FEL2013 - List of Keywords (FEL)

Paper	Title	Other Keywords	Page
MOOBNO01	First Lasing of FERMI FEL-2	laser, injection, free-electron-laser, 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]

MOICNO01	Generation of a Train of Short Pulses by Means of FEL Emission of a Combed Electron Beam	electron, radiation, undulator, laser	2
	V. Petrillo Universita' degli Studi di Milano, Milano, Italy M.P. Anania, M. Bellaveglia, E. Chiadroni, D. Di Giovenale, G. Di Pirro, M. Ferrario, G. Gatti, R. Pompili, C. Vaccarezza, F. Villa INFN/LNF, Frascati (Roma), Italy M. Artioli ENEA-Bologna, Bologna, Italy A. Bacci, A.R. Rossi Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy F. Ciocci, G. Dattoli, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia ENEA C.R. Frascati, Frascati (Roma), Italy A. Mostacci Rome University La Sapienza, Roma, Italy P. Musumeci UCLA, Los Angeles, California, USA J.V. Rau ISM-CNR, Rome, Italy
	We present a direct and powerful method for generating train of radiation pulses based on the FEL radiation from a multi-peaked electron beam produced with a combed laser pulse accelerated and compressed in a linac by the velocity bunching technique. The electron beam, constituted by two bunches, can be extracted from the accelerating section when they are temporaly superimposed but separated in energy, so that each of them is characterized by a different value of the Lorentz factor. When driven in the FEL undulator, they emit two separate spectral lines, according to the FEL resonance condition, that interfere producing fringes in the time-domain. In this way a train of regular pulses can be obtained, without limitation in frequency, and with the perspective of reaching the attosecond domain in the X ray regime.
	Slides MOICNO01 [8.836 MB]

MOOCNO01	Emittance Control in the Presence of Collective Effects in the FERMI@Elettra Free Electron Laser Linac Driver	emittance, electron, linac, brightness	6
	S. Di Mitri, E. Allaria, D. Castronovo, M. Cornacchia, P. Craievich, M. Dal Forno, G. De Ninno, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, E. Karantzoulis, A.A. Lutman, G. Penco, C. Serpico, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy P. Craievich PSI, Villigen PSI, Switzerland M. Dal Forno University of Trieste, Trieste, Italy G. De Ninno, S. Spampinati University of Nova Gorica, Nova Gorica, Slovenia E. Ferrari Università degli Studi di Trieste, Trieste, Italy L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy A.A. Lutman SLAC, Menlo Park, California, USA
	Recent beam transport experiments conducted on the the linac driving the FERMI@Elettra free electron laser have provided new insights concerning the transverse emittance degradation due to both coherent synchrotron radiation (CSR) and geometric transverse wakefield (GTW), together with methods to counteract such degradation. For beam charges of several 100's of pC, optics control in a magnetic compressor results to minimize the CSR once the H-function is considered. We successfully extended this approach to the case of a modified double bend achromat system, opening the door to relatively large bending angles and compact transfer lines. At the same time, the GTWs excited in few mm diameter iris collimators** and accelerating structures have been characterized in terms of the induced emittance growth. A model integrating both CSR and GTW effects suggests that there is a limit on the maximum obtainable electron beam brightness in the presence of such collective effects. * S. Di Mitri et al., PRST-AB 15, 020701 (2012) S. Di Mitri et al., PRL 110, 014801 (2013) * S. Di Mitri et al., PRST-AB 15, 061001 (2012)
	Slides MOOCNO01 [6.919 MB]

MOPSO02	Measurement of Electron-Beam and Seed Laser Properties Using an Energy Chirped Electron Beam	electron, laser, simulation, linac	24
	E. Allaria, G. De Ninno, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Fröhlich, G. Penco, P. Sigalotti, S. Spampinati, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno, S. Spampinati University of Nova Gorica, Nova Gorica, Slovenia E. Ferrari Università degli Studi di Trieste, Trieste, Italy
	We present a new method that uses CCD images of the FERMI electron beam at the dump spectrometer after the undulator to determine various electron beam and external seed laser properties. By taking advantage of the correlation between time and electron beam energy for a quasi-linearly chirped electron beam and the fact that the FERMI seed laser pulse (~180 fs) is much shorter than the electron beam duration (~1 ps), measurements of the e-beam pulse length and temporally local energy chirp and current are possible. Moreover, the scheme allows accurate determination of the timing jitter between the electron beam and the seed laser, as well as a measure of the latter's effective pulse length in the FEL undulators. The scheme can be also provide an independent measure of the energy transferred from the electron beam to the FEL output radiation. We describe the proposed method as well as some experimental results obtained at the seeded FERMI FEL.

MOPSO04	Theoretical Analysis of a Laser Undulator-Based High Gain FEL	laser, undulator, electron, radiation	27
	P. Baxevanis, R.D. Ruth SLAC, Menlo Park, California, USA
	The use of laser (or RF) undulators is nowadays considered attractive for FEL applications, particularly those that aim to utilize relatively low-energy electron beams. In the context of the standard theoretical analysis, the counter-propagating laser pulse is usually treated in the plane-wave approximation, neglecting amplitude and phase variation. In this paper, we develop a three-dimensional, analytical theory of a high-gain FEL based on a laser or RF undulator, taking into account the longitudinal variation of the undulator field amplitude, the laser Gouy phase and the effects of emittance and energy spread in the electron beam. Working in the framework of the Vlasov-Maxwell formalism, we derive a self-consistent equation for the radiation amplitude in the linear regime, which is then solved to good approximation by means of an orthogonal expansion technique []. Numerical results obtained from our analysis are used in the study of an example of a compact, laser undulator-based, X-ray FEL. P. Baxevanis, R. Ruth, Z. Huang, Phys. Rev. ST-AB 16, 010705 (2013).

MOPSO08	Unaveraged Modelling of a LWFA Driven FEL	simulation, electron, radiation, undulator	43
	L.T. Campbell, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom F.J. Grüner, A.R. Maier CFEL, Hamburg, Germany F.J. Grüner, A.R. Maier Uni HH, Hamburg, Germany F.J. Grüner LMU, Garching, Germany
	Preliminary simulations of a Laser Wakefield Field Accelerator driven FEL are presented using the 3D unaveraged, broad bandwidth FEL simulation code Puffin. The radius of the matched low emittance electron beam suggests that the FEL interaction will be strongly affected by radiation diffraction. The parameter scaling and comparison between 3D and equivalent 1D simulations appears to confirm the interaction is diffraction dominated. Nevertheless, output powers are predicted to be greater than those of similar unaveraged FEL models. Possible reasons for the discrepancies between the averaged and unaveraged simulation results are discussed. [1] - AR Maier, A Meseck, S Reiche, CB Schroeder, T Seggebrock, and F Gruner, Phys Rev X 2, 031019 (2012)

MOPSO09	Investigation of a 2-Colour Undulator FEL Using Puffin	undulator, electron, radiation, bunching	47
	L.T. Campbell, B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom S. Reiche PSI, Villigen PSI, Switzerland
	The unaveraged FEL code Puffin* is used to investigate a 2 color FEL. In the scheme under investigation, undulator modules are tuned alternately to generate 2 frequencies quasi-simultaneously, which should result in greater stability than generating them consecutively. The advantage of using Puffin is that it provides the capability of modelling a broad bandwidth spectrum. For example, radiation at 1nm and 2.4nm is difficult to model simultaneously in standard averaged FEL codes. An unaveraged code like Puffin is able to model 2 (or more) wavelengths with a much wider spacing. * LT Campbell and BWJ McNeil, Phys. Plasmas 19, 093119 (2012)

MOPSO17	The Present Status of the Theory of the FEL-based Hadron Beam Cooling	electron, hadron, kicker, ion	52
	A. Elizarov, V. Litvinenko BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The coherent electron cooling (CeC)* device is one of the new facilities under construction in BNL. The CeC is a realization of the stochastic cooling with an electron beam serving as a pick-up and kicker. Hadrons generate electron density perturbations in the modulator section, then these perturbations are amplified in an FEL, and then, they accelerate (or decelerate) hadrons in the kicker by electric field with respect to their velocities. Here we present the theoretical description of the modulator sector,, where the electron density perturbations are formed and our new results on the time evolution of these perturbations in the FEL section, where they are amplified. V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009). A. Elizarov, V. Litvinenko, G. Wang, IPAC'12, weppr099 (2012). * A. Elizarov, V. Litvinenko, IPAC'13, mopwo088 (2013).

MOPSO27	Study of CSR Effects in the Jefferson Laboratory FEL Driver	simulation, radiation, dipole, linac	58
	C.C. Hall, S. Biedron, T.A. Burleson, S.V. Milton, A.L. Morin CSU, Fort Collins, Colorado, USA S.V. Benson, D. Douglas, P.E. Evtushenko, F.E. Hannon, R. Li, C. Tennant, S. Zhang JLAB, Newport News, Virginia, USA B.E. Carlsten, J.W. Lewellen LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the Office of Naval Research and the High Energy Laser Joint Technology. Jefferson Laboratory work also received supported under U.S. DOE Contract No. DE-AC05-06OR23177. In a recent experiment conducted on the Jefferson Laboratory IR FEL driver the effects of Coherent Synchrotron Radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR chicane. This experiment also provides a valuable opportunity to benchmark existing CSR models in a system that may not be fully represented by a 1-D CSR model. Here we present results from this experiment and compare to initial simulations of CSR in the magnetic compression chicane of the machine. Finally, we touch upon the possibility for CSR induced microbunching gain in the magnetic compression chicane, and show that parameters in the machine are such that it should be thoroughly damped.

MOPSO30	Simple Setups for Carrier-envelope-phase Stable Single-cycle Attosecond Pulse Generation	undulator, electron, laser, radiation	63
	J. Hebling, G. Almási, J.A. Fülöp, M.I. Mechler, Z. Tibai, Gy. Tóth University of Pecs, Pécs, Hungary
	Funding: Work supported by Hungarian Research Fund (OTKA), grant number 101846, and from SROP-4.2.1.B-10/2/KONV-2010-0002 and SROP-4.2.2/B-10/1-2010-0029 Robust methods for producing waveform-controlled half-cycle–few-cycle pulses in the mid-infrared (MIR)–extreme ultraviolet (EUV) spectral range are proposed. They are based on coherent Thomson scattering of THz pulses on relativistic ultrathin electron layers and coherent undulator radiation of relativistic ultrathin electron layers, respectively. The ultrathin electron layers are produced by microbunching of ultrashort electron bunches by a TW power laser in a modulator undulator. According to our numerical calculations it is possible to generate as short as 10 nm long electron layers if a single-period modulator undulator with period length significantly shorter than the resonant one is used and the undulator parameter is only K=0.25. Thomson scattering of THz pulses on ultrathin electron layers with only 50 MeV energy can generate for example 170 as long single-cycle pulses at 80 nm wavelength with 0.1 nJ energy. Coherent undulator radiation of ultrathin electron layers with 450 MeV energy can generate single-cycle radiation in the 20 nm – 1000 nm wavelength range. The corresponding pulse energy and pulse duration vary in the 10 pJ – 2 nJ and 47 as – 2.1 fs ranges, respectively.

MOPSO31	Quasiperiodic Method of Averaging Applied to Planar Undulator Motion Excited by a Fixed Traveling Wave	resonance, undulator, radiation, electron	762
	K.A. Heinemann, J.A. Ellison UNM, Albuquerque, New Mexico, USA M. Vogt DESY, Hamburg, Germany
	Funding: The work of JAE and KH was supported by DOE under DE-FG-99ER41104. The work of MV was supported by DESY. We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the X-Ray FEL regime.* We study the associated 6D Lorentz system as the wavelength of the traveling wave varies. The 6D system is reduced, without approximation, to a 2D system (for a scaled energy deviation and generalized ponderomotive phase) in a form for a rigorous asymptotic analysis using the Method of Averaging (MoA), a long time perturbation theory. As the wavelength varies the system passes through resonant and nonresonant (NR) zones and we develop NR and near-to-resonant (NtoR) normal form approximations. For a special initial condition, on resonance, we obtain the well-known FEL pendulum system. We prove NR and NtoR first-order averaging theorems, in a novel way, which give optimal error bounds for the approximations. The NR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the analysis has not been done with the generality here nor has the standard FEL pendulum system been derived with error bounds. * J.A. Ellison, K. Heinemann, M. Vogt, M. Gooden: arXiv:1303.5797 [physics.acc-ph]

MOPSO34	Highly Efficient, High-energy THz Pulses from Cryo-cooled Lithium Niobate for Accelerator and FEL Applications	electron, laser, acceleration, cryogenics	68
	K.-H. Hong, E. Granados, S.-W. Huang, W.R. Huang, F.X. Kaertner, R. Koustuban, L.E. Zapata MIT, Cambridge, Massachusetts, USA F.X. Kaertner CFEL, Hamburg, Germany
	Funding: This work was supported by DARPA under contract N66001-1-11-4192. Intense, ultrafast THz fields are of great interest for electron acceleration, beam manipulation and measurement, and pump-probe experiments with coherent soft/hard x-ray sources based on FELs or inverse Compton scattering sources. Acceleration at THz frequencies has an advantage over RF in terms of accessing high electric-field gradients (>100 MV/cm), while the beam delivery can be treated quasi-optically. However, high-field THz pulse generation is still demanding when compared with conventional RF generation. In this paper, we present highly efficient, single-cycle, 0.45 THz pulse generation by optical rectification of 1.03 μm pulses in cryogenically cooled lithium niobate (LN). Using a near-optimal duration of 680 fs and a pump energy of 1.2 mJ, we report conversion efficiencies above 3% [1], >10 times higher than previous report (0.24%) [2]. Cryogenic cooling of lithium niobate significantly reduces the THz absorption, which will enable the scaling of THz pulse energies to the mJ. We will also report on polarization and mode conversion using segmented THz waveplates to generate radially-polarized TEM01 modes, suitable for THz electron acceleration in dielectric waveguide. [1] S.-W. Huang et al., Opt. Lett. 38, 796-798 (2013). [2] J. A. Fülöp et al., Opt. Lett. 37, 557-559 (2012).

MOPSO40	CLARA Accelerator Design and Simulations	linac, laser, emittance, simulation	72
	P.H. Williams, D. Angal-Kalinin, J.A. Clarke, F. Jackson, J.K. Jones, B.P.M. Liggins, J.W. McKenzie, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Science & Technology Facilities Council We present the accelerator design for CLARA (Compact Linear Advanced Research Accelerator) at Daresbury Laboratory. CLARA will be a testbed for novel FEL configurations. The accelerator will consist of an RF photoinjector, S-band acceleration and transport to 250MeV including X-band linearisation and magnetic bunch compression. We describe the transport in detail. Beam dynamics simulations are then used to define a set of operating working points suitable for the different FEL schemes intended to be tested on CLARA.

MOPSO49	Numerical Accuracy When Solving the FEL Equations	simulation, electron, undulator, bunching	82
	R.R. Lindberg ANL, Argonne, USA
	Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357 The usual method of numerically solving the FEL equations involves dividing both the e-beam and radiation field into "slices" that are loaded one at a time into memory. This scheme is only first order accurate in the discretization of the ponderomotive phase because having only one slice in memory effectively results in a first order interpolation of the field-particle coupling. While experience has shown that FEL simulations work quite well, the first order accuracy opens the door to two possible ways of speeding up simulation time. First, one can consider higher order algorithms; unfortunately, these methods appear to require all the particle and field data in memory at the same time, and therefore will typically only be important for either small (probably 1D) problems or for parallel simulations run on many processors. Second, one may consistently solving the equations to some low order using faster, simpler algorithms (replacing, for example, the usual RK4). The latter is particularly attractive, although in practice it may be desirable to retain higher order methods when integrating along z. We investigate some of the possibilities.

MOPSO51	Feasibility of an XUV FEL Oscillator at ASTA	undulator, electron, simulation, cryomodule	88
	A.H. Lumpkin Fermilab, Batavia, USA H. Freund LANL, Los Alamos, New Mexico, USA M.W. Reinsch LBNL, Berkeley, California, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. A significant opportunity exists at the Advanced Superconducting Test Accelerator (ASTA) facility presently under construction at Fermilab to enable the first XUV free electron laser (FEL) oscillator experiments. The ultrabright beam from the L-band photoinjector will provide sufficient gain to compensate for reduced mirror reflectances in the VUV-XUV regimes, the 3-MHz micropulse repetition rate for 1 ms will support an oscillator configuration, the SCRF linac will provide stable energy, and the eventual GeV-scale energy with three TESLA-type cryomodules will satisfy the FEL resonance condition in the XUV regime. Concepts based on combining such beams with a 5-cm-period undulator and optical resonator cavity for an FEL oscillator are described. We used the 68% reflectances for normal incidence on multilayer metal mirrors developed at LBNL. Initial simulations using GINGER with an oscillator module and MEDUSA:OPC show saturation for the 13.4-nm case after 300 and 350 passes, respectively,of the 3000 pulses. Initially, VUV experiments could begin in the 180- to 120-nm regime using MgF2-coated Al mirrors with only one cryomodule installed and beam energies of 250-300 MeV. LBNL X-ray optics site: http://xdb.lbl.gov/Section4

MOPSO57	Measurement of Wigner Distribution Function for Beam Characterization of FELs	laser, free-electron-laser, electron, 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.

MOPSO59	The Influence of the Magnetic Field Inhomogeneity on the Spontaneous Radiation and the Gain in the Plane Wiggler	electron, wiggler, laser, undulator	97
	K.B. Oganesyan ANSL, Yerevan, Armenia
	Funding: ISTC We calculate the spectral distribution of spontaneous emission and the gain of electrons moving in plane wiggler with inhomogeneous magnetic field. We show that electrons do complicated motion consisting of slow(strophotron) and fast(undulator) parts. We average the equations of motion over fast undulator part and obtain equations for connected motion. It is shown, that the account of inhomogenity of the magnetic field leads to appearence of additional peaks in the spectral distribution of spontaneous radiation and the gain.

MOPSO65	Suppression of Wakefield Induced Energy Spread Inside an Undulator Through Current Shaping	wakefield, undulator, impedance, electron	108
	J. Qiang, C.E. Mitchell LBNL, Berkeley, California, USA
	Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Wakefields from resistive wall and surface roughness inside an undulatory can cause significant growth of beam energy spread and limit the performance of x-ray FEL radiation. In this paper, we propose a method to mitigate such energy modulation by appropriately conditioning the electron beam current profile. Numerical example and potential applications will also be discussed.

MOPSO66	Start-to-end Simulation of a Next Generation Light Source Using the Real Number of Electrons	electron, simulation, emittance, radiation	112
	J. Qiang, J.N. Corlett, P. Emma, C.E. Mitchell, C. F. Papadopoulos, G. Penn, M.W. Reinsch, R.D. Ryne, M. Venturini LBNL, Berkeley, California, USA S. Reiche PSI, Villigen PSI, Switzerland
	Funding: This research was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Start-to-end simulation plays an important role in design and optimization of next generation light sources. In this paper, we will present start-to-end (from the photocathode to the end of undulator) simulations of a high repetition rate FEL-based Next Generation Light Source driven by CW superconducting linac with the real number of electrons (~2 billion electrons/bunch) using the multi-physics parallel beam dynamics code IMPACT. We will discuss challenges, numerical methods and physical models used in the simulation. We will also present simulation results of a beam transporting through photoinjector, beam delivery system, and final X-ray FEL radiation.

MOPSO69	Free-Electron Lasers Driven by Laser-Plasma Accelerators Using Decompression or Dispersion	electron, undulator, plasma, laser	117
	C.B. Schroeder, E. Esarey, W. Leemans, J. van Tilborg LBNL, Berkeley, California, USA Y. Ding, Z. Huang SLAC, Menlo Park, California, USA F.J. Grüner, A.R. Maier CFEL, Hamburg, Germany
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Laser-plasma accelerators (LPAs) compactly produce fs beams with kA peak current and low (sub-micron) transverse emittance. Presently, the energy spread (percent-level) hinders the FEL application. Slippage of the fs beam in the FEL also suppresses lasing in the soft-x-ray, and longer, wavelength regimes. Given experimentally demonstrated LPA electron beam parameters, we discuss methods of beam phase space manipulation after the LPA to achieve FEL lasing. Decompression is examined as a solution to reduce the slice energy spread and slippage effects. We present a theoretical analysis of the stretched (and chirped) LPA beam in the FEL and determine the optimal decompression. Dispersion, coupled to a transverse gradient undulator (TGU), is also considered to enable LPA-driven FELs. Using a TGU has the advantages of shorter pulse duration, smaller bandwidth, and wavelength stabilization. We present numerical modeling for SASE and seeded XUV and soft x-ray FELs driven by LPAs after beam manipulation (decompression and/or dispersion). Recent advances in LPA performance will be presented, and experimental plans to demonstrate LPA-driven FEL lasing at LBNL will be discussed.

MOPSO73	Suface Roughness Wakefield in FEL Undulator	wakefield, impedance, undulator, electron	127
	G.V. Stupakov SLAC, Menlo Park, California, USA S. Reiche PSI, Villigen PSI, Switzerland
	Among several wakefield models for the FEL undulator vacuum chamber a simple sinusoidal wall modulation with a small ratio of height to wavelength is especially attractive because of its simplicity [1]. The model neglects a so called resonant mode wakefield and has an (integrable) singularity at the origin which makes difficult its use in practical simulations. In this work we generalize the longitudinal wake of a sinusoidally modulated wall to include the effect of the resonant mode. This also removes the singularity of the wake at the origin. The new wake is used to evaluate the roughness wakefield effect in the undulator of SwissFEL. [1] G. Stupakov, in "Nonlinear and Collective Phenomena in Beam Physics 1998" Workshop, New York (1999), no. 468 in AIP Conference Proceedings, pp. 334–47.

MOPSO74	Reevaluation of Coherent Electron Cooling Gain Factor	electron, undulator, hadron, radiation	132
	G.V. Stupakov SLAC, Menlo Park, California, USA M.S. Zolotorev LBNL, Berkeley, California, USA
	In Ref. [1] the authors put forward a concept of coherent electron cooling of hadrons. At the core of the concept lies the following idea: a density perturbation induced by an hadron in a co-propagating relativistic electron beam is amplified by several orders of magnitude in a free electron laser (FEL). After the FEL the electron beam is merged again with the hadron one and the amplified electric field in the electron beam acts back on each hadron resulting, after many repetitions, in cooling of the hadron beam. The efficiency of the process is critically determined by the amplification factor of the longitudinal electric field induced by the hadron in the electron beam. In this work we show that this factor is actually considerably smaller than the (conventionally defined) FEL gain with the smallness parameter to be the relative bandwidth of the FEL amplifier. [1] V. N. Litvinenko and Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).

MOPSO76	FEL Operation With the Superconducting RF Photo Gun at ELBE	gun, laser, SRF, cavity	136
	J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, R. Schurig, W. Seidel, H. Vennekate, R. Xiang HZDR, Dresden, Germany T. Kamps, J. Rudolph HZB, Berlin, Germany I. Will MBI, Berlin, Germany
	The superconducting RF photoinjector (SRF gun) operating with a 31/2-cell niobium cavity and Cs2Te photocathodes is installed at the ELBE radiation center. The gun provides beams for ELBE as well as in a separate diagnostics beam line for beam parameter measurements. Since 2012 a new UV driver laser system developed by MBI has been installed for the SRF gun . It delivers CW or bust mode pulses with 13 MHz repetition rate or with reduced rates of 500, 200, and 100 kHz at an average UV power of about 1 W. The new laser allows the gun to serve as the driver for the infrared FELs at ELBE. In the first successful experiment a 250 μA beam with 3.3 MeV from SRF gun was injected into ELBE, further accelerated in the ELBE superconducting linac modules and then guided to the U100 undulator. First lasing was achieved at the wavelength of 41 μm. The spectrum, detuning curve and further parameters were measured.

MOPSO81	Broad-band Amplifier Based on Two-stream Instability	electron, plasma, free-electron-laser, 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.

MOPSO82	JLIFE: The Jefferson Lab Interactive Front End for the Optical Propagation Code	controls, laser, GUI, factory	149
	A.M. Watson, M.D. Shinn JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC and supported by the ONR, the Joint Technology Office, and the DOE under U.S. DOE Contract No. DE-AC05-06OR23177. We present details on a graphical interface for the open source software program Optical Propagation Code, or OPC. [1] This interface, written in Java, allows a user with no knowledge of OPC to create an optical system, with lenses, mirrors, apertures, etc. and the appropriate drifts between them. The Java code creates the appropriate Perl script that serves as the input for OPC. The mode profile is then output at each optical element. The display can be either an intensity profile along the x axis, or as an isometric 3D plot which can be tilted and rotated. These profiles can be saved. Examples of the input and output will be presented. [1] J. G. Karssenberg, P. J. M. van der Slot, I. V. Volokhine, J. W. J. Verschuur, and K.-J. Boller, “Modeling paraxial wave propagation in free-electron laser oscillators”, JAP 100, 093106 (2006).

MOPSO84	Numerical Investigations of Transverse Gradient Undulator Based Novel Light Sources	electron, laser, undulator, simulation	152
	T. Zhang, D. Wang, G.L. Wang, H.F. Yao SINAP, Shanghai, People's Republic of China J.S. Liu, C. Wang, W.T. Wang, Z.N. Zeng Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China J.Q. Wang, S.H. Wang IHEP, Beijing, People's Republic of China
	With the stat-of-the-art laser technique, the quality of electron beam generated from laser-plasma accelerator (LPA) is now becoming much more better. The natural merits LPA beam, e.g. high peak current, ultra-low emittance and ultra-short bunch length, etc., pave the way to the novel light sources, especially in the realm of developing much compact X-ray light sources, e.g. table-top X-ray free-electron laser, although the radiation power is limited by the rather larger energy spread than conventional LINAC. Luckily, much more power could be extracted by using the undulator with transverse gradient (TGU) when energy spread effect could be compensated. Here we introduce a novel soft x-ray light source driven by LPA based on TGU technique. Meanwhile we present a simple idea on how to achieve much higher rep-rate (e.g. ~100 kHz) storage ring based FELs boosted by TGU.

TUOBNO03	An RF Deflecting Cavity Based Spreader System for Next Generation Light Sources	gun, cavity, dipole, electron	173
	C. Sun, L.R. Doolittle, P. Emma, J.-Y. Jung, M. Placidi, A. Ratti LBNL, Berkeley, California, USA
	Lawrence Berkeley National Laboratory (LBNL) is developing design concepts for a multi-beamline (up to 10 lines) soft x-ray FEL array powered by a superconducting linear accelerator with a high bunch repetition rate of approximately one MHz. The FEL array requires a beam spreader system which can distribute individual electron bunches from the linac to each independently configurable beamline. We propose a new spreader system using RF deflecting cavities to deflect electron bunches as an alternative design to the fast kicker scheme. This RF approach offers more stable deflection amplitude while removing the limitations on the bunch repetition rate characteristic of the kicker approach. In this work, we describes the design concept of this RF based spreader system, including technical choices, design parameters and beamline optics. [1] M. Placidi et al., Proceedings of IPAC2012, New Orleans, Louisiana, USA, pp.1765-1767
	Slides TUOBNO03 [1.391 MB]

TUOCNO01	Electron Beam Longitudinal Phase Space Manipulation by Means of an AD-HOC Photoinjector Laser Pulse Shaping	electron, linac, laser, simulation	180
	G. Penco, D. Castronovo, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, W.M. Fawley, L. Giannessi, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	In a seeded FEL machine as FERMI, the interplay between the electrons energy curvature and the seed laser frequency chirp has a relevant impact on the output FEL spectrum. It is therefore crucial controlling and manipulating the electron beam longitudinal phase space at the undulator entrance. In case of very short bunches, i.e. high compression scheme, the longitudinal wakefields generated in the linac induce a positive quadratic curvature in the electrons longitudinal phase space that is hard to compensate by tuning the phase of the main RF sections or the possible high harmonic cavity. At FERMI we have experimentally exploited a longitudinal ramp current distribution at the cathode, obtained with an ad-hoc photoinjector laser pulse shaping, to linearize the longitudinal wakefields in the downstream linac and flatten the electrons energy distribution, as theoretical foreseen in [1]. Longitudinal phase space measurements in this novel configuration are here presented, providing a comparison with the typical longitudinal flat-top profile. [1] Phys. Rev. Special Topics - Accel. and Beams 9 (12), 120701 (2006)
	Slides TUOCNO01 [28.792 MB]

TUOCNO05	Design Concepts for a Next Generation Light Source at LBNL	linac, electron, laser, undulator	193
	J.N. Corlett, A.P. Allezy, D. Arbelaez, K.M. Baptiste, J.M. Byrd, C.S. Daniels, S. De Santis, W.W. Delp, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, J.G. Floyd, J.P. Harkins, G. Huang, J.-Y. Jung, D. Li, T.P. Lou, T.H. Luo, G. Marcus, M.T. Monroy, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, S. Paret, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, H.J. Qian, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, R.W. Schoenlein, C. Serrano, J.W. Staples, C. Steier, C. Sun, M. Venturini, W.L. Waldron, W. Wan, T. Warwick, R.P. Wells, R.B. Wilcox, S. Zimmermann, M.S. Zolotorev LBNL, Berkeley, California, USA C. Adolphsen, K.L.F. Bane, Y. Ding, Z. Huang, C.D. Nantista, C.-K. Ng, H.-D. Nuhn, C.H. Rivetta, G.V. Stupakov SLAC, Menlo Park, California, USA D. Arenius, G. Neil, T. Powers, J.P. Preble JLAB, Newport News, Virginia, USA C.M. Ginsburg, R.D. Kephart, A.L. Klebaner, T.J. Peterson, A.I. Sukhanov Fermilab, Batavia, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 The NGLS collaboration is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately 1 MHz. The CW superconducting linear accelerator design is based on developments of TESLA and ILC technology, and is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches from the linac are distributed by RF deflecting cavities to the array of independently configurable FEL beamlines with nominal bunch rates of ~100 kHz in each FEL, with uniform pulse spacing, and some FELs capable of operating at the full linac bunch rate. Individual FELs may be configured for different modes of operation, including self-seeded and external-laser-seeded, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from femtoseconds and shorter, to hundreds of femtoseconds. In this paper we describe current design concepts, and progress in R&D activities.
	Slides TUOCNO05 [5.982 MB]

TUPSO01	Corrector Response Based Alignment at FERMI	alignment, quadrupole, linac, wakefield	205
	M. Aiba, M. Böge PSI, Villigen PSI, Switzerland D. Castronovo, S. Di Mitri, L. Fröhlich, G. Gaio Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The components of an FEL accelerator generally need to be beam-based aligned in order to meet the design performance. We are developing new technique, where dipole corrector responses are used instead of orbit difference measurements. When an orbit feedback is running, any change in beam orbit is compensated by the actuators, i.e., the dipole correctors. For example, the spurious dispersion through linac rf structures, which is a source of emittance degradation, is measured through orbit differences for various beam momenta in the conventional way while dipole corrector responses are examined in the new method. The advantages are localization of misalignments, stable measurement as the orbit is kept constant, and automatic averaging and beam jitter filtering by the feedback loop. Furthermore, this method potentially allows us to detect transverse wakefield kicks, which are also an emittance degradation source, by looking into the dipole corrector responses to a change in bunch charge or bunch length. The results from a series of machine development shifts will be presented.

TUPSO14	Transverse Deflecting Structures for Bunch Length and Slice Emittance Measurements on SwissFEL	linac, emittance, diagnostics, undulator	236
	P. Craievich, R. Ischebeck, F. Löhl, G.L. Orlandi, E. Prat PSI, Villigen PSI, Switzerland
	The SwissFEL project, under development at the Paul Scherrer Institut, will produce FEL radiation in a wavelength range from 0.1 nm to 7 nm. 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 magnetic chicanes will compress the beam between 2.5 fs rms and 25 fs rms depending on the operation mode. The bunch length and slice parameters will be measured after the first bunch compressor (330 MeV) by using an S-band transverse deflecting structure (TDS). A C-band TDS will be employed to measure the longitudinal parameters of the beam just upstream the undulator beamline (5.8 GeV). With the designed transverse beam optics, an integrated deflecting voltage of 70 MV is required in order to achieve a longitudinal resolution on the femtosecond time scale. In this paper we present the TDS measurement systems to be used at SwissFEL, with a particular emphasis on the new C-band device, including hardware, lattice layout and beam optics.

TUPSO15	Beam Diagnostic Requirements for the Next Generation Light Source	diagnostics, linac, emittance, feedback	242
	S. De Santis, J.M. Byrd, J.N. Corlett, P. Emma, D. Filippetto, M. Placidi, H.J. Qian, F. Sannibale LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The NGLS project consists in a 2.4 GeV superconducting linac accelerating sub-1 μm normalized emittance bunches used to produce high intensity soft X-ray short pulses from multiple FEL beamlines. The 1 MHz bunch repetition rate, and the consequent high beam power, present special challenges, but also opportunities, in the design of the various electron beam diagnostic devices. The wide range of beam characteristics, from the photoinjector to the undulators, require the adoption of different diagnostics optimized to each machine section and to the specific application of each individual measurement. In this paper we present our plans for the NGLS beam diagnostics, discussing the special requirements and challenges.

TUPSO24	Dispersion Based Beam Tilt Correction	quadrupole, sextupole, emittance, electron	267
	M.W. Guetg, B. Beutner, E. Prat, S. Reiche PSI, Villigen PSI, Switzerland
	In Free Electron Lasers (FEL), a transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch and therefore the FEL performance. The dominant sources of slice misalignments for FELs are the incoherent and coherent synchrotron radiation within bunch compressors as well as transverse wake fields in the accelerating cavities. This is of particular importance for over-compression which is required for one of the key operation modes for the SwissFEL planned at the Paul Scherrer Institute. The centroid shift is corrected using corrector magnets in dispersive sections, e.g. the bunch compressors. First and second order corrections are achieved by pairs of sextupole and quadrupole magnets in the horizontal plane while skew quadrupoles correct to first order in the vertical plane. Simulations and measurements at the SwissFEL Injector Test Facility are done to investigate the proposed correction scheme for SwissFEL. This paper presents the methods and results obtained.

TUPSO35	The MAX IV Linac as X-Ray FEL Injector: Comparison of Two Compression Schemes	linac, emittance, wakefield, electron	294
	O. Karlberg, F. Curbis, S. Thorin, S. Werin MAX-lab, Lund, Sweden
	The MAX IV linac will be used for injections and top up of two storage rings and at the same time provide a high brightness pulses to a short pulse facility (SPF) and an X-ray FEL (phase 2). Compression in the linac is done in two double achromats which implies a positive R56 unlike the commonly used chicane compressor scheme with negative R56. Compression using the achromats scheme requires the electron bunch to be accelerated on a falling RF slope resulting in an energy chirp that longitudinal wakefields will boost along the linac. This permits a stronger compression. In this proceeding we will present how the longitudinal wakefields interact with the bunch compression in the double achromat scheme compared with the chicane compression case. Focus is brought on how the unique MAX IV linac lattice is fully capable to cope with the high demands of an FEL injector. The charge related electron beam jitter in both set-ups will also be investigated.

TUPSO45	Initial Streak Camera Measurements of the S-band Linac Beam for the University of Hawaii FEL Oscillator	electron, linac, undulator, radiation	325
	A.H. Lumpkin Fermilab, Batavia, USA M.R. Hadmack, J.M.D. Kowalczyk, J. Madey, E.B. Szarmes University of Hawaii, Honolulu, HI, USA
	Funding: Work at Fermilab supported by Fermi Research Alliance, LLC under U.S.DOE Contract No.DE-AC02-07CH11359. Work at UH supported by U.S. Dept. of Homeland Security grant No. 20120-DN-077-AR1045-02. The S-band linac driven Mark V free-electron laser oscillator (FELO) at the University of Hawai‘i operates in the mid-IR at electron beam energies of 40-45 MeV with a four microsecond macropulse length. Recently investigations of the electron beam micropulse bunch length and phase as a function of macropulse time became of interest for potentially optimizing the FELO performance. These studies involved the implementation of a Hamamatsu C5680 streak camera with dual sweep capabilities and the transport of optical transition radiation (OTR) generated at an upstream Cu mirror and of coherent spontaneous emission radiation (CSER) generated in the undulator to the streak camera location outside of the linac tunnel. Both a fast single-sweep vertical unit and a synchroscan unit tuned to 119.0 MHz were used. Initial results include measurements of the individual CSER (on the FEL7th harmonic at 652 nm) micropulse bunch lengths (3 to 5 ps FWHM), the CSER signal intensity variation along macropulse time, and a detected phase slew of 4 ps over the last 700 ns of the macropulse. Complementary OTR measurements are also being evaluated and will be presented as available.

TUPSO49	Electric Field Dependence of Photoemission From n- and p- Type SI Crystals	cathode, lattice, free-electron-laser, 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)

TUPSO50	Numerical Study on Electron Beam Properties in Triode Type Thermionic RF Gun	cavity, gun, cathode, electron	344
	M. Mishima, M. Inukai, T. Kii, K. Masuda, H. Negm, H. Ohgaki, K. Okumura, M. Omer, K. Torgasin, K. Yoshida, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	The KU-FEL(Kyoto University- Free Electron Laser) facility uses a thermionic 4.5 cell S-band RF gun for electron beam generation because of such advantages over photocathode rf guns as lower cost, higher average current, longer cathode lifetime, and less vacuum requirement. The main disadvantage of using a thermionic RF gun is the back bombardment effect, which causes energy drop in macro pulse of FEL. A triode structure for RF gun was designed in order to minimize the inherent back-bombardment effect. The 2D-simulation has shown significant reduction of back-bombardment power, longitudinal emittance, and an increase of peak current. A coaxial RF cavity was fabricated based on the design for modification of the existing RF gun to a triode type one. The coaxial RF cavity is equipped with gasket tuning system in order to adjust the cavity resonance frequency. However the frequency adjustment by variation of gasket thickness changes the coaxial cavity geometry and might affect the predicted beam optics. Another parameter influencing beam optics is the position of thermionic cathode to be installed in the coaxial cavity, which might vary due to misalignment. K. Masuda, et al., Proceedings of FEL 2009, Liverpool, Pages 281-284 (2009). **K. Torgasin, et al., Proceedings of FEL 2012, Nara(2012).

TUPSO52	R&D Towards a Delta-type Undulator for the LCLS	undulator, vacuum, polarization, radiation	348
	H.-D. Nuhn, S.D. Anderson, G.B. Bowden, Y. Ding, G.L. Gassner, Z. Huang, E.M. Kraft, Yu.I. Levashov, F. Peters, F.E. Reese, J.J. Welch, Z.R. Wolf, J. Wu SLAC, Menlo Park, California, USA A.B. Temnykh Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The LCLS generates linearly polarized, intense, high brightness x-ray pulses from planar fixed-gap undulators. While the fixed-gap design supports a very successful and tightly controlled alignment concept, it provides only limited taper capability (up to 1% through canted pole and horizontal position adjustability) and lacks polarization control. The latter is of great importance for soft x-ray experiments. A new compact undulator design (Delta) has been developed and tested with a 30-cm-long in-vacuum prototype at Cornell University, which adds those missing properties to the LCLS undulator design and is readily adapted to the LCLS alignment concept. Tuning Delta undulators within tight, FEL type tolerances is a challenge due to the fact that the magnetic axis and the magnet blocks are not easily accessible for measurements and tuning in the fully assembled state. An R&D project is underway to install a 3.2-m long out-of-vacuum device in place of the last LCLS undulator, to provide controllable levels of polarized radiation and to develop measurement and tuning techniques to achieve x-ray FEL type tolerances. Presently, the installation of the device is scheduled for August 2013.

TUPSO58	Developments of a High-average-current Thermionic RF Gun for ERLs and FELs	gun, cavity, cathode, electron	359
	J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd AES, Princeton, New Jersey, USA
	Funding: Supported by ONR under Contract No. N00014-10-C-0191. The development of a high-average-current thermionic RF gun with the required beam performance for lasing would provide significant cost of ownership and reliability gains for high-average-power energy recovery linac (ERL) and free electron laser (FEL) devices. The beam for these applications requires high quality and high performance, specifically: low transverse emittance, short pulse duration and high average current. We are developing a gridded thermionic cathode embedded in a copper one-and-half cell UHF cavity to generate the electron beam. The fundamental RF and higher harmonics are combined on the grid and a gated DC voltage controls the beam emission from the cathode. Simulations indicate that short pulse ~ 10 psec, < 1 MeV electron beams with low-emittance ~ 15 mm-mrad at currents ≥ 100 mA can be generated. The elimination of sensitive photocathodes and their drive laser systems would provide significant capital cost saving, improved reliability and uptime due to increased robustness and hence operating and lifecycle cost savings as well. We will present the gun design and performance simulations and the progress achieved to date in optimizing the device.

TUPSO60	Status of the Undulator Systems for the European X-ray Free Electron Laser	undulator, controls, laser, electron	367
	J. Pflüger, M. Bagha-Shanjani, A. Beckmann, K.H. Berndgen, P. Biermordt, G. Deron, U. Englisch, S. Karabekyan, B. Ketenoğlu, M. Knoll, Y. Li, F. Wolff-Fabris, M. Yakopov XFEL. EU, Hamburg, Germany
	The three undulator systems for the European XFEL consist of a total of 91 Undulator Cells. Each cell consists of an Undulator Segment and an intersection. They will be operational by end of 2015. The serial production of the 91 Undulator Segments is a great challenge and without precedence. It is now in full swing. This contribution gives an overview over the most important design aspects as well as the experience and strategy with the serial production. Representative results of magnetic performance are given. The status of the other system components is briefly described.

TUPSO62	Status of the Planar Undulator Applied in HUST THz-FEL Oscillator	undulator, radiation, electron, focusing	372
	B. Qin, X. Lei, K.F. Liu, X. Liu, P. Tan, Y.Q. Xiong, J. Yang, L. Yang HUST, Wuhan, People's Republic of China Y.B. Wang Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
	To fulfill the physical requirement of a 50-100 um Free Electron Laser (FEL) oscillator, design considerations of a planar undulator are described. Some technical issues, including the tolerances study, the beam match, the field measurement setup and the influence on the magnetic field by the waveguide are discussed as well.

TUPSO64	Short SASE-FEL Pulses at FLASH	laser, electron, radiation, free-electron-laser	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.

TUPSO66	Transport of Terahertz-Wave Coherent Synchrotron Radiation With a Free-electron Laser Beamline at LEBRA	electron, radiation, undulator, linac	383
	N. Sei, H. Ogawa AIST, Tsukuba, Ibaraki, Japan K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Sakai, T. Tanaka LEBRA, Funabashi, Japan
	Funding: This work was supported by JSPS Grant-in-Aid for Challenging Exploratory Research 2365696. Nihon University and AIST have jointly developed terahertz-wave coherent synchrotron radiation (CSR) at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. We have already observed intense terahertz-wave radiation from a bending magnet located above an undulator, and confirmed it to be CSR. To avoid a damage caused by ionizing radiation, we worked on transporting the CSR to an experimental room which was next to the accelerator room. By using a beamline of an infrared free-electron laser, the CSR more than 1 mW was successfully transported to the experimental room. The transport of the CSR and imaging experiments with the CSR at LEBARA will be reported. : N. Sei et al., “Observation of intense terahertz-wave coherent synchrotron radiation at LEBRA”, J. Phys. D, 46 (2013) 045104.

TUPSO80	The MAX IV Linac and First Design for an Upgrade to 5 GeV to Drive an X-ray FEL	linac, simulation, electron, storage-ring	413
	S. Thorin, F. Curbis, N. Čutić, M. Eriksson, O. Karlberg, F. Lindau, A.W.L. Mak, E. Mansten, S. Werin MAX-lab, Lund, Sweden
	The installation of the MAX IV linear accelerator is in full progress, and commissioning is planned to start in the second quarter of 2014. The 3 GeV linac will be used as a full energy injector for the two storage rings, and as a high brightness driver for a Short Pulse linac light source. The linac has been deigned to also handle the high demands of an FEL injector. The long term strategic plan for the MAX IV laboratory includes an extension of the linac to 5 GeV and an X-ray FEL. In this paper we present the both design concept and status of the MAX IV linac along with parameters of the 3 GeV high quality electron pulses. We also present the first design and simulation results of the upgrade to a 5 GeV X-ray FEL driver.

TUPSO81	Challenges for Detection of Highly Intense FEL Radiation: Photon Beam Diagnostics at FLASH1 and FLASH2	photon, diagnostics, electron, radiation	417
	K.I. Tiedtke, M. Braune, G. Brenner, S. Dziarzhytski, B. Faatz, J. Feldhaus, B. Keitel, M. Kuhlmann, H. Kühn, E. Plönjes, A.A. Sorokin, R. Treusch DESY, Hamburg, Germany
	In spite of the evident progress in the development of FEL facilities, the characterization of important FEL photon beam parameters during FEL-commissioning and user experiments is still a great challenge. In particular pulse-resolved photon beam characterization is essential for most user experiments, but the unique properties of FEL radiation properties such as extremely high peak powers and short pulse lengths makes the shot-to-shot monitoring of important parameters very difficult. Therefore, sophisticated concepts have been developed and used at FLASH in order to measure radiation pulse intensity, beam position and spectral as well as temporal distribution – always coping with the highly demanding requirements of user experiments as well as machine operation. Here, an overview on the photon diagnostic devices operating at FLASH and FLASH II will be presented, with emphasizes on the pulse resolving intensity and energy detectors based on photoionization of rare gases.

TUPSO83	Quantum Efficiency and Transverse Momentum From Metals	electron, brightness, vacuum, laser	424
	T. Vecchione, D. Dowell SLAC, Menlo Park, California, USA J. Feng, H.A. Padmore, W. Wan LBNL, Berkeley, California, USA
	Funding: Work supported by US DOE contracts DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC000571. QE and transverse momentum are key parameters limiting the achievable brightness of FELs. Despite the importance, little data is available to substantiate current models. Expressions for each and experimental confirmation of each expression with respect to excess energy are presented. Novel instrumentation and analysis techniques developed are described.

TUPSO87	High-Field Laser-Based Terahertz Source for SwissFEL	laser, controls, radiation, photon	438
	C. Vicario, C.P. Hauri, B. Monoszlai, C. Ruchert PSI, Villigen PSI, Switzerland C.P. Hauri EPFL, Lausanne, Switzerland
	We present efficient laser-driven THz generation by optical rectification in various organic materials yielding transient fields up to 150 MV/m and 0.5 Tesla. The generated spectra extend over the entire THz gap (0.1-10 THz). Manipulation of the absolute phase by dispersion control is demonstrated for 5-octave spanning, single-cycle pulses. The presented source will be applied to the future SwissFEL as Xray photon temporal diagnostics and for pump-and-probe experiments.

TUPSO88	New Concept for the SwissFEL Gun Laser	laser, cathode, gun, electron	442
	A. Trisorio, M.C. Divall, C.P. Hauri, C. Vicario PSI, Villigen PSI, Switzerland A. Courjaud Amplitude Systemes, Pessac, France
	The operation of Swiss FEL put very stringent constrains on the gun laser system. First the parameters, such as energy stability, timing jitter, double pulse operation, temporal and spatial pulse shape of the ultra-violet laser pulses used to generate the photo-electrons are challenging even for the state of the art laser technologies. Second, the laser system must be extremely stable, reliable and its maintenance cost as low as possible. In this perspective, we prospected for alternative technologies to the well known, commonly used but costly Ti:sapphire laser systems. We show that a hybrid Yb fiber and solid state Yb:CaF2 amplifier system can be a very interesting approach. This gain medium allows the production of sub-500 fs, high fidelity, high stability, high energy pulses in the ultra-violet with low timing jitter. The system profits of the mature, stable direct diode pumping technology and optimized design. It delivers the two high-energy, shaped UV pulses separated by 28 ns to produce the photo-electrons, a short IR probe (<100 fs FWHM) to temporally characterize those pulses and the two stretched IR pulses ( 50 ps FWHM) necessary for the laser heater.

TUPSO89	A Femtosecond Resolution Electro-optic Diagnostic Using a Nanosecond-pulse Laser	laser, diagnostics, target, optics	447
	D.A. Walsh, W.A. Gillespie University of Dundee, Nethergate, Dundee, Scotland, United Kingdom S.P. Jamison Cockcroft Institute, Warrington, Cheshire, United Kingdom S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: This project has been funded by CERN as part of the CLIC-UK programme Contract Number KE1865/DG/CLIC Electro-optic diagnostics with a target time resolution of 20fs RMS, and with intrinsically improved stability and reliability, are being developed. The new system is based on explicit temporal measurement of an electro-optically upconverted pulse, following interaction of the bunch with a quasi-CW probe pulse. The electro-optic effect generates an “optical-replica” of the longitudinal charge distribution from the narrow-bandwidth probe, simultaneously up-converting the bunch spectrum to optical frequencies. By using Frequency Resolved Optical Gating (FROG), an extension of autocorrelation, the optical replica can then be characterised on a femtosecond time scale. This scheme therefore bypasses the requirement for unreliable femtosecond laser systems. The high pulse energy required for single-shot pulse measurement via FROG will be produced through optical parametric amplification of the optical-replica pulses. The complete system will be based on a single nanosecond-pulse laser – resulting in a reliable system with greatly relaxed timing requirements.

WEIANO01	Towards Zeptosecond-scale Pulses From X-ray Free Electron Lasers	electron, radiation, undulator, laser	458
	D.J. Dunning, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom B.W.J. MᶜNeil USTRAT/SUPA, Glasgow, United Kingdom
	The short wavelength and high peak power of the present generation of Free-Electron Lasers (FELs) opens the possibility of ultra-short pulses even surpassing the present (~10-100 attosecond) capabilities of other light sources – but only if x-ray FELs can be made to generate pulses consisting of just a few optical cycles. For hard x-ray operation (<~0.1nm), this corresponds to durations of approximately a single attosecond, and below into the zeptosecond scale. This talk will describe a proposed method [1] to generate trains of few-cycle pulses, at GW peak powers, from existing x-ray FEL facilities by using a relatively short 'afterburner'. Such pulses would enhance research opportunity in atomic dynamics and push capability towards the investigation of electronic-nuclear and nuclear dynamics. The corresponding multi-colour spectral output, with a bandwidth envelope increased by up to two orders of magnitudes over SASE, also has potential applications. [1] D.J. Dunning, B.W.J. McNeil, N.R. Thompson, Phys. Rev. Lett. 110, 104801 (2013).
	Slides WEIANO01 [3.492 MB]

WEOANO01	New Scheme to Generate a Multi-terawatt and Attosecond X-ray Pulse in XFELs	electron, target, laser, undulator	464
	T. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	A new scheme to be applied in XFELs has been recently proposed, which effectively compresses the X-ray pulse, i.e., shortens the pulse length and enhances the peak power by means of inducing a periodic current enhancement with an optical laser and applying a temporal shift between the X-ray and electron beams. In this paper, detailed mechanism of the new scheme is explained together with numerical results applied to the SACLA XFEL facility. T. Tanaka, PRL 110, 084801 (2013)
	Slides WEOANO01 [4.177 MB]

WEOANO03	Longitudinal Coherence in an FEL With a Reduced Level of Shot Noise	electron, laser, radiation, undulator	469
	V.A. Goryashko Private Address, Uppsala, Sweden V.G. Ziemann Uppsala University, Uppsala, Sweden
	For a planar free electron laser (FEL) configuration we study self-amplified coherent spontaneous emission driven by a gradient of the bunch current in the presence of different levels of noise in bunches [1]. We calculate the probability density distribution of the maximum power of the radiation pulses for different levels of shot noise. It turns out that the temporal coherence quickly increases as the noise level reduces. We also show that the FEL based on coherent spontaneous emission produces almost Fourier transform limited pulses and the time-bandwidth product is mainly determined by the bunch length and the interaction distance in an undulator. We also propose a scheme that permits the formation of electron bunches with a reduced level of noise and a high gradient of the current at the bunch tail to enhance coherent spontaneous emission. The presented scheme uses effects of noise reduction and controlled microbunching instability and consists of a laser heater, a bunch compressor, and a shot noise suppression section. The noise factor and microbunching gain of the overall proposed scheme with and without laser heater are estimated. V.A. Goryashko and V. Ziemann, Phys. Rev. ST Accel. Beams 16, 030702 (2013).
	Slides WEOANO03 [1.999 MB]

WEOCNO03	3-D Theory of a High Gain Free-Electron Laser Based on a Transverse Gradient Undulator	electron, undulator, emittance, radiation	481
	P. Baxevanis, Y. Ding, Z. Huang, R.D. Ruth SLAC, Menlo Park, California, USA
	The performance of a free-electron laser (FEL) depends significantly on the various parameters of the driving electron beam. In particular, a large energy spread in the beam results in a great reduction of the FEL gain, an effect which is relevant when one considers FELs driven by plasma accelerators or storage rings. For such cases, one possible solution is to use a transverse gradient undulator (TGU) [,]. In this concept, the energy spread problem is mitigated by properly dispersing the e-beam and introducing a linear, transverse field dependence in the undulator. This paper presents a self-consistent theoretical analysis of a TGU-based high gain FEL, taking into account three-dimensional (3-D) effects and beam size variations along the undulator [*]. The results of our theory compare favorably with simulation and are used in fast optimization studies of various X-ray FEL configurations. T. Smith et al., J. Appl. Phys. 50, 4580 (1979). Z. Huang, Y. Ding, C. Schroeder, Phys. Rev. Lett. 109, 204801 (2012). *P. Baxevanis, R. Ruth, Z. Huang, Phys. Rev. ST-AB 16, 010705 (2013).
	Slides WEOCNO03 [3.217 MB]

WEPSO01	Free Electron Lasers in 2013	electron, undulator, laser, free-electron-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.

WEPSO02	Results and Perspectives on the FEL Seeding Activities at FLASH	laser, undulator, electron, radiation	491
	J. Bödewadt, C. Lechner Uni HH, Hamburg, Germany
	In recent years, several methods of free-electron laser (FEL) seeding, such as high-gain harmonic generation (HGHG), self-seeding, or direct FEL amplification of external seed pulses, have proven to generate intense, highly coherent radiation pulses in the extreme ultraviolet (XUV), soft- (SXR) and hard (HXR) X-ray spectral range. At DESY in Hamburg, the FEL facility FLASH is currently being upgraded by a second undulator beamline (FLASH2) which allows for the implementation of various seeding schemes. The development of high repetition-rate, high-power laser systems allows for the production of seed sources which match the bunch-train pattern of FLASH. Furthermore, the FLASH1 beamline arrangement is well suited for testing various seeding schemes including HGHG, EEHG, HHG-seeding, and hybrid schemes. In this contribution, we* give an overview of latest results and planned FEL seeding activities at FLASH. *Joern Boedewadt on behalf of the FLASH seeding collaboration (DESY, U Hamburg, TU Dortmund, U Uppsala, U Stockholm)

WEPSO04	The Conceptual Design of CLARA, a Novel FEL Test Facility for Ultra-short Pulse Generation	electron, laser, undulator, free-electron-laser	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, electron, undulator, free-electron-laser	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.

WEPSO06	The Test-FEL at MAX-lab: Implementation of the HHG Source and First Results	laser, electron, radiation, undulator	507
	F. Curbis, N. Čutić, F. Lindau, E. Mansten, S. Werin MAX-lab, Lund, Sweden F. Brizuela, B. Kim, A. L'Huillier Lund University, Division of Atomic Physics, Lund, Sweden M. Gisselbrecht SLF, Lund, Sweden
	The test-FEL at MAX-lab is a development set-up for seeding techniques. After the successful demonstration of coherent harmonic generation from a conventional laser, the new layout now presents a gas target for generation of harmonics. The drive laser will be up-converted and the low harmonics (around 100 nm) will seed the electron beam. The energy modulated electrons will then be bunched in the dispersive section and will radiate in the second undulator. We will detect the second harmonic of the HHG radiation around 50 nm. This experiment has several challenges never tried before: co-propagation of the electron beam and the drive laser, interaction of the electron beam with the gas in the target, no-focusing of the harmonics and no drive laser removal. The commissioning will show if this kind of in-line chamber has advantages with respect to more traditional approaches with optical beam transport. The results are relevant for many facilities that are planning to implement HHG seeding in the near future.

WEPSO07	Simulation Studies for an X-ray FEL Based on an Extension of the MAX IV Linac	linac, undulator, electron, radiation	510
	F. Curbis, N. Čutić, O. Karlberg, F. Lindau, A.W.L. Mak, E. Mansten, S. Thorin, S. Werin MAX-lab, Lund, Sweden
	It is well known that the few X-ray FELs around the world are severely overbooked by users. Having a medium energy linac, such as the one now being installed at the MAX IV laboratory, it becomes natural to think about slightly increasing the electron energy to drive an X-ray FEL. This development is now included in the long term strategic plan for the MAX IV laboratory. We will present the current FEL studies based on an extension of the MAX IV linac to 5 GeV to reach the Angstrom region. The injector for the MAX IV accelerator complex is also equipped with a photocathode gun, capable of producing low emittance electron beam. The bunch compression and linearization of the beam is taken care by two double achromats. The basic FEL layout would consist of short period undulators with tapering for extracting all the power from the electron beam. Self-seeding is considered as an option for increasing the spectral and intensity stability.

WEPSO09	Two-Color Self-seeding and Scanning the Energy of Seeded Beams at LCLS	photon, electron, background, free-electron-laser	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.

WEPSO10	Increased Stability Requirements for Seeded Beams at LCLS	linac, klystron, undulator, electron	518
	F.-J. Decker, W.S. Colocho, Z. Huang, R.H. Iverson, A. Krasnykh, A.A. Lutman, M.N. Nguyen, T.O. Raubenheimer, M.C. Ross, J.L. Turner, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515. Running the Linac Coherent Light Source (LCLS) with self-seeded photon beams requires better electron beam stability, especially in energy, to reduce the otherwise huge intensity variations of more than 100%. Code was written to identify and quantify the different jitter sources. Some improvements are being addressed, especially the stability of the modulator high voltage of some critical RF stations. Special setups like running the beam off crest in the last part of the linac can also be used to reduce the energy jitter. Even a slight dependence on the transverse position was observed. The intensity jitter distribution of a seeded beam is still more contained with peaks up too twice the average intensity, compared to the jitter distribution of a SASE beam going through a monochromator, which can have damaging spikes up to 5 times the average intensity.

WEPSO11	Coherent X-Ray Seeding Source for Driving FELs	cavity, undulator, electron, radiation	522
	A. Novokhatski, F.-J. Decker, R.O. Hettel, Z. Huang, H.-D. Nuhn, M.K. Sullivan SLAC, Menlo Park, California, USA
	Funding: "Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515 The success of the hard X-ray self-seeding experiment at the LCLS is very important in that it provided narrow, nearly transform-limited bandwidth from the FEL, fulfilling a beam quality requirement for experimental applications requiring highly monochromatic X-rays. Yet, because the HXRSS signal is generated random spikes of noise, it is not a truly continuous monochromatic seed signal and even higher FEL performance would be achieved using a continuous seed source. We propose developing such a source using an X-ray cavity to achieve a continuous, narrow band X-ray seed signal. This cavity consists of four crystals with corresponding Bragg angles of about 45 degrees for each. We will analyze and the interaction of X-rays and electron beams with this cavity. This source uses a train of electron bunches initially accelerated in a linear accelerator which then pass through a radiator element situated within an X-ray cavity. The number of bunches is proportional to the achievable Q-value of the X-ray cavity and may be in the range of 10-100. We do not need a high output power of X-ray beams, which leads to relaxed electron beam requirements. We will consider several options.

WEPSO14	Towards High Frequency Operation with a Multi-Grating Smith-Purcell FEL	simulation, radiation, electron, bunching	525
	J.T. Donohue CENBG, Gradignan, France J. Gardelle CEA, LE BARP cedex, France
	Three-dimensional simulations and experiments have shown that, for a grating equipped with sidewalls, copious emission of coherent Smith-Purcell (SP) radiation at the fundamental frequency of the evanescent surface wave is possible 1, 2. Since the underlying theory is scale invariant, the wavelength emitted is reduced in proportion to a uniform rescaling of the grating. In order to increase our 5 GHz to 100 GHz , the grating surface would be reduced by a factor of 400, which would lead to greatly reduced power. In addition, the required beam might be hard to generate. To avoid this, we propose to use several gratings in parallel with no overall reduction in the total width and the same beam as in our microwave experiment. For this scheme to succeed, it is essential that the bunching in the different gratings be coherent. . Simulations suggest that this occurs for as much as a ten-fold scale reduction. To test this idea, an experiment is using several gratings is being performed. 1. J. T. Donohue and J. Gardelle, Appl. Phys. Lett. 99, 161112 (2011). 2. J. Gardelle, P. Modin and J.T. Donohue, Appl. Phys. Lett. 100, 131103 (2012),.

WEPSO17	High-resolution Seeding Monochromator Design for NGLS	optics, electron, undulator, brightness	529
	Y. Feng, J.B. Hastings, J. Wu SLAC, Menlo Park, California, USA P. Emma, R.W. Schoenlein, T. Warwick LBNL, Berkeley, California, USA
	Funding: DOE/BES A high-resolution soft X-ray seeding monochromator has been designed for self-seeding the Next-Generation Light Source (NGLS). The seeding monochromator system consists of a single variable-line-spacing grating, three mirrors and an exit slit and operates in the “fixed-focus” mode to achieve complete tuning of the seeding energy in range from 200 to 2000 eV with a nearly constant resolving power of over 2x104. The optical delay is less than 1 ps. The design is based upon a fully coherent treatment of the SASE FEL beam propagating from the upstream SASE undulator through the entire seeding monochromator system. This approach guides the design optimization in order to preserve the transverse beam profile entering the seeding undulator to ensure maximum efficiency.

WEPSO19	A Full Beam 1D Simulation Code for Modeling Hybrid HGHG/EEHG Seeding Schemes for Evaluating the Dependence of Bunching Factor Bandwidth on Multiple Parameters	bunching, laser, simulation, electron	533
	C.M. Fortgang, B.E. Carlsten, Q.R. Marksteiner, N.A. Yampolsky LANL, Los Alamos, New Mexico, USA
	Multiple seeding schemes are available for design of narrow-band, short-wavelength FELs. Analysis of such schemes often focus on the amplitude of the final bunching factor b, and how far it is above shot noise. Only under ideal conditions is the bandwidth of b FT limited. We have developed a 1D simulation tool that models complex hybrid seeding schemes using macro properties of the entire beam bunch to assess effects on both the amplitude and bandwidth of b. In particular the effects on bunching factor from using non-ideal beam driven radiators for downstream modulators, energy slew and curvature, and energy spread are investigated with the 1D tool.

WEPSO20	Wake Monochromator in Asymmetric and Symmetric Bragg and Laue Geometry for Self-seeding the European X-ray FEL	photon, coupling, undulator, scattering	538
	G. Geloni, V. Kocharyan, E. Saldin, S. Serkez, M. Tolkiehn DESY, Hamburg, Germany
	We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging bealine at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (σ polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to pi/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

WEPSO22	FERMI@Elettra Status Report	electron, laser, linac, free-electron-laser	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.

WEPSO24	Compact XFEL Light Source	electron, emittance, laser, cathode	757
	W.S. Graves, K.K. Berggren, F.X. Kaertner, D.E. Moncton MIT, Cambridge, Massachusetts, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: This work was supported by DARPA grant N66001-11-1-4192, CFEL DESY, DOE grants DE-FG02-10ER46745, and NSF grant DMR-1042342. X-ray free electron laser studies are presented that rely on a nanostructured electron beam interacting with a “laser undulator” configured in the head-on inverse Compton scattering geometry. The structure in the electron beam is created by a nanoengineered cathode that produces a transversely modulated electron beam. Electron optics demagnify the modulation period and then an emittance exchange line translates the modulation to the longitudinal direction resulting in coherent bunching at x-ray wavelength. The predicted output radiation at 1 keV from a 7 MeV electron beam reaches 10 nJ or 6X10⁸ photons per shot and is fully coherent in all dimensions, a result of the dominant mode growth transversely and the longitudinal coherence imposed by the electron beam nanostructure. This output is several orders of magnitude higher than incoherent inverse Compton scattering and occupies a much smaller phase space volume, reaching peak brilliance of 10²⁷ and average brilliance of 10¹⁷ photons/(mm² mrad² 0.1% sec).

WEPSO26	Status of the Flash Facility	photon, electron, undulator, radiation	550
	K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt DESY, Hamburg, Germany
	The free-electron laser user facility FLASH at DESY (Hamburg, Germany)finished its 4th user period in February 2013. In total 2715 hours of SASE radiation has been delivered to user experiments with photon wavelengths between 4.2 nm and 44 nm with up to 5000 photon pulses per second. After a shutdown to connect the second undulator line - FLASH2 - to the FLASH linac, and a following commissioning period, FLASH is scheduled to continue user operation in October 2013. The year 2014 will be dedicated to the 5th period of user experiments. The commissioning of FLASH2 will take place in 2014 parallel to FLASH1 user operation.

WEPSO27	Recent LCLS Performance From 250 to 500 eV	undulator, diagnostics, electron, laser	554
	R.H. Iverson, J. Arthur, U. Bergmann, C. Bostedt, J.D. Bozek, A. Brachmann, W.S. Colocho, F.-J. Decker, Y. Ding, Y. Feng, J.C. Frisch, J.N. Galayda, T. Galetto, Z. Huang, E.M. Kraft, J. Krzywinski, J.C. Liu, H. Loos, X.S. Mao, S.P. Moeller, H.-D. Nuhn, A.A. Prinz, D.F. Ratner, T.O. Raubenheimer, S.H. Rokni, W.F. Schlotter, P.M. Schuh, T.J. Smith, M. Stanek, P. Stefan, M.K. Sullivan, J.L. Turner, J.J. Turner, J.J. Welch, J. Wu, F. Zhou SLAC, Menlo Park, California, USA P. Emma LBNL, Berkeley, California, USA R. Soufli LLNL, Livermore, California, USA
	Funding: Work supported by US Department of Energy contract DE-AC02-76SF00515 and BES. The Linac Coherent Light Source is an X-ray free-electron laser at the SLAC National Accelerator Laboratory. It produces coherent soft and hard X-rays with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources and a range of pulse durations from 500 to <10 fs. The facility has been operating at X-ray energy from 500 to 10,000eV. Users have expressed great interest in doing experiments with X-Rays near the carbon absorption edge at 284eV. We describe the operation and performance of the LCLS in the newly established regime between 250 and 500eV. [1] Emma, P. et al., “First lasing and operation of an ˚angstrom-wavelength free-electron laser,” Nature Pho- ton. 4(9), 641–647 (2010).

WEPSO28	Fast Electron Beam and FEL Diagnostics at the ALICE IR-FEL at Daresbury Laboratory	electron, cavity, laser, diagnostics	557
	F. Jackson, D. Angal-Kalinin, D.J. Dunning, J.K. Jones, A. Kalinin, T.T. Thakker, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D. Angal-Kalinin, D.J. Dunning, J.K. Jones, N. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The ALICE facility at Daresbury Laboratory is an energy recovery based infra-red free electron laser of the oscillator type that has been operational since 2010. Recently fast diagnostics have been installed to perform combined measurements on pulse-by pulse FEL pulse energy and bunch-by-bunch electron bunch position and arrival time. These measurements have highlighted and quantified fast instabilities in the electron beam and consequently the FEL output, and are presented and discussed here.

WEPSO30	Integrating the FHI-FEL Into the FHI Research Environment - Design and Implementation Aspects	controls, cavity, EPICS, ion	562
	H. Junkes, W. Erlebach, S. Gewinner, U. Hoppe, A. Liedke, G. Meijer, W. Schöllkopf, M. Wesemann, G. von Helden FHI, Berlin, Germany H. Bluem, D. Dowell, R. Lange, A.M.M. Todd, L.M. Young AES, Princeton, New Jersey, USA S.B. Webb ORNL, Oak Ridge, Tennessee, USA
	The new mid-infrared FEL at the Fritz-Haber-Institut (FHI) was presented at the FEL12 conference. It will be used for spectroscopic investigations of molecules, clusters, nanoparticles and surfaces. This facility must be easy to use by the scientists at FHI, and should be seamlessly integrated into the existing research environment. The Experimental Physics and Industrial Control System (EPICS) software framework was chosen to build the FHI-FEL control system, and will also be used to interface the user systems. The graphical operator interface is based on the Control System Studio (CSS) package. It covers radiation safety monitoring as well as controlling the complete set of building automation and utility devices, regardless of their particular function. A user interface (subset of the operator interface) allows user-provided experiment-control software (KouDa, LabVIEW, Matlab) to connect with an EPICS Gateway providing secured access. The EPICS Channel Archiver continuously records selected process variable data and provides a web server offering archive and near real-time data. A sample experiment installation demonstrates how this user interface can be used efficiently. W. Schöllkopf et al., FIRST LASING OF THE IR FEL AT THE FRITZ-HABER-INSTITUT, BERLIN, Conference FEL12

WEPSO34	Proposal for a Scheme to Generate a 10 tw Power Level, Femtosecond X-ray Pulses for Bio-imaging of Single Protein Molecules at the European XFEL	undulator, photon, electron, radiation	574
	V. Kocharyan, G. Geloni, E. Saldin, S. Serkez, I. Zagorodnov DESY, Hamburg, Germany O. Yefanov CFEL, Hamburg, Germany
	Crucial parameters for bio-imaging experiments are photon energy range, peak power and pulse duration. For a fixed resolution, the largest diffraction signals are achieved at the longest wavelength supporting that resolution. In order to perform these experiments at the European XFEL, we propose to use a novel configuration combining self-seeding and undulator tapering techniques with the emittance-spoiler method. Experiments at the LCLS confirmed the feasibility of these three techniques. Their combination allows obtaining a dramatic increase the XFEL output peak power and a shortening of the photon pulse duration to levels sufficient for performing bio-imaging of single protein molecules at the optimal photon-energy range between 3 keV and 5 keV. We show here that it is possible to achieve up to a 100-fold increase in peak-power of the X-ray pulses at the European XFEL: the X-ray beam would be delivered in 10 fs-long pulses with 50 mJ energy each at a photon energy around 4 keV. We confirm by simulations that one can achieve diffraction before destruction with a resolution of 0.25 nm resolution.

WEPSO41	Feasibility Studies for Echo-enabled Harmonic Generation on CLARA	laser, bunching, electron, radiation	588
	I.P.S. Martin, R. Bartolini Diamond, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom N. Thompson Cockcroft Institute, Warrington, Cheshire, United Kingdom N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The Compact Linear Accelerator for Research and Applications (CLARA) is a proposed single-pass FEL test facility, designed to facilitate experimental studies of advanced FEL techniques applicable to the next generation of light source facilities. One such scheme under consideration is Echo-Enabled Harmonic Generation (EEHG). In this paper we explore the suitability of CLARA for carrying out studies of this scheme, combining analytical and numerical calculations to determine likely hardware operating ranges, parameters tolerances and estimated FEL performance. A possible adaptation to convert EEHG into a short-pulse scheme is also considered.

WEPSO46	Study on the fluctuation of electron beam position in KU-FEL	gun, electron, cavity, feedback	602
	K. Okumura, M. Inukai, T. Kii, T. Konstantin, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, M. Omer, Y. Tsugamura, K. Yoshida, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	Stability of electron beam is important for stable FEL operation. In Kyoto University MIR-FEL facility (KU-FEL), a BPM (Beam Position Monitor) system consisting of six 4-button electrode type BPMs was installed for monitoring of the electron beam position. The fluctuation of the electron beam position has been observed in horizontal and vertical directions. The origin of the beam position fluctuation is not clarified. In horizontal direction, the main fluctuation source is expected to be the energy fluctuation. As the one of candidate of the energy fluctuation, the cavity temperature of the RF gun has been suspected because the gun is operated in detuned condition [1] which enhances beam energy dependence on the cavity temperature. Another candidate is considered to be the fluctuation of the RF power fed to the gun. Therefore, we start to study the effect of the cavity temperature and the RF power on the position of electron beam. In this conference, we will present the measured result and numerical evaluation of the beam position dependence on temperature and RF power. [1] H. Zen, et al, “Beam Energy Compensation in a Thermionic RF Gun by Cavity Detuning,” IEEE transaction on nuclear science, Vol.56, No. 3, Pages 1487-1491 (2009)

WEPSO48	Simulation Studies of FELs for a Next Generation Light Source	undulator, electron, photon, simulation	609
	G. Penn, P. Emma, G. Marcus, J. Qiang, M.W. Reinsch LBNL, Berkeley, California, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Several possible FEL beamlines for a Next Generation Light Source are studied. These beamlines collectively cover a wide range of photon energies and pulse lengths. Microbunching and transverse offsets within the electron beam, generated through the linac, have the potential to significantly impact the longitudinal and transverse coherence of the x-ray pulses. We evaluate these effects and set tolerances on beam properties required to obtain the desired properties of the x-ray pulses.

WEPSO51	Self-seeding Design for SwissFEL	undulator, simulation, electron, radiation	618
	E. Prat, S. Reiche PSI, Villigen PSI, Switzerland
	The SwissFEL facility, planned at the Paul Scherrer Institute, will provide SASE and self-seeded FEL radiation at a hard (1-7 Å) and soft (7-70 Å) X-ray FEL beamlines. This paper presents the current status of the self-seeding design for SwissFEL. The layout and full 6D start-to-end simulation results are presented for the hard X-ray beamline. Studies for different charges and optimization of the first and second undulator stages are shown.

WEPSO53	Harmonic Lasing at the LCLS	electron, radiation, undulator, simulation	623
	D.F. Ratner, Z. Huang, P.A. Montanez SLAC, Menlo Park, California, USA E. Allaria Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy W.M. Fawley, L.N. Rodes LBNL, Berkeley, California, USA E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Funding: Department of Energy The LCLS beamlines deliver X-rays to users at photon energies up to 24 keV. With the fundamental wavelength limited to around 10 keV, there is user interest in the third harmonic, which can reach a few percent of the total beam power. McNeil et al* and Schneidmiller and Yurkov** have showed that introducing phase shifts or attenuators into the undulator line can increase harmonic power by driving lasing at the third harmonic. With the development of self-seeding chicanes, LCLS is now in position for a proof-of-principle experiment. Here we present simulations and plans for an experimental test following commissioning of the Soft X-ray Self-Seeding system. B.W.J. McNeil, G.R.M. Robb, M.W. Poole and N.R. Thompson, Phys. Rev. Lett., 96 084801 (2006) *E. Schneidmiller and M. Yurkov, PR-STAB, 14 080702 (2012)

WEPSO56	Optical Design and Time-dependent Wavefront Propagation Simulation for a Hard X-Ray Split- and delay-unit for the European XFEL	photon, simulation, instrumentation, undulator	627
	S. Roling, B. Siemer, F. Wahlert, M. Wöstmann, H. Zacharias Universität Muenster, Physikalisches Institut, Muenster, Germany S. Braun, P. Gawlitza Fraunhofer IWS, Dresden, Germany O.V. Chubar BNL, Upton, Long Island, New York, USA L. Samoylova, H. Sinn XFEL. EU, Hamburg, Germany E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany F. Siewert HZB, Berlin, Germany E. Ziegler ESRF, Grenoble, France
	For the European XFEL an x-ray split- and delay-unit (SDU) is built covering photon energies from 5 keV up to 20 keV. This SDU will enable time-resolved x-ray pump / x-ray probe experiments as well as sequential diffractive imaging on a femtosecond to picosecond time scale. The wavefront of the x-ray FEL pulses will be split by an edge of a silicon mirror coated with Mo/B4C and W/B4C multilayers. Both partial beams will then pass variable delay lines. For different wavelengths the angle of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. Hence, maximum delays between ± 2.5 ps at hν = 20 keV and up to ± 33 ps at hν = 5 keV will be possible. The time-dependent wave-optics simulations have been done with SRW software, for the fundamental and the 3rd harmonic. The XFEL radiation was simulated both in the Gaussian approximation as well as using an output of time-dependent SASE code FAST. Main features of the optical layout, including diffraction on the splitter edge, and optics imperfections were taken into account. Impact of these effects on the possibility to characterize spatial-temporal properties of FEL pulses are analyzed.

WEPSO57	Optimization of a Dedicated Bio-imaging Beamline at the European X-ray Fel	undulator, electron, photon, radiation	632
	E. Saldin, G. Geloni, V. Kocharyan, S. Serkez DESY, Hamburg, Germany
	We recently proposed a basic concept for design and layout of a dedicated undulator source for bio-imaging experiments at the European XFEL. Here we present an optimization of that concept. The core of the scheme is composed by soft and hard X-ray self-seeding setups. Using an improved design for both monochromators it is possible to increase the design electron energy up to 17.5 GeV in photon energy range between 2 keV and 13 keV, which is the most preferable for life science experiments. Operating at such high electron energy one increases the X-ray output peak power. Moreover, 17.5 GeV is the preferred operation energy for SASE1 and SASE2 users. This choice will reduce the interference with other undulator lines. We include a study of the performance of the self-seeding scheme accounting for spatiotemporal coupling caused by the use of a single crystal monochromator. This distortion can be easily suppressed by the right choice of diamond crystal planes. The proposed undulator source yields about the same performance as in the case for a X-ray seed pulse with no coupling. Simulations show that the FEL power reaches 2 TW in the 3 keV - 5 keV photon energy range.

WEPSO59	A Possible Upgrade of FLASH for Harmonic Lasing Down to 1.3 nm	undulator, electron, radiation, simulation	646
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. We demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10³¹ photons/(s mrad² mm² 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation.

WEPSO60	A Method for Obtaining High Degree of Circular Polarization at X-ray FELs	undulator, radiation, bunching, polarization	651
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Baseline design of many X-ray FEL undulators assumes a planar configuration which results in a linear polarization of SASE FEL radiation. However, many users experiments would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a helical afterburner, but then one should have an efficient method to suppress linearly polarized background from the main undulator. In this paper we consider a new method for such a suppression which is illustrated with the parameters of the soft X-ray undulator SASE3 of the European X-ray FEL.

WEPSO62	The IR and THz Free Electron Laser at the Fritz-Haber-Institut	free-electron-laser, 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.

WEPSO64	Grating Monochromator for Soft X-ray Self-seeding the European XFEL	undulator, photon, electron, optics	667
	S. Serkez, G. Geloni, V. Kocharyan, E. Saldin DESY, Hamburg, Germany
	Self-seeding implementation in the soft X-ray wavelength range involves gratings as dispersive elements. We study a very compact self-seeding scheme with a grating monochromator originally designed at SLAC, which can be straightforwardly installed in the SASE3 undulator beamline at the European XFEL. The design is based on a toroidal VLS grating at a fixed incidence angle, and without entrance slit. It covers the spectral range from 300 eV to 1000 eV. The performance was evaluated using wave optics method vs ray tracing methods. Wave optics analysis takes into account the actual beam wavefront of the radiation from the FEL source, third order aberrations, and errors from optical elements. We show that, without exit slit, the self-seeding scheme gives the same resolving power (about 7000) as with an exit slit. Wave optics is also naturally applicable to calculations of the scheme efficiency, which include the monochromator transmittance and the effect of the mismatching between seed beam and electron beam. Simulations show that the FEL power reaches 1 TW, with a spectral density about two orders of magnitude higher than that for the SASE pulse at saturation.

WEPSO65	LEBRA Free Electron Laser as a Radiation Source for Photochemical Reactions in Living Organisms	radiation, electron, controls, laser	675
	F. Shishikura, K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Sakai, T. Tanaka LEBRA, Funabashi, Japan
	The radiation sources commonly used in plant applications are commercially available lamps developed for human lighting applications (fluorescent, metal halide, high-pressure sodium, incandescent, light-emitting diode, and laser diode). In contrast, free-electron lasers (FELs) such as LEBRA-FEL produce high-energy, tunable pulse radiation and thus are promising radiation sources for photochemical research. An advantage of LEBRA-FEL is that the peak intensity ranges from 0.35 to 6.5 microns which are wavelengths coinciding with the absorption peaks of living organisms. Previously, we established a microscopic irradiation technique for delivering visible FEL light to single cells through a tapered glass rod (< 10 microns). However, it is still unclear whether LEBRA-FEL can produce sufficient radiant energy at wavelengths effective for triggering photochemical reactions in living organisms. The aim of this study was to evaluate the effectiveness of LEBRA-FEL in lettuce-seed germination tests. Results show promotion by red light and inhibition by far-red light, indicating that LEBRA-FEL can be used to control lettuce-seed germination.

WEPSO67	Progress with the FERMI Laser Heater Commissioning	laser, linac, electron, undulator	680
	S. Spampinati, E. Allaria, D. Castronovo, M. Dal Forno, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, G. Penco, C. Spezzani, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	FERMI@ELETTRA is a seeded free electron laser facility composed by one linac and two FEL lines named FEL-1 and FEL-2. FEL-1 works in HGHG configuration, while FEL2 is a HGHG cascade implementing "fresh bunch" injection into the second stage. Perfomance of FEL-1 and FEL-2 lines have benefited from the use of the laser heater system, which is located right after the injector, at 100 MeV beam energy. Proper tuning of the laser heater parameters has allowed control of the microbunching instability, which is otherwise expected to degrade the high brightness electron beam quality sufficiently to reduce the FEL power. The laser heater was commissioned one year ago and positive effects upon microbunching instabilities and FEL-1 performance was soon observed. In this work we presents further measurements of microbunching suppression in two compressors scheme showing directly the reduction of beam slice energy spread due to laser heater action. We present measuerements showing the impact of the laser heater on FEL2

WEPSO68	Effect of Coulomb Collisions on Echo-enabled Harmonic Generation	undulator, laser, bunching, scattering	684
	G.V. Stupakov SLAC, Menlo Park, California, USA
	Echo Enabled Harmonic Generation (EEHG) for FEL seeding is sensitive to the intrabeam scattering (IBS) effect. The reason for this is that in the process of generation high-harmonic density modulation in the beam the phase space evolves through a stage with narrow energy bands, which are characterized by the energy spread many times smaller than the beam energy spread. Energy diffusion caused by IBS tends to smear our these bands leading to diminished bunching factors at high harmonics. In the previous work [1] IBS in EEHG was studied in a simple model of a drift. This work extends the analysis of [1] to realistic lattices, and is applied to some of the existing practical designs of EEHG seeding. [1] G. Stupakov, Effect of Coulomb Collisions on Echo-Enabled Harmonic Generation (EEHG), in Proceedings of the 2011 FEL Conference, Shanghai, China, 2011.

WEPSO69	Optical Cavity Losses Calculation and Optimization of THz FEL with a Waveguide	coupling, cavity, radiation, undulator	689
	P. Tan, Q. Fu, L. Li, B. Qin, K. Xiong, Y.Q. Xiong HUST, Wuhan, People's Republic of China
	Funding: the Fundamental Research Funds for the Central Universities，HUST：2012QN080 The optical cavity with waveguide is used in most long wavelength free electron lasers. In this paper, the losses, gains and modes of a terahertz FEL sources in Huazhong Univeristy of Science and Technology(HUST) are analysis. Then the radii of curvature of the optical mirrors and shapes of the waveguide are optimized.

WEPSO70	Fully Phase Matched High Harmonics Generation in a Hollow Waveguide for Free Electron Laser Seeding	laser, photon, electron, free-electron-laser	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.

WEPSO73	High Average Power Seed Laser Design for High Reprate FELs	laser, electron, vacuum, controls	697
	R.B. Wilcox, G. Marcus, G. Penn LBNL, Berkeley, California, USA T. Metzger, M. Schultze TRUMPF Scientific Lasers GmbH + Co. KG, Munchen-Unterfoehring, Germany
	Funding: US Department of Energy, under Contract Numbers DE-AC02-0SCH11231. In the proposed Next Generation Light Source (NGLS), FEL designs use lasers to seed the FEL in an HGHG scheme or bunch the electron beam in an E-SASE scheme. The FELs would run at 100kHz to 1MHz, requiring high average power lasers. For the seeded FEL, laser modulation is applied at 200-240nm, with 250-700MW peak power depending on pulse length, which can vary from 100-10fs. The laser consists of a broadband oscillator and amplitude/phase shaper seeding an optical parametric amplifier (OPA). After recompression, the ~800nm pulse is converted to the fourth harmonic. Losses could be high enough to require 250W at 100kHz, making the OPA ~100x more powerful than existing femtosecond OPAs. In the E-SASE scheme, a single cycle of 5 micron light bunches the beam, which then radiates a short X-ray burst. This requires 100% fractional bandwidth, and precise phase control of the e-field within the pulse, as well as broad band compensation of dispersion throughout the laser path. Bandwidth can be increased by splitting the amplified spectrum into segments and coherently recombining. We present design concepts that are expected to meet requirements, and identify R&D needs.

WEPSO78	Harmonic Lasing Self-seeded FEL	undulator, simulation, electron, resonance	700
	M.V. Yurkov, E. Schneidmiller DESY, Hamburg, Germany
	In this paper we perform analysis of capabilities of SASE FELs at the European XFEL for generation of narrow band radiation. An approach based on application of harmonic lasing self-seeding (HLSS) is under study[]. Effective harmonic lasing occurs in the exponential gain regime in the first part of the undulator, making sure that the fundamental frequency is well below saturation. In the second part of the undulator the value of undulator parameter is reduced such that now the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental, i.e. brilliance increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level. E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15, 080702 (2012)

WEPSO80	Coherence Properties of the Radiation From FLASH	radiation, emittance, undulator, electron	704
	M.V. Yurkov, E. Schneidmiller DESY, Hamburg, Germany
	Several user groups at FLASH use higher odd harmonics (3rd and 5th) of the radiation in experiments. Some applications require knowledge of coherence properties of the radiation at he fundamental and higher harmonics. In this paper we presents results of the studies of coherence properties of the radiation from FLASH operating at radiation wavelength of 6.x nm at the fundamental harmonic, and higher odd harmonics (2.x nm and 1.x nm) at electron energy of 1 GeV.

WEPSO84	Present Status of Kyoto University Free Electron Laser	undulator, electron, cavity, vacuum	711
	H. Zen, M. Inukai, T. Kii, R. Kinjo, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, K. Okumura, M. Omer, K. Torgasin, K. Yoshida Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A mid-infrared FEL named as KU-FEL (Kyoto University FEL) has been developed for energy related sciences [1]. After the achievement of the first lasing and the power saturation in 2008 [2, 3], we have been working to extend the tunable range of the FEL [4]. By replacing the original 1.6-m undulator into a 1.8 m one, the tunable range was expanded from 10-13 to 5-15 μm in January 2012. Then we fabricated a new undulator duct to reduce the minimum undulator gap from 20 to 15 mm. At 15-mm gap, the FEL gain can be expected to be twice as high as that at 20 mm gap. Commissioning of the new duct will be done in the end of this April. In this presentation, we will report on the result of the commissioning such as tunable range of KU-FEL and the estimated FEL gain, which would be compared with a simulation. [1] H. Zen, et al., Infrared Phys. Techn., 51, 382 (2008) [2] H. Ohgaki, et al., Proc. of FEL08, 4 (2008) [3] H. Ohgaki, et al., Proc. of FEL2009, 572 (2009) [4] H. Zen, et al., Proc. of FEL2012

WEPSO89	Design of a Resonator for the CSU THz FEL	higher-order-mode, coupling, undulator, radiation	719
	P.J.M. van der Slot Mesa+, Enschede, The Netherlands S. Biedron, S.V. Milton, P.J.M. van der Slot CSU, Fort Collins, Colorado, USA
	Funding: This research is support by Office of Naval Research Global, grant number N62909-10-1-7151 A 6-MeV L-band linac will be used to drive a planar, fixed gap, 2.5-cm period, hybrid undulator with parabolic pole faces. Consequently, this system is capable of generating wavelengths from 160 to 600 μm. In this paper we discuss the design of an optical resonator for this system. The resonator uses hole-coupled mirrors to allow for a straight electron beam line. The Rayleigh length, the position of the waist of the cold-cavity mode and the hole radii will be investigated to optimize the performance of the FEL.

THIANO01	Double Stage Seeded FEL with Fresh Bunch Injection Technique at FERMI	electron, undulator, bunching, laser	723
	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, L. Giannessi, 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
	Seeding a FEL with an external coherent source has been extensively studied in the last decades as it can provide a way to enhance the radiation brightness and stability, with respect to that available from SASE. An efficient scheme for seed a VUV-soft x ray FEL uses, a powerful, long wavelength external laser to induce on the electron beam coherent bunching at the harmonics of the laser wavelength. When the bunching is further amplified by FEL interaction in the radiator, the scheme is called high gain harmonic generation (HGHG). The need of high power seed sources and of small energy spread are at the main limits for a direct extension of the HGHG scheme to short wavelengths. The fresh bunch scheme was proposed as a way to overcome these limitations; the scheme foresees the FEL radiation produced by one HGHG stage as an external seed in a second HGHG stage. We report the latest results obtained at FERMI that uses the two-stage HGHG scheme for generation of FEL pulses in the soft x-ray. A characterization of the FEL performance in terms of power, bandwidth and stability is reported. Starting from the FERMI results we will discuss extension of the scheme toward shorter wavelengths.
	Slides THIANO01 [9.355 MB]

THOANO01	Stable Operation of HHG-Seeded EUV-FEL at the SCSS Test Accelerator	electron, laser, feedback, undulator	728
	H. Tomizawa, T. Hara, T. Ishikawa, K. Ogawa, H. Tanaka, T. Tanaka, T. Togashi, K. Togawa, M. Yabashi RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan M. Aoyama, K. Yamakawa JAEA/Kansai, Kyoto, Japan A. Iwasaki, S. Owada, T. Sato, K. Yamanouchi The University of Tokyo, Tokyo, Japan S. Matsubara, Y. Okayasu, T. Watanabe JASRI/SPring-8, Hyogo, Japan K. Midorikawa, E. Takahashi RIKEN, Saitama, Japan
	We performed the higher-order harmonic (HH) seeded FEL operation at a 61.2 nm fundamental wavelength, using a seeding source of HH pulses from a Ti:sapphire laser at the SCSS (EUV-FEL) accelerator. It is important for the HH seeded FEL scheme to synchronize the seeding laser pulses to the electron bunches. We constructed the relative arrival timing monitor based on Electro-Optic sampling (EOS). Since the EOS-probe laser pulses were optically split from HH-driving laser pulses, the arrival time difference of the seeding laser pulses, with respect to the electron bunches, were measured bunch-by-bunch. This non-invasive EOS monitor made uninterrupted, real-time monitoring possible even during the seeded FEL operation. The EOS system was used for the arrival timing feedback with a few-hundred-femtosecond adjustability for continual operation of the HH-seeded FEL. By using the EOS-locking system, the HH seeded FEL was operated over half a day with a 20-30% hit rate. The output pulse energy reached 20uJ at the 61.2 nm wavelength. A user experiment was performed by using the seeded EUV-EL and a clear difference between the SASE-FEL and the seeded FEL was observed.
	Slides THOANO01 [11.493 MB]

THOBNO01	Three Unique FEL Designs for the Next Generation Light Source	undulator, photon, radiation, laser	734
	G. Penn, D. Arbelaez, J.N. Corlett, P. Emma, G. Marcus, S. Prestemon, M.W. Reinsch, R.B. Wilcox LBNL, Berkeley, California, USA A. Zholents ANL, Argonne, USA
	The NGLS is a next generation light source initiative spearheaded by the Lawrence Berkeley National Laboratory and based on an array of free-electron lasers (FEL) driven by a CW, 1-MHz bunch rate, superconducting linear accelerator. The facility is being designed to produce high peak and high average brightness coherent soft x-rays in the wavelength range of 1-12 nm, with shorter wavelengths accessible in harmonics or in expansion FELs. The facility performance requirements are based on a wide spectrum of scientific research objectives, requiring high flux, narrow-to-wide bandwidth, broad wavelength tunability, femtosecond pulse durations, and two-color pulses with variable relative timing and polarization, all of which cannot be encompassed in one FEL design. In addition, the cost of the facility requires building in a phased approach with perhaps three initial FELs and up to 9-10 FELs in the long term. We describe three very unique and complimentary FEL designs here as candidates for the first NGLS configuration.
	Slides THOBNO01 [1.331 MB]

THOBNO02	Transverse Gradient Undulators for a Storage Ring X-ray FEL Oscillator	electron, undulator, storage-ring, emittance	740
	R.R. Lindberg, K.-J. Kim ANL, Argonne, USA Y. Cai, Y. Ding, Z. Huang SLAC, Menlo Park, California, USA
	Funding: Work supported by U.S. Dept.~of Energy, Office of Basic Energy Sciences, Contract No.~DE-AC02-06CH11357. An x-ray FEL oscillator (XFELO) is a fully coherent 4th generation source with complementary scientific applications to those based on self-amplified spontaneous emission. While the naturally high repetition rate, intrinsic stability, and very small emittance produced by an ultimate storage ring (USR) makes it a potential candidate to drive an XFELO, the energy spread is typically an order of magnitude too large for sufficient gain. On the other hand, Smith and coworkers* showed how the energy spread requirement can be effectively mitigated with a transverse gradient undulator (TGU): since the TGU has a field strength that varies with transverse position, by properly correlating the electron energy with transverse position one can approximately satisfy the FEL resonance condition for all electrons. Motivated by recent work in the high-gain regime**, we investigate the utility of a TGU for low gain FELs at x-ray wavelengths. We find that a TGU may make an XFELO realizable in the largest ultimate storage rings now under consideration (e.g., in either the old Tevatron or PEP-II tunnel). K.-J. Kim, Y. Shvyd'ko and S. Reiche, PRL 100 244802 (2008). T. Smith, et al., J. Appl. Phys. 50, 4580 (1979). * Z. Huang, Y. Ding, and C.B. Schroeder, PRL 109, 204801 (2012).
	Slides THOBNO02 [1.208 MB]

THOCNO04	Jitter-free Time Resolved Resonant CDI Experiments Using Two-color FEL Pulses Generated by the Same Electron Bunch	electron, laser, undulator, polarization	753
	M. Zangrando, E. Allaria, F. Bencivenga, F. Capotondi, D. Castronovo, P. Cinquegrana, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, R. Ivanov, M. Kiskinova, B. Mahieu, N. Mahne, C. Masciovecchio, I. Nikolov, E. Pedersoli, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy G. De Ninno, D. Gauthier University of Nova Gorica, Nova Gorica, Slovenia D. Fausti Università degli Studi di Trieste, Trieste, Italy L. Giannessi ENEA C.R. Frascati, Frascati (Roma), Italy M. Zangrando IOM-CNR, Trieste, Italy
	The generation of two-color FEL pulses by the same electron bunch at FERMI-FEL has opened unprecedented opportunity for jitter-free FEL pump-FEL probe time resolved coherent diffraction imaging (CDI) experiments in order to access spatial aspects in dynamic processes. This possibility was first explored in proof-of-principle resonant CDI experiments using specially designed sample consisting of Ti grating. The measurements performed tuning the energies of the FEL pulses to the Ti M-absorption edge clearly demonstrated the time dependence of Ti optical constants while varying the FEL-pump intensity and probe time delay. The next planned CDI experiments in 2013 will explore transient states in multicomponent nanostructures and magnetic systems, using the controlled linear or circular polarization of the two-color FEL pulses with temporal resolution in the fs to ps range.
	Slides THOCNO04 [8.778 MB]

Paper

Title

Other Keywords

Page

MOOBNO01

First Lasing of FERMI FEL-2

laser, injection, free-electron-laser, 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]

MOICNO01

Generation of a Train of Short Pulses by Means of FEL Emission of a Combed Electron Beam

electron, radiation, undulator, laser

2

V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
M.P. Anania, M. Bellaveglia, E. Chiadroni, D. Di Giovenale, G. Di Pirro, M. Ferrario, G. Gatti, R. Pompili, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
M. Artioli
ENEA-Bologna, Bologna, Italy
A. Bacci, A.R. Rossi
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
F. Ciocci, G. Dattoli, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia
ENEA C.R. Frascati, Frascati (Roma), Italy
A. Mostacci
Rome University La Sapienza, Roma, Italy
P. Musumeci
UCLA, Los Angeles, California, USA
J.V. Rau
ISM-CNR, Rome, Italy

We present a direct and powerful method for generating train of radiation pulses based on the FEL radiation from a multi-peaked electron beam produced with a combed laser pulse accelerated and compressed in a linac by the velocity bunching technique. The electron beam, constituted by two bunches, can be extracted from the accelerating section when they are temporaly superimposed but separated in energy, so that each of them is characterized by a different value of the Lorentz factor. When driven in the FEL undulator, they emit two separate spectral lines, according to the FEL resonance condition, that interfere producing fringes in the time-domain. In this way a train of regular pulses can be obtained, without limitation in frequency, and with the perspective of reaching the attosecond domain in the X ray regime.

Slides MOICNO01 [8.836 MB]

MOOCNO01

Emittance Control in the Presence of Collective Effects in the FERMI@Elettra Free Electron Laser Linac Driver

emittance, electron, linac, brightness

6

S. Di Mitri, E. Allaria, D. Castronovo, M. Cornacchia, P. Craievich, M. Dal Forno, G. De Ninno, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, E. Karantzoulis, A.A. Lutman, G. Penco, C. Serpico, S. Spampinati, C. Spezzani, M. Trovò, M. Veronese
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
P. Craievich
PSI, Villigen PSI, Switzerland
M. Dal Forno
University of Trieste, Trieste, Italy
G. De Ninno, S. Spampinati
University of Nova Gorica, Nova Gorica, Slovenia
E. Ferrari
Università degli Studi di Trieste, Trieste, Italy
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
A.A. Lutman
SLAC, Menlo Park, California, USA

Recent beam transport experiments conducted on the the linac driving the FERMI@Elettra free electron laser have provided new insights concerning the transverse emittance degradation due to both coherent synchrotron radiation (CSR) and geometric transverse wakefield (GTW), together with methods to counteract such degradation. For beam charges of several 100's of pC, optics control in a magnetic compressor results to minimize the CSR once the H-function is considered*. We successfully extended this approach to the case of a modified double bend achromat system, opening the door to relatively large bending angles and compact transfer lines**. At the same time, the GTWs excited in few mm diameter iris collimators*** and accelerating structures have been characterized in terms of the induced emittance growth. A model integrating both CSR and GTW effects suggests that there is a limit on the maximum obtainable electron beam brightness in the presence of such collective effects.
* S. Di Mitri et al., PRST-AB 15, 020701 (2012)
** S. Di Mitri et al., PRL 110, 014801 (2013)
*** S. Di Mitri et al., PRST-AB 15, 061001 (2012)

Slides MOOCNO01 [6.919 MB]

MOPSO02

Measurement of Electron-Beam and Seed Laser Properties Using an Energy Chirped Electron Beam

electron, laser, simulation, linac

24

E. Allaria, G. De Ninno, S. Di Mitri, W.M. Fawley, E. Ferrari, L. Fröhlich, G. Penco, P. Sigalotti, S. Spampinati, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno, S. Spampinati
University of Nova Gorica, Nova Gorica, Slovenia
E. Ferrari
Università degli Studi di Trieste, Trieste, Italy

We present a new method that uses CCD images of the FERMI electron beam at the dump spectrometer after the undulator to determine various electron beam and external seed laser properties. By taking advantage of the correlation between time and electron beam energy for a quasi-linearly chirped electron beam and the fact that the FERMI seed laser pulse (~180 fs) is much shorter than the electron beam duration (~1 ps), measurements of the e-beam pulse length and temporally local energy chirp and current are possible. Moreover, the scheme allows accurate determination of the timing jitter between the electron beam and the seed laser, as well as a measure of the latter's effective pulse length in the FEL undulators. The scheme can be also provide an independent measure of the energy transferred from the electron beam to the FEL output radiation. We describe the proposed method as well as some experimental results obtained at the seeded FERMI FEL.

MOPSO04

Theoretical Analysis of a Laser Undulator-Based High Gain FEL

laser, undulator, electron, radiation

27

P. Baxevanis, R.D. Ruth
SLAC, Menlo Park, California, USA

The use of laser (or RF) undulators is nowadays considered attractive for FEL applications, particularly those that aim to utilize relatively low-energy electron beams. In the context of the standard theoretical analysis, the counter-propagating laser pulse is usually treated in the plane-wave approximation, neglecting amplitude and phase variation. In this paper, we develop a three-dimensional, analytical theory of a high-gain FEL based on a laser or RF undulator, taking into account the longitudinal variation of the undulator field amplitude, the laser Gouy phase and the effects of emittance and energy spread in the electron beam. Working in the framework of the Vlasov-Maxwell formalism, we derive a self-consistent equation for the radiation amplitude in the linear regime, which is then solved to good approximation by means of an orthogonal expansion technique [*]. Numerical results obtained from our analysis are used in the study of an example of a compact, laser undulator-based, X-ray FEL.
*P. Baxevanis, R. Ruth, Z. Huang, Phys. Rev. ST-AB 16, 010705 (2013).

MOPSO08

Unaveraged Modelling of a LWFA Driven FEL

simulation, electron, radiation, undulator

43

L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
F.J. Grüner, A.R. Maier
CFEL, Hamburg, Germany
F.J. Grüner, A.R. Maier
Uni HH, Hamburg, Germany
F.J. Grüner
LMU, Garching, Germany

Preliminary simulations of a Laser Wakefield Field Accelerator driven FEL are presented using the 3D unaveraged, broad bandwidth FEL simulation code Puffin. The radius of the matched low emittance electron beam suggests that the FEL interaction will be strongly affected by radiation diffraction. The parameter scaling and comparison between 3D and equivalent 1D simulations appears to confirm the interaction is diffraction dominated. Nevertheless, output powers are predicted to be greater than those of similar unaveraged FEL models. Possible reasons for the discrepancies between the averaged and unaveraged simulation results are discussed.
[1] - AR Maier, A Meseck, S Reiche, CB Schroeder, T Seggebrock, and F Gruner, Phys Rev X 2, 031019 (2012)

MOPSO09

Investigation of a 2-Colour Undulator FEL Using Puffin

undulator, electron, radiation, bunching

47

L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
S. Reiche
PSI, Villigen PSI, Switzerland

The unaveraged FEL code Puffin* is used to investigate a 2 color FEL. In the scheme under investigation, undulator modules are tuned alternately to generate 2 frequencies quasi-simultaneously, which should result in greater stability than generating them consecutively. The advantage of using Puffin is that it provides the capability of modelling a broad bandwidth spectrum. For example, radiation at 1nm and 2.4nm is difficult to model simultaneously in standard averaged FEL codes. An unaveraged code like Puffin is able to model 2 (or more) wavelengths with a much wider spacing.
* LT Campbell and BWJ McNeil, Phys. Plasmas 19, 093119 (2012)

MOPSO17

The Present Status of the Theory of the FEL-based Hadron Beam Cooling

electron, hadron, kicker, ion

52

A. Elizarov, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The coherent electron cooling (CeC)* device is one of the new facilities under construction in BNL. The CeC is a realization of the stochastic cooling with an electron beam serving as a pick-up and kicker. Hadrons generate electron density perturbations in the modulator section, then these perturbations are amplified in an FEL, and then, they accelerate (or decelerate) hadrons in the kicker by electric field with respect to their velocities. Here we present the theoretical description of the modulator sector**,***, where the electron density perturbations are formed and our new results on the time evolution of these perturbations in the FEL section, where they are amplified.
* V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** A. Elizarov, V. Litvinenko, G. Wang, IPAC'12, weppr099 (2012).
*** A. Elizarov, V. Litvinenko, IPAC'13, mopwo088 (2013).

MOPSO27

Study of CSR Effects in the Jefferson Laboratory FEL Driver

simulation, radiation, dipole, linac

58

C.C. Hall, S. Biedron, T.A. Burleson, S.V. Milton, A.L. Morin
CSU, Fort Collins, Colorado, USA
S.V. Benson, D. Douglas, P.E. Evtushenko, F.E. Hannon, R. Li, C. Tennant, S. Zhang
JLAB, Newport News, Virginia, USA
B.E. Carlsten, J.W. Lewellen
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the Office of Naval Research and the High Energy Laser Joint Technology. Jefferson Laboratory work also received supported under U.S. DOE Contract No. DE-AC05-06OR23177.
In a recent experiment conducted on the Jefferson Laboratory IR FEL driver the effects of Coherent Synchrotron Radiation (CSR) on beam quality were studied. The primary goal of this work was to explore CSR output and effect on the beam with variation of the bunch compression in the IR chicane. This experiment also provides a valuable opportunity to benchmark existing CSR models in a system that may not be fully represented by a 1-D CSR model. Here we present results from this experiment and compare to initial simulations of CSR in the magnetic compression chicane of the machine. Finally, we touch upon the possibility for CSR induced microbunching gain in the magnetic compression chicane, and show that parameters in the machine are such that it should be thoroughly damped.

MOPSO30

Simple Setups for Carrier-envelope-phase Stable Single-cycle Attosecond Pulse Generation

undulator, electron, laser, radiation

63

J. Hebling, G. Almási, J.A. Fülöp, M.I. Mechler, Z. Tibai, Gy. Tóth
University of Pecs, Pécs, Hungary

Funding: Work supported by Hungarian Research Fund (OTKA), grant number 101846, and from SROP-4.2.1.B-10/2/KONV-2010-0002 and SROP-4.2.2/B-10/1-2010-0029
Robust methods for producing waveform-controlled half-cycle–few-cycle pulses in the mid-infrared (MIR)–extreme ultraviolet (EUV) spectral range are proposed. They are based on coherent Thomson scattering of THz pulses on relativistic ultrathin electron layers and coherent undulator radiation of relativistic ultrathin electron layers, respectively. The ultrathin electron layers are produced by microbunching of ultrashort electron bunches by a TW power laser in a modulator undulator. According to our numerical calculations it is possible to generate as short as 10 nm long electron layers if a single-period modulator undulator with period length significantly shorter than the resonant one is used and the undulator parameter is only K=0.25. Thomson scattering of THz pulses on ultrathin electron layers with only 50 MeV energy can generate for example 170 as long single-cycle pulses at 80 nm wavelength with 0.1 nJ energy. Coherent undulator radiation of ultrathin electron layers with 450 MeV energy can generate single-cycle radiation in the 20 nm – 1000 nm wavelength range. The corresponding pulse energy and pulse duration vary in the 10 pJ – 2 nJ and 47 as – 2.1 fs ranges, respectively.

MOPSO31

Quasiperiodic Method of Averaging Applied to Planar Undulator Motion Excited by a Fixed Traveling Wave

resonance, undulator, radiation, electron

762

K.A. Heinemann, J.A. Ellison
UNM, Albuquerque, New Mexico, USA
M. Vogt
DESY, Hamburg, Germany

Funding: The work of JAE and KH was supported by DOE under DE-FG-99ER41104. The work of MV was supported by DESY.
We present a mathematical analysis of planar motion of energetic electrons moving through a planar dipole undulator, excited by a fixed planar polarized plane wave Maxwell field in the X-Ray FEL regime.* We study the associated 6D Lorentz system as the wavelength of the traveling wave varies. The 6D system is reduced, without approximation, to a 2D system (for a scaled energy deviation and generalized ponderomotive phase) in a form for a rigorous asymptotic analysis using the Method of Averaging (MoA), a long time perturbation theory. As the wavelength varies the system passes through resonant and nonresonant (NR) zones and we develop NR and near-to-resonant (NtoR) normal form approximations. For a special initial condition, on resonance, we obtain the well-known FEL pendulum system. We prove NR and NtoR first-order averaging theorems, in a novel way, which give optimal error bounds for the approximations. The NR case is an example of quasiperiodic averaging where the small divisor problem enters in the simplest possible way. To our knowledge the analysis has not been done with the generality here nor has the standard FEL pendulum system been derived with error bounds.
* J.A. Ellison, K. Heinemann, M. Vogt, M. Gooden: arXiv:1303.5797 [physics.acc-ph]

MOPSO34

Highly Efficient, High-energy THz Pulses from Cryo-cooled Lithium Niobate for Accelerator and FEL Applications

electron, laser, acceleration, cryogenics

68

K.-H. Hong, E. Granados, S.-W. Huang, W.R. Huang, F.X. Kaertner, R. Koustuban, L.E. Zapata
MIT, Cambridge, Massachusetts, USA
F.X. Kaertner
CFEL, Hamburg, Germany

Funding: This work was supported by DARPA under contract N66001-1-11-4192.
Intense, ultrafast THz fields are of great interest for electron acceleration, beam manipulation and measurement, and pump-probe experiments with coherent soft/hard x-ray sources based on FELs or inverse Compton scattering sources. Acceleration at THz frequencies has an advantage over RF in terms of accessing high electric-field gradients (>100 MV/cm), while the beam delivery can be treated quasi-optically. However, high-field THz pulse generation is still demanding when compared with conventional RF generation. In this paper, we present highly efficient, single-cycle, 0.45 THz pulse generation by optical rectification of 1.03 μm pulses in cryogenically cooled lithium niobate (LN). Using a near-optimal duration of 680 fs and a pump energy of 1.2 mJ, we report conversion efficiencies above 3% [1], >10 times higher than previous report (0.24%) [2]. Cryogenic cooling of lithium niobate significantly reduces the THz absorption, which will enable the scaling of THz pulse energies to the mJ. We will also report on polarization and mode conversion using segmented THz waveplates to generate radially-polarized TEM01 modes, suitable for THz electron acceleration in dielectric waveguide.
[1] S.-W. Huang et al., Opt. Lett. 38, 796-798 (2013).
[2] J. A. Fülöp et al., Opt. Lett. 37, 557-559 (2012).

MOPSO40

CLARA Accelerator Design and Simulations

linac, laser, emittance, simulation

72

P.H. Williams, D. Angal-Kalinin, J.A. Clarke, F. Jackson, J.K. Jones, B.P.M. Liggins, J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Science & Technology Facilities Council
We present the accelerator design for CLARA (Compact Linear Advanced Research Accelerator) at Daresbury Laboratory. CLARA will be a testbed for novel FEL configurations. The accelerator will consist of an RF photoinjector, S-band acceleration and transport to 250MeV including X-band linearisation and magnetic bunch compression. We describe the transport in detail. Beam dynamics simulations are then used to define a set of operating working points suitable for the different FEL schemes intended to be tested on CLARA.

MOPSO49

Numerical Accuracy When Solving the FEL Equations

simulation, electron, undulator, bunching

82

R.R. Lindberg
ANL, Argonne, USA

Funding: U.S. Dept. of Energy Office of Sciences under Contract No. DE-AC02-06CH11357
The usual method of numerically solving the FEL equations involves dividing both the e-beam and radiation field into "slices" that are loaded one at a time into memory. This scheme is only first order accurate in the discretization of the ponderomotive phase because having only one slice in memory effectively results in a first order interpolation of the field-particle coupling. While experience has shown that FEL simulations work quite well, the first order accuracy opens the door to two possible ways of speeding up simulation time. First, one can consider higher order algorithms; unfortunately, these methods appear to require all the particle and field data in memory at the same time, and therefore will typically only be important for either small (probably 1D) problems or for parallel simulations run on many processors. Second, one may consistently solving the equations to some low order using faster, simpler algorithms (replacing, for example, the usual RK4). The latter is particularly attractive, although in practice it may be desirable to retain higher order methods when integrating along z. We investigate some of the possibilities.

MOPSO51

Feasibility of an XUV FEL Oscillator at ASTA

undulator, electron, simulation, cryomodule

88

A.H. Lumpkin
Fermilab, Batavia, USA
H. Freund
LANL, Los Alamos, New Mexico, USA
M.W. Reinsch
LBNL, Berkeley, California, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
A significant opportunity exists at the Advanced Superconducting Test Accelerator (ASTA) facility presently under construction at Fermilab to enable the first XUV free electron laser (FEL) oscillator experiments. The ultrabright beam from the L-band photoinjector will provide sufficient gain to compensate for reduced mirror reflectances in the VUV-XUV regimes, the 3-MHz micropulse repetition rate for 1 ms will support an oscillator configuration, the SCRF linac will provide stable energy, and the eventual GeV-scale energy with three TESLA-type cryomodules will satisfy the FEL resonance condition in the XUV regime. Concepts based on combining such beams with a 5-cm-period undulator and optical resonator cavity for an FEL oscillator are described. We used the 68% reflectances for normal incidence on multilayer metal mirrors developed at LBNL*. Initial simulations using GINGER with an oscillator module and MEDUSA:OPC show saturation for the 13.4-nm case after 300 and 350 passes, respectively,of the 3000 pulses. Initially, VUV experiments could begin in the 180- to 120-nm regime using MgF2-coated Al mirrors with only one cryomodule installed and beam energies of 250-300 MeV.
*LBNL X-ray optics site: http://xdb.lbl.gov/Section4

MOPSO57

Measurement of Wigner Distribution Function for Beam Characterization of FELs

laser, free-electron-laser, electron, 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.

MOPSO59

The Influence of the Magnetic Field Inhomogeneity on the Spontaneous Radiation and the Gain in the Plane Wiggler

electron, wiggler, laser, undulator

97

K.B. Oganesyan
ANSL, Yerevan, Armenia

Funding: ISTC
We calculate the spectral distribution of spontaneous emission and the gain of electrons moving in plane wiggler with inhomogeneous magnetic field. We show that electrons do complicated motion consisting of slow(strophotron) and fast(undulator) parts. We average the equations of motion over fast undulator part and obtain equations for connected motion. It is shown, that the account of inhomogenity of the magnetic field leads to appearence of additional peaks in the spectral distribution of spontaneous radiation and the gain.

MOPSO65

Suppression of Wakefield Induced Energy Spread Inside an Undulator Through Current Shaping

wakefield, undulator, impedance, electron

108

J. Qiang, C.E. Mitchell
LBNL, Berkeley, California, USA

Funding: This work was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Wakefields from resistive wall and surface roughness inside an undulatory can cause significant growth of beam energy spread and limit the performance of x-ray FEL radiation. In this paper, we propose a method to mitigate such energy modulation by appropriately conditioning the electron beam current profile. Numerical example and potential applications will also be discussed.

MOPSO66

Start-to-end Simulation of a Next Generation Light Source Using the Real Number of Electrons

electron, simulation, emittance, radiation

112

J. Qiang, J.N. Corlett, P. Emma, C.E. Mitchell, C. F. Papadopoulos, G. Penn, M.W. Reinsch, R.D. Ryne, M. Venturini
LBNL, Berkeley, California, USA
S. Reiche
PSI, Villigen PSI, Switzerland

Funding: This research was supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Start-to-end simulation plays an important role in design and optimization of next generation light sources. In this paper, we will present start-to-end (from the photocathode to the end of undulator) simulations of a high repetition rate FEL-based Next Generation Light Source driven by CW superconducting linac with the real number of electrons (~2 billion electrons/bunch) using the multi-physics parallel beam dynamics code IMPACT. We will discuss challenges, numerical methods and physical models used in the simulation. We will also present simulation results of a beam transporting through photoinjector, beam delivery system, and final X-ray FEL radiation.

MOPSO69

Free-Electron Lasers Driven by Laser-Plasma Accelerators Using Decompression or Dispersion

electron, undulator, plasma, laser

117

C.B. Schroeder, E. Esarey, W. Leemans, J. van Tilborg
LBNL, Berkeley, California, USA
Y. Ding, Z. Huang
SLAC, Menlo Park, California, USA
F.J. Grüner, A.R. Maier
CFEL, Hamburg, Germany

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Laser-plasma accelerators (LPAs) compactly produce fs beams with kA peak current and low (sub-micron) transverse emittance. Presently, the energy spread (percent-level) hinders the FEL application. Slippage of the fs beam in the FEL also suppresses lasing in the soft-x-ray, and longer, wavelength regimes. Given experimentally demonstrated LPA electron beam parameters, we discuss methods of beam phase space manipulation after the LPA to achieve FEL lasing. Decompression is examined as a solution to reduce the slice energy spread and slippage effects. We present a theoretical analysis of the stretched (and chirped) LPA beam in the FEL and determine the optimal decompression. Dispersion, coupled to a transverse gradient undulator (TGU), is also considered to enable LPA-driven FELs. Using a TGU has the advantages of shorter pulse duration, smaller bandwidth, and wavelength stabilization. We present numerical modeling for SASE and seeded XUV and soft x-ray FELs driven by LPAs after beam manipulation (decompression and/or dispersion). Recent advances in LPA performance will be presented, and experimental plans to demonstrate LPA-driven FEL lasing at LBNL will be discussed.

MOPSO73

Suface Roughness Wakefield in FEL Undulator

wakefield, impedance, undulator, electron

127

G.V. Stupakov
SLAC, Menlo Park, California, USA
S. Reiche
PSI, Villigen PSI, Switzerland

Among several wakefield models for the FEL undulator vacuum chamber a simple sinusoidal wall modulation with a small ratio of height to wavelength is especially attractive because of its simplicity [1]. The model neglects a so called resonant mode wakefield and has an (integrable) singularity at the origin which makes difficult its use in practical simulations. In this work we generalize the longitudinal wake of a sinusoidally modulated wall to include the effect of the resonant mode. This also removes the singularity of the wake at the origin. The new wake is used to evaluate the roughness wakefield effect in the undulator of SwissFEL.
[1] G. Stupakov, in "Nonlinear and Collective Phenomena in Beam Physics 1998" Workshop, New York (1999), no. 468 in AIP Conference Proceedings, pp. 334–47.

MOPSO74

Reevaluation of Coherent Electron Cooling Gain Factor

electron, undulator, hadron, radiation

132

G.V. Stupakov
SLAC, Menlo Park, California, USA
M.S. Zolotorev
LBNL, Berkeley, California, USA

In Ref. [1] the authors put forward a concept of coherent electron cooling of hadrons. At the core of the concept lies the following idea: a density perturbation induced by an hadron in a co-propagating relativistic electron beam is amplified by several orders of magnitude in a free electron laser (FEL). After the FEL the electron beam is merged again with the hadron one and the amplified electric field in the electron beam acts back on each hadron resulting, after many repetitions, in cooling of the hadron beam. The efficiency of the process is critically determined by the amplification factor of the longitudinal electric field induced by the hadron in the electron beam. In this work we show that this factor is actually considerably smaller than the (conventionally defined) FEL gain with the smallness parameter to be the relative bandwidth of the FEL amplifier.
[1] V. N. Litvinenko and Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).

MOPSO76

FEL Operation With the Superconducting RF Photo Gun at ELBE

gun, laser, SRF, cavity

136

J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, R. Schurig, W. Seidel, H. Vennekate, R. Xiang
HZDR, Dresden, Germany
T. Kamps, J. Rudolph
HZB, Berlin, Germany
I. Will
MBI, Berlin, Germany

The superconducting RF photoinjector (SRF gun) operating with a 31/2-cell niobium cavity and Cs2Te photocathodes is installed at the ELBE radiation center. The gun provides beams for ELBE as well as in a separate diagnostics beam line for beam parameter measurements. Since 2012 a new UV driver laser system developed by MBI has been installed for the SRF gun . It delivers CW or bust mode pulses with 13 MHz repetition rate or with reduced rates of 500, 200, and 100 kHz at an average UV power of about 1 W. The new laser allows the gun to serve as the driver for the infrared FELs at ELBE. In the first successful experiment a 250 μA beam with 3.3 MeV from SRF gun was injected into ELBE, further accelerated in the ELBE superconducting linac modules and then guided to the U100 undulator. First lasing was achieved at the wavelength of 41 μm. The spectrum, detuning curve and further parameters were measured.

MOPSO81

Broad-band Amplifier Based on Two-stream Instability

electron, plasma, free-electron-laser, 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.

MOPSO82

JLIFE: The Jefferson Lab Interactive Front End for the Optical Propagation Code

controls, laser, GUI, factory

149

A.M. Watson, M.D. Shinn
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC and supported by the ONR, the Joint Technology Office, and the DOE under U.S. DOE Contract No. DE-AC05-06OR23177.
We present details on a graphical interface for the open source software program Optical Propagation Code, or OPC. [1] This interface, written in Java, allows a user with no knowledge of OPC to create an optical system, with lenses, mirrors, apertures, etc. and the appropriate drifts between them. The Java code creates the appropriate Perl script that serves as the input for OPC. The mode profile is then output at each optical element. The display can be either an intensity profile along the x axis, or as an isometric 3D plot which can be tilted and rotated. These profiles can be saved. Examples of the input and output will be presented.
[1] J. G. Karssenberg, P. J. M. van der Slot, I. V. Volokhine, J. W. J. Verschuur, and K.-J. Boller, “Modeling paraxial wave propagation in free-electron laser oscillators”, JAP 100, 093106 (2006).

MOPSO84

Numerical Investigations of Transverse Gradient Undulator Based Novel Light Sources

electron, laser, undulator, simulation

152

T. Zhang, D. Wang, G.L. Wang, H.F. Yao
SINAP, Shanghai, People's Republic of China
J.S. Liu, C. Wang, W.T. Wang, Z.N. Zeng
Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China
J.Q. Wang, S.H. Wang
IHEP, Beijing, People's Republic of China

With the stat-of-the-art laser technique, the quality of electron beam generated from laser-plasma accelerator (LPA) is now becoming much more better. The natural merits LPA beam, e.g. high peak current, ultra-low emittance and ultra-short bunch length, etc., pave the way to the novel light sources, especially in the realm of developing much compact X-ray light sources, e.g. table-top X-ray free-electron laser, although the radiation power is limited by the rather larger energy spread than conventional LINAC. Luckily, much more power could be extracted by using the undulator with transverse gradient (TGU) when energy spread effect could be compensated. Here we introduce a novel soft x-ray light source driven by LPA based on TGU technique. Meanwhile we present a simple idea on how to achieve much higher rep-rate (e.g. ~100 kHz) storage ring based FELs boosted by TGU.

TUOBNO03

An RF Deflecting Cavity Based Spreader System for Next Generation Light Sources

gun, cavity, dipole, electron

173

C. Sun, L.R. Doolittle, P. Emma, J.-Y. Jung, M. Placidi, A. Ratti
LBNL, Berkeley, California, USA

Lawrence Berkeley National Laboratory (LBNL) is developing design concepts for a multi-beamline (up to 10 lines) soft x-ray FEL array powered by a superconducting linear accelerator with a high bunch repetition rate of approximately one MHz. The FEL array requires a beam spreader system which can distribute individual electron bunches from the linac to each independently configurable beamline. We propose a new spreader system using RF deflecting cavities to deflect electron bunches as an alternative design to the fast kicker scheme. This RF approach offers more stable deflection amplitude while removing the limitations on the bunch repetition rate characteristic of the kicker approach. In this work, we describes the design concept of this RF based spreader system, including technical choices, design parameters and beamline optics.
[1] M. Placidi et al., Proceedings of IPAC2012, New Orleans, Louisiana, USA, pp.1765-1767

Slides TUOBNO03 [1.391 MB]

TUOCNO01

Electron Beam Longitudinal Phase Space Manipulation by Means of an AD-HOC Photoinjector Laser Pulse Shaping

electron, linac, laser, simulation

180

G. Penco, D. Castronovo, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, W.M. Fawley, L. Giannessi, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

In a seeded FEL machine as FERMI, the interplay between the electrons energy curvature and the seed laser frequency chirp has a relevant impact on the output FEL spectrum. It is therefore crucial controlling and manipulating the electron beam longitudinal phase space at the undulator entrance. In case of very short bunches, i.e. high compression scheme, the longitudinal wakefields generated in the linac induce a positive quadratic curvature in the electrons longitudinal phase space that is hard to compensate by tuning the phase of the main RF sections or the possible high harmonic cavity. At FERMI we have experimentally exploited a longitudinal ramp current distribution at the cathode, obtained with an ad-hoc photoinjector laser pulse shaping, to linearize the longitudinal wakefields in the downstream linac and flatten the electrons energy distribution, as theoretical foreseen in [1]. Longitudinal phase space measurements in this novel configuration are here presented, providing a comparison with the typical longitudinal flat-top profile.
[1] Phys. Rev. Special Topics - Accel. and Beams 9 (12), 120701 (2006)

Slides TUOCNO01 [28.792 MB]

TUOCNO05

Design Concepts for a Next Generation Light Source at LBNL

linac, electron, laser, undulator

193

J.N. Corlett, A.P. Allezy, D. Arbelaez, K.M. Baptiste, J.M. Byrd, C.S. Daniels, S. De Santis, W.W. Delp, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, J.G. Floyd, J.P. Harkins, G. Huang, J.-Y. Jung, D. Li, T.P. Lou, T.H. Luo, G. Marcus, M.T. Monroy, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, S. Paret, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, H.J. Qian, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, R.W. Schoenlein, C. Serrano, J.W. Staples, C. Steier, C. Sun, M. Venturini, W.L. Waldron, W. Wan, T. Warwick, R.P. Wells, R.B. Wilcox, S. Zimmermann, M.S. Zolotorev
LBNL, Berkeley, California, USA
C. Adolphsen, K.L.F. Bane, Y. Ding, Z. Huang, C.D. Nantista, C.-K. Ng, H.-D. Nuhn, C.H. Rivetta, G.V. Stupakov
SLAC, Menlo Park, California, USA
D. Arenius, G. Neil, T. Powers, J.P. Preble
JLAB, Newport News, Virginia, USA
C.M. Ginsburg, R.D. Kephart, A.L. Klebaner, T.J. Peterson, A.I. Sukhanov
Fermilab, Batavia, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The NGLS collaboration is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately 1 MHz. The CW superconducting linear accelerator design is based on developments of TESLA and ILC technology, and is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches from the linac are distributed by RF deflecting cavities to the array of independently configurable FEL beamlines with nominal bunch rates of ~100 kHz in each FEL, with uniform pulse spacing, and some FELs capable of operating at the full linac bunch rate. Individual FELs may be configured for different modes of operation, including self-seeded and external-laser-seeded, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from femtoseconds and shorter, to hundreds of femtoseconds. In this paper we describe current design concepts, and progress in R&D activities.

Slides TUOCNO05 [5.982 MB]

TUPSO01

Corrector Response Based Alignment at FERMI

alignment, quadrupole, linac, wakefield

205

M. Aiba, M. Böge
PSI, Villigen PSI, Switzerland
D. Castronovo, S. Di Mitri, L. Fröhlich, G. Gaio
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The components of an FEL accelerator generally need to be beam-based aligned in order to meet the design performance. We are developing new technique, where dipole corrector responses are used instead of orbit difference measurements. When an orbit feedback is running, any change in beam orbit is compensated by the actuators, i.e., the dipole correctors. For example, the spurious dispersion through linac rf structures, which is a source of emittance degradation, is measured through orbit differences for various beam momenta in the conventional way while dipole corrector responses are examined in the new method. The advantages are localization of misalignments, stable measurement as the orbit is kept constant, and automatic averaging and beam jitter filtering by the feedback loop. Furthermore, this method potentially allows us to detect transverse wakefield kicks, which are also an emittance degradation source, by looking into the dipole corrector responses to a change in bunch charge or bunch length. The results from a series of machine development shifts will be presented.

TUPSO14

Transverse Deflecting Structures for Bunch Length and Slice Emittance Measurements on SwissFEL

linac, emittance, diagnostics, undulator

236

P. Craievich, R. Ischebeck, F. Löhl, G.L. Orlandi, E. Prat
PSI, Villigen PSI, Switzerland

The SwissFEL project, under development at the Paul Scherrer Institut, will produce FEL radiation in a wavelength range from 0.1 nm to 7 nm. 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 magnetic chicanes will compress the beam between 2.5 fs rms and 25 fs rms depending on the operation mode. The bunch length and slice parameters will be measured after the first bunch compressor (330 MeV) by using an S-band transverse deflecting structure (TDS). A C-band TDS will be employed to measure the longitudinal parameters of the beam just upstream the undulator beamline (5.8 GeV). With the designed transverse beam optics, an integrated deflecting voltage of 70 MV is required in order to achieve a longitudinal resolution on the femtosecond time scale. In this paper we present the TDS measurement systems to be used at SwissFEL, with a particular emphasis on the new C-band device, including hardware, lattice layout and beam optics.

TUPSO15

Beam Diagnostic Requirements for the Next Generation Light Source

diagnostics, linac, emittance, feedback

242

S. De Santis, J.M. Byrd, J.N. Corlett, P. Emma, D. Filippetto, M. Placidi, H.J. Qian, F. Sannibale
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The NGLS project consists in a 2.4 GeV superconducting linac accelerating sub-1 μm normalized emittance bunches used to produce high intensity soft X-ray short pulses from multiple FEL beamlines. The 1 MHz bunch repetition rate, and the consequent high beam power, present special challenges, but also opportunities, in the design of the various electron beam diagnostic devices. The wide range of beam characteristics, from the photoinjector to the undulators, require the adoption of different diagnostics optimized to each machine section and to the specific application of each individual measurement. In this paper we present our plans for the NGLS beam diagnostics, discussing the special requirements and challenges.

TUPSO24

Dispersion Based Beam Tilt Correction

quadrupole, sextupole, emittance, electron

267

M.W. Guetg, B. Beutner, E. Prat, S. Reiche
PSI, Villigen PSI, Switzerland

In Free Electron Lasers (FEL), a transverse centroid misalignment of longitudinal slices in an electron bunch reduces the effective overlap between radiation field and electron bunch and therefore the FEL performance. The dominant sources of slice misalignments for FELs are the incoherent and coherent synchrotron radiation within bunch compressors as well as transverse wake fields in the accelerating cavities. This is of particular importance for over-compression which is required for one of the key operation modes for the SwissFEL planned at the Paul Scherrer Institute. The centroid shift is corrected using corrector magnets in dispersive sections, e.g. the bunch compressors. First and second order corrections are achieved by pairs of sextupole and quadrupole magnets in the horizontal plane while skew quadrupoles correct to first order in the vertical plane. Simulations and measurements at the SwissFEL Injector Test Facility are done to investigate the proposed correction scheme for SwissFEL. This paper presents the methods and results obtained.

TUPSO35

The MAX IV Linac as X-Ray FEL Injector: Comparison of Two Compression Schemes

linac, emittance, wakefield, electron

294

O. Karlberg, F. Curbis, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

The MAX IV linac will be used for injections and top up of two storage rings and at the same time provide a high brightness pulses to a short pulse facility (SPF) and an X-ray FEL (phase 2). Compression in the linac is done in two double achromats which implies a positive R56 unlike the commonly used chicane compressor scheme with negative R56. Compression using the achromats scheme requires the electron bunch to be accelerated on a falling RF slope resulting in an energy chirp that longitudinal wakefields will boost along the linac. This permits a stronger compression. In this proceeding we will present how the longitudinal wakefields interact with the bunch compression in the double achromat scheme compared with the chicane compression case. Focus is brought on how the unique MAX IV linac lattice is fully capable to cope with the high demands of an FEL injector. The charge related electron beam jitter in both set-ups will also be investigated.

TUPSO45

Initial Streak Camera Measurements of the S-band Linac Beam for the University of Hawaii FEL Oscillator

electron, linac, undulator, radiation

325

A.H. Lumpkin
Fermilab, Batavia, USA
M.R. Hadmack, J.M.D. Kowalczyk, J. Madey, E.B. Szarmes
University of Hawaii, Honolulu, HI, USA

Funding: Work at Fermilab supported by Fermi Research Alliance, LLC under U.S.DOE Contract No.DE-AC02-07CH11359. Work at UH supported by U.S. Dept. of Homeland Security grant No. 20120-DN-077-AR1045-02.
The S-band linac driven Mark V free-electron laser oscillator (FELO) at the University of Hawai‘i operates in the mid-IR at electron beam energies of 40-45 MeV with a four microsecond macropulse length. Recently investigations of the electron beam micropulse bunch length and phase as a function of macropulse time became of interest for potentially optimizing the FELO performance. These studies involved the implementation of a Hamamatsu C5680 streak camera with dual sweep capabilities and the transport of optical transition radiation (OTR) generated at an upstream Cu mirror and of coherent spontaneous emission radiation (CSER) generated in the undulator to the streak camera location outside of the linac tunnel. Both a fast single-sweep vertical unit and a synchroscan unit tuned to 119.0 MHz were used. Initial results include measurements of the individual CSER (on the FEL7th harmonic at 652 nm) micropulse bunch lengths (3 to 5 ps FWHM), the CSER signal intensity variation along macropulse time, and a detected phase slew of 4 ps over the last 700 ns of the macropulse. Complementary OTR measurements are also being evaluated and will be presented as available.

TUPSO49

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

cathode, lattice, free-electron-laser, 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)

TUPSO50

Numerical Study on Electron Beam Properties in Triode Type Thermionic RF Gun

cavity, gun, cathode, electron

344

M. Mishima, M. Inukai, T. Kii, K. Masuda, H. Negm, H. Ohgaki, K. Okumura, M. Omer, K. Torgasin, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

The KU-FEL(Kyoto University- Free Electron Laser) facility uses a thermionic 4.5 cell S-band RF gun for electron beam generation because of such advantages over photocathode rf guns as lower cost, higher average current, longer cathode lifetime, and less vacuum requirement. The main disadvantage of using a thermionic RF gun is the back bombardment effect, which causes energy drop in macro pulse of FEL. A triode structure for RF gun was designed in order to minimize the inherent back-bombardment effect. The 2D-simulation has shown significant reduction of back-bombardment power, longitudinal emittance, and an increase of peak current*. A coaxial RF cavity was fabricated based on the design for modification of the existing RF gun to a triode type one. The coaxial RF cavity is equipped with gasket tuning system in order to adjust the cavity resonance frequency**. However the frequency adjustment by variation of gasket thickness changes the coaxial cavity geometry and might affect the predicted beam optics. Another parameter influencing beam optics is the position of thermionic cathode to be installed in the coaxial cavity, which might vary due to misalignment.
*K. Masuda, et al., Proceedings of FEL 2009, Liverpool, Pages 281-284 (2009).
**K. Torgasin, et al., Proceedings of FEL 2012, Nara(2012).

TUPSO52

R&D Towards a Delta-type Undulator for the LCLS

undulator, vacuum, polarization, radiation

348

H.-D. Nuhn, S.D. Anderson, G.B. Bowden, Y. Ding, G.L. Gassner, Z. Huang, E.M. Kraft, Yu.I. Levashov, F. Peters, F.E. Reese, J.J. Welch, Z.R. Wolf, J. Wu
SLAC, Menlo Park, California, USA
A.B. Temnykh
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The LCLS generates linearly polarized, intense, high brightness x-ray pulses from planar fixed-gap undulators. While the fixed-gap design supports a very successful and tightly controlled alignment concept, it provides only limited taper capability (up to 1% through canted pole and horizontal position adjustability) and lacks polarization control. The latter is of great importance for soft x-ray experiments. A new compact undulator design (Delta) has been developed and tested with a 30-cm-long in-vacuum prototype at Cornell University, which adds those missing properties to the LCLS undulator design and is readily adapted to the LCLS alignment concept. Tuning Delta undulators within tight, FEL type tolerances is a challenge due to the fact that the magnetic axis and the magnet blocks are not easily accessible for measurements and tuning in the fully assembled state. An R&D project is underway to install a 3.2-m long out-of-vacuum device in place of the last LCLS undulator, to provide controllable levels of polarized radiation and to develop measurement and tuning techniques to achieve x-ray FEL type tolerances. Presently, the installation of the device is scheduled for August 2013.

TUPSO58

Developments of a High-average-current Thermionic RF Gun for ERLs and FELs

gun, cavity, cathode, electron

359

J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd
AES, Princeton, New Jersey, USA

Funding: Supported by ONR under Contract No. N00014-10-C-0191.
The development of a high-average-current thermionic RF gun with the required beam performance for lasing would provide significant cost of ownership and reliability gains for high-average-power energy recovery linac (ERL) and free electron laser (FEL) devices. The beam for these applications requires high quality and high performance, specifically: low transverse emittance, short pulse duration and high average current. We are developing a gridded thermionic cathode embedded in a copper one-and-half cell UHF cavity to generate the electron beam. The fundamental RF and higher harmonics are combined on the grid and a gated DC voltage controls the beam emission from the cathode. Simulations indicate that short pulse ~ 10 psec, < 1 MeV electron beams with low-emittance ~ 15 mm-mrad at currents ≥ 100 mA can be generated. The elimination of sensitive photocathodes and their drive laser systems would provide significant capital cost saving, improved reliability and uptime due to increased robustness and hence operating and lifecycle cost savings as well. We will present the gun design and performance simulations and the progress achieved to date in optimizing the device.

TUPSO60

Status of the Undulator Systems for the European X-ray Free Electron Laser

undulator, controls, laser, electron

367

J. Pflüger, M. Bagha-Shanjani, A. Beckmann, K.H. Berndgen, P. Biermordt, G. Deron, U. Englisch, S. Karabekyan, B. Ketenoğlu, M. Knoll, Y. Li, F. Wolff-Fabris, M. Yakopov
XFEL. EU, Hamburg, Germany

The three undulator systems for the European XFEL consist of a total of 91 Undulator Cells. Each cell consists of an Undulator Segment and an intersection. They will be operational by end of 2015. The serial production of the 91 Undulator Segments is a great challenge and without precedence. It is now in full swing. This contribution gives an overview over the most important design aspects as well as the experience and strategy with the serial production. Representative results of magnetic performance are given. The status of the other system components is briefly described.

TUPSO62

Status of the Planar Undulator Applied in HUST THz-FEL Oscillator

undulator, radiation, electron, focusing

372

B. Qin, X. Lei, K.F. Liu, X. Liu, P. Tan, Y.Q. Xiong, J. Yang, L. Yang
HUST, Wuhan, People's Republic of China
Y.B. Wang
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China

To fulfill the physical requirement of a 50-100 um Free Electron Laser (FEL) oscillator, design considerations of a planar undulator are described. Some technical issues, including the tolerances study, the beam match, the field measurement setup and the influence on the magnetic field by the waveguide are discussed as well.

TUPSO64

Short SASE-FEL Pulses at FLASH

laser, electron, radiation, free-electron-laser

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.

TUPSO66

Transport of Terahertz-Wave Coherent Synchrotron Radiation With a Free-electron Laser Beamline at LEBRA

electron, radiation, undulator, linac

383

N. Sei, H. Ogawa
AIST, Tsukuba, Ibaraki, Japan
K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan

Funding: This work was supported by JSPS Grant-in-Aid for Challenging Exploratory Research 2365696.
Nihon University and AIST have jointly developed terahertz-wave coherent synchrotron radiation (CSR) at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University. We have already observed intense terahertz-wave radiation from a bending magnet located above an undulator, and confirmed it to be CSR*. To avoid a damage caused by ionizing radiation, we worked on transporting the CSR to an experimental room which was next to the accelerator room. By using a beamline of an infrared free-electron laser, the CSR more than 1 mW was successfully transported to the experimental room. The transport of the CSR and imaging experiments with the CSR at LEBARA will be reported.
*: N. Sei et al., “Observation of intense terahertz-wave coherent synchrotron radiation at LEBRA”, J. Phys. D, 46 (2013) 045104.

TUPSO80

The MAX IV Linac and First Design for an Upgrade to 5 GeV to Drive an X-ray FEL

linac, simulation, electron, storage-ring

413

S. Thorin, F. Curbis, N. Čutić, M. Eriksson, O. Karlberg, F. Lindau, A.W.L. Mak, E. Mansten, S. Werin
MAX-lab, Lund, Sweden

The installation of the MAX IV linear accelerator is in full progress, and commissioning is planned to start in the second quarter of 2014. The 3 GeV linac will be used as a full energy injector for the two storage rings, and as a high brightness driver for a Short Pulse linac light source. The linac has been deigned to also handle the high demands of an FEL injector. The long term strategic plan for the MAX IV laboratory includes an extension of the linac to 5 GeV and an X-ray FEL. In this paper we present the both design concept and status of the MAX IV linac along with parameters of the 3 GeV high quality electron pulses. We also present the first design and simulation results of the upgrade to a 5 GeV X-ray FEL driver.

TUPSO81

Challenges for Detection of Highly Intense FEL Radiation: Photon Beam Diagnostics at FLASH1 and FLASH2

photon, diagnostics, electron, radiation

417

K.I. Tiedtke, M. Braune, G. Brenner, S. Dziarzhytski, B. Faatz, J. Feldhaus, B. Keitel, M. Kuhlmann, H. Kühn, E. Plönjes, A.A. Sorokin, R. Treusch
DESY, Hamburg, Germany

In spite of the evident progress in the development of FEL facilities, the characterization of important FEL photon beam parameters during FEL-commissioning and user experiments is still a great challenge. In particular pulse-resolved photon beam characterization is essential for most user experiments, but the unique properties of FEL radiation properties such as extremely high peak powers and short pulse lengths makes the shot-to-shot monitoring of important parameters very difficult. Therefore, sophisticated concepts have been developed and used at FLASH in order to measure radiation pulse intensity, beam position and spectral as well as temporal distribution – always coping with the highly demanding requirements of user experiments as well as machine operation. Here, an overview on the photon diagnostic devices operating at FLASH and FLASH II will be presented, with emphasizes on the pulse resolving intensity and energy detectors based on photoionization of rare gases.

TUPSO83

Quantum Efficiency and Transverse Momentum From Metals

electron, brightness, vacuum, laser

424

T. Vecchione, D. Dowell
SLAC, Menlo Park, California, USA
J. Feng, H.A. Padmore, W. Wan
LBNL, Berkeley, California, USA

Funding: Work supported by US DOE contracts DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC000571.
QE and transverse momentum are key parameters limiting the achievable brightness of FELs. Despite the importance, little data is available to substantiate current models. Expressions for each and experimental confirmation of each expression with respect to excess energy are presented. Novel instrumentation and analysis techniques developed are described.

TUPSO87

High-Field Laser-Based Terahertz Source for SwissFEL

laser, controls, radiation, photon

438

C. Vicario, C.P. Hauri, B. Monoszlai, C. Ruchert
PSI, Villigen PSI, Switzerland
C.P. Hauri
EPFL, Lausanne, Switzerland

We present efficient laser-driven THz generation by optical rectification in various organic materials yielding transient fields up to 150 MV/m and 0.5 Tesla. The generated spectra extend over the entire THz gap (0.1-10 THz). Manipulation of the absolute phase by dispersion control is demonstrated for 5-octave spanning, single-cycle pulses. The presented source will be applied to the future SwissFEL as Xray photon temporal diagnostics and for pump-and-probe experiments.

TUPSO88

New Concept for the SwissFEL Gun Laser

laser, cathode, gun, electron

442

A. Trisorio, M.C. Divall, C.P. Hauri, C. Vicario
PSI, Villigen PSI, Switzerland
A. Courjaud
Amplitude Systemes, Pessac, France

The operation of Swiss FEL put very stringent constrains on the gun laser system. First the parameters, such as energy stability, timing jitter, double pulse operation, temporal and spatial pulse shape of the ultra-violet laser pulses used to generate the photo-electrons are challenging even for the state of the art laser technologies. Second, the laser system must be extremely stable, reliable and its maintenance cost as low as possible. In this perspective, we prospected for alternative technologies to the well known, commonly used but costly Ti:sapphire laser systems. We show that a hybrid Yb fiber and solid state Yb:CaF2 amplifier system can be a very interesting approach. This gain medium allows the production of sub-500 fs, high fidelity, high stability, high energy pulses in the ultra-violet with low timing jitter. The system profits of the mature, stable direct diode pumping technology and optimized design. It delivers the two high-energy, shaped UV pulses separated by 28 ns to produce the photo-electrons, a short IR probe (<100 fs FWHM) to temporally characterize those pulses and the two stretched IR pulses ( 50 ps FWHM) necessary for the laser heater.

TUPSO89

A Femtosecond Resolution Electro-optic Diagnostic Using a Nanosecond-pulse Laser

laser, diagnostics, target, optics

447

D.A. Walsh, W.A. Gillespie
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
S.P. Jamison
Cockcroft Institute, Warrington, Cheshire, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: This project has been funded by CERN as part of the CLIC-UK programme Contract Number KE1865/DG/CLIC
Electro-optic diagnostics with a target time resolution of 20fs RMS, and with intrinsically improved stability and reliability, are being developed. The new system is based on explicit temporal measurement of an electro-optically upconverted pulse, following interaction of the bunch with a quasi-CW probe pulse. The electro-optic effect generates an “optical-replica” of the longitudinal charge distribution from the narrow-bandwidth probe, simultaneously up-converting the bunch spectrum to optical frequencies. By using Frequency Resolved Optical Gating (FROG), an extension of autocorrelation, the optical replica can then be characterised on a femtosecond time scale. This scheme therefore bypasses the requirement for unreliable femtosecond laser systems. The high pulse energy required for single-shot pulse measurement via FROG will be produced through optical parametric amplification of the optical-replica pulses. The complete system will be based on a single nanosecond-pulse laser – resulting in a reliable system with greatly relaxed timing requirements.

WEIANO01

Towards Zeptosecond-scale Pulses From X-ray Free Electron Lasers

electron, radiation, undulator, laser

458

D.J. Dunning, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom

The short wavelength and high peak power of the present generation of Free-Electron Lasers (FELs) opens the possibility of ultra-short pulses even surpassing the present (~10-100 attosecond) capabilities of other light sources – but only if x-ray FELs can be made to generate pulses consisting of just a few optical cycles. For hard x-ray operation (<~0.1nm), this corresponds to durations of approximately a single attosecond, and below into the zeptosecond scale. This talk will describe a proposed method [1] to generate trains of few-cycle pulses, at GW peak powers, from existing x-ray FEL facilities by using a relatively short 'afterburner'. Such pulses would enhance research opportunity in atomic dynamics and push capability towards the investigation of electronic-nuclear and nuclear dynamics. The corresponding multi-colour spectral output, with a bandwidth envelope increased by up to two orders of magnitudes over SASE, also has potential applications.
[1] D.J. Dunning, B.W.J. McNeil, N.R. Thompson, Phys. Rev. Lett. 110, 104801 (2013).

Slides WEIANO01 [3.492 MB]

WEOANO01

New Scheme to Generate a Multi-terawatt and Attosecond X-ray Pulse in XFELs

electron, target, laser, undulator

464

T. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

A new scheme to be applied in XFELs has been recently proposed*, which effectively compresses the X-ray pulse, i.e., shortens the pulse length and enhances the peak power by means of inducing a periodic current enhancement with an optical laser and applying a temporal shift between the X-ray and electron beams. In this paper, detailed mechanism of the new scheme is explained together with numerical results applied to the SACLA XFEL facility.
*T. Tanaka, PRL 110, 084801 (2013)

Slides WEOANO01 [4.177 MB]

WEOANO03

Longitudinal Coherence in an FEL With a Reduced Level of Shot Noise

electron, laser, radiation, undulator

469

V.A. Goryashko
Private Address, Uppsala, Sweden
V.G. Ziemann
Uppsala University, Uppsala, Sweden

For a planar free electron laser (FEL) configuration we study self-amplified coherent spontaneous emission driven by a gradient of the bunch current in the presence of different levels of noise in bunches [1]. We calculate the probability density distribution of the maximum power of the radiation pulses for different levels of shot noise. It turns out that the temporal coherence quickly increases as the noise level reduces. We also show that the FEL based on coherent spontaneous emission produces almost Fourier transform limited pulses and the time-bandwidth product is mainly determined by the bunch length and the interaction distance in an undulator. We also propose a scheme that permits the formation of electron bunches with a reduced level of noise and a high gradient of the current at the bunch tail to enhance coherent spontaneous emission. The presented scheme uses effects of noise reduction and controlled microbunching instability and consists of a laser heater, a bunch compressor, and a shot noise suppression section. The noise factor and microbunching gain of the overall proposed scheme with and without laser heater are estimated.
V.A. Goryashko and V. Ziemann, Phys. Rev. ST Accel. Beams 16, 030702 (2013).

Slides WEOANO03 [1.999 MB]

WEOCNO03

3-D Theory of a High Gain Free-Electron Laser Based on a Transverse Gradient Undulator

electron, undulator, emittance, radiation

481

P. Baxevanis, Y. Ding, Z. Huang, R.D. Ruth
SLAC, Menlo Park, California, USA

The performance of a free-electron laser (FEL) depends significantly on the various parameters of the driving electron beam. In particular, a large energy spread in the beam results in a great reduction of the FEL gain, an effect which is relevant when one considers FELs driven by plasma accelerators or storage rings. For such cases, one possible solution is to use a transverse gradient undulator (TGU) [*,**]. In this concept, the energy spread problem is mitigated by properly dispersing the e-beam and introducing a linear, transverse field dependence in the undulator. This paper presents a self-consistent theoretical analysis of a TGU-based high gain FEL, taking into account three-dimensional (3-D) effects and beam size variations along the undulator [***]. The results of our theory compare favorably with simulation and are used in fast optimization studies of various X-ray FEL configurations.
*T. Smith et al., J. Appl. Phys. 50, 4580 (1979).
**Z. Huang, Y. Ding, C. Schroeder, Phys. Rev. Lett. 109, 204801 (2012).
***P. Baxevanis, R. Ruth, Z. Huang, Phys. Rev. ST-AB 16, 010705 (2013).

Slides WEOCNO03 [3.217 MB]

WEPSO01

Free Electron Lasers in 2013

electron, undulator, laser, free-electron-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.

WEPSO02

Results and Perspectives on the FEL Seeding Activities at FLASH

laser, undulator, electron, radiation

491

J. Bödewadt, C. Lechner
Uni HH, Hamburg, Germany

In recent years, several methods of free-electron laser (FEL) seeding, such as high-gain harmonic generation (HGHG), self-seeding, or direct FEL amplification of external seed pulses, have proven to generate intense, highly coherent radiation pulses in the extreme ultraviolet (XUV), soft- (SXR) and hard (HXR) X-ray spectral range. At DESY in Hamburg, the FEL facility FLASH is currently being upgraded by a second undulator beamline (FLASH2) which allows for the implementation of various seeding schemes. The development of high repetition-rate, high-power laser systems allows for the production of seed sources which match the bunch-train pattern of FLASH. Furthermore, the FLASH1 beamline arrangement is well suited for testing various seeding schemes including HGHG, EEHG, HHG-seeding, and hybrid schemes. In this contribution, we* give an overview of latest results and planned FEL seeding activities at FLASH.
*Joern Boedewadt on behalf of the FLASH seeding collaboration (DESY, U Hamburg, TU Dortmund, U Uppsala, U Stockholm)

WEPSO04

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

electron, laser, undulator, free-electron-laser

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, electron, undulator, free-electron-laser

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.

WEPSO06

The Test-FEL at MAX-lab: Implementation of the HHG Source and First Results

laser, electron, radiation, undulator

507

F. Curbis, N. Čutić, F. Lindau, E. Mansten, S. Werin
MAX-lab, Lund, Sweden
F. Brizuela, B. Kim, A. L'Huillier
Lund University, Division of Atomic Physics, Lund, Sweden
M. Gisselbrecht
SLF, Lund, Sweden

The test-FEL at MAX-lab is a development set-up for seeding techniques. After the successful demonstration of coherent harmonic generation from a conventional laser, the new layout now presents a gas target for generation of harmonics. The drive laser will be up-converted and the low harmonics (around 100 nm) will seed the electron beam. The energy modulated electrons will then be bunched in the dispersive section and will radiate in the second undulator. We will detect the second harmonic of the HHG radiation around 50 nm. This experiment has several challenges never tried before: co-propagation of the electron beam and the drive laser, interaction of the electron beam with the gas in the target, no-focusing of the harmonics and no drive laser removal. The commissioning will show if this kind of in-line chamber has advantages with respect to more traditional approaches with optical beam transport. The results are relevant for many facilities that are planning to implement HHG seeding in the near future.

WEPSO07

Simulation Studies for an X-ray FEL Based on an Extension of the MAX IV Linac

linac, undulator, electron, radiation

510

F. Curbis, N. Čutić, O. Karlberg, F. Lindau, A.W.L. Mak, E. Mansten, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

It is well known that the few X-ray FELs around the world are severely overbooked by users. Having a medium energy linac, such as the one now being installed at the MAX IV laboratory, it becomes natural to think about slightly increasing the electron energy to drive an X-ray FEL. This development is now included in the long term strategic plan for the MAX IV laboratory. We will present the current FEL studies based on an extension of the MAX IV linac to 5 GeV to reach the Angstrom region. The injector for the MAX IV accelerator complex is also equipped with a photocathode gun, capable of producing low emittance electron beam. The bunch compression and linearization of the beam is taken care by two double achromats. The basic FEL layout would consist of short period undulators with tapering for extracting all the power from the electron beam. Self-seeding is considered as an option for increasing the spectral and intensity stability.

WEPSO09

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

photon, electron, background, free-electron-laser

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.

WEPSO10

Increased Stability Requirements for Seeded Beams at LCLS

linac, klystron, undulator, electron

518

F.-J. Decker, W.S. Colocho, Z. Huang, R.H. Iverson, A. Krasnykh, A.A. Lutman, M.N. Nguyen, T.O. Raubenheimer, M.C. Ross, J.L. Turner, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Department of Energy, Contract DE-AC02-76SF00515.
Running the Linac Coherent Light Source (LCLS) with self-seeded photon beams requires better electron beam stability, especially in energy, to reduce the otherwise huge intensity variations of more than 100%. Code was written to identify and quantify the different jitter sources. Some improvements are being addressed, especially the stability of the modulator high voltage of some critical RF stations. Special setups like running the beam off crest in the last part of the linac can also be used to reduce the energy jitter. Even a slight dependence on the transverse position was observed. The intensity jitter distribution of a seeded beam is still more contained with peaks up too twice the average intensity, compared to the jitter distribution of a SASE beam going through a monochromator, which can have damaging spikes up to 5 times the average intensity.

WEPSO11

Coherent X-Ray Seeding Source for Driving FELs

cavity, undulator, electron, radiation

522

A. Novokhatski, F.-J. Decker, R.O. Hettel, Z. Huang, H.-D. Nuhn, M.K. Sullivan
SLAC, Menlo Park, California, USA

Funding: "Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515
The success of the hard X-ray self-seeding experiment at the LCLS is very important in that it provided narrow, nearly transform-limited bandwidth from the FEL, fulfilling a beam quality requirement for experimental applications requiring highly monochromatic X-rays. Yet, because the HXRSS signal is generated random spikes of noise, it is not a truly continuous monochromatic seed signal and even higher FEL performance would be achieved using a continuous seed source. We propose developing such a source using an X-ray cavity to achieve a continuous, narrow band X-ray seed signal. This cavity consists of four crystals with corresponding Bragg angles of about 45 degrees for each. We will analyze and the interaction of X-rays and electron beams with this cavity. This source uses a train of electron bunches initially accelerated in a linear accelerator which then pass through a radiator element situated within an X-ray cavity. The number of bunches is proportional to the achievable Q-value of the X-ray cavity and may be in the range of 10-100. We do not need a high output power of X-ray beams, which leads to relaxed electron beam requirements. We will consider several options.

WEPSO14

Towards High Frequency Operation with a Multi-Grating Smith-Purcell FEL

simulation, radiation, electron, bunching

525

J.T. Donohue
CENBG, Gradignan, France
J. Gardelle
CEA, LE BARP cedex, France

Three-dimensional simulations and experiments have shown that, for a grating equipped with sidewalls, copious emission of coherent Smith-Purcell (SP) radiation at the fundamental frequency of the evanescent surface wave is possible 1, 2. Since the underlying theory is scale invariant, the wavelength emitted is reduced in proportion to a uniform rescaling of the grating. In order to increase our 5 GHz to 100 GHz , the grating surface would be reduced by a factor of 400, which would lead to greatly reduced power. In addition, the required beam might be hard to generate. To avoid this, we propose to use several gratings in parallel with no overall reduction in the total width and the same beam as in our microwave experiment. For this scheme to succeed, it is essential that the bunching in the different gratings be coherent. . Simulations suggest that this occurs for as much as a ten-fold scale reduction. To test this idea, an experiment is using several gratings is being performed.
1. J. T. Donohue and J. Gardelle, Appl. Phys. Lett. 99, 161112 (2011).
2. J. Gardelle, P. Modin and J.T. Donohue, Appl. Phys. Lett. 100, 131103 (2012),.

WEPSO17

High-resolution Seeding Monochromator Design for NGLS

optics, electron, undulator, brightness

529

Y. Feng, J.B. Hastings, J. Wu
SLAC, Menlo Park, California, USA
P. Emma, R.W. Schoenlein, T. Warwick
LBNL, Berkeley, California, USA

Funding: DOE/BES
A high-resolution soft X-ray seeding monochromator has been designed for self-seeding the Next-Generation Light Source (NGLS). The seeding monochromator system consists of a single variable-line-spacing grating, three mirrors and an exit slit and operates in the “fixed-focus” mode to achieve complete tuning of the seeding energy in range from 200 to 2000 eV with a nearly constant resolving power of over 2x104. The optical delay is less than 1 ps. The design is based upon a fully coherent treatment of the SASE FEL beam propagating from the upstream SASE undulator through the entire seeding monochromator system. This approach guides the design optimization in order to preserve the transverse beam profile entering the seeding undulator to ensure maximum efficiency.

WEPSO19

A Full Beam 1D Simulation Code for Modeling Hybrid HGHG/EEHG Seeding Schemes for Evaluating the Dependence of Bunching Factor Bandwidth on Multiple Parameters

bunching, laser, simulation, electron

533

C.M. Fortgang, B.E. Carlsten, Q.R. Marksteiner, N.A. Yampolsky
LANL, Los Alamos, New Mexico, USA

Multiple seeding schemes are available for design of narrow-band, short-wavelength FELs. Analysis of such schemes often focus on the amplitude of the final bunching factor b, and how far it is above shot noise. Only under ideal conditions is the bandwidth of b FT limited. We have developed a 1D simulation tool that models complex hybrid seeding schemes using macro properties of the entire beam bunch to assess effects on both the amplitude and bandwidth of b. In particular the effects on bunching factor from using non-ideal beam driven radiators for downstream modulators, energy slew and curvature, and energy spread are investigated with the 1D tool.

WEPSO20

Wake Monochromator in Asymmetric and Symmetric Bragg and Laue Geometry for Self-seeding the European X-ray FEL

photon, coupling, undulator, scattering

538

G. Geloni, V. Kocharyan, E. Saldin, S. Serkez, M. Tolkiehn
DESY, Hamburg, Germany

We discuss the use of self-seeding schemes with wake monochromators to produce TW power, fully coherent pulses for applications at the dedicated bio-imaging bealine at the European X-ray FEL, a concept for an upgrade of the facility beyond the baseline previously proposed by the authors. We exploit the asymmetric and symmetric Bragg and Laue reflections (σ polarization) in diamond crystal. Optimization of the bio-imaging beamline is performed with extensive start-to-end simulations, which also take into account effects such as the spatio-temporal coupling caused by the wake monochromator. The spatial shift is maximal in the range for small Bragg angles. A geometry with Bragg angles close to pi/2 would be a more advantageous option from this viewpoint, albeit with decrease of the spectral tunability. We show that it will be possible to cover the photon energy range from 3 keV to 13 keV by using four different planes of the same crystal with one rotational degree of freedom.

WEPSO22

FERMI@Elettra Status Report

electron, laser, linac, free-electron-laser

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.

WEPSO24

Compact XFEL Light Source

electron, emittance, laser, cathode

757

W.S. Graves, K.K. Berggren, F.X. Kaertner, D.E. Moncton
MIT, Cambridge, Massachusetts, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work was supported by DARPA grant N66001-11-1-4192, CFEL DESY, DOE grants DE-FG02-10ER46745, and NSF grant DMR-1042342.
X-ray free electron laser studies are presented that rely on a nanostructured electron beam interacting with a “laser undulator” configured in the head-on inverse Compton scattering geometry. The structure in the electron beam is created by a nanoengineered cathode that produces a transversely modulated electron beam. Electron optics demagnify the modulation period and then an emittance exchange line translates the modulation to the longitudinal direction resulting in coherent bunching at x-ray wavelength. The predicted output radiation at 1 keV from a 7 MeV electron beam reaches 10 nJ or 6X10⁸ photons per shot and is fully coherent in all dimensions, a result of the dominant mode growth transversely and the longitudinal coherence imposed by the electron beam nanostructure. This output is several orders of magnitude higher than incoherent inverse Compton scattering and occupies a much smaller phase space volume, reaching peak brilliance of 10²⁷ and average brilliance of 10¹⁷ photons/(mm² mrad² 0.1% sec).

WEPSO26

Status of the Flash Facility

photon, electron, undulator, radiation

550

K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

The free-electron laser user facility FLASH at DESY (Hamburg, Germany)finished its 4th user period in February 2013. In total 2715 hours of SASE radiation has been delivered to user experiments with photon wavelengths between 4.2 nm and 44 nm with up to 5000 photon pulses per second. After a shutdown to connect the second undulator line - FLASH2 - to the FLASH linac, and a following commissioning period, FLASH is scheduled to continue user operation in October 2013. The year 2014 will be dedicated to the 5th period of user experiments. The commissioning of FLASH2 will take place in 2014 parallel to FLASH1 user operation.

WEPSO27

Recent LCLS Performance From 250 to 500 eV

undulator, diagnostics, electron, laser

554

R.H. Iverson, J. Arthur, U. Bergmann, C. Bostedt, J.D. Bozek, A. Brachmann, W.S. Colocho, F.-J. Decker, Y. Ding, Y. Feng, J.C. Frisch, J.N. Galayda, T. Galetto, Z. Huang, E.M. Kraft, J. Krzywinski, J.C. Liu, H. Loos, X.S. Mao, S.P. Moeller, H.-D. Nuhn, A.A. Prinz, D.F. Ratner, T.O. Raubenheimer, S.H. Rokni, W.F. Schlotter, P.M. Schuh, T.J. Smith, M. Stanek, P. Stefan, M.K. Sullivan, J.L. Turner, J.J. Turner, J.J. Welch, J. Wu, F. Zhou
SLAC, Menlo Park, California, USA
P. Emma
LBNL, Berkeley, California, USA
R. Soufli
LLNL, Livermore, California, USA

Funding: Work supported by US Department of Energy contract DE-AC02-76SF00515 and BES.
The Linac Coherent Light Source is an X-ray free-electron laser at the SLAC National Accelerator Laboratory. It produces coherent soft and hard X-rays with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources and a range of pulse durations from 500 to <10 fs. The facility has been operating at X-ray energy from 500 to 10,000eV. Users have expressed great interest in doing experiments with X-Rays near the carbon absorption edge at 284eV. We describe the operation and performance of the LCLS in the newly established regime between 250 and 500eV.
[1] Emma, P. et al., “First lasing and operation of an ˚angstrom-wavelength free-electron laser,” Nature Pho-
ton. 4(9), 641–647 (2010).

WEPSO28

Fast Electron Beam and FEL Diagnostics at the ALICE IR-FEL at Daresbury Laboratory

electron, cavity, laser, diagnostics

557

F. Jackson, D. Angal-Kalinin, D.J. Dunning, J.K. Jones, A. Kalinin, T.T. Thakker, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin, D.J. Dunning, J.K. Jones, N. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The ALICE facility at Daresbury Laboratory is an energy recovery based infra-red free electron laser of the oscillator type that has been operational since 2010. Recently fast diagnostics have been installed to perform combined measurements on pulse-by pulse FEL pulse energy and bunch-by-bunch electron bunch position and arrival time. These measurements have highlighted and quantified fast instabilities in the electron beam and consequently the FEL output, and are presented and discussed here.

WEPSO30

Integrating the FHI-FEL Into the FHI Research Environment - Design and Implementation Aspects

controls, cavity, EPICS, ion

562

H. Junkes, W. Erlebach, S. Gewinner, U. Hoppe, A. Liedke, G. Meijer, W. Schöllkopf, M. Wesemann, G. von Helden
FHI, Berlin, Germany
H. Bluem, D. Dowell, R. Lange, A.M.M. Todd, L.M. Young
AES, Princeton, New Jersey, USA
S.B. Webb
ORNL, Oak Ridge, Tennessee, USA

The new mid-infrared FEL at the Fritz-Haber-Institut (FHI) was presented at the FEL12 conference*. It will be used for spectroscopic investigations of molecules, clusters, nanoparticles and surfaces. This facility must be easy to use by the scientists at FHI, and should be seamlessly integrated into the existing research environment. The Experimental Physics and Industrial Control System (EPICS) software framework was chosen to build the FHI-FEL control system, and will also be used to interface the user systems. The graphical operator interface is based on the Control System Studio (CSS) package. It covers radiation safety monitoring as well as controlling the complete set of building automation and utility devices, regardless of their particular function. A user interface (subset of the operator interface) allows user-provided experiment-control software (KouDa, LabVIEW, Matlab) to connect with an EPICS Gateway providing secured access. The EPICS Channel Archiver continuously records selected process variable data and provides a web server offering archive and near real-time data. A sample experiment installation demonstrates how this user interface can be used efficiently.
* W. Schöllkopf et al., FIRST LASING OF THE IR FEL AT THE FRITZ-HABER-INSTITUT, BERLIN, Conference FEL12

WEPSO34

Proposal for a Scheme to Generate a 10 tw Power Level, Femtosecond X-ray Pulses for Bio-imaging of Single Protein Molecules at the European XFEL

undulator, photon, electron, radiation

574

V. Kocharyan, G. Geloni, E. Saldin, S. Serkez, I. Zagorodnov
DESY, Hamburg, Germany
O. Yefanov
CFEL, Hamburg, Germany

Crucial parameters for bio-imaging experiments are photon energy range, peak power and pulse duration. For a fixed resolution, the largest diffraction signals are achieved at the longest wavelength supporting that resolution. In order to perform these experiments at the European XFEL, we propose to use a novel configuration combining self-seeding and undulator tapering techniques with the emittance-spoiler method. Experiments at the LCLS confirmed the feasibility of these three techniques. Their combination allows obtaining a dramatic increase the XFEL output peak power and a shortening of the photon pulse duration to levels sufficient for performing bio-imaging of single protein molecules at the optimal photon-energy range between 3 keV and 5 keV. We show here that it is possible to achieve up to a 100-fold increase in peak-power of the X-ray pulses at the European XFEL: the X-ray beam would be delivered in 10 fs-long pulses with 50 mJ energy each at a photon energy around 4 keV. We confirm by simulations that one can achieve diffraction before destruction with a resolution of 0.25 nm resolution.

WEPSO41

Feasibility Studies for Echo-enabled Harmonic Generation on CLARA

laser, bunching, electron, radiation

588

I.P.S. Martin, R. Bartolini
Diamond, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom
N. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Compact Linear Accelerator for Research and Applications (CLARA) is a proposed single-pass FEL test facility, designed to facilitate experimental studies of advanced FEL techniques applicable to the next generation of light source facilities. One such scheme under consideration is Echo-Enabled Harmonic Generation (EEHG). In this paper we explore the suitability of CLARA for carrying out studies of this scheme, combining analytical and numerical calculations to determine likely hardware operating ranges, parameters tolerances and estimated FEL performance. A possible adaptation to convert EEHG into a short-pulse scheme is also considered.

WEPSO46

Study on the fluctuation of electron beam position in KU-FEL

gun, electron, cavity, feedback

602

K. Okumura, M. Inukai, T. Kii, T. Konstantin, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, M. Omer, Y. Tsugamura, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

Stability of electron beam is important for stable FEL operation. In Kyoto University MIR-FEL facility (KU-FEL), a BPM (Beam Position Monitor) system consisting of six 4-button electrode type BPMs was installed for monitoring of the electron beam position. The fluctuation of the electron beam position has been observed in horizontal and vertical directions. The origin of the beam position fluctuation is not clarified. In horizontal direction, the main fluctuation source is expected to be the energy fluctuation. As the one of candidate of the energy fluctuation, the cavity temperature of the RF gun has been suspected because the gun is operated in detuned condition [1] which enhances beam energy dependence on the cavity temperature. Another candidate is considered to be the fluctuation of the RF power fed to the gun. Therefore, we start to study the effect of the cavity temperature and the RF power on the position of electron beam. In this conference, we will present the measured result and numerical evaluation of the beam position dependence on temperature and RF power.
[1] H. Zen, et al, “Beam Energy Compensation in a Thermionic RF Gun by Cavity Detuning,” IEEE transaction on nuclear science, Vol.56, No. 3, Pages 1487-1491 (2009)

WEPSO48

Simulation Studies of FELs for a Next Generation Light Source

undulator, electron, photon, simulation

609

G. Penn, P. Emma, G. Marcus, J. Qiang, M.W. Reinsch
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Several possible FEL beamlines for a Next Generation Light Source are studied. These beamlines collectively cover a wide range of photon energies and pulse lengths. Microbunching and transverse offsets within the electron beam, generated through the linac, have the potential to significantly impact the longitudinal and transverse coherence of the x-ray pulses. We evaluate these effects and set tolerances on beam properties required to obtain the desired properties of the x-ray pulses.

WEPSO51

Self-seeding Design for SwissFEL

undulator, simulation, electron, radiation

618

E. Prat, S. Reiche
PSI, Villigen PSI, Switzerland

The SwissFEL facility, planned at the Paul Scherrer Institute, will provide SASE and self-seeded FEL radiation at a hard (1-7 Å) and soft (7-70 Å) X-ray FEL beamlines. This paper presents the current status of the self-seeding design for SwissFEL. The layout and full 6D start-to-end simulation results are presented for the hard X-ray beamline. Studies for different charges and optimization of the first and second undulator stages are shown.

WEPSO53

Harmonic Lasing at the LCLS

electron, radiation, undulator, simulation

623

D.F. Ratner, Z. Huang, P.A. Montanez
SLAC, Menlo Park, California, USA
E. Allaria
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
W.M. Fawley, L.N. Rodes
LBNL, Berkeley, California, USA
E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Funding: Department of Energy
The LCLS beamlines deliver X-rays to users at photon energies up to 24 keV. With the fundamental wavelength limited to around 10 keV, there is user interest in the third harmonic, which can reach a few percent of the total beam power. McNeil et al* and Schneidmiller and Yurkov** have showed that introducing phase shifts or attenuators into the undulator line can increase harmonic power by driving lasing at the third harmonic. With the development of self-seeding chicanes, LCLS is now in position for a proof-of-principle experiment. Here we present simulations and plans for an experimental test following commissioning of the Soft X-ray Self-Seeding system.
*B.W.J. McNeil, G.R.M. Robb, M.W. Poole and N.R. Thompson, Phys. Rev. Lett., 96 084801 (2006)
**E. Schneidmiller and M. Yurkov, PR-STAB, 14 080702 (2012)

WEPSO56

Optical Design and Time-dependent Wavefront Propagation Simulation for a Hard X-Ray Split- and delay-unit for the European XFEL

photon, simulation, instrumentation, undulator

627

S. Roling, B. Siemer, F. Wahlert, M. Wöstmann, H. Zacharias
Universität Muenster, Physikalisches Institut, Muenster, Germany
S. Braun, P. Gawlitza
Fraunhofer IWS, Dresden, Germany
O.V. Chubar
BNL, Upton, Long Island, New York, USA
L. Samoylova, H. Sinn
XFEL. EU, Hamburg, Germany
E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany
F. Siewert
HZB, Berlin, Germany
E. Ziegler
ESRF, Grenoble, France

For the European XFEL an x-ray split- and delay-unit (SDU) is built covering photon energies from 5 keV up to 20 keV. This SDU will enable time-resolved x-ray pump / x-ray probe experiments as well as sequential diffractive imaging on a femtosecond to picosecond time scale. The wavefront of the x-ray FEL pulses will be split by an edge of a silicon mirror coated with Mo/B4C and W/B4C multilayers. Both partial beams will then pass variable delay lines. For different wavelengths the angle of incidence onto the multilayer mirrors will be adjusted in order to match the Bragg condition. Hence, maximum delays between ± 2.5 ps at hν = 20 keV and up to ± 33 ps at hν = 5 keV will be possible. The time-dependent wave-optics simulations have been done with SRW software, for the fundamental and the 3rd harmonic. The XFEL radiation was simulated both in the Gaussian approximation as well as using an output of time-dependent SASE code FAST. Main features of the optical layout, including diffraction on the splitter edge, and optics imperfections were taken into account. Impact of these effects on the possibility to characterize spatial-temporal properties of FEL pulses are analyzed.

WEPSO57

Optimization of a Dedicated Bio-imaging Beamline at the European X-ray Fel

undulator, electron, photon, radiation

632

E. Saldin, G. Geloni, V. Kocharyan, S. Serkez
DESY, Hamburg, Germany

We recently proposed a basic concept for design and layout of a dedicated undulator source for bio-imaging experiments at the European XFEL. Here we present an optimization of that concept. The core of the scheme is composed by soft and hard X-ray self-seeding setups. Using an improved design for both monochromators it is possible to increase the design electron energy up to 17.5 GeV in photon energy range between 2 keV and 13 keV, which is the most preferable for life science experiments. Operating at such high electron energy one increases the X-ray output peak power. Moreover, 17.5 GeV is the preferred operation energy for SASE1 and SASE2 users. This choice will reduce the interference with other undulator lines. We include a study of the performance of the self-seeding scheme accounting for spatiotemporal coupling caused by the use of a single crystal monochromator. This distortion can be easily suppressed by the right choice of diamond crystal planes. The proposed undulator source yields about the same performance as in the case for a X-ray seed pulse with no coupling. Simulations show that the FEL power reaches 2 TW in the 3 keV - 5 keV photon energy range.

WEPSO59

A Possible Upgrade of FLASH for Harmonic Lasing Down to 1.3 nm

undulator, electron, radiation, simulation

646

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

We propose the 3rd harmonic lasing in a new FLASH undulator as a way to produce intense, narrow-band, and stable SASE radiation down to 1.3 nm with the present accelerator energy of 1.25 GeV. To provide optimal conditions for harmonic lasing, we suggest to suppress the fundamental with the help of a special set of phase shifters. We rely on the standard technology of gap-tunable planar hybrid undulators, and choose the period of 2.3 cm and the minimum gap of 0.9 cm; total length of the undulator system is 34.5 m. We demonstrate that the 3rd harmonic lasing at 1.3 nm provides peak power at a gigawatt level and the narrow intrinsic bandwidth, 0.1% (FWHM). Pulse duration can be controlled in the range of a few tens of femtoseconds, and the peak brilliance reaches the value of 10³¹ photons/(s mrad² mm² 0.1% BW). With the given undulator design, a standard option of lasing at the fundamental wavelength to saturation is possible through the entire water window and at longer wavelengths. In this paper we briefly consider additional options such as polarization control, bandwidth reduction, self-seeding, X-ray pulse compression, and two-color operation.

WEPSO60

A Method for Obtaining High Degree of Circular Polarization at X-ray FELs

undulator, radiation, bunching, polarization

651

E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

Baseline design of many X-ray FEL undulators assumes a planar configuration which results in a linear polarization of SASE FEL radiation. However, many users experiments would profit from using a circularly polarized radiation. As a cheap upgrade one can consider an installation of a helical afterburner, but then one should have an efficient method to suppress linearly polarized background from the main undulator. In this paper we consider a new method for such a suppression which is illustrated with the parameters of the soft X-ray undulator SASE3 of the European X-ray FEL.

WEPSO62

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

free-electron-laser, 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.

WEPSO64

Grating Monochromator for Soft X-ray Self-seeding the European XFEL

undulator, photon, electron, optics

667

S. Serkez, G. Geloni, V. Kocharyan, E. Saldin
DESY, Hamburg, Germany

Self-seeding implementation in the soft X-ray wavelength range involves gratings as dispersive elements. We study a very compact self-seeding scheme with a grating monochromator originally designed at SLAC, which can be straightforwardly installed in the SASE3 undulator beamline at the European XFEL. The design is based on a toroidal VLS grating at a fixed incidence angle, and without entrance slit. It covers the spectral range from 300 eV to 1000 eV. The performance was evaluated using wave optics method vs ray tracing methods. Wave optics analysis takes into account the actual beam wavefront of the radiation from the FEL source, third order aberrations, and errors from optical elements. We show that, without exit slit, the self-seeding scheme gives the same resolving power (about 7000) as with an exit slit. Wave optics is also naturally applicable to calculations of the scheme efficiency, which include the monochromator transmittance and the effect of the mismatching between seed beam and electron beam. Simulations show that the FEL power reaches 1 TW, with a spectral density about two orders of magnitude higher than that for the SASE pulse at saturation.

WEPSO65

LEBRA Free Electron Laser as a Radiation Source for Photochemical Reactions in Living Organisms

radiation, electron, controls, laser

675

F. Shishikura, K. Hayakawa, Y. Hayakawa, M. Inagaki, K. Nakao, K. Nogami, T. Sakai, T. Tanaka
LEBRA, Funabashi, Japan

The radiation sources commonly used in plant applications are commercially available lamps developed for human lighting applications (fluorescent, metal halide, high-pressure sodium, incandescent, light-emitting diode, and laser diode). In contrast, free-electron lasers (FELs) such as LEBRA-FEL produce high-energy, tunable pulse radiation and thus are promising radiation sources for photochemical research. An advantage of LEBRA-FEL is that the peak intensity ranges from 0.35 to 6.5 microns which are wavelengths coinciding with the absorption peaks of living organisms. Previously, we established a microscopic irradiation technique for delivering visible FEL light to single cells through a tapered glass rod (< 10 microns). However, it is still unclear whether LEBRA-FEL can produce sufficient radiant energy at wavelengths effective for triggering photochemical reactions in living organisms. The aim of this study was to evaluate the effectiveness of LEBRA-FEL in lettuce-seed germination tests. Results show promotion by red light and inhibition by far-red light, indicating that LEBRA-FEL can be used to control lettuce-seed germination.

WEPSO67

Progress with the FERMI Laser Heater Commissioning

laser, linac, electron, undulator

680

S. Spampinati, E. Allaria, D. Castronovo, M. Dal Forno, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, G. Penco, C. Spezzani, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

FERMI@ELETTRA is a seeded free electron laser facility composed by one linac and two FEL lines named FEL-1 and FEL-2. FEL-1 works in HGHG configuration, while FEL2 is a HGHG cascade implementing "fresh bunch" injection into the second stage. Perfomance of FEL-1 and FEL-2 lines have benefited from the use of the laser heater system, which is located right after the injector, at 100 MeV beam energy. Proper tuning of the laser heater parameters has allowed control of the microbunching instability, which is otherwise expected to degrade the high brightness electron beam quality sufficiently to reduce the FEL power. The laser heater was commissioned one year ago and positive effects upon microbunching instabilities and FEL-1 performance was soon observed. In this work we presents further measurements of microbunching suppression in two compressors scheme showing directly the reduction of beam slice energy spread due to laser heater action. We present measuerements showing the impact of the laser heater on FEL2

WEPSO68

Effect of Coulomb Collisions on Echo-enabled Harmonic Generation

undulator, laser, bunching, scattering

684

G.V. Stupakov
SLAC, Menlo Park, California, USA

Echo Enabled Harmonic Generation (EEHG) for FEL seeding is sensitive to the intrabeam scattering (IBS) effect. The reason for this is that in the process of generation high-harmonic density modulation in the beam the phase space evolves through a stage with narrow energy bands, which are characterized by the energy spread many times smaller than the beam energy spread. Energy diffusion caused by IBS tends to smear our these bands leading to diminished bunching factors at high harmonics. In the previous work [1] IBS in EEHG was studied in a simple model of a drift. This work extends the analysis of [1] to realistic lattices, and is applied to some of the existing practical designs of EEHG seeding.
[1] G. Stupakov, Effect of Coulomb Collisions on Echo-Enabled Harmonic Generation (EEHG), in Proceedings of the 2011 FEL Conference, Shanghai, China, 2011.

WEPSO69

Optical Cavity Losses Calculation and Optimization of THz FEL with a Waveguide

coupling, cavity, radiation, undulator

689

P. Tan, Q. Fu, L. Li, B. Qin, K. Xiong, Y.Q. Xiong
HUST, Wuhan, People's Republic of China

Funding: the Fundamental Research Funds for the Central Universities，HUST：2012QN080
The optical cavity with waveguide is used in most long wavelength free electron lasers. In this paper, the losses, gains and modes of a terahertz FEL sources in Huazhong Univeristy of Science and Technology(HUST) are analysis. Then the radii of curvature of the optical mirrors and shapes of the waveguide are optimized.

WEPSO70

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

laser, photon, electron, free-electron-laser

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.

WEPSO73

High Average Power Seed Laser Design for High Reprate FELs

laser, electron, vacuum, controls

697

R.B. Wilcox, G. Marcus, G. Penn
LBNL, Berkeley, California, USA
T. Metzger, M. Schultze
TRUMPF Scientific Lasers GmbH + Co. KG, Munchen-Unterfoehring, Germany

Funding: US Department of Energy, under Contract Numbers DE-AC02-0SCH11231.
In the proposed Next Generation Light Source (NGLS), FEL designs use lasers to seed the FEL in an HGHG scheme or bunch the electron beam in an E-SASE scheme. The FELs would run at 100kHz to 1MHz, requiring high average power lasers. For the seeded FEL, laser modulation is applied at 200-240nm, with 250-700MW peak power depending on pulse length, which can vary from 100-10fs. The laser consists of a broadband oscillator and amplitude/phase shaper seeding an optical parametric amplifier (OPA). After recompression, the ~800nm pulse is converted to the fourth harmonic. Losses could be high enough to require 250W at 100kHz, making the OPA ~100x more powerful than existing femtosecond OPAs. In the E-SASE scheme, a single cycle of 5 micron light bunches the beam, which then radiates a short X-ray burst. This requires 100% fractional bandwidth, and precise phase control of the e-field within the pulse, as well as broad band compensation of dispersion throughout the laser path. Bandwidth can be increased by splitting the amplified spectrum into segments and coherently recombining. We present design concepts that are expected to meet requirements, and identify R&D needs.

WEPSO78

Harmonic Lasing Self-seeded FEL

undulator, simulation, electron, resonance

700

M.V. Yurkov, E. Schneidmiller
DESY, Hamburg, Germany

In this paper we perform analysis of capabilities of SASE FELs at the European XFEL for generation of narrow band radiation. An approach based on application of harmonic lasing self-seeding (HLSS) is under study[*]. Effective harmonic lasing occurs in the exponential gain regime in the first part of the undulator, making sure that the fundamental frequency is well below saturation. In the second part of the undulator the value of undulator parameter is reduced such that now the fundamental mode is resonant to the wavelength, previously amplified as the harmonic. The amplification process proceeds in the fundamental mode up to saturation. In this case the bandwidth is defined by the harmonic lasing (i.e. it is reduced by a significant factor depending on harmonic number) but the saturation power is still as high as in the reference case of lasing at the fundamental, i.e. brilliance increases. Application of the undulator tapering in the deep nonlinear regime would allow to generate higher peak powers approaching TW level.
* E.A. Schneidmiller and M.V. Yurkov, Phys. Rev. ST-AB 15, 080702 (2012)

WEPSO80

Coherence Properties of the Radiation From FLASH

radiation, emittance, undulator, electron

704

M.V. Yurkov, E. Schneidmiller
DESY, Hamburg, Germany

Several user groups at FLASH use higher odd harmonics (3rd and 5th) of the radiation in experiments. Some applications require knowledge of coherence properties of the radiation at he fundamental and higher harmonics. In this paper we presents results of the studies of coherence properties of the radiation from FLASH operating at radiation wavelength of 6.x nm at the fundamental harmonic, and higher odd harmonics (2.x nm and 1.x nm) at electron energy of 1 GeV.

WEPSO84

Present Status of Kyoto University Free Electron Laser

undulator, electron, cavity, vacuum

711

H. Zen, M. Inukai, T. Kii, R. Kinjo, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, K. Okumura, M. Omer, K. Torgasin, K. Yoshida
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A mid-infrared FEL named as KU-FEL (Kyoto University FEL) has been developed for energy related sciences [1]. After the achievement of the first lasing and the power saturation in 2008 [2, 3], we have been working to extend the tunable range of the FEL [4]. By replacing the original 1.6-m undulator into a 1.8 m one, the tunable range was expanded from 10-13 to 5-15 μm in January 2012. Then we fabricated a new undulator duct to reduce the minimum undulator gap from 20 to 15 mm. At 15-mm gap, the FEL gain can be expected to be twice as high as that at 20 mm gap. Commissioning of the new duct will be done in the end of this April. In this presentation, we will report on the result of the commissioning such as tunable range of KU-FEL and the estimated FEL gain, which would be compared with a simulation.
[1] H. Zen, et al., Infrared Phys. Techn., 51, 382 (2008)
[2] H. Ohgaki, et al., Proc. of FEL08, 4 (2008)
[3] H. Ohgaki, et al., Proc. of FEL2009, 572 (2009)
[4] H. Zen, et al., Proc. of FEL2012

WEPSO89

Design of a Resonator for the CSU THz FEL

higher-order-mode, coupling, undulator, radiation

719

P.J.M. van der Slot
Mesa+, Enschede, The Netherlands
S. Biedron, S.V. Milton, P.J.M. van der Slot
CSU, Fort Collins, Colorado, USA

Funding: This research is support by Office of Naval Research Global, grant number N62909-10-1-7151
A 6-MeV L-band linac will be used to drive a planar, fixed gap, 2.5-cm period, hybrid undulator with parabolic pole faces. Consequently, this system is capable of generating wavelengths from 160 to 600 μm. In this paper we discuss the design of an optical resonator for this system. The resonator uses hole-coupled mirrors to allow for a straight electron beam line. The Rayleigh length, the position of the waist of the cold-cavity mode and the hole radii will be investigated to optimize the performance of the FEL.

THIANO01

Double Stage Seeded FEL with Fresh Bunch Injection Technique at FERMI

electron, undulator, bunching, laser

723

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, L. Giannessi, 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

Seeding a FEL with an external coherent source has been extensively studied in the last decades as it can provide a way to enhance the radiation brightness and stability, with respect to that available from SASE. An efficient scheme for seed a VUV-soft x ray FEL uses, a powerful, long wavelength external laser to induce on the electron beam coherent bunching at the harmonics of the laser wavelength. When the bunching is further amplified by FEL interaction in the radiator, the scheme is called high gain harmonic generation (HGHG). The need of high power seed sources and of small energy spread are at the main limits for a direct extension of the HGHG scheme to short wavelengths. The fresh bunch scheme was proposed as a way to overcome these limitations; the scheme foresees the FEL radiation produced by one HGHG stage as an external seed in a second HGHG stage. We report the latest results obtained at FERMI that uses the two-stage HGHG scheme for generation of FEL pulses in the soft x-ray. A characterization of the FEL performance in terms of power, bandwidth and stability is reported. Starting from the FERMI results we will discuss extension of the scheme toward shorter wavelengths.

Slides THIANO01 [9.355 MB]

THOANO01

Stable Operation of HHG-Seeded EUV-FEL at the SCSS Test Accelerator

electron, laser, feedback, undulator

728

H. Tomizawa, T. Hara, T. Ishikawa, K. Ogawa, H. Tanaka, T. Tanaka, T. Togashi, K. Togawa, M. Yabashi
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
M. Aoyama, K. Yamakawa
JAEA/Kansai, Kyoto, Japan
A. Iwasaki, S. Owada, T. Sato, K. Yamanouchi
The University of Tokyo, Tokyo, Japan
S. Matsubara, Y. Okayasu, T. Watanabe
JASRI/SPring-8, Hyogo, Japan
K. Midorikawa, E. Takahashi
RIKEN, Saitama, Japan

We performed the higher-order harmonic (HH) seeded FEL operation at a 61.2 nm fundamental wavelength, using a seeding source of HH pulses from a Ti:sapphire laser at the SCSS (EUV-FEL) accelerator. It is important for the HH seeded FEL scheme to synchronize the seeding laser pulses to the electron bunches. We constructed the relative arrival timing monitor based on Electro-Optic sampling (EOS). Since the EOS-probe laser pulses were optically split from HH-driving laser pulses, the arrival time difference of the seeding laser pulses, with respect to the electron bunches, were measured bunch-by-bunch. This non-invasive EOS monitor made uninterrupted, real-time monitoring possible even during the seeded FEL operation. The EOS system was used for the arrival timing feedback with a few-hundred-femtosecond adjustability for continual operation of the HH-seeded FEL. By using the EOS-locking system, the HH seeded FEL was operated over half a day with a 20-30% hit rate. The output pulse energy reached 20uJ at the 61.2 nm wavelength. A user experiment was performed by using the seeded EUV-EL and a clear difference between the SASE-FEL and the seeded FEL was observed.

Slides THOANO01 [11.493 MB]

THOBNO01

Three Unique FEL Designs for the Next Generation Light Source

undulator, photon, radiation, laser

734

G. Penn, D. Arbelaez, J.N. Corlett, P. Emma, G. Marcus, S. Prestemon, M.W. Reinsch, R.B. Wilcox
LBNL, Berkeley, California, USA
A. Zholents
ANL, Argonne, USA

The NGLS is a next generation light source initiative spearheaded by the Lawrence Berkeley National Laboratory and based on an array of free-electron lasers (FEL) driven by a CW, 1-MHz bunch rate, superconducting linear accelerator. The facility is being designed to produce high peak and high average brightness coherent soft x-rays in the wavelength range of 1-12 nm, with shorter wavelengths accessible in harmonics or in expansion FELs. The facility performance requirements are based on a wide spectrum of scientific research objectives, requiring high flux, narrow-to-wide bandwidth, broad wavelength tunability, femtosecond pulse durations, and two-color pulses with variable relative timing and polarization, all of which cannot be encompassed in one FEL design. In addition, the cost of the facility requires building in a phased approach with perhaps three initial FELs and up to 9-10 FELs in the long term. We describe three very unique and complimentary FEL designs here as candidates for the first NGLS configuration.

Slides THOBNO01 [1.331 MB]

THOBNO02

Transverse Gradient Undulators for a Storage Ring X-ray FEL Oscillator

electron, undulator, storage-ring, emittance

740

R.R. Lindberg, K.-J. Kim
ANL, Argonne, USA
Y. Cai, Y. Ding, Z. Huang
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. Dept.~of Energy, Office of Basic Energy Sciences, Contract No.~DE-AC02-06CH11357.
An x-ray FEL oscillator (XFELO) is a fully coherent 4th generation source with complementary scientific applications to those based on self-amplified spontaneous emission*. While the naturally high repetition rate, intrinsic stability, and very small emittance produced by an ultimate storage ring (USR) makes it a potential candidate to drive an XFELO, the energy spread is typically an order of magnitude too large for sufficient gain. On the other hand, Smith and coworkers** showed how the energy spread requirement can be effectively mitigated with a transverse gradient undulator (TGU): since the TGU has a field strength that varies with transverse position, by properly correlating the electron energy with transverse position one can approximately satisfy the FEL resonance condition for all electrons. Motivated by recent work in the high-gain regime***, we investigate the utility of a TGU for low gain FELs at x-ray wavelengths. We find that a TGU may make an XFELO realizable in the largest ultimate storage rings now under consideration (e.g., in either the old Tevatron or PEP-II tunnel).
* K.-J. Kim, Y. Shvyd'ko and S. Reiche, PRL 100 244802 (2008).
** T. Smith, et al., J. Appl. Phys. 50, 4580 (1979).
*** Z. Huang, Y. Ding, and C.B. Schroeder, PRL 109, 204801 (2012).

Slides THOBNO02 [1.208 MB]

THOCNO04

Jitter-free Time Resolved Resonant CDI Experiments Using Two-color FEL Pulses Generated by the Same Electron Bunch

electron, laser, undulator, polarization

753

M. Zangrando, E. Allaria, F. Bencivenga, F. Capotondi, D. Castronovo, P. Cinquegrana, M.B. Danailov, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, W.M. Fawley, E. Ferrari, L. Fröhlich, L. Giannessi, R. Ivanov, M. Kiskinova, B. Mahieu, N. Mahne, C. Masciovecchio, I. Nikolov, E. Pedersoli, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
G. De Ninno, D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia
D. Fausti
Università degli Studi di Trieste, Trieste, Italy
L. Giannessi
ENEA C.R. Frascati, Frascati (Roma), Italy
M. Zangrando
IOM-CNR, Trieste, Italy

The generation of two-color FEL pulses by the same electron bunch at FERMI-FEL has opened unprecedented opportunity for jitter-free FEL pump-FEL probe time resolved coherent diffraction imaging (CDI) experiments in order to access spatial aspects in dynamic processes. This possibility was first explored in proof-of-principle resonant CDI experiments using specially designed sample consisting of Ti grating. The measurements performed tuning the energies of the FEL pulses to the Ti M-absorption edge clearly demonstrated the time dependence of Ti optical constants while varying the FEL-pump intensity and probe time delay. The next planned CDI experiments in 2013 will explore transient states in multicomponent nanostructures and magnetic systems, using the controlled linear or circular polarization of the two-color FEL pulses with temporal resolution in the fs to ps range.

Slides THOCNO04 [8.778 MB]