FEL2014 - List of Keywords (linac)

Paper	Title	Other Keywords	Page
MOP022	Pulse by Pulse Electron Beam Distribution for Multi-beamline Operation at SACLA	electron, operation, kicker, septum	71
	T. Hara, T. Inagaki, C. Kondo, Y. Otake, H. Takebe, H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan K. Fukami JASRI/SPring-8, Hyogo-ken, Japan
	In order to meet the increasing demand for XFEL user operation, the second undulator beamline (BL2) will be installed during the 2014 summer shutdown at SACLA. Following the installation of BL2, a pulse by pulse electron beam distribution system composed of a kicker and a DC twin-septum magnet, which are currently under development, is planned be installed in January 2015. To distribute the electron beam on a bunch-to-bunch basis, the electron beam is deflected into 0 and ±10 mrad directions at 60 Hz by the kicker, and then the DC twin-septum magnet augments the separation angle to ±50 mrad. The kicker magnet is driven by a 60 Hz trapezoidal waveform and stability less than 30 ppm (peak-peak) has been achieved. This pulse by pulse distribution system will be also used for the beam injection to the upgraded low emittance ring of SPring-8 (SPring-8-II) in future. Since the SPring-8-II storage ring has a small dynamic aperture, low emittance is required for the injection beam. Also the beam injection in parallel with the XFEL operation enables to save the running cost of the injector during top-up operation.

MOP039	High Stability Resonant Kicker Development for the SwissFEL Switch Yard	kicker, operation, dipole, electron	103
	M. Paraliev, H.-H. Braun, S. Dordevic, C.H. Gough PSI, Villigen PSI, Switzerland
	The SwissFEL is a linac-based X-ray free electron laser facility under construction at the Paul Scherrer Institute. The facility will provide femtosecond, high brightness X-ray pulses for fundamental and applied science research. To increase facility efficiency, a double bunch operation is planned to serve simultaneously two experimental stations at the full linac repetition rate. The main linac will accelerate two electron bunches spaced 28 ns apart and a fast and stable deflecting system will be used to separate the two bunches into two different undulator lines. The deflecting system uses a novel concept based on resonant kicker magnets. A prototype kicker magnet and its control system were designed and built. Since stability is crucial, the stability performance of the prototype was studied. The peak to peak amplitude stability of ±11 ppm (3.5 ppm rms) was achieved, which is well within the FEL tolerance of ±80 ppm. The layout of the deflecting system and the key design parameters are also presented.

MOP062	FEL Proposal Based on CLIC X-Band Structure	FEL, klystron, undulator, linear-collider	186
	A.A. Aksoy, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey E. Adli University of Oslo, Oslo, Norway D. Angal-Kalinin, J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc SLSA, Clayton, Australia N. Charitonidis, A. Grudiev, A. Latina, D. Schulte, I. Syratchev, W. Wuensch CERN, Geneva, Switzerland G. D'Auria, S. Di Mitri Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy W. Fang, Q. Gu SINAP, Shanghai, People's Republic of China E.N. Gazis National Technical University of Athens, Athens, Greece M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden Z. Nergiz Nigde University, Nigde, Turkey
	A linear accelerating structure with an average loaded gradient of 100 MV/m at X-Band frequencies has been demonstrated in the CLIC study. Recently, it has been proposed to use this structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by an RF source created by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the structure choice and conceptual design parameters of a facility which could generate laser photon pulses below Angstrom. Shorter wavelengths can also be reached with slightly increasing the energy.

MOP067	Prospects for CW Operation of the European XFEL in Hard X-ray Regime	electron, undulator, operation, FEL	210
	R. Brinkmann, E. Schneidmiller, J.K. Sekutowicz, M.V. Yurkov DESY, Hamburg, Germany
	The European XFEL will operate nominally at 17.5 GeV in SP (short pulse) mode with 0.65 ms long bunch train and 10 Hz repetition rate. A possible upgrade of the linac to CW (continuous wave) or LP (long pulse) modes with a corresponding reduction of electron beam energy is under discussion since many years. Recent successes in the dedicated R&D program allow to forecast a technical feasibility of such an upgrade in the foreseeable future. One of the challenges is to provide sub-Angstroem FEL operation in CW and LP modes. In this paper we perform a preliminary analysis of a possible operation of the European XFEL in the hard X-ray regime in CW and LP modes with the energies of 7 GeV and 10 GeV, respectively. We consider lasing in the baseline XFEL undulator as well as in a new undulator with a reduced period. We show that, with reasonable requirements on electron beam quality, lasing on the fundamental will be possible in sub-Angstroem regime. As an option for generation of brilliant photon beams at short wavelengths we also consider harmonic lasing that has recently attracted a significant attention.

TUA04	Status of the SwissFEL C-band Linac	klystron, network, electron, free-electron-laser	322
	F. Löhl, J. Alex, H. Blumer, M. Bopp, H.-H. Braun, A. Citterio, U. Ellenberger, H. Fitze, H. Jöhri, T. Kleeb, L. Paly, J.-Y. Raguin, L. Schulz, R. Zennaro, C. Zumbach PSI, Villigen PSI, Switzerland
	The linear accelerator of SwissFEL will be based on C- band technology. This paper summarizes the latest results that were achieved with the first prototype components. Fur- thermore, the progress and plans of the series production are discussed.
	Slides TUA04 [11.482 MB]

TUP009	A Simple Method for Generating a Few Femtosecond Pulses in Seeded FELs	electron, laser, FEL, radiation	371
	H.T. Li, Z.G. He, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Work supported by Major State Basic Research Development Program of China (2011CB808301) and the Fundamental Research Funds for the Central Universities of China (WK2310000045) We propose a simple method to generate a few femtosecond pulses in seeded FELs. We use a longitudinal energy-chirped electron beam passing through a dogleg where transverse dispersion will generate a horizontal energy chirp, then in the modulator, a seed laser with narrow beam radius will only modulate the centre part of electron beam and short pulses in high harmonics will be generated in the radiator. Using a representative realistic set of parameters, we show that 30 nm XUV pulse with duration of 8 femtoseconds (FWHM) and peak power of GW level can be generated from a 180 nm UV seed laser with beam waist of 75 m.

TUP054	Status of Electron Beam Slicing Project at NSLS-II, BNL	electron, radiation, storage-ring, photon	496
	A. He, F.J. Willeke, L.-H. Yu BNL, Upton, Long Island, New York, USA
	The Electron Beam Slicing (e-beam slicing) at NSLS-II, Brookhaven National Laboratory, supported by the Laboratory Directed Research and Development (LDRD) Program, is focused on the development of the new method to generate ultra-short x-ray pulses using focused short low energy (∼20 MeV) electron bunches to create short slices of electrons from the circulating electron bunches in a synchrotron radiation storage ring. The e-beam slicing activities are staged in 3 main phases. In Phases 0, the theory of e-beam slicing is developed, the low energy linac compressor is simulation designed, the radiation separation between the satellite and core is analyzed by simulation and the properties of the e-beam slicing system are discussed and compared with other ultra-short x- ray sources. Phase 0 has completed successfully, Phase 1 is under way. This paper presents an update on the status of Phase 0.

TUP073	High Power Operation of the THz FEL at ISIR, Osaka University	FEL, electron, operation, gun	528
	K. Kawase, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, G. Isoyama, R. Kato, K. Kubo, K. Miyazaki, S. Suemine, A. Tokuchi, R. Tsutsumi, M. Yaguchi ISIR, Osaka, Japan
	The THz FEL at Osaka University is based on the L-band linac that provides a multi-bunch electron beam with an 8 us duration in the energy range from 12.5 to 20 MeV. Although the RF frequency of the linac is 1.3 GHz, the bunch intervals are expanded to 9.2 ns for the FEL using a sub-harmonic buncher system that operates at 10⁸ MHz, to enhance the bunch charge to 1 nC/bunch. The FEL covers the wavelength range from 30 to 150 um, and maximum energies of the macropulse and the micropulse are 3.7 mJ and 11 uJ, respectively, at ~70 um measured at an experimental station. To enhance the FEL power further, the electron beam current cannot be increased simply because the beam loading in the acceleration tube is too high. To solve this problem, we have developed a 27 MHz grid pulser for the thermionic electron gun that makes the bunch intervals 4 times longer and increases charge of the bunch 4 times higher whereas the beam loading is the same as that in the 108 MHz mode. In this new operation mode, where a single FEL pulse lases in the cavity, we have succeeded in obtaining the micropulse energy exceeding 100 uJ at a wavelength of 68 um.

TUP079	A Swedish Compact Linac-based THz/X-ray Source at FREIA	electron, cavity, radiation, gun	545
	V.A. Goryashko Private Address, Uppsala, Sweden A. Opanasenko NSC/KIPT, Kharkov, Ukraine V. Zhaunerchyk University of Gothenburg, Gothenburg, Sweden
	THz radiation enables probing and controlling low-energy excitations in matter such as molecular rotations, DNA dynamics, spin waves and Cooper pairs. In view of growing interest to the THz radiation, the Swedish FEL Center and FREIA Laboratory are working on the conceptual design of a compact multicolor photon source for multidisciplinary research. We present the design of such a source driven by high-brightness electron bunches produced by a superconducting linear accelerator. A THz source is envisioned as an FEL oscillator since this enables not only generation of THz pulses with a bandwidth down to 0.01% (with inter-pulse locking technique) but also generation of short pulses with several cycles in duration by detuning the resonator. For pump-probe experiments, the THz source will be complemented with an X-ray source. One of the most promising options is the inverse Compton scattering of quantum laser pulses from electron bunches. Such an X-ray source will operate in water window with output intensity comparable to a second generation synchrotron. The envisioned THz/X-ray source is compact with a cost comparable to the cost of one beamline at a synchrotron.

TUP080	Towards an X-ray FEL at the MAX IV Laboratory	FEL, electron, gun, laser	549
	S. Werin, F. Curbis, M. Eriksson, C. Quitmann, S. Thorin MAX-lab, Lund, Sweden P. Johnsson Lund University, Lund, Sweden
	The design of the 3 GeV linac for the MAX IV facility was done to provide the ability to host a future FEL in the hard X-ray as well as in the soft X-ray range. The linear accelerator, with its two bunch compressors, is now under commissioning. Through the years increasing details for the actual FEL have been discussed and presented. In parallel a steering group for the science case for a Swedish FEL has worked and engaged a large number of Swedish user groups. These two paths are now converging into a joint project to develop the concept of an FEL at MAX IV. We will report on the paths to FEL performance based on the 3 GeV injector, FEL design considerations, the scientific preparation of the project, the linac commissioning and the strategy and priorities.

TUP089	The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) Project	electron, undulator, FEL, radiation	585
	A.A. Aksoy, Ö. Karslı, C. Kaya, O. Yavaş Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey P. Arıkan Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey S. Özkorucuklu Istanbul University, Istanbul, Turkey
	Funding: Work is supported by Ministry of Development of Turkey with Grand No: DPT2006K-120470 The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) which is proposed as a first facility of Turkish Accelerator Center (TAC) Project will operate two Infra-Red Free Electron Lasers (IR-FEL) covering the range of 3-250 microns. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. The facility aims to be first user laboratory in the region of Turkey in which both electromagnetic radiation and particles will be used. In this paper, we discuss design goals of the project and present status and road map of the project.

TUP091	Developments in the CLARA FEL Test Facility Accelerator Design and Simulations	FEL, gun, cavity, diagnostics	589
	P.H. Williams, D. Angal-Kalinin, A.D. Brynes, J.K. Jones, B.P.M. Liggins, J.W. McKenzie, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S. Spampinati Cockcroft Institute, Warrington, Cheshire, United Kingdom
	We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. These comprise a revised front-end to ensure integration with the existing VELA line, simulations of a magnetically compressed ultra-short mode and a post-FEL diagnostics section. We also present first considerations on the inclusion of final acceleration using X-band structures.

TUP093	A Beam Test of Corrugated Structure for Passive Linearizer	simulation, quadrupole, electron, controls	593
	H.-S. Kang, J.H. Hong PAL, Pohang, Kyungbuk, Republic of Korea
	A dechirper which is a vacuum chamber of two corrugated, metallic plates with adjustable gap was successfully tested at Pohang, in August 2013. Another beam test was carried out to test the same structure to see if the corrugated plates may work as a linearizer. The test result will be presented together with the simulation result.

THA03	A Plan for the Development of Superconducting Undulator Prototypes for LCLS-II and Future FELs	undulator, FEL, vacuum, electron	649
	P. Emma, N.R. Holtkamp, H.-D. Nuhn SLAC, Menlo Park, California, USA D. Arbelaez, J.N. Corlett, S.A. Myers, S. Prestemon, D. Schlueter LBNL, Berkeley, California, USA C.L. Doose, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, G. Pile, E. Trakhtenberg ANL, Argonne, Ilinois, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515, DE-AC02-05CH11231, and DE-AC02-06CH11357. Undulators serve as the primary source of radiation for modern storage rings, and more recently for the advent of Free-Electron Lasers (FELs). The performance of future FELs can be greatly enhanced using the much higher magnetic fields of superconducting undulators (SCU). For example, the LCLS-II hard x-ray undulator can be shortened by up to 70 m using an SCU in place of a PMU (permanent magnet undulator), or its spectral performance can be critically improved when using a similar length. In addition, SCUs are expected to be orders of magnitude less sensitive to radiation dose; a major issue at LCLS-II with its 1-MHz electron bunch rate. We present a funded R&D collaboration between SLAC, ANL, and LBNL, which aims to demonstrate the viability of superconducting undulators for FELs by building, testing, measuring, and tuning two 1.5-m long planar SCU prototypes using two different technologies: NbTi at ANL and Nb3Sn at LBNL. Our goal is to review and reassess the LCLS-II HXR baseline plans (PMU) in July of 2015, after the development and evaluation of both prototypes, possibly in favor of an SCU for LCLS-II.
	Slides THA03 [29.468 MB]

THP002	Beam Energy Management and RF Failure Compensation Scenarios for the European XFEL	klystron, operation, optics, quadrupole	672
	B. Beutner DESY, Hamburg, Germany
	The operation of complex systems as the driver linacs for free-electron-lasers is limited by the reliability of the individual components. Failures of RF systems can therefore constrict FEL availability. Typically reserves are included in the overall linac voltage capacity to allow for redistribution of acceleration in case of an RF failure. However, such redistributions of the acceleration of the linac affects the beam dynamics of the machine. While the effects on the optics can easily be compensated by rescaling of the quadrupole magnet strength, the bunch compression set-up requires a more involved investigation. In this paper we discuss studies for an energy management system for the European XFEL.

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

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

THP012	Error Analysis for Linac Lattice of Hard X-ray FEL Line in PAL-XFEL*	emittance, simulation, lattice, alignment	703
	H. Yang, J.H. Han, H.-S. Kang, I.S. Ko PAL, Pohang, Kyungbuk, Republic of Korea
	Funding: *This work was supported by MSIP, Korea. PAL-XFEL consists of the hard x-ray line for 0.06 – 1-nm FEL and the soft x-ray line for 1 – 10-nm FEL. The linac of hard x-ray line is designed to generate 10-GeV, 200-pC, and 3-kA electron beam. It consists of S-band accelerating columns, an X-band linearizer, three bunch compressors (BC). We conduct error simulation in order to evaluate the tolerances of machine parameters and alignments. First, the machine tolerances and beam jitter levels are calculated in the simulations with dynamic errors and we find out the optimized lattice to satisfy the target tolerance of machine. Second, we conduct simulations with misalignment. We quantify the emittance dilution by misalignments, especially those of BCs. In order to compensate the misalignments, the methods of beam correction like Beam Based Alignment (BBA) are presented and the effects of emittance improvements are calculated.
	Poster THP012 [0.736 MB]

THP025	Linear Accelerator Design for the LCLS-II FEL Facility	electron, undulator, FEL, laser	743
	P. Emma, J.C. Frisch, Z. Huang, H. Loos, A. Marinelli, T.J. Maxwell, Y. Nosochkov, T.O. Raubenheimer, L. Wang, J.J. Welch, M. Woodley SLAC, Menlo Park, California, USA J. Qiang, M. Venturini LBNL, Berkeley, California, USA A. Saini, N. Solyak Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515. The LCLS-II is an FEL facility proposed in response to the July 2013 BESAC advisory committee, which recommended the construction of a new FEL light source with a high-repetition rate and a broad photon energy range from 0.2 keV to at least 5 keV. A new CW 4-GeV electron linac is being designed to meet this need, using a superconducting (SC) L-band (1.3 GHz) linear accelerator capable of operating with a continuous bunch repetition rate up to 1 MHz at ~16 MV/m. This new 700-m linac is to be built at SLAC in the existing tunnel, making use of existing facilities and providing two separate FELs, preserving the operation of the existing FEL, which can be fed from either the existing copper or the new SC linac. We briefly describe the acceleration, bunch compression, beam transport, beam switching, and electron beam diagnostics. The high-power and low-level RF, and cryogenic systems are described elsewhere.
	Poster THP025 [0.627 MB]

THP029	MOGA OPTIMIZATION DESIGN OF LCLS-II LINAC CONFIGURATIONS	emittance, undulator, FEL, simulation	763
	L. Wang, P. Emma, Y. Nosochkov, T.O. Raubenheimer, M. Woodley, F. Zhou SLAC, Menlo Park, California, USA C. F. Papadopoulos, J. Qiang, M. Venturini LBNL, Berkeley, California, USA
	The Linac Coherent Light Source II (LCLS-II) will generate extremely intense X-ray flashes to be used by researchers from all over the world. The FEL is powered by 4 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. LCLS-II will provide large flexibility in bunch charge and peak current. Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters including bunch compressors system, linearizer, de-chirper, RF phase and laser heater, in order to minimize the energy spread, collective effects and emittance. The strong resistive wall wake field along the 2km bypass beam line acts as a natural de-chirper. This paper summarizes the optimization of various configurations.
	Poster THP029 [0.702 MB]

THP058	Solid-State Switch for a Klystron Modulator for Stable Operation of a THz- FEL	FEL, klystron, electron, operation	868
	G. Isoyama, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, R. Kato, K. Kawase, K. Miyazaki, A. Tokuchi, R. Tsutsumi, M. Yaguchi ISIR, Osaka, Japan F. Kamitsukasa Osaka University, Graduate School of Science, Osaka, Japan
	We have been conducting studies on upgrade of the THz-FEL and its applications, using the L-band electron linac at ISIR, Osaka University. The stability of the FEL is crucial for these studies and the operation of the FEL depends on characteristics of the electron beam, especially on stability of the electron energy, which is strongly affected by the RF power and its phase provided to the linac. We uses a klystron modulator with the a highly stable charging system to the PFN with a fractional variation of 8×10^-5 (peak-to-peak), but the klystron voltage varies by one order of magnitude larger due probably to the thyratron used as a high voltage and high current switch in the klystron modulator. In order to make the stability of the FEL higher, we have developed a solid-state switch using static induction thyristors. The performance of the switch is as follows; the maximum holding voltage is 25 kV, the maximum current is 6 kA for the pulse duration of 10 us, the switching time is 270 ns, and the maximum repetition frequency is 10 Hz. The intensity fluctuation of the FEL macropulse is reduced to a few percents using the solid state switch.

THP064	High Repetition Rate S-band Photoinjector Design for the CLARA FEL	gun, cavity, FEL, emittance	889
	J.W. McKenzie, L.S. Cowie, P. Goudket, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom T.J. Jones STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom V.V. Paramonov RAS/INR, Moscow, Russia
	We present the design of a 1.5cell S-band photoinjector RF gun intended to be operated at repetition rates up to 400 Hz in single bunch mode. This gun is intended for use at the proposed CLARA (Compact Linear Accelerator for Research and Applications) FEL test facility at Daresbury Laboratory in the UK and will first be tested and characterised on VELA (Versatile Electron Linear Accelerator) in 2015. The final cavity design is presented including optimisation for CLARA beam dynamics, and choice of a novel coaxial H-shaped coupler.

THP073	Optics Measurements at FLASH2	optics, extraction, undulator, emittance	902
	M. Scholz, B. Faatz, M. Vogt, J. Zemella DESY, Hamburg, Germany
	FLASH2 is a newly build second beam line at FLASH, the soft X-ray FEL at DESY, Hamburg. Unlike the existing beam line FLASH1, it is equipped with variable gap undulators. This beam line is currently being commissioned. Both undulator beam lines of FLASH are driven by a common linear accelerator. Fast kickers and a septum are installed at the end of the linac to distribute the electron bunches of every train between FLASH1 and FLASH2. A specific beam optic in the extraction arc with horizontal beam waists in the bending magnets is mandatory in order to mitigate CSR effects. Here we will show first results of measurements and compare to simulations.

Paper

Title

Other Keywords

Page

MOP022

Pulse by Pulse Electron Beam Distribution for Multi-beamline Operation at SACLA

electron, operation, kicker, septum

71

T. Hara, T. Inagaki, C. Kondo, Y. Otake, H. Takebe, H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
K. Fukami
JASRI/SPring-8, Hyogo-ken, Japan

In order to meet the increasing demand for XFEL user operation, the second undulator beamline (BL2) will be installed during the 2014 summer shutdown at SACLA. Following the installation of BL2, a pulse by pulse electron beam distribution system composed of a kicker and a DC twin-septum magnet, which are currently under development, is planned be installed in January 2015. To distribute the electron beam on a bunch-to-bunch basis, the electron beam is deflected into 0 and ±10 mrad directions at 60 Hz by the kicker, and then the DC twin-septum magnet augments the separation angle to ±50 mrad. The kicker magnet is driven by a 60 Hz trapezoidal waveform and stability less than 30 ppm (peak-peak) has been achieved. This pulse by pulse distribution system will be also used for the beam injection to the upgraded low emittance ring of SPring-8 (SPring-8-II) in future. Since the SPring-8-II storage ring has a small dynamic aperture, low emittance is required for the injection beam. Also the beam injection in parallel with the XFEL operation enables to save the running cost of the injector during top-up operation.

MOP039

High Stability Resonant Kicker Development for the SwissFEL Switch Yard

kicker, operation, dipole, electron

103

M. Paraliev, H.-H. Braun, S. Dordevic, C.H. Gough
PSI, Villigen PSI, Switzerland

The SwissFEL is a linac-based X-ray free electron laser facility under construction at the Paul Scherrer Institute. The facility will provide femtosecond, high brightness X-ray pulses for fundamental and applied science research. To increase facility efficiency, a double bunch operation is planned to serve simultaneously two experimental stations at the full linac repetition rate. The main linac will accelerate two electron bunches spaced 28 ns apart and a fast and stable deflecting system will be used to separate the two bunches into two different undulator lines. The deflecting system uses a novel concept based on resonant kicker magnets. A prototype kicker magnet and its control system were designed and built. Since stability is crucial, the stability performance of the prototype was studied. The peak to peak amplitude stability of ±11 ppm (3.5 ppm rms) was achieved, which is well within the FEL tolerance of ±80 ppm. The layout of the deflecting system and the key design parameters are also presented.

MOP062

FEL Proposal Based on CLIC X-Band Structure

FEL, klystron, undulator, linear-collider

186

A.A. Aksoy, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
E. Adli
University of Oslo, Oslo, Norway
D. Angal-Kalinin, J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.J. Boland, T.K. Charles, R.T. Dowd, G. LeBlanc
SLSA, Clayton, Australia
N. Charitonidis, A. Grudiev, A. Latina, D. Schulte, I. Syratchev, W. Wuensch
CERN, Geneva, Switzerland
G. D'Auria, S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
W. Fang, Q. Gu
SINAP, Shanghai, People's Republic of China
E.N. Gazis
National Technical University of Athens, Athens, Greece
M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
Z. Nergiz
Nigde University, Nigde, Turkey

A linear accelerating structure with an average loaded gradient of 100 MV/m at X-Band frequencies has been demonstrated in the CLIC study. Recently, it has been proposed to use this structure to drive an FEL linac. In contrast to CLIC the linac would be powered by klystrons not by an RF source created by a drive beam. The main advantage of this proposal is achieving the required energies in a very short distance, thus the facility would be rather compact. In this study, we present the structure choice and conceptual design parameters of a facility which could generate laser photon pulses below Angstrom. Shorter wavelengths can also be reached with slightly increasing the energy.

MOP067

Prospects for CW Operation of the European XFEL in Hard X-ray Regime

electron, undulator, operation, FEL

210

R. Brinkmann, E. Schneidmiller, J.K. Sekutowicz, M.V. Yurkov
DESY, Hamburg, Germany

The European XFEL will operate nominally at 17.5 GeV in SP (short pulse) mode with 0.65 ms long bunch train and 10 Hz repetition rate. A possible upgrade of the linac to CW (continuous wave) or LP (long pulse) modes with a corresponding reduction of electron beam energy is under discussion since many years. Recent successes in the dedicated R&D program allow to forecast a technical feasibility of such an upgrade in the foreseeable future. One of the challenges is to provide sub-Angstroem FEL operation in CW and LP modes. In this paper we perform a preliminary analysis of a possible operation of the European XFEL in the hard X-ray regime in CW and LP modes with the energies of 7 GeV and 10 GeV, respectively. We consider lasing in the baseline XFEL undulator as well as in a new undulator with a reduced period. We show that, with reasonable requirements on electron beam quality, lasing on the fundamental will be possible in sub-Angstroem regime. As an option for generation of brilliant photon beams at short wavelengths we also consider harmonic lasing that has recently attracted a significant attention.

TUA04

Status of the SwissFEL C-band Linac

klystron, network, electron, free-electron-laser

322

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

The linear accelerator of SwissFEL will be based on C- band technology. This paper summarizes the latest results that were achieved with the first prototype components. Fur- thermore, the progress and plans of the series production are discussed.

Slides TUA04 [11.482 MB]

TUP009

A Simple Method for Generating a Few Femtosecond Pulses in Seeded FELs

electron, laser, FEL, radiation

371

H.T. Li, Z.G. He, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by Major State Basic Research Development Program of China (2011CB808301) and the Fundamental Research Funds for the Central Universities of China (WK2310000045)
We propose a simple method to generate a few femtosecond pulses in seeded FELs. We use a longitudinal energy-chirped electron beam passing through a dogleg where transverse dispersion will generate a horizontal energy chirp, then in the modulator, a seed laser with narrow beam radius will only modulate the centre part of electron beam and short pulses in high harmonics will be generated in the radiator. Using a representative realistic set of parameters, we show that 30 nm XUV pulse with duration of 8 femtoseconds (FWHM) and peak power of GW level can be generated from a 180 nm UV seed laser with beam waist of 75 m.

TUP054

Status of Electron Beam Slicing Project at NSLS-II, BNL

electron, radiation, storage-ring, photon

496

A. He, F.J. Willeke, L.-H. Yu
BNL, Upton, Long Island, New York, USA

The Electron Beam Slicing (e-beam slicing) at NSLS-II, Brookhaven National Laboratory, supported by the Laboratory Directed Research and Development (LDRD) Program, is focused on the development of the new method to generate ultra-short x-ray pulses using focused short low energy (∼20 MeV) electron bunches to create short slices of electrons from the circulating electron bunches in a synchrotron radiation storage ring. The e-beam slicing activities are staged in 3 main phases. In Phases 0, the theory of e-beam slicing is developed, the low energy linac compressor is simulation designed, the radiation separation between the satellite and core is analyzed by simulation and the properties of the e-beam slicing system are discussed and compared with other ultra-short x- ray sources. Phase 0 has completed successfully, Phase 1 is under way. This paper presents an update on the status of Phase 0.

TUP073

High Power Operation of the THz FEL at ISIR, Osaka University

FEL, electron, operation, gun

528

K. Kawase, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, G. Isoyama, R. Kato, K. Kubo, K. Miyazaki, S. Suemine, A. Tokuchi, R. Tsutsumi, M. Yaguchi
ISIR, Osaka, Japan

The THz FEL at Osaka University is based on the L-band linac that provides a multi-bunch electron beam with an 8 us duration in the energy range from 12.5 to 20 MeV. Although the RF frequency of the linac is 1.3 GHz, the bunch intervals are expanded to 9.2 ns for the FEL using a sub-harmonic buncher system that operates at 10⁸ MHz, to enhance the bunch charge to 1 nC/bunch. The FEL covers the wavelength range from 30 to 150 um, and maximum energies of the macropulse and the micropulse are 3.7 mJ and 11 uJ, respectively, at ~70 um measured at an experimental station. To enhance the FEL power further, the electron beam current cannot be increased simply because the beam loading in the acceleration tube is too high. To solve this problem, we have developed a 27 MHz grid pulser for the thermionic electron gun that makes the bunch intervals 4 times longer and increases charge of the bunch 4 times higher whereas the beam loading is the same as that in the 108 MHz mode. In this new operation mode, where a single FEL pulse lases in the cavity, we have succeeded in obtaining the micropulse energy exceeding 100 uJ at a wavelength of 68 um.

TUP079

A Swedish Compact Linac-based THz/X-ray Source at FREIA

electron, cavity, radiation, gun

545

V.A. Goryashko
Private Address, Uppsala, Sweden
A. Opanasenko
NSC/KIPT, Kharkov, Ukraine
V. Zhaunerchyk
University of Gothenburg, Gothenburg, Sweden

THz radiation enables probing and controlling low-energy excitations in matter such as molecular rotations, DNA dynamics, spin waves and Cooper pairs. In view of growing interest to the THz radiation, the Swedish FEL Center and FREIA Laboratory are working on the conceptual design of a compact multicolor photon source for multidisciplinary research. We present the design of such a source driven by high-brightness electron bunches produced by a superconducting linear accelerator. A THz source is envisioned as an FEL oscillator since this enables not only generation of THz pulses with a bandwidth down to 0.01% (with inter-pulse locking technique) but also generation of short pulses with several cycles in duration by detuning the resonator. For pump-probe experiments, the THz source will be complemented with an X-ray source. One of the most promising options is the inverse Compton scattering of quantum laser pulses from electron bunches. Such an X-ray source will operate in water window with output intensity comparable to a second generation synchrotron. The envisioned THz/X-ray source is compact with a cost comparable to the cost of one beamline at a synchrotron.

TUP080

Towards an X-ray FEL at the MAX IV Laboratory

FEL, electron, gun, laser

549

S. Werin, F. Curbis, M. Eriksson, C. Quitmann, S. Thorin
MAX-lab, Lund, Sweden
P. Johnsson
Lund University, Lund, Sweden

The design of the 3 GeV linac for the MAX IV facility was done to provide the ability to host a future FEL in the hard X-ray as well as in the soft X-ray range. The linear accelerator, with its two bunch compressors, is now under commissioning. Through the years increasing details for the actual FEL have been discussed and presented. In parallel a steering group for the science case for a Swedish FEL has worked and engaged a large number of Swedish user groups. These two paths are now converging into a joint project to develop the concept of an FEL at MAX IV. We will report on the paths to FEL performance based on the 3 GeV injector, FEL design considerations, the scientific preparation of the project, the linac commissioning and the strategy and priorities.

TUP089

The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) Project

electron, undulator, FEL, radiation

585

A.A. Aksoy, Ö. Karslı, C. Kaya, O. Yavaş
Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey
P. Arıkan
Gazi University, Faculty of Arts and Sciences, Teknikokullar, Ankara, Turkey
S. Özkorucuklu
Istanbul University, Istanbul, Turkey

Funding: Work is supported by Ministry of Development of Turkey with Grand No: DPT2006K-120470
The Turkish Accelerator and Radiation Laboratory in Ankara (TARLA) which is proposed as a first facility of Turkish Accelerator Center (TAC) Project will operate two Infra-Red Free Electron Lasers (IR-FEL) covering the range of 3-250 microns. The facility will consist of an injector fed by a thermionic triode gun with two-stage RF bunch compression, two superconducting accelerating modules operating at continuous wave (CW) mode and two independent optical resonator systems with different undulator period lengths. The electron beam will also be used to generate Bremsstrahlung radiation. The facility aims to be first user laboratory in the region of Turkey in which both electromagnetic radiation and particles will be used. In this paper, we discuss design goals of the project and present status and road map of the project.

TUP091

Developments in the CLARA FEL Test Facility Accelerator Design and Simulations

FEL, gun, cavity, diagnostics

589

P.H. Williams, D. Angal-Kalinin, A.D. Brynes, J.K. Jones, B.P.M. Liggins, J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S. Spampinati
Cockcroft Institute, Warrington, Cheshire, United Kingdom

We present recent developments in the accelerator design of CLARA (Compact Linear Accelerator for Research and Applications), the proposed UK FEL test facility at Daresbury Laboratory. These comprise a revised front-end to ensure integration with the existing VELA line, simulations of a magnetically compressed ultra-short mode and a post-FEL diagnostics section. We also present first considerations on the inclusion of final acceleration using X-band structures.

TUP093

A Beam Test of Corrugated Structure for Passive Linearizer

simulation, quadrupole, electron, controls

593

H.-S. Kang, J.H. Hong
PAL, Pohang, Kyungbuk, Republic of Korea

A dechirper which is a vacuum chamber of two corrugated, metallic plates with adjustable gap was successfully tested at Pohang, in August 2013. Another beam test was carried out to test the same structure to see if the corrugated plates may work as a linearizer. The test result will be presented together with the simulation result.

THA03

A Plan for the Development of Superconducting Undulator Prototypes for LCLS-II and Future FELs

undulator, FEL, vacuum, electron

649

P. Emma, N.R. Holtkamp, H.-D. Nuhn
SLAC, Menlo Park, California, USA
D. Arbelaez, J.N. Corlett, S.A. Myers, S. Prestemon, D. Schlueter
LBNL, Berkeley, California, USA
C.L. Doose, J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, G. Pile, E. Trakhtenberg
ANL, Argonne, Ilinois, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515, DE-AC02-05CH11231, and DE-AC02-06CH11357.
Undulators serve as the primary source of radiation for modern storage rings, and more recently for the advent of Free-Electron Lasers (FELs). The performance of future FELs can be greatly enhanced using the much higher magnetic fields of superconducting undulators (SCU). For example, the LCLS-II hard x-ray undulator can be shortened by up to 70 m using an SCU in place of a PMU (permanent magnet undulator), or its spectral performance can be critically improved when using a similar length. In addition, SCUs are expected to be orders of magnitude less sensitive to radiation dose; a major issue at LCLS-II with its 1-MHz electron bunch rate. We present a funded R&D collaboration between SLAC, ANL, and LBNL, which aims to demonstrate the viability of superconducting undulators for FELs by building, testing, measuring, and tuning two 1.5-m long planar SCU prototypes using two different technologies: NbTi at ANL and Nb3Sn at LBNL. Our goal is to review and reassess the LCLS-II HXR baseline plans (PMU) in July of 2015, after the development and evaluation of both prototypes, possibly in favor of an SCU for LCLS-II.

Slides THA03 [29.468 MB]

THP002

Beam Energy Management and RF Failure Compensation Scenarios for the European XFEL

klystron, operation, optics, quadrupole

672

B. Beutner
DESY, Hamburg, Germany

The operation of complex systems as the driver linacs for free-electron-lasers is limited by the reliability of the individual components. Failures of RF systems can therefore constrict FEL availability. Typically reserves are included in the overall linac voltage capacity to allow for redistribution of acceleration in case of an RF failure. However, such redistributions of the acceleration of the linac affects the beam dynamics of the machine. While the effects on the optics can easily be compensated by rescaling of the quadrupole magnet strength, the bunch compression set-up requires a more involved investigation. In this paper we discuss studies for an energy management system for the European XFEL.

THP004

Start-to-End Error Studies for FLUTE

laser, simulation, timing, gun

682

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

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

THP010

Analysis of Beam Stability in the KAERI Ultrashort Pulse Accelerator

electron, timing, kicker, septum

697

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

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

THP012

Error Analysis for Linac Lattice of Hard X-ray FEL Line in PAL-XFEL*

emittance, simulation, lattice, alignment

703

H. Yang, J.H. Han, H.-S. Kang, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: *This work was supported by MSIP, Korea.
PAL-XFEL consists of the hard x-ray line for 0.06 – 1-nm FEL and the soft x-ray line for 1 – 10-nm FEL. The linac of hard x-ray line is designed to generate 10-GeV, 200-pC, and 3-kA electron beam. It consists of S-band accelerating columns, an X-band linearizer, three bunch compressors (BC). We conduct error simulation in order to evaluate the tolerances of machine parameters and alignments. First, the machine tolerances and beam jitter levels are calculated in the simulations with dynamic errors and we find out the optimized lattice to satisfy the target tolerance of machine. Second, we conduct simulations with misalignment. We quantify the emittance dilution by misalignments, especially those of BCs. In order to compensate the misalignments, the methods of beam correction like Beam Based Alignment (BBA) are presented and the effects of emittance improvements are calculated.

Poster THP012 [0.736 MB]

THP025

Linear Accelerator Design for the LCLS-II FEL Facility

electron, undulator, FEL, laser

743

P. Emma, J.C. Frisch, Z. Huang, H. Loos, A. Marinelli, T.J. Maxwell, Y. Nosochkov, T.O. Raubenheimer, L. Wang, J.J. Welch, M. Woodley
SLAC, Menlo Park, California, USA
J. Qiang, M. Venturini
LBNL, Berkeley, California, USA
A. Saini, N. Solyak
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
The LCLS-II is an FEL facility proposed in response to the July 2013 BESAC advisory committee, which recommended the construction of a new FEL light source with a high-repetition rate and a broad photon energy range from 0.2 keV to at least 5 keV. A new CW 4-GeV electron linac is being designed to meet this need, using a superconducting (SC) L-band (1.3 GHz) linear accelerator capable of operating with a continuous bunch repetition rate up to 1 MHz at ~16 MV/m. This new 700-m linac is to be built at SLAC in the existing tunnel, making use of existing facilities and providing two separate FELs, preserving the operation of the existing FEL, which can be fed from either the existing copper or the new SC linac. We briefly describe the acceleration, bunch compression, beam transport, beam switching, and electron beam diagnostics. The high-power and low-level RF, and cryogenic systems are described elsewhere.

Poster THP025 [0.627 MB]

THP029

MOGA OPTIMIZATION DESIGN OF LCLS-II LINAC CONFIGURATIONS

emittance, undulator, FEL, simulation

763

L. Wang, P. Emma, Y. Nosochkov, T.O. Raubenheimer, M. Woodley, F. Zhou
SLAC, Menlo Park, California, USA
C. F. Papadopoulos, J. Qiang, M. Venturini
LBNL, Berkeley, California, USA

The Linac Coherent Light Source II (LCLS-II) will generate extremely intense X-ray flashes to be used by researchers from all over the world. The FEL is powered by 4 GeV superconducting linear accelerator, operating with a 1 MHz bunch repetition rate. LCLS-II will provide large flexibility in bunch charge and peak current. Multi-Objective Genetic Algorithm (MOGA) is applied to optimize the machine parameters including bunch compressors system, linearizer, de-chirper, RF phase and laser heater, in order to minimize the energy spread, collective effects and emittance. The strong resistive wall wake field along the 2km bypass beam line acts as a natural de-chirper. This paper summarizes the optimization of various configurations.

Poster THP029 [0.702 MB]

THP058

Solid-State Switch for a Klystron Modulator for Stable Operation of a THz- FEL

FEL, klystron, electron, operation

868

G. Isoyama, M. Fujimoto, S. Funakoshi, K. Furukawa, A. Irizawa, R. Kato, K. Kawase, K. Miyazaki, A. Tokuchi, R. Tsutsumi, M. Yaguchi
ISIR, Osaka, Japan
F. Kamitsukasa
Osaka University, Graduate School of Science, Osaka, Japan

We have been conducting studies on upgrade of the THz-FEL and its applications, using the L-band electron linac at ISIR, Osaka University. The stability of the FEL is crucial for these studies and the operation of the FEL depends on characteristics of the electron beam, especially on stability of the electron energy, which is strongly affected by the RF power and its phase provided to the linac. We uses a klystron modulator with the a highly stable charging system to the PFN with a fractional variation of 8×10^-5 (peak-to-peak), but the klystron voltage varies by one order of magnitude larger due probably to the thyratron used as a high voltage and high current switch in the klystron modulator. In order to make the stability of the FEL higher, we have developed a solid-state switch using static induction thyristors. The performance of the switch is as follows; the maximum holding voltage is 25 kV, the maximum current is 6 kA for the pulse duration of 10 us, the switching time is 270 ns, and the maximum repetition frequency is 10 Hz. The intensity fluctuation of the FEL macropulse is reduced to a few percents using the solid state switch.

THP064

High Repetition Rate S-band Photoinjector Design for the CLARA FEL

gun, cavity, FEL, emittance

889

J.W. McKenzie, L.S. Cowie, P. Goudket, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
T.J. Jones
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia

We present the design of a 1.5cell S-band photoinjector RF gun intended to be operated at repetition rates up to 400 Hz in single bunch mode. This gun is intended for use at the proposed CLARA (Compact Linear Accelerator for Research and Applications) FEL test facility at Daresbury Laboratory in the UK and will first be tested and characterised on VELA (Versatile Electron Linear Accelerator) in 2015. The final cavity design is presented including optimisation for CLARA beam dynamics, and choice of a novel coaxial H-shaped coupler.

THP073

Optics Measurements at FLASH2

optics, extraction, undulator, emittance

902

M. Scholz, B. Faatz, M. Vogt, J. Zemella
DESY, Hamburg, Germany

FLASH2 is a newly build second beam line at FLASH, the soft X-ray FEL at DESY, Hamburg. Unlike the existing beam line FLASH1, it is equipped with variable gap undulators. This beam line is currently being commissioned. Both undulator beam lines of FLASH are driven by a common linear accelerator. Fast kickers and a septum are installed at the end of the linac to distribute the electron bunches of every train between FLASH1 and FLASH2. A specific beam optic in the extraction arc with horizontal beam waists in the bending magnets is mandatory in order to mitigate CSR effects. Here we will show first results of measurements and compare to simulations.