FEL2013 - List of Keywords (linac)

Paper	Title	Other Keywords	Page
MOOCNO01	Emittance Control in the Presence of Collective Effects in the FERMI@Elettra Free Electron Laser Linac Driver	emittance, FEL, electron, 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]

MOOCNO02	Multi-Objective Genetic Optimization for LCLS-II X-Ray FEL	emittance, undulator, simulation, wakefield	12
	L. Wang, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	The Linac Coherent Light Source II (LCLS-II) will build on the success of the world's most powerful X-ray laser, the Linac Coherent Light Source (LCLS). It will add two new X-ray laser beams and room for additional new instruments, greatly increasing the number of experiments carried out each year. Multiple operation modes are proposed to accommodate a variety of user requirements. There are a large number of variables and objectives in the design. For each operation mode, Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters in order to minimize the jitters, energy spread, collective effects and emittance. The optimal designs for various operation modes are presented in this paper. The phase and voltage of the linac RF, R56 at the two bunch compressors are optimized. The CSR (coherent synchrotron radiation) can induce large emittance growth, which is minimized by optimizing the phase advance between the compressor and the bend section. The final emittance at the beginning of the undulator is just about 1um and even lower.
	Slides MOOCNO02 [3.046 MB]

MOPSO02	Measurement of Electron-Beam and Seed Laser Properties Using an Energy Chirped Electron Beam	electron, laser, FEL, simulation	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.

MOPSO27	Study of CSR Effects in the Jefferson Laboratory FEL Driver	FEL, simulation, radiation, dipole	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.

MOPSO40	CLARA Accelerator Design and Simulations	FEL, 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.

TUOBNO01	Beam Diagnostics for Coherent Optical Radiation Induced by the Microbunching Instability	gun, laser, diagnostics, radiation	169
	A.H. Lumpkin Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The generation of the ultrabright beams required by modern free-electron lasers (FELs) has generally relied on chicane-based bunch compressions that often result in the microbunching instability. Following compression, spectral enhancements can extend even into the visible wavelengths through the longitudinal space charge impedances. Optical transition radiation (OTR) screens have been extensively used for transverse electron beam size measurements for the bright beams, but the presence of longitudinal microstructures (microbunching) in the electron beam or the leading edge spikes can result in strong, localized coherent enhancements (COTR) that mask the actual beam profile. We now have evidence for the effects in both rf photocathode-gun injected linacs* and thermionic-cathode-gun injected linacs*. Since the first observations, significant efforts have been made to characterize, model, and mitigate COTR effects on beam diagnostics. An update on the state-of-the-art for diagnosing these effects will be given as illustrated by examples at APS, LCLS, SCSS, SACLA, and NLCTA. A.H. Lumpkin et al.,Phys. Rev. ST Accel. Beams 12, 040704 (2009). **H. Tanaka,"Commissioning of the Japanese XFEL at Spring8, Proceedings of IPAC2011, San Sebastián, Spain, 21-25 (2011).
	Slides TUOBNO01 [1.805 MB]

TUOCNO01	Electron Beam Longitudinal Phase Space Manipulation by Means of an AD-HOC Photoinjector Laser Pulse Shaping	electron, FEL, 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]

TUOCNO04	Feasibility of CW and LP Operation of the XFEL Linac	cryomodule, HOM, cavity, electron	189
	J.K. Sekutowicz, V. Ayvazyan, J. Branlard, M. Ebert, J. Eschke, T. Feldmann, A. Gössel, D. Kostin, I.M. Kudla, W. Merz, F. Mittag, C. Müller, R. Onken, I. Sandvoss, E. Schneidmiller, A.A. Sulimov, M.V. Yurkov DESY, Hamburg, Germany W. Cichalewski, A. Piotrowski, K.P. Przygoda TUL-DMCS, Łódź, Poland K. Czuba Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland W. Jałmużna Embedded Integrated Control Systems GmbH, Hamburg, Germany J. Szewiński NCBJ, Świerk/Otwock, Poland
	The European XFEL superconducting linac is based on cavities and cryomodules (CM) developed for TESLA linear collider. The XFEL linac will operate nominally in short pulse (sp) mode with 1.3 ms RF pulses (650 μs rise time and 650 μs long bunch train). For 240 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 bunches per second can be accelerated to 17.5 GeV to generate uniquely high average brilliance photon beams at very short wavelengths. While many experiments can take advantage of full bunch trains, others prefer an increased to several μ-seconds intra-pulse distance between bunches, or short bursts with a kHz repetition rate. For these types of experiments, the high average brilliance can be preserved only with duty factors much larger than that of the currently proposed sp operation. In this contribution, we discuss progress in the R&D program for future upgrade of the European XFEL linac, namely an operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for more flexibility in the electron and photon beam time structure.
	Slides TUOCNO04 [8.910 MB]

TUOCNO05	Design Concepts for a Next Generation Light Source at LBNL	FEL, 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, FEL, 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.

TUPSO12	RF Design Approach for an NGLS Linac	cavity, cryomodule, cryogenics, controls	226
	A. Ratti, J.M. Byrd, J.N. Corlett, L.R. Doolittle, P. Emma, M. Venturini, R.P. Wells LBNL, Berkeley, California, USA C. Adolphsen, C.D. Nantista SLAC, Menlo Park, California, USA D. Arenius, S.V. Benson, D. Douglas, A. Hutton, G. Neil, W. Oren, G.P. Williams JLAB, Newport News, Virginia, USA C.M. Ginsburg, R.D. Kephart, 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 Next Generation Light Source (NGLS) is a design concept for a multibeamline soft x-ray FEL array powered by a ~2.4 GeV CW superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. This paper describes the concepts for the cavity and cryostat design operating at 1.3 GHZ and based on minimal modifications to the design of ILC cryomodules, This leverages the extensive experience derived from R&D that resulted in the ILC design. Due to the different nature of the two applications, particular attention is given now to high loaded Q operation and microphonics control, as well as high reliability and expected up time. The work describes the design and configuration of the linac, including choice of gradient, possible modes of operation, cavity design and RF power, as well as the consequent requirements for the cryogenic system.

TUPSO13	Superconducting Linac Design Concepts for a Next Generation Light Source at LBNL	cavity, cryomodule, HOM, controls	229
	J.N. Corlett, J.M. Byrd, L.R. Doolittle, P. Emma, A. Ratti, F. Sannibale, M. Venturini, R.P. Wells, S. Zimmermann LBNL, Berkeley, California, USA C. Adolphsen, C.D. Nantista 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 in CW mode, with a high bunch repetition rate of approximately 1 MHz. The superconducting linear accelerator design concept is based on existing TESLA and ILC technology, developed for this CW application in a light source. In this paper we describe design options and preferred approaches for the NGLS SRF linac components, cryomodules, and cryosystems.

TUPSO14	Transverse Deflecting Structures for Bunch Length and Slice Emittance Measurements on SwissFEL	emittance, diagnostics, undulator, FEL	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, emittance, feedback, FEL	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.

TUPSO17	Status of the Manufacturing Process for the SwissFEL C-Band Accelerating Structures	vacuum, laser, radio-frequency, coupling	245
	U. Ellenberger, H. Blumer, L. Paly, C. Zumbach Paul Scherrer Institute, Villigen PSI, Switzerland M. Bopp, H. Fitze, F. Löhl PSI, Villigen PSI, Switzerland
	For the SwissFEL project a total of 104 C-band (or approximately 6 GHz for 5’712 MHz required) accelerating structures are needed. After developing and RF-testing of several short structures (0.5m), three 2meter prototypes have been produced successfully in-house. Avoiding any RF-tuning after fabrication, a high precision machining of the components is necessary. Special procedures were developed and handling equipment was built in order to maintain the accuracy during stacking and vacuum brazing of the parts for the C-band structures. This paper summarizes the manufacturing techniques and the mechanical test results for constant subvolumes to match the required klystron frequency of 5’712 MHz

TUPSO35	The MAX IV Linac as X-Ray FEL Injector: Comparison of Two Compression Schemes	emittance, wakefield, FEL, 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.

TUPSO41	The Ultrashort Beam Linac System and Proposed Coherent THz Radiation Sources at NSRRC	electron, radiation, gun, undulator	309
	W.K. Lau, A.P. Lee NSRRC, Hsinchu, Taiwan N.Y. Huang, Z.Y. Wei NTHU, Hsinchu, Taiwan
	The NSRRC ultrashort beam facility is a low energy linac system which is being built to produce femtosecond electron beam for novel light source development. Experiments on prebunched THz FEL and inverse Compton scattering x-ray source are under study. The electron source is a 2998 MHz, 1.5-cell thermionic rf gun with uneven full-cell to half-cell field ratio that is optimized to produce a energy-chirped electron beam. With movable slits in its vacuum vessel, the alpha magnet system is served also as a beam selector. Further bunch compression is done by velocity bunching in the rf linac. Recent progress of the construction of this facility as well as the design study of a prebunched THz FEL with this ultrashort electron beam will be reported.

TUPSO43	Status of the SwissFEL C-band Linear Accelerator	controls, klystron, low-level-rf, vacuum	317
	F. Löhl, J. Alex, H. Blumer, M. Bopp, H.-H. Braun, A. Citterio, H. Fitze, H. Jöhri, T. Kleeb, L. Paly, J.-Y. Raguin, L. Schulz, R. Zennaro PSI, Villigen PSI, Switzerland U. Ellenberger Paul Scherrer Institute, Villigen PSI, Switzerland
	This paper will summarize the status of the linear accelerator of the Swiss free-electron laser SwissFEL. It will be based on C-band technology and will use solid-state modulators and a novel type of C-band accelerating structures which has been designed at PSI. Initial test results of first 2 m long structures will be presented together with measurements performed with the first BOC-type pulse compressors. Furthermore, we will present first results of a water cooling system for the accelerating structures and the pulse compressors.

TUPSO45	Initial Streak Camera Measurements of the S-band Linac Beam for the University of Hawaii FEL Oscillator	FEL, electron, 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.

TUPSO66	Transport of Terahertz-Wave Coherent Synchrotron Radiation With a Free-electron Laser Beamline at LEBRA	FEL, electron, radiation, undulator	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.

TUPSO78	Design of a Collimation System for the Next Generation Light Source at LBNL	collimation, kicker, gun, undulator	410
	C. Steier, P. Emma, H. Nishimura, C. F. Papadopoulos, H.J. Qian, F. Sannibale, C. Sun LBNL, Berkeley, California, USA
	Funding: This work is 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. The planned Next Generation Light Source at LBNL is designed to deliver MHz repetition rate electron beams to an array of free electron lasers. Because of the high beam power approaching one MW in such a facility, effective beam collimation is extremely important to minimize radiation damage, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. We describe the conceptual design of a collimation system, including detailed simulations to verify its effectiveness.

TUPSO80	The MAX IV Linac and First Design for an Upgrade to 5 GeV to Drive an X-ray FEL	FEL, 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.

WEIBNO01	Super-radiant Linac-based THz Sources in 2013	laser, undulator, electron, photon	474
	M. Gensch HZDR, Dresden, Germany
	There is a growing interest in THz and far infrared light sources for use in material studies. Both coherent radiative sources (CSR, COTR, etc.) and FEL sources have been developed in the last few years to address this need. This talk will describe recent developments in this growing field.

WEPSO07	Simulation Studies for an X-ray FEL Based on an Extension of the MAX IV Linac	FEL, 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.

WEPSO10	Increased Stability Requirements for Seeded Beams at LCLS	FEL, 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.

WEPSO22	FERMI@Elettra Status Report	FEL, electron, laser, 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.

WEPSO31	THz Radiation Source Potential of the R&D ERL at BNL	gun, electron, SRF, emittance	566
	D. Kayran, I. Ben-Zvi, Y.C. Jing, B. Sheehy BNL, Upton, Long Island, New York, USA
	Funding: Work supported by BSA DOE, Contract No. DE-AC02-98CH10886 An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is under commissioning at Brookhaven National Laboratory (BNL) for testing concepts for high-energy electron cooling and electron-ion colliders. This ERL will be used as a test bed to study issues relevant for very high current ERLs. High repetition rate (9.5 MHz), CW operation and high performance of electron beam with some additional components make this ERL an excellent driver for high power coherent THz radiation source. We discuss potential use of BNL ERL as a source of THz radiation and results of the beam dynamics simulation. We present the status and commissioning progress of the ERL. Ilan Ben-Zvi. et al. Coherent harmonic generation of THz radiation using wakefield bunching (presented at this conference)

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

WEPSO44	Design Studies for FLUTE, A Linac-based Source of Terahertz Radiation	radiation, laser, gun, simulation	598
	S. Naknaimueang, V. Judin, S. Marsching, A.-S. Müller, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schuh, M. Schwarz, M. Weber, P. Wesolowski KIT, Karlsruhe, Germany W. Hillert, M. Schedler ELSA, Bonn, Germany
	FLUTE is a linac-based THz source with nominal beam energy of 40-50 MeV which is presently under construction at KIT. It will be operated in a wide bunch charge range and will use different electron bunch compression schemes. The source will also study different mechanisms of radiation generation and serve as a test facility for related accelerator technology. This contribution presents the results of an overall optimization of the accelerator and a bunch compressor. A usage of a dispersive compressor and a velocity buncher, as well as combination of both are discussed. It is shown that bunch lengths in the range of a few femtoseconds can be achieved at very low bunch charges, while nC-bunches can be compressed down to approximately 200 fs. The utilization of both schemes results in high THz radiation fields at the experimental port.

WEPSO67	Progress with the FERMI Laser Heater Commissioning	FEL, laser, 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

WEPSO88	High Precision Electronics for Single Pass Applications	controls, instrumentation, alignment, pick-up	715
	M. Žnidarčič, R. Hrovatin I-Tech, Solkan, Slovenia M. Satoh KEK, Ibaraki, Japan
	Monitoring and subsequent optimization of electron Linacs and transfer lines requires specific instrumentation for beam position data acquisition and processing. Libera Single Pass E is the newly developed instrument intended for position and charge monitoring in basic and multi-mode operation LINACs. Development, initial measurements and verification of the instrumentation performance were conducted in the Instrumentation Technologies' laboratories, followed by the characterization measurements of the unit carried out at KEK Linac facility.

Paper

Title

Other Keywords

Page

MOOCNO01

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

emittance, FEL, electron, 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]

MOOCNO02

Multi-Objective Genetic Optimization for LCLS-II X-Ray FEL

emittance, undulator, simulation, wakefield

12

L. Wang, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

The Linac Coherent Light Source II (LCLS-II) will build on the success of the world's most powerful X-ray laser, the Linac Coherent Light Source (LCLS). It will add two new X-ray laser beams and room for additional new instruments, greatly increasing the number of experiments carried out each year. Multiple operation modes are proposed to accommodate a variety of user requirements. There are a large number of variables and objectives in the design. For each operation mode, Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters in order to minimize the jitters, energy spread, collective effects and emittance. The optimal designs for various operation modes are presented in this paper. The phase and voltage of the linac RF, R56 at the two bunch compressors are optimized. The CSR (coherent synchrotron radiation) can induce large emittance growth, which is minimized by optimizing the phase advance between the compressor and the bend section. The final emittance at the beginning of the undulator is just about 1um and even lower.

Slides MOOCNO02 [3.046 MB]

MOPSO02

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

electron, laser, FEL, simulation

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.

MOPSO27

Study of CSR Effects in the Jefferson Laboratory FEL Driver

FEL, simulation, radiation, dipole

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.

MOPSO40

CLARA Accelerator Design and Simulations

FEL, 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.

TUOBNO01

Beam Diagnostics for Coherent Optical Radiation Induced by the Microbunching Instability

gun, laser, diagnostics, radiation

169

A.H. Lumpkin
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The generation of the ultrabright beams required by modern free-electron lasers (FELs) has generally relied on chicane-based bunch compressions that often result in the microbunching instability. Following compression, spectral enhancements can extend even into the visible wavelengths through the longitudinal space charge impedances. Optical transition radiation (OTR) screens have been extensively used for transverse electron beam size measurements for the bright beams, but the presence of longitudinal microstructures (microbunching) in the electron beam or the leading edge spikes can result in strong, localized coherent enhancements (COTR) that mask the actual beam profile. We now have evidence for the effects in both rf photocathode-gun injected linacs* and thermionic-cathode-gun injected linacs**. Since the first observations, significant efforts have been made to characterize, model, and mitigate COTR effects on beam diagnostics. An update on the state-of-the-art for diagnosing these effects will be given as illustrated by examples at APS, LCLS, SCSS, SACLA, and NLCTA.
*A.H. Lumpkin et al.,Phys. Rev. ST Accel. Beams 12, 040704 (2009).
**H. Tanaka,"Commissioning of the Japanese XFEL at Spring8, Proceedings of IPAC2011, San Sebastián, Spain, 21-25 (2011).

Slides TUOBNO01 [1.805 MB]

TUOCNO01

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

electron, FEL, 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]

TUOCNO04

Feasibility of CW and LP Operation of the XFEL Linac

cryomodule, HOM, cavity, electron

189

J.K. Sekutowicz, V. Ayvazyan, J. Branlard, M. Ebert, J. Eschke, T. Feldmann, A. Gössel, D. Kostin, I.M. Kudla, W. Merz, F. Mittag, C. Müller, R. Onken, I. Sandvoss, E. Schneidmiller, A.A. Sulimov, M.V. Yurkov
DESY, Hamburg, Germany
W. Cichalewski, A. Piotrowski, K.P. Przygoda
TUL-DMCS, Łódź, Poland
K. Czuba
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
W. Jałmużna
Embedded Integrated Control Systems GmbH, Hamburg, Germany
J. Szewiński
NCBJ, Świerk/Otwock, Poland

The European XFEL superconducting linac is based on cavities and cryomodules (CM) developed for TESLA linear collider. The XFEL linac will operate nominally in short pulse (sp) mode with 1.3 ms RF pulses (650 μs rise time and 650 μs long bunch train). For 240 ns bunch spacing and 10 Hz RF-pulse repetition rate, up to 27000 bunches per second can be accelerated to 17.5 GeV to generate uniquely high average brilliance photon beams at very short wavelengths. While many experiments can take advantage of full bunch trains, others prefer an increased to several μ-seconds intra-pulse distance between bunches, or short bursts with a kHz repetition rate. For these types of experiments, the high average brilliance can be preserved only with duty factors much larger than that of the currently proposed sp operation. In this contribution, we discuss progress in the R&D program for future upgrade of the European XFEL linac, namely an operation in the continuous wave (cw) and long pulse (lp) mode, which will allow for more flexibility in the electron and photon beam time structure.

Slides TUOCNO04 [8.910 MB]

TUOCNO05

Design Concepts for a Next Generation Light Source at LBNL

FEL, 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, FEL, 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.

TUPSO12

RF Design Approach for an NGLS Linac

cavity, cryomodule, cryogenics, controls

226

A. Ratti, J.M. Byrd, J.N. Corlett, L.R. Doolittle, P. Emma, M. Venturini, R.P. Wells
LBNL, Berkeley, California, USA
C. Adolphsen, C.D. Nantista
SLAC, Menlo Park, California, USA
D. Arenius, S.V. Benson, D. Douglas, A. Hutton, G. Neil, W. Oren, G.P. Williams
JLAB, Newport News, Virginia, USA
C.M. Ginsburg, R.D. Kephart, 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 Next Generation Light Source (NGLS) is a design concept for a multibeamline soft x-ray FEL array powered by a ~2.4 GeV CW superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. This paper describes the concepts for the cavity and cryostat design operating at 1.3 GHZ and based on minimal modifications to the design of ILC cryomodules, This leverages the extensive experience derived from R&D that resulted in the ILC design. Due to the different nature of the two applications, particular attention is given now to high loaded Q operation and microphonics control, as well as high reliability and expected up time. The work describes the design and configuration of the linac, including choice of gradient, possible modes of operation, cavity design and RF power, as well as the consequent requirements for the cryogenic system.

TUPSO13

Superconducting Linac Design Concepts for a Next Generation Light Source at LBNL

cavity, cryomodule, HOM, controls

229

J.N. Corlett, J.M. Byrd, L.R. Doolittle, P. Emma, A. Ratti, F. Sannibale, M. Venturini, R.P. Wells, S. Zimmermann
LBNL, Berkeley, California, USA
C. Adolphsen, C.D. Nantista
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 in CW mode, with a high bunch repetition rate of approximately 1 MHz. The superconducting linear accelerator design concept is based on existing TESLA and ILC technology, developed for this CW application in a light source. In this paper we describe design options and preferred approaches for the NGLS SRF linac components, cryomodules, and cryosystems.

TUPSO14

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

emittance, diagnostics, undulator, FEL

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, emittance, feedback, FEL

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.

TUPSO17

Status of the Manufacturing Process for the SwissFEL C-Band Accelerating Structures

vacuum, laser, radio-frequency, coupling

245

U. Ellenberger, H. Blumer, L. Paly, C. Zumbach
Paul Scherrer Institute, Villigen PSI, Switzerland
M. Bopp, H. Fitze, F. Löhl
PSI, Villigen PSI, Switzerland

For the SwissFEL project a total of 104 C-band (or approximately 6 GHz for 5’712 MHz required) accelerating structures are needed. After developing and RF-testing of several short structures (0.5m), three 2meter prototypes have been produced successfully in-house. Avoiding any RF-tuning after fabrication, a high precision machining of the components is necessary. Special procedures were developed and handling equipment was built in order to maintain the accuracy during stacking and vacuum brazing of the parts for the C-band structures. This paper summarizes the manufacturing techniques and the mechanical test results for constant subvolumes to match the required klystron frequency of 5’712 MHz

TUPSO35

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

emittance, wakefield, FEL, 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.

TUPSO41

The Ultrashort Beam Linac System and Proposed Coherent THz Radiation Sources at NSRRC

electron, radiation, gun, undulator

309

W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan
N.Y. Huang, Z.Y. Wei
NTHU, Hsinchu, Taiwan

The NSRRC ultrashort beam facility is a low energy linac system which is being built to produce femtosecond electron beam for novel light source development. Experiments on prebunched THz FEL and inverse Compton scattering x-ray source are under study. The electron source is a 2998 MHz, 1.5-cell thermionic rf gun with uneven full-cell to half-cell field ratio that is optimized to produce a energy-chirped electron beam. With movable slits in its vacuum vessel, the alpha magnet system is served also as a beam selector. Further bunch compression is done by velocity bunching in the rf linac. Recent progress of the construction of this facility as well as the design study of a prebunched THz FEL with this ultrashort electron beam will be reported.

TUPSO43

Status of the SwissFEL C-band Linear Accelerator

controls, klystron, low-level-rf, vacuum

317

F. Löhl, J. Alex, H. Blumer, M. Bopp, H.-H. Braun, A. Citterio, H. Fitze, H. Jöhri, T. Kleeb, L. Paly, J.-Y. Raguin, L. Schulz, R. Zennaro
PSI, Villigen PSI, Switzerland
U. Ellenberger
Paul Scherrer Institute, Villigen PSI, Switzerland

This paper will summarize the status of the linear accelerator of the Swiss free-electron laser SwissFEL. It will be based on C-band technology and will use solid-state modulators and a novel type of C-band accelerating structures which has been designed at PSI. Initial test results of first 2 m long structures will be presented together with measurements performed with the first BOC-type pulse compressors. Furthermore, we will present first results of a water cooling system for the accelerating structures and the pulse compressors.

TUPSO45

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

FEL, electron, 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.

TUPSO66

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

FEL, electron, radiation, undulator

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.

TUPSO78

Design of a Collimation System for the Next Generation Light Source at LBNL

collimation, kicker, gun, undulator

410

C. Steier, P. Emma, H. Nishimura, C. F. Papadopoulos, H.J. Qian, F. Sannibale, C. Sun
LBNL, Berkeley, California, USA

Funding: This work is 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.
The planned Next Generation Light Source at LBNL is designed to deliver MHz repetition rate electron beams to an array of free electron lasers. Because of the high beam power approaching one MW in such a facility, effective beam collimation is extremely important to minimize radiation damage, prevent quenches of superconducting cavities, limit dose rates outside of the accelerator tunnel and prevent equipment damage. We describe the conceptual design of a collimation system, including detailed simulations to verify its effectiveness.

TUPSO80

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

FEL, 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.

WEIBNO01

Super-radiant Linac-based THz Sources in 2013

laser, undulator, electron, photon

474

M. Gensch
HZDR, Dresden, Germany

There is a growing interest in THz and far infrared light sources for use in material studies. Both coherent radiative sources (CSR, COTR, etc.) and FEL sources have been developed in the last few years to address this need. This talk will describe recent developments in this growing field.

WEPSO07

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

FEL, 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.

WEPSO10

Increased Stability Requirements for Seeded Beams at LCLS

FEL, 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.

WEPSO22

FERMI@Elettra Status Report

FEL, electron, laser, 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.

WEPSO31

THz Radiation Source Potential of the R&D ERL at BNL

gun, electron, SRF, emittance

566

D. Kayran, I. Ben-Zvi, Y.C. Jing, B. Sheehy
BNL, Upton, Long Island, New York, USA

Funding: Work supported by BSA DOE, Contract No. DE-AC02-98CH10886
An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is under commissioning at Brookhaven National Laboratory (BNL) for testing concepts for high-energy electron cooling and electron-ion colliders. This ERL will be used as a test bed to study issues relevant for very high current ERLs. High repetition rate (9.5 MHz), CW operation and high performance of electron beam with some additional components make this ERL an excellent driver for high power coherent THz radiation source*. We discuss potential use of BNL ERL as a source of THz radiation and results of the beam dynamics simulation. We present the status and commissioning progress of the ERL.
*Ilan Ben-Zvi. et al. Coherent harmonic generation of THz radiation using wakefield bunching (presented at this conference)

WEPSO37

Femtosecond Fiber Timing Distribution System for the Linac Coherent Light Source

laser, electron, free-electron-laser, background

583

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

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

WEPSO44

Design Studies for FLUTE, A Linac-based Source of Terahertz Radiation

radiation, laser, gun, simulation

598

S. Naknaimueang, V. Judin, S. Marsching, A.-S. Müller, M.J. Nasse, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schuh, M. Schwarz, M. Weber, P. Wesolowski
KIT, Karlsruhe, Germany
W. Hillert, M. Schedler
ELSA, Bonn, Germany

FLUTE is a linac-based THz source with nominal beam energy of 40-50 MeV which is presently under construction at KIT. It will be operated in a wide bunch charge range and will use different electron bunch compression schemes. The source will also study different mechanisms of radiation generation and serve as a test facility for related accelerator technology. This contribution presents the results of an overall optimization of the accelerator and a bunch compressor. A usage of a dispersive compressor and a velocity buncher, as well as combination of both are discussed. It is shown that bunch lengths in the range of a few femtoseconds can be achieved at very low bunch charges, while nC-bunches can be compressed down to approximately 200 fs. The utilization of both schemes results in high THz radiation fields at the experimental port.

WEPSO67

Progress with the FERMI Laser Heater Commissioning

FEL, laser, 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

WEPSO88

High Precision Electronics for Single Pass Applications

controls, instrumentation, alignment, pick-up

715

M. Žnidarčič, R. Hrovatin
I-Tech, Solkan, Slovenia
M. Satoh
KEK, Ibaraki, Japan

Monitoring and subsequent optimization of electron Linacs and transfer lines requires specific instrumentation for beam position data acquisition and processing. Libera Single Pass E is the newly developed instrument intended for position and charge monitoring in basic and multi-mode operation LINACs. Development, initial measurements and verification of the instrumentation performance were conducted in the Instrumentation Technologies' laboratories, followed by the characterization measurements of the unit carried out at KEK Linac facility.