Electronics, New Jersey, USA
F.X. Kaertner
CFEL, Hamburg, Germany
F.X. Kaertner
MIT, Cambridge, Massachusetts, USA
A. Uttamadoss
PU, Princeton, New Jersey, USA

Funding: This work is supported by Department of Energy under STTR grant DE-C0004702.
We present the design and progress of a femtosecond fiber timing distribution system for the Linac Coherent Light Source (LCLS) at SLAC to enable the machine diagnostic at the 10 fs level. The LCLS at the SLAC is the world’s first hard x-ray free-electron laser (FEL) with unprecedented peak brightness and pulse duration. The time-resolved optical/x-ray pump-probe experiments on this facility open the era of exploring the ultrafast dynamics of atoms, molecules, proteins, and condensed matter. However, the temporal resolution of current experiments is limited by the time jitter between the optical and x-ray pulses. Recently, sub-25 fs rms jitter is achieved from an x-ray/optical cross-correlator at the LCLS, and external seeding is expected to reduce the intrinsic timing jitter, which would enable full synchronization of the optical and x-ray pulses with sub-10 fs precision. Of such a technique, synchronization between seed and pump lasers would be implemented. Preliminary test results of the major components for a 4 link system will be presented. Currently, the system is geared towards diagnostics to study the various sources of jitter at the LCLS.
*P. Emma et al.,Nat. Photonics 4,641-647(2010).
*J. Kim et al.,Opt. Lett,, 31,3659(2006).
*J. Kim et al.,Opt. Lett,, 32,1044(2007).
*J.Kim et al.,Nat. Photonics 2,733-736(2008).

WEPSO62

The IR and THz Free Electron Laser at the Fritz-Haber-Institut

FEL, laser, electron

657

W. Schöllkopf, W. Erlebach, S. Gewinner, G. Heyne, H. Junkes, A. Liedke, G. Meijer, V. Platschkowski, G. von Helden
FHI, Berlin, Germany
H. Bluem, D. Dowell, K. Jordan, R. Lange, J. Rathke, A.M.M. Todd, L.M. Young
AES, Princeton, New Jersey, USA
M.A. Davidsaver
BNL, Upton, New York, USA
S.C. Gottschalk
STI, Washington, USA
U. Lehnert, P. Michel, W. Seidel, R. Wünsch
HZDR, Dresden, Germany
H. Loos
SLAC, Menlo Park, California, USA

A mid-infrared oscillator FEL with a design wavelength range from 4 to 50 μm has been commissioned at the Fritz-Haber-Institut in Berlin, Germany, for applications in molecular and cluster spectroscopy as well as surface science. The accelerator consists of a thermionic gridded electron gun, a subharmonic buncher and two S-band standing-wave copper structures. The device was designed to meet challenging specifications, including a final energy adjustable in the range of 15 to 50 MeV, low longitudinal emittance (< 50 keV-psec) and transverse emittance (< 20 π mm-mrad), at more than 200 pC bunch charge with aμpulse repetition rate of 1 GHz and a macro pulse length of up to 15 μs. Two isochronous achromatic 180 degree bends deliver the beam to the undulators, only one of which is presently installed, and to the beam dumps. Calculations of the FEL gain and IR-cavity losses predict that lasing will be possible in the wavelength range from less than 4 to more than 50 μm. First lasing was achieved at a wavelength of 16 μm in 2012*. We will describe the FEL system design and performance, provide examples of lasing, and touch on the first anticipated user experiments.
* W. Schöllkopf et al., MOOB01, Proc. FEL 2012.

WEPSO70

Fully Phase Matched High Harmonics Generation in a Hollow Waveguide for Free Electron Laser Seeding

laser, FEL, photon, electron

693

C. Vicario
INFN/LNF, Frascati (Roma), Italy
F. Ardana-Lamas, C.P. Hauri, A. Trisorio
PSI, Villigen PSI, Switzerland
C.P. Hauri
EPFL, Lausanne, Switzerland
G. Lambert, V. Malka, B. Vodungbo, P. Zeitoun
LOA, Palaiseau, France

Funding: LASERLAB-EUROPE, grant n◦ 228334 PARIS ERC project (Contract No. 226424) Swiss National Science Foundation under grant PP00P2_128493
A bright high harmonic source is presented delivering up to 10¹¹ photons per second around a central photon energy of 120 eV. Fully phase matched harmonics are generated in an elongated capillary reaching a cut-off energy of 160 eV. The high HHG fluence opens new perspectives towards seeding FELs at shorter wavelengths than the state of the art. Characterization of the phase matching conditions in the capillary is presented.