FEL 2006 - List of Keywords (linac)

A B C D E F G H I K L M O P Q R S T U V W

linac

Paper	Title	Other Keywords	Page
MOAAU05	The First Lasing of 193 nm SASE, 4th Harmonic HGHG and ESASE at the NSLS SDL	laser, electron, undulator, diagnostics	18
	X. J. Wang, J. B. Murphy, J. Rose, Y. Shen, T. Tsang, T. Watanabe BNL, Upton, Long Island, New York
	After successfully achieving SASE lasing at 198 nm on April 20, 2006, we have also observed the first 4th harmonic High Gain Harmonic Generation (HGHG) with a 795 nm seed laser. We will report the progress and experimental characterization of the 198 nm SASE and 4th harmonic HGHG.
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MOBAU03	The European XFEL Project	electron, undulator, radiation, photon	24
	R. Brinkmann DESY, Hamburg
	The European X-ray Free Electron Laser XFEL is a 4th generation synchrotron radiation facility based on the SASE FEL concept and the superconducting TESLA technology for the linear accelerator. This multi-user facility will provide photon beams in a wavelength regime from 0.1nm to 5nm in three FEL beam lines and hard X-rays in two spontaneous radiation beam lines, serving in total 10 experimental stations in the first stage. The project is in an advanced planning and technical preparation stage and its construction as a European/International facility near DESY in Hamburg will start in 2007. This talk gives an overview of the overall layout and parameters of the facility, with emphasis on the accelerator design, technology and physics.
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MOPPH009	Beam Dynamics Experiments and Analysis on CSR Effects at FLASH	simulation, space-charge, electron, RF-structure	56
	B. Beutner, W. Decking, M. Dohlus, T. Limberg, M. Roehrs DESY, Hamburg
	High peak currents at the FLASH linac are produced using magnetic bunch compressor chicanes. In these magnetic chicanes, the energy distribution along an electron bunch is changed by the emission of coherent synchrotron radiation (CSR). Due to dispersion, these energy changes lead to transverse displacements along the bunch. The projection into the longitudinal horizontal plane is observed with a transverse deflecting rf-structure. Measurements of CSR induced transverse displacements are presented and compared with simulations.

MOPPH032	Analysis of FEL Oscillations in a Perfectly Synchronized Optical Cavity	electron, undulator, laser, radiation	107
	N. Nishimori JAEA/FEL, Ibaraki-ken
	We analyze free electron laser (FEL) oscillations in a perfectly synchronized optical cavity by solving the one dimensional FEL equations. The radiation stored in the cavity is shown to finally evolve into an intense few-cycle optical pulse in the high gain and low loss regime. The evolution of the leading slope of the optical pulse, which is defined from the front edge toward the primary peak, is found to play an important role in generating the intense few-cycle pulse. The phase space evolution of electrons on the second pass which interact with the leading slope of a SASE output pulse is obtained in a perturbation method similar to that used in our previous study for a SASE FEL. The resulting analytical solution of the leading slope in the 2nd pass is shown to be approximated by that of a SASE FEL with FEL parameter greater than rho. The same perturbation method can thus be used to the subsequent passes. The peak amplitude and the pulse length at saturation are found to scale with the electron beam density and optical cavity loss. Those scalings accounts for the intense few-cycle FEL pulses observed in a high power FEL. N. Nishimori, Phys. Rev. ST-AB 8, 100701 (2005).

MOPPH051	Development and Application of Figures of Merit to Evaluate the Output of HGHG FEL Cascades	radiation, background, electron, simulation	154
	B. C. Kuske, R. Follath, A. Meseck BESSY GmbH, Berlin
	In the design of Free Electron Lasers, parameters like the peak power and the spectral power were established as figures of merit to evaluate the FEL output quality. However, spectra obtained with FEL studies using bunches from start-to-end simulations do not have a purely Gaussian profile, so that these simple parameters can no longer be used as figures of merit. Furthermore, criteria such as the signal-to-noise ratio and the stability of the source point, which is of extreme importance for the transport of the radiation to the user experiment, should be included in the design considerations. This paper suggests different criteria and parameters to describe and compare the FEL output, which are not readily provided by the common FEL codes. An IDL code has been written, that extracts this information from the regular GENESIS output. This procedure will be used to analyze the output of the BESSY FEL.

MOPPH054	FERMI @ Elettra: A Seeded FEL Facility for EUV and Soft X-Rays	electron, undulator, laser, radiation	166
	J. N. Corlett, L. R. Doolittle, W. M. Fawley, S. M. Lidia, G. Penn, I. V. Pogorelov, J. Qiang, A. Ratti, J. W. Staples, R. B. Wilcox, A. Zholents LBNL, Berkeley, California E. Allaria, C. J. Bocchetta, D. Bulfone, F. C. Cargnello, D. Cocco, P. Craievich, G. D'Auria, M. B. Danailov, G. De Ninno, S. Di Mitri, B. Diviacco, M. Ferianis, A. Galimberti, A. Gambitta, M. Giannini, F. Iazzourene, E. Karantzoulis, M. Lonza, F. M. Mazzolini, G. Penco, L. Rumiz, S. Spampinati, G. Tromba, M. Trovo, A. Vascotto, M. Veronese, M. Zangrando ELETTRA, Basovizza, Trieste M. Cornacchia, P. Emma, Z. Huang, J. Wu SLAC, Menlo Park, California W. Graves, F. X. Kaertner, D. Wang MIT, Middleton, Massachusetts
	We describe the conceptual design and major performance parameters for the FERMI FEL project funded for construction at the Sincrotrone Trieste, Italy. This user facility complements the existing storage ring light source at Sincrotrone Trieste, and will be the first facility to be based on seeded harmonic cascade FELs. Seeded FELs provide high peak-power pulses, with controlled temporal duration of the coherent output allowing tailored x-ray output for time-domain explorations with short pulses of 100 fs or less, and high resolution with output bandwidths of the order of meV. The facility uses the existing 1.2 GeV S-band linac, driven by electron beam from a new high-brightness rf photocathode gun, and will provide tunable output over a range from ~100 nm to ~10 nm, and APPLE undulator radiators allow control of x-ray polarization. Initially, two FEL cascades are planned, a single-stage harmonic generation to operate over ~100 nm to ~40 nm, and a two-stage cascade operating from ~40 nm to ~10 nm or shorter wavelengh, each with spatially and temporally coherent output, and peak power in the GW range.

MOPPH058	Start-to-end Time-Dependent Study of FEL Output Sensitivity to Electron-beam Jitters for the First Stage of the FERMI@Elettra Project	electron, simulation, photon, emittance	178
	G. De Ninno, E. Allaria, M. Trovo ELETTRA, Basovizza, Trieste
	Sensitivity of the output laser pulse to electron-beam jitters is one of the major issues affecting the expected performance of both SASE and seeded FEL's. Focusing on the first stage of the FERMI@Elettra project, in this paper we present results of time-dependent numerical simulations in which the codes GENESIS and GINGER have been used to process a large number of electron-beam distributions generated at the gun using the code GPT and propagated through the linac using the code ELEGANT.

MOPPH061	The Test Facility for Harmonic Generation at the MAX-lab Injector Linac	undulator, laser, electron, gun	182
	S. Werin, M. Brandin, T. Hansen, S. Thorin MAX-lab, Lund M. Abo-Bakr, J. Bahrdt, K. Goldammer BESSY GmbH, Berlin A. L'Huillier, J. Larsson, A. Persson, C.-G. Wahlstrom New Affiliation Request Pending, -TBS-
	The MAX-lab injector linac system will be used in a test set-up for developing and testing techniques important for the designs of the BESSY FEL and the MAX IV FEL proposals. The first goal is using a 400 MeV electron beam to generate third harmonic photons at 90 nm from a 266 nm seed laser. The installations at MAX-lab are being improved by a new photo cathode RF gun (to improve emittance and peak current), an optical klystron (2 undulators + chicane, supplied by BESSY) and a combined synchronised laser system for both the RF-gun and the seeding system. The injector optics and transport system are also being retuned to allow the necessary electron beam compression. The project is a part of the EUROFEL collaboration.

MOPPH066	Chirped Pulse Amplification Experiment at 800 nm	electron, laser, undulator, dipole	194
	L.-H. Yu, D. F.L. Liu, J. Rose, T. V. Shaftan, T. Tsang, X. J. Wang, T. Watanabe BNL, Upton, Long Island, New York
	We report the chirped pulse amplification (CPA) experiment carried out using 800 nm direct seed and NISUS undulator as free electron laser amplifier at SDL of BNL. The experiment indicated that due to saturation in the center part of the chirped electron bunch the output pulse shape has a dip in the middle, as result the edge of the bunch has higher power than the center. Hence the output spectrum also showed a dip in the center, resulting a larger FWHM bandwidth than the seed. An interesting result is that the output of the 800 nm chirped FEL pulse was compressed and generated a pulse length shorter than what the seed itself can be compressed to.

MOPPH071	Design Status of PAL-XFEL	undulator, radiation, electron, space-charge	210
	T.-Y. Lee, Y. S. Bae, J. Choi, J. Y. Huang, H.-S. Kang, C. Kim, D. E. Kim, M. Kim, I. S. Ko, J.-S. Oh, Y. W. Parc PAL, Pohang, Kyungbuk Y. Kim FEL/Duke University, Durham, North Carolina J. H. Park POSTECH, Pohang, Kyungbuk
	Pohang Accelerator Laboratory has a plan to build an X-ray FEL machine. This new machine will utilize the existing 2.5 GeV injection linac to the storage ring by upgrading its energy up to 3.7 GeV or more. The target wavelength will be 3-4.5 Angstrom and its third harmonic 1-1.5 Angstrom will also be used. The project will proceed in two stages: In the first stage, a VUV SASE machine with 385 MeV will be constructed and tested for the proof-of-principle. The full X-ray machine will be constructed in the next stage.

MOPPH072	Ultra High Brightness Accelerator Design	emittance, electron, acceleration, cathode	214
	R. J. Bakker, A. Adelmann, A. Anghel, M. Dehler, R. Ganter, S. C. Leemann, K. L. Li, M. Pedrozzi, J.-Y. Raguin, L. Rivkin, V. Schlott, F. Q. Wei, A. F. Wrulich PSI, Villigen
	The Low Emittance Gun (LEG) Project at the Paul Scherrer Institute (PSI) in Switzerland incorporates the development of an ultra low emittance electron-source to drive a cost-effective X-ray FEL. For this purpose the source is based on field-emitter technology followed by high gradient (1 MV, 0.25 GV/m) acceleration. However, even with such a design the emerging electron beam is fragile and it is not evident that the low emittance can be preserved in the following acceleration process. Here we present a concept to achieve this goal, i.e., the status of the electron source development and an overview of the acceleration concept. Emphasis is given to a 250 MeV accelerator design, which is suited to serve as an injector for an X-ray FEL at 0.1 nm (12.4 keV) and boosts the electron beam into a regime where space-charge forces become less dominant. K. Li et al., Proceedings of the FEL2005 Conference, Stanford, CA, USA, p. 483 (2005)

TUAAU01	Performance Achievements and Challenges for FELs Based on Energy Recovery Linacs	electron, laser, recirculation, radiation	252
	G. A. Krafft Jefferson Lab, Newport News, Virginia
	During the past decade several groups have assembled free electron lasers based on energy recovered linacs (ERLs). Such arrangements have been built to obtain high average power electron and photon beams, by using high repetition rate beam pulses driving FEL oscillators. In this talk the performance of many existing and several proposed facilities from around the world are analyzed and reviewed. Going forward, many questions must be addressed to achieve still better performance including: higher average current injectors, better optimized accelerating cavities, higher energy acceptance and lower loss beam recirculation systems, and better optical cavity designs for dealing with the optical beam power circulating in the ERL FELs. The talk presents some of the current thinking on each of these issues.
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TUAAU02	Future Light Sources: Integration of Lasers, FELs and Accelerators at 4GLS	electron, radiation, undulator, laser	257
	J. A. Clarke CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
	4GLS is a novel next generation proposal for a UK national light source to be sited at Daresbury Laboratory, based on a superconducting energy recovery linac (ERL) with both high average current photon sources (undulators and bending magnets) and three high peak current free electron lasers. Key features are a high gain, seeded FEL amplifier to generate XUV radiation and the prospect of advanced research arising from unique combinations of sources with femtosecond pulse structure. The conceptual design is now completed and a CDR recently published. The 4GLS concept will be summarised, highlighting how the significant design challenges have been addressed, and the project status and plans explained.
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TUAAU03	FEL Oscillation with a High Extraction Efficiency at JAEA ERL FEL	electron, undulator, quadrupole, laser	265
	N. Nishimori JAEA/FEL, Ibaraki-ken R. Hajima, H. Iijima, N. Kikuzawa, E. J. Minehara, R. Nagai, T. Nishitani, M. Sawamura JAEA/ERL, Ibaraki
	One of challenges that high power FEL oscillators with energy recovery linac (ERL) are facing is to increase the extraction FEL efficiency as high as possible. The high efficiency oscillation relaxes the total beam current needed for high power lasing and makes the FEL optical pulse length shorter, which is useful for various applications. A Bates type recovery loop with energy acceptance well in excess of 10% allows an ERL FEL at Jefferson Lab to operate with a high FEL efficiency. A triple bend achromat loop with energy acceptance of 7% has been used in an ERL FEL at Japan Atomic Energy Agency (JAEA). Recently we have achieved the efficiency exceeding 2%, which accompanies large energy spread beyond the energy acceptance of the loop, by doubling the electron bunch repetition rate*. The optical pulse can now interact with a fresh electron bunch every round trip, while it overlapped with an injected electron every two round trips before the doubling of the bunch repetition. This talk will summarize our recent development of a high power FEL with a high extraction efficiency at JAEA ERL FEL. S. Benson et al., in proceedings of the FEL2004, (2004) 229. R. Hajima et al., Nucl. Instr. and Meth. A445 (2000) 384. * R. Nagai et al., in these proceedings.
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TUAAU05	Optical Design of the Energy Recovery Linac FEL at Peking University	undulator, emittance, simulation, space-charge	277
	Z. C. Liu, J.-E. Chen, J. K. Hao, K. X. Liu, X. Y. Lu, S. W. Quan, B. C. Zhang, K. Zhao, G. M. wang PKU/IHIP, Beijing
	Peking University is currently building an Energy Recovery Linac FEL (PERFEL). The system is consisted of the DC-SC photocathode injector, the superconducting main linac which is composed of two nine cell TESLA-type cavities and the beam transport system. The objective of the PERFEL is to build a testbed for the study of beam dynamics and accelerator technology for energy recovery except to provide infrared FEL. In this paper the main parameters of the PERFEL are described and the optical design for the beam transport of PERFEL is presented. The simulation is carried out using the typical particle tracking codes such as elegant. *Corresponding author. Tel: +86-10-6275-8528; Fax: +86-10-6275-1875. Email address: kxliu@pku.edu.cn
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TUBAU06	Investigations of the Longitudinal Electron Bunch Structure at the FLASH Linac with a Transverse Deflecting RF-Structure	emittance, quadrupole, electron, dipole	300
	M. Roehrs, C. Gerth, H. Schlarb DESY, Hamburg
	At the FLASH linac at DESY, electron bunches with high peak currents are produced by bunch shortening in two magnetic chicanes induced by a nearly linear energy-time gradient. Thereby the high current region of a compressed bunch is distorted by coherent synchrotron radiation and space charge forces. Consequences of these effects are a degradation of time-sliced transverse emittance, slice centroid shifts and characteristic energy-time correlations. In this paper we present measurements of the aforementioned quantities for different compression schemes with a transverse deflecting rf-waveguide (LOLA). The structure allows to establish the longitudinal density profile of single bunches on the vertical axis of an OTR-screen. The horizontal time-sliced emittance can be reconstructed from measurements of the slice widths for different quadrupole settings. By dispersing vertically streaked bunches horizontally with a dipole, the energy-time correlation can be directly obtained in a single shot measurement. The measurement results are compared to simulations.
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TUPPH002	Development of Frequency-Resolved Optical Gating for Measurement of Correlation between Time and Frequency of Chirped FEL	simulation, laser, polarization, electron	308
	H. Iijima, R. Hajima, E. J. Minehara, R. Nagai, N. Nishimori JAEA/ERL, Ibaraki
	A femtosecond infrared-chirped FEL is an effective way of dissociating molecules without the intramolecular vibrational redistribution. At Japan Atomic Energy Agency (JAEA), an energy recovery linac (ERL) has been investigated to produce high power FEL at far-infrared region. Normally the long-pulse electron beam is operated by the ERL; therefore the high-power chirped pulse can be generated. Until now, the amount of chirp in the pulse was measured to be f/f₀ = 14% with the wavelength of 23 μm and the pulse width of 320 fs at FWHM. However the correlation between time and frequency in the chirped pulse was not measured. In order to measure the correlation between time and frequency in the chirped pulse directly, we have started to construct an FEL transport system and the frequency-resolved optical grating in new experimental room. The chirped pulse is guided to the experimental room by a 22-m vacuum duct which avoids the absorption of infrared radiation by water vapor. The optical focusing systems are located at the entrance and exit of the vacuum duct. Now we are measuring basic parameters of the chirped pulse (beam size, power and so on) in the experimental room.

TUPPH005	Beam Current Doubling of JAEA ERL-FEL	electron, beam-transport, extraction, acceleration	312
	R. Nagai, R. Hajima, H. Iijima, N. Kikuzawa, E. J. Minehara, N. Nishimori, T. Nishitani, M. Sawamura JAEA/ERL, Ibaraki
	An energy-recovery linac (ERL) for a high-power free-electron laser (FEL) R&D program is in progress at Japan Atomic Energy Agency (JAEA). The first energy-recovery operation and FEL lasing was demonstrated in 2002 by remodeling the original superconducting linac. In the first demonstration, the accelerated beam current was same as the original linac. One of the benefits of the ERL is that the accelerating beam current can be easily increase by changing micro-pulse repetition rate without increasing the main linac RF source. After the first demonstration, the e-gun, the injector RF source, the low-level RF controller, and the operation system were improved for the beam current doubling. The doubled beam acceleration and FEL lasing have been successfully achieved with 10mA of beam current and 0.7kW of FEL power.

TUPPH006	Performance of a Conventional Analog Phi-A Type Low-Level RF Controller	feedback, free-electron-laser, laser, monitoring	316
	R. Nagai, R. Hajima, H. Iijima, N. Kikuzawa, E. J. Minehara, N. Nishimori, T. Nishitani, M. Sawamura JAEA/ERL, Ibaraki
	For an FEL application and an ERL light source, high-stability of accelerator RF amplitude and phase is required. A low-level RF controller (LLC) of the JAEA-ERL has been improved to ensure high-stability accelerating RF field. The LLC is a conventional analog phi-A type controller with following functions: the feedback gain, loop-offset phase and time constant can be varied during operation to obtain optimum parameters for the high-stability RF field, all the circuits are contained in a temperature controlled oven. The LLC performance is tested for a 499.8MHz superconducting cavity and a 1300MHz copper cavity. The phase and amplitude stabilities of the 499.8MHz superconducting cavity within a 1ms macro-pulse are 0.0055deg-rms and 7.64×10^-5, respectively. For the 1300MHz copper cavity, pulse mode and CW mode were tested. In the case of pulse mode, the phase and amplitude stabilities are 0.011deg-rms and 7.64×10^-5, respectively. In the case of CW mode, the phase and amplitude stabilities are 0.011deg-rms and 6.68×10^-5, respectively.

TUPPH009	A Design Study of a FIR/THz-FEL for High Magnetic Field Research	radiation, resonance, wiggler, electron	327
	M. Tecimer, L. C. Brunel, J. van Tol NHMFL, Tallahassee, Florida G. Neil Jefferson Lab, Newport News, Virginia
	Presently a conceptual design work for a NIR-FIR FEL system at the NHMFL/FSU is being undertaken. The system is intended to combine high magnetic field research with an intense, tuneable photon source, spanning the spectral region ~2–10⁰⁰ microns. Here, we present a design study involving the FIR/THz part of the NHMFL FEL design proposal. The suggested long-wavelength FEL encompasses in the first phase a thermionic injector (similar to that in use at the Forschungszentrum-Rossendorf ELBE facility) with a planned ~2 mA average current and a ~10 MeV superconducting rf linac module operating at 1.3 GHz. The broadband outcoupling over the envisaged FIR/THz spectral range (100–110⁰ microns) is accomplished by adopting a single (variable height slot) outcoupler in a waveguided cavity. Besides the performance predictions of the suggested long-wavelength FEL, techniques for the generation of high peak power, nanoseconds long THz pulses (for magnetic resonance applications) are also reported.

TUPPH032	Development of Powerful FEMs for X, Ka and W Bands for Physical and Industrial Applications	radiation, electron, controls, wiggler	390
	M. Einat CJS, Ariel N. S. Ginzburg, N. Yu. Peskov, M. I. Petelin IAP/RAS, Nizhny Novgorod A. Gover, Y. Socol University of Tel-Aviv, Faculty of Engineering, Tel-Aviv A. Kaminsky, S. Sedykh JINR, Dubna, Moscow Region J. Lucas University of Liverpool, Liverpool
	FEMs are among the main sources of powerful microwave pulses from X to W-bands. Interest to such sources is caused by the large number of potential physical and industrial applications, requiring a wide variety of the radiation parameters. The new generation of the accelerators (SLAC, CERN) requires sources of ~100 MW pulse RF power at 30-38 GHz with a narrow spectrum. Material processing stations require kW-level average power. Alternatively, spectroscopic and biological experiments require lower power but for a specific frequency spectrum. The possibility to develop such sources is being studied at Tel-Aviv University, IAP RAS, JINR and The University of Liverpool within the framework of the INTAS collaboration project. Three successful FEM experiments have been carried out: Electrostatic-accelerator driven 70-130 GHz Tandem-FEM with kW-level pulse power (Tel-Aviv University.) Linac-driven 30-GHz FEM-oscillator with pulse RF power of ~ 20 MW (JINR + IAP RAS) Sub-relativistic e-beam industrial FEM tunable over X-band with output power up 1 kW (The University of Liverpool). The presentation summarizes the progress in the development of FEMs and their applications.

TUPPH038	Commissioning of S-band RF GUN and Linac for the Mark-III FEL Facility at Duke University	gun, cathode, electron, emittance	411
	Y. Kim, G. Edwards, M. Emamian, J. Gustavsson, S. M. Hartman, G. Swift, P. W. Wallace, P. Wang FEL/Duke University, Durham, North Carolina
	At the Free Electron Laser (FEL) Laboratory of Duke University, there is an S-band linac based Mark III FEL facility which can supply coherent FEL photon beam in the infrared wavelength range. To supply high quality electron beams and to have excellent pulse structure, we installed a new S-band RF GUN with the LaB6 cathode for the Mark III FEL facility in 2005. Since maximum repetition rates of macropulse and micropulse are 15 Hz and 2856 MHz, respectively, our new RF GUN can generate 17142 bunches within a 6 us long bunch train, and maximum 257130 bunches within one second. In this paper, we describe recent commissioning experiences of our newly installed S-band RF GUN and Linac for the Mark III FEL facility.

TUPPH040	Emittance Compensation of Superconducting Gun and Linac System for Beams with Large Chromatic Variance	emittance, focusing, gun, chromatic-effects	419
	B. Buckley Cornell University, Ithaca, New York D. Kayran, V. Litvinenko BNL, Upton, Long Island, New York
	Among the methods of emittance compensation for a superconducting rf gun and linac system include utilizing a solenoid and drift space after the gun to achieve a specific beam envelope with zero beam divergence before entrance into the linac. Studies on this method have assumed minimal energy spread in the beam. However, in cases where chromatic effects cannot be ignored this one solenoid emittance compensation technique is inadequate. Proposed is a new method of emittance compensation utilizing two solenoids in order to minimize emittance in beams with large energy spread. We present a theoretical basis for the new technique along with a computer optimized configuration. The results are compared with previous methods of emittance compensation.

TUPPH072	Generation and Characterization of the Microbunched Beams in the Range from 0.3 to 500 Femtoseconds	target, electron, radiation, laser	481
	V. Yakimenko, M. Babzien, K. Kusche BNL, Upton, Long Island, New York E. K. Kallos, P. Muggli UCLA, Los Angeles, California W. D. Kimura STI, Washington
	The presentation will cover recent experimental results on generation and measurement of the beams with the bunch lengthes from 0.3 to 500 fs at Brookhaven Accelerator Test Facility. Double beam structure is produced at 100 fs - 0.5 ps time scale using compression in the magnetic chicane - "dog leg" arrangement. The beam structure is characterized using interferometer and 6 mm long plasma wakefield channel with the controllable plasma density. Arbitrary number of 10-100 femtosecond microbunches is sliced out of 5 ps long beam using wire mesh. CSR interferometer is used for detailed characterization of the beams. Accuracy of the bunch length measurement using CSR energy is greatly improved for the 0.3 fs bunches by spectral measurements of multiple harmonics.

TUCAU02	The Rossendorf IR-FEL ELBE	electron, laser, radiation, undulator	488
	P. Michel, H. Buettig, F. G. Gabriel, M. Helm, U. Lehnert, Ch. Schneider, R. Schurig, W. Seidel, D. Stehr, J. Teichert, S. Winnerl, R. Wuensch FZR, Dresden
	The radiation source ELBE is the central research facility in the Forschungszentrum Rossendorf. The machine is based on a 40 MeV superconducting RF Linac wich can be operated up to 1 mA in cw mode. After commissioning the Bremsstrahlung and the X-ray facilities in 2002, and 2003 respectively, and the first lasing of the mid-IR FEL (4-22 um) in 2004 about 7000 hours user beam-time have been provided. At present a second FEL for long IR waves (15-150 um) using a partial waveguide is under commissioning. Besides in-house users especially the IR beam is available to external users in the FELBE (FEL@ELBE) program witch is a part of the integrated activity on synchrotron and free electron laser science in the EU. In this talk the fundamental features of the ELBE IR FEL's and the parameters demanded by users are displayed. In addition, an overview about user experimental work and important machine date like availability are shown. Future projects like the combination of the new High Magnetic Field lab with the ELBE-IR beams will be described.
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TUCAU03	Status of the Novosibirsk High Power Terahertz FEL	radiation, electron, undulator, laser	492
	N. Vinokurov, N. Gavrilov, B. A. Knyazev, E. I. Kolobanov, V. V. Kotenkov, V. V. Kubarev, G. Kulipanov, A. N. Matveenko, L. E. Medvedev, S. V. Miginsky, L. A. Mironenko, A. D. Oreshkov, A. V. Ovchar, V. Ovchar, V. M. Popik, T. V. Salikova, M. A. Scheglov, S. S. Serednyakov, O. A. Shevchenko, A. N. Skrinsky, V. G. Tcheskidov BINP SB RAS, Novosibirsk
	The first stage of Novosibirsk high power free electron laser (FEL) was commissioned in 2003. It is based on the normal conducting CW energy recovery linac (ERL). Now the FEL provides electromagnetic radiation in the wavelength range 120 - 230 micron. The maximum average power is 400 W. The minimum measured linewidth is 0.3%, which is close to the Fourier-transform limit. Four user stations are in operation now. Manufacturing of the second stage of the FEL (based on the four-turn ERL) is in progress.
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TUCAU04	FEL Activities in India	undulator, gun, electron, plasma	496
	S. Krishnagopal, B. Biswas, S. Chouksey, S. K. Gupta, U. Kale, A. Kumar, V. Kumar, S. Lal, P. Mehta, P. Nerpagar, K. K. Pant RRCAT, Indore (M. P.)
	We are building a Compact Ultrafast Terahertz Free-Electron Laser (CUTE- FEL), designed to lase between 50 - 100 microns. It will be driven by a 15 MeV electron beam from a Plane-Wave Transformer linac. The undulator is a 5 cm period, 2.5 m long, PPM planar undulator. We present details of the FEL design and the present status of activities. We also present very preliminary plans for a short-wavelength SASE FEL in India.
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THBAU03	How to Obtain High Quality Electron Bunches in the Presence of Normal Conducting LINAC Wake Fields	electron, emittance, laser, radiation	537
	S. Di Mitri ELETTRA, Basovizza, Trieste
	The dynamics of electron beams involved in Free Electron Lasers (FELs) projects is an interplay between sources of 6-dimensional emittance dilution and methods of emittance preservation. Relatively long bunches are required for harmonic cascade seeded FELs in order to accommodate the timing jitter and the seed provided by the bunch itself at each stage of the cascade. A high quality is required from such electron beams (small transverse emittance and energy spread) together with a uniform distribution in time along the usable part of the bunch; non-linearity in the longitudinal phase space and in the transverse planes are also issues. A complex longitudinal phase space dynamics characterizes the study often in presence of by the Coherent Synchrotron Radiation (CSR) generated in magnetic compressors. This paper reviews specific problems related to the electron beam dynamics dominated by bunches of kA peak current and varying length (0.1 to 2 ps) in the presence of normal conducting linac wakefields. Methods implemented to minimize the 6-dimensonal phase space degradation are discussed. Results of high beam quality performance are illustrated with particles tracking codes.
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	Talk

THPPH003	A High Average Power RF-Photoinjector Gun Cavity Developed for the BESSY Soft X-ray FEL	gun, emittance, electron, laser	560
	F. Marhauser, M. Dirsat, V. Duerr, A. Meseck, R. Richter, E. Weihreter BESSY GmbH, Berlin G. Asova, J. W. Baehr, H.-J. Grabosch, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, A. Oppelt, B. Petrosyan, L. Staykov, F. Stephan DESY Zeuthen, Zeuthen O. Kalekin Humboldt Universität zu Berlin, Berlin J. R. Roensch Uni HH, Hamburg F. Tonisch DESY, Hamburg
	A 1.3-GHz, high duty factor, high-repetition-rate rf photoinjector gun cavity has been developed at BESSY. RF conditioning and high-power tests have been performed at the Photoinjector Test Facility at DESY Zeuthen (PITZ). The measurement results will be presented in this paper.

THPPH016	First Experience with the Machine Protections System of FLASH	undulator, beam-losses, radiation, laser	587
	L. Fröhlich Uni HH, Hamburg M. Görler, P. Göttlicher, D. Noelle, D. Pugachov, H. Schlarb, S. Schreiber, M. Staack, M. Werner DESY, Hamburg A. Hamdi, M. Luong, J. Novo CEA, Gif-sur-Yvette
	Superconducting LINACs provide high brightness beams with substantial beam power. The design of the TTF2 machine is 70 kW beam power at the dump, XFEL will run 2 dump systems with 600 kW each. From this numbers is becomes very clear, that protections systems are required. This paper will present the design and implementation of the machine protection system of the FLASH facility, and will report on the first operational experience.

THPPH027	Ramping Longitudinal Distribution Studies for the FERMI@ELETTRA Injector	space-charge, cathode, emittance, electron	621
	G. Penco, M. Trovo ELETTRA, Basovizza, Trieste S. M. Lidia LBNL, Berkeley, California
	In the Fermi Linac optimization studies it comes out the request to have at the exit of the photoinjector a linear ramp in the current distribution along the bunch as alternative option with respect to the flat-top. This requirement is translated in the photoinjector optimization in a big issue. In fact the longitudinal bunch profile at the exit of the photoinjector is affected by the strong non linearity of the space charge fields at the cathode and in the drift between the gun and the first booster. The knowledge of the space charge fields at the cathode plays in important role in finding the optimum driven laser pulse shape. At this purpose an analytical description of the space charge fields produced by a bunch with an arbitrary current distribution at the cathode is provided. Space charge codes (GPT and ASTRA) have been used to evaluate the evolution of several ramping profiles from the cathode to the entrance of the first booster and the results are presented in this paper.

THPPH028	Further Studies in the FERMI@ELETTRA Photoninjector Optimization	emittance, laser, gun, electron	625
	M. Trovo, G. Penco ELETTRA, Basovizza, Trieste S. M. Lidia LBNL, Berkeley, California
	In the framework of the FERMI@ELETTRA project we are presently studying an electron beam configuration satisfying the bunch energy requirements coming out from the FEL photon production system. The multi-particles tracking code results concerning the photoinjector set up which includes the RF gun and the first two accelerating sections are presented in this paper, describing two possible electron bunch configurations, which satisfy the FEL operation modes. Both injector configurations aim to match the linac requirements to have a ramped current profile at the exit of the photoinjector. Moreover sensitivity studies, time and energy jitters estimations are presented for both cases.

THPPH033	Sub-Pico-Second Trigger System for the SCSS Prototype Accelerator	acceleration, electron, target, controls	645
	Y. Otake, H. Maesaka, T. Shintake RIKEN Spring-8 Harima, Hyogo T. Fukui, N. Hosoda, T. Ohata, T. Ohshima JASRI/SPring-8, Hyogo-ken
	At RIKEN, Harima Institute, the project (SCSS) of X-FEL including the 8 GeV linac is in progress. Now, to verify feasibility of X-FEL, the 250 MeV test electron linac is building at SPring-8. A time jitter of the order of ten femto-seconds is required to the timing system of the 8 GeV linac, because of a beam pulse width of several ten femto-seconds. However, realizing this jitter value is very difficult by the present electronics technology. Therefore, we temporarily set a sub-pico-seconds time jitter as a development target, because the beam pulse width of the test linac is several pico-seconds. This jitter value had possibility to be achieved by the present technology. In accordance with the target, we developed a very low noise reference signal source that generates 238 MHz and 5712 MHz RF signals, a master trigger VME module having output pulses synchronized by 238 MHz, and a trigger delay VME module synchronized by 5712 MHz. The time jitter of the delay module is less than 700 fs, and the SSB noise of the 5712 MHz reference signal source is less than -120 dBc at 1 kHz offset. These values are enough for our present requirement.

THPPH041	Longitudinal Phase-Space Measurements of a High-Brightness Single-Bunch Beam	electron, radiation, photon, single-bunch	676
	R. Kato, T. Igo, G. Isoyama, S. Kashiwagi, Y. Kon ISIR, Osaka
	The performance of a SASE-FEL strongly depends on the beam parameters, such as a longitudinal beam profile, a bunch charge, transverse emittances and an energy profile. The correlation between the longitudinal electron positions in a bunch and their energies has a critical effect on the temporal evolution of the optical pulse of SASE, and various methods to evaluate the longitudinal phase-space profile are under intense study. A new technique to measure the longitudinal phase-space distribution of the bunched electrons in one-shot using the combination of an energy profile monitor and a streak camera are currently under development at ISIR, Osaka University. In this contribution, preliminary experimental results of the measurements are presented.

THPPH043	Stable RF Phase Insensitive to the Modulator Voltage Fluctuation of the C-band Main Linac for SCSS XFEL	klystron, acceleration, electron, emittance	684
	J.-S. Oh, T. Hara, T. Inagaki, J.-S. Oh, T. Shintake, K. Shirasawa RIKEN Spring-8 Harima, Hyogo
	The SCSS (SPring-8 Compact SASE Source) XFEL requires extremely stable RF system in both amplitude and phase. The fluctuation of RF output is mainly caused by modulation of the klystron beam-voltage pulse, which is directly governed by the charging stability of a klystron modulator. During R&D study on beam stability, we found a special operation point, where the beam energy gain is insensitive to the modulator voltage fluctuation. This phase can cancel out the both fluctuations and provide constant accelerating field. The stable phase depends on the klystron parameters such as the length of drift tube, operating voltage, efficiency. It is about 9 degree in case of the C-band main linac for SCSS XFEL. The bunch length after bunch compressor is so short that additional longitudinal energy spread due to the RF curvature is about 5% of the one caused by the longitudinal wake field. The particle energy is high enough so that longitudinal defocusing is negligible. The reduction of beam energy due to off-crest acceleration is less than 2%. This paper shows the analytical relation of the stable phase. ELEGANT simulation shows no appreciable degradation of the slice parameters.

THPPH054	Linac Coherent Light Source Undulator RF BPM System	dipole, undulator, coupling, vacuum	706
	R. M. Lill, L. H. Morrison, G. J. Waldschmidt, D. R. Walters ANL, Argonne, Illinois R. Johnson, Z. Li, S. Smith, T. Straumann SLAC, Menlo Park, California
	The LCLS will be the world's first x-ray free electron laser when it becomes operational in 2009. LCLS is currently in the construction phase. The beam position monitor (BPM) system planned for the LCLS undulator will incorporate a high resolution X-band cavity BPM system described in this paper. The X-band cavity BPM system will provide high-resolution measurements of the electron beam trajectory on a pulse-to-pulse basis and over many shots. The X-band cavity BPM size, simple fabrication and high resolution make it an ideal choice for the LCLS beam position detection. We will discuss the system specifications, design, and prototype test results.

THPPH057	Modeling and Measurement of Mu-Metal Shielding Effect on the Magnetic Performance of an LCLS Undulator*	undulator, shielding, simulation, dipole	718
	S. Sasaki, E. Trakhtenberg, I. Vasserman ANL, Argonne, Illinois
	In a previous paper (FEL05), we presented results showing that the Earth's field might give a significant effect on the LCLS undulator performance due to a large concentration of the field by the undulator poles. Based on the result of model calculation, we decided to shield the Earth's field by surrounding the undulator backing structure with a 1-mm-thick mu-metal sheet. First, the effect of the shield was modeled using the code RADIA. According to the calculation, the shielding factor of a C-shape mu-metal shield was better than a factor of 8. Second, we measured the Earth's field shielding effect without an undulator. In our measurement laboratory, the vertical component of the Earth's field was 0.5 gauss. It was suppressed to smaller than 0.1 gauss with the shield. After these background measurements, we examined the effect of the shield with an undulator in place. The measurement results show very good agreement with the model calculation.

THPPH066	Longitudinal Phase Space Characterization of Electron Bunches At the JLab FEL Facility	electron, laser, diagnostics, monitoring	740
	S. Zhang, S. V. Benson, D. Douglas, D. Hardy, G. Neil, M. D. Shinn Jefferson Lab, Newport News, Virginia
	We report the latest measurement of the longitudinal phase space of electron bunches on our 10kW free-electron laser facility. The design and construction of an all reflective optical transport has made it possible to make full use of broadband synchrotron radiation and perform a high-efficiency dispersion-free measurement with a remote fast streak camera. The evolution of the longitudinal phase space can be observed live when the accelerating RF phase is tuned. The results for different beam setups including low and high current will be presented.

THPPH070	Optimum Beam Creation In Photoinjectors Using Space-Charge Expansion	emittance, laser, simulation, space-charge	752
	M. P. Dunning, A. M. Cook, R. J. England, J. B. Rosenzweig UCLA, Los Angeles, California M. Bellaveglia, M. Boscolo, L. Catani, A. Cianchi, G. Di Pirro, M. Ferrario, D. Filippetto, G. Gatti, L. Palumbo, C. Vicario INFN/LNF, Frascati (Roma) S. M. Jones Jet Propulsion Laboratory, Pasadena, California P. Musumeci INFN-Roma, Roma
	It has recently been shown that by illuminating a photocathode with an ultra-short laser pulse of appropriate transverse profile, a uniform density, ellipsoidally shaped bunch is dynamically formed, which then has linear space-charge fields in all dimensions inside of the bunch. We study here this process, and its marriage to the standard emittance compensation scenario that is implemented in most modern photoinjectors. It is seen that the two processes are compatible, with simulations indicating that a very high brightness beam can be obtained. The scheme has produced stimulus for a series of experiments at the SPARC injector at Frascati in 2006-2007. An initial time-resolved experiment has been performed involving Cerenkov radiation produced at an aerogel. We discuss the results of this preliminary experiment, as well as plans for future experiments to resolve the ellipsoidal bunch shape at low energy. Future measurements at high energy based on fs resolution RF sweepers are discussed, and prospects for using the very low longitudinal emittance beam in a future bunch compressor to produce 10 micron long beams are evaluated.