FEL 2007 - List of Keywords (linac)

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linac

Paper	Title	Other Keywords	Page
MOPPH005	Improvements of the Tracking Code Astra for the Simulation of Dark Current Losses in the FLASH Linac	simulation, gun, space-charge, vacuum	22
	S. M. Meykopff, L. Fröhlich DESY, Hamburg
	At the Free Electron Laser in Hamburg FLASH, the activation of components due to dark current emitted by the gun has become a serious problem. To improve the understanding of dark current transport in the linac, simulations with the Astra tracking code have been conducted. These studies require a big amount of computing time due to the high number of simulated macroparticles. Therefore, the parallelized version of Astra had to be enhanced by features like dynamic load balancing and an improved aperture model. The paper will provide an overview of the new features and discuss possible remedies of the dark current problem based on the simulation results.

MOPPH023	Enhancing FEL Power with Phase Shifters	undulator, radiation, electron, simulation	69
	A. Chao, Z. Huang SLAC, Menlo Park, California D. F. Ratner Stanford University, Stanford, Califormia
	Undulator taper is a well-known technique to increase the FEL efficiency past saturation by maintaining the resonant condition. In this paper, we demonstrate that shifting the electron bunch phase relative to the radiation is equivalent to tapering the undulator parameter. Using discrete phase changes derived from optimized undulator tapers for the LCLS x-ray FEL, we show that placing appropriate phase shifters between undulator sections can reproduce the power enhancement of these undulator tapers. The phase shifters are relatively easy to implement and operate, and hence can be used to aid or replace the undulator taper for optimizing the FEL performance.

MOPPH043	Control and Diagnostic System of Novosibirsk FEL Radiation	radiation, controls, undulator, diagnostics	111
	V. V. Kubarev, E. V. Makashov, K. S. Palagin, S. S. Serednyakov BINP SB RAS, Novosibirsk
	The architecture the main capabilities of control and diagnostic system of the Novosibirsk FEL coherent radiation are described. The client-server model is used for software, controlling this system. The developed software is capable to work both in client and server mode. Also it can control various equipment – from FEL optical cavity mirrors to local equipment of users stations. The mode of control program operation and controlled equipment are determinates by external configuration files. Some results of the system operation are also presented.

MOPPH046	Operation of Near-infrared FEL at Nihon University	electron, coupling, undulator, klystron	114
	A. Enomoto, S. Fukuda, K. Furukawa, S. Michizono, S. Ohsawa KEK, Ibaraki Y. Hayakawa, K. Nakao, K. Nogami, T. Tanaka, K. Hayakawa LEBRA, Funabashi M. Inagaki, T. Kuwada, T. Sakai, I. Sato Nihon University
	The near-infrared FEL at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University has been operated for a variety of scientific applications since 2003. The stability of the FEL power was improved appreciably by the advanced stability of the 125 MeV electron linac. Currently fundamental FEL wavelength ranges from 1 to 6 microns, which is restricted by the electron energy and the optical devices. The higher harmonics in the visible region is also available. The maximum macropulse output energy of 60 mJ/pulse has been obtained at a wavelength of 1725 nm. The short FEL resonator at LEBRA causes relatively high optical energy density on the surface of the resonator mirrors; present copper-based Ag mirrors in use at LEBRA are not durable enough for long term operation. As an alternative way of generating intense harmonics in the visible to near-UV region, second and third harmonic generation by means of non-linear optical devices has been tested for the FELs around 1.5 microns as input fundamental photons.

MOPPH048	ARC-EN-CIEL Project Electron Beam Dynamics	electron, emittance, focusing, quadrupole	118
	M.-E. Couprie, A. Loulergue, C. Bruni SOLEIL, Gif-sur-Yvette
	ARC-EN-CIEL project is based on the development of fourth generation light source of high brilliance and tunable in the UV-X domain. The project will evolved into three phases leading to different light performances: first and second phases are in single pass configuration with energy of 220 MeV and 1 GeV respectively, while third phase comports recirculation loops at 1 GeV and 2 GeV. For delivering a high brilliance light source with high peak power short pulses, the high charge electron beam should have subpicoseconde duration with low emittance and energy spread. In order to keep optimal slice characteristics for light production, phase space non linearities due to optics aberrations and collective effects should be minimized. In ERL configuration, a critical consequence of collective effects is the Beam Break Up instability, which forms a feedback loop between the beam and the cavities. This contribution aims at presenting the electron beam dynamics for the ARC-EN-CIEL project in single pass and ERL configuration, especially on the conditions for minimizing non linearities and Beam Break Up instability.

MOPPH058	Status of the SPARX Project	emittance, undulator, radiation, simulation	142
	D. Filippetto INFN/LNF, Frascati (Roma)
	The SPARX project consists in an Soft-X-ray-FEL facility jointly supported by MUR(Research Department of Italian Government), Regione Lazio, CNR, ENEA, INFN and the University of Roma Tor Vergata. It is the natural extension of the ongoing activities of the SPARC collaboration. The aim is the generation of electron beams characterized by ultra-high peak brightness at the energy of 1 and 2 GeV, for the first and the second phase respectively. The beam is expected to drive a single pass FEL experiment in the range of 13.5-6 nm and 6-1.5 nm, at 1 GeV and 2 GeV respectively, both in SASE and SEEDED FEL configurations. A hybrid scheme of RF and magnetic compression will be adopted, based on the expertise achieved at the SPARC. high brightness photoinjector presently under commissioning at Frascati INFN-LNF Laboratory.

MOPPH061	Design of the PAL Test FEL Machine	undulator, emittance, simulation, electron	149
	J. Choi, J. Y. Huang, H.-S. Kang, I. S. Ko, T.-Y. Lee, J.-S. Oh, S. J. Park, M. Kim PAL, Pohang, Kyungbuk C. M. Yim POSTECH, Pohang, Kyungbuk
	In a road to the PAL-XFEL, the 1st stage will be to build a test machine, whose design parameters are presented here. It will be a 230 MeV machine that has the target wavelength of visible range. The design details and simulation results are shown in this paper.

MOPPH073	Thermal and Non-thermal Laser Cutting Utilizing Advanced Industrial Lasers and ERL-FELs	laser, electron, free-electron-laser, factory	175
	E. J. Minehara JAEA/FEL, Ibaraki-ken
	The JAEA and JLAB energy-recovery free-electron lasers (ERL-FEL) have successfully demonstrated capabilities of a few hundreds fs ultra-fast pulse lasing, 6-9% high conversion efficiency, one GW high peak power, a few kW average power, and wide tunability of infrared wavelength regions. Utilizing the high average and high peak power lasing and energy-recovery linac (ERL) technology, we could realize a more powerful and more efficient FEL than 20kW and 25%, respectively, for nuclear industry, pharmacy, medical, defense, shipbuilding, semiconductor industry, chemical industries, environmental sciences, space-debris cleaning, power beaming and so on very near future. We have performed their thermal and non-thermal cutting and machining experiments and characterized their resultant effects. In order to compare some characteristic differences of thermal and non-thermal laser cutting utilizing advanced industrial laser like fiber, and water-guided ones and the ERL-FELs, we have performed some cutting trials of them. In the presentation, we plan to discuss these differences and how to apply all the lasers to the above applications in the fields.

MOPPH074	Preliminary Design of the Proposed IR-FEL in India	electron, simulation, undulator, radiation	179
	V. Kumar, S. Krishnagopal RRCAT, Indore (M. P.)
	We propose to build a infra-red free-electron laser facility in India. We present details of the preliminary design of the FEL.

TUBAU03	STARS – an FEL to Demonstrate Cascaded HGHG	radiation, emittance, electron, laser	220
	M. Abo-Bakr, W. Anders, J. Bahrdt, R. Follath, K. Goldammer, S. C. Hessler, K. Holldack, T. Kamps, B. C. Kuske, A. Meseck, T. Quast, J. Knobloch BESSY GmbH, Berlin
	BESSY plans to build the BESSY Soft X-ray FEL facility, a second generation FEL for the VUV and soft x-ray range. The TDR was evaluated by the German Science Council and recommended for funding subject to the condition that cascaded high-gain harmonic generation (HGHG) be demonstrated beforehand. To this end, BESSY is proposing the demonstration facility STARS for a two-stage HGHG FEL. For efficient lasing from 40 nm to 70 nm, a 325 MeV driver linac is required. It consists of a normal-conducting gun, superconducting TESLA-type modules modified for CW operation and a bunch compressor. The two-stage HGHG cascade employs variable gap undulators, with the final amplifier being an APPLE-III device for full polarization control. A beamline with user experiment completes STARS, which is planned to remain operational even after the BESSY FEL comes online. This paper summarizes the layout of STARS, the main parameters and the expected performance.

TUPPH006	FEL Potential of the High Current ERLs at BNL	electron, emittance, gun, simulation	232
	I. Ben-Zvi, V. Litvinenko, E. Pozdeyev, D. Kayran BNL, Upton, Long Island, New York
	An ampere class 20 MeV superconducting Energy Recovery Linac (ERL) is under construction at Brookhaven National Laboratory (BNL)* for testing concepts for high-energy electron cooling and electron-ion colliders. This ERL prototype will be used as a test bed to study issues relevant for very high current ERLs. High average current and high performance of electron beam with some additional components make this ERL an excellent driver for high power far infrared Free Electron Laser (FEL). A possibility for future up-grade to a two-pass ERL is considered. We present the status and our plans for construction and commissioning of the ERL. We discus a FEL potential based on electron beam provided by BNL ERL. * Litvinenko, V. N. et al. High current energy recovery linac at BNL. Proc. 26th International Free Electron Laser Conference and 11th FEL Users Workshop (FEL 2004).

WEAAU04	Superconducting Photoinjector for High-Power Free Electron Lasers	gun, electron, cathode, emittance	290
	A. Burrill, R. Calaga, X. Chang, R. Grover, R. C. Gupta, H. Hahn, L. Hammons, D. Kayran, J. Kewisch, R. F. Lambiase, V. Litvinenko, G. T. McIntyre, D. Naik, D. Pate, D. Phillips, E. Pozdeyev, T. Rao, J. Smedley, R. J. Todd, D. Weiss, Q. Wu, A. Zaltsman, I. Ben-Zvi BNL, Upton, Long Island, New York M. D. Cole, M. Falletta, D. Holmes, J. Rathke, T. Schultheiss, A. M.M. Todd, R. Wong AES, Medford, NY
	One of the frontiers in FEL science is that of high power. In order to reach power in the megawatt range, one requires a current of the order of one ampere with a reasonably good emittance. The superconducting laser-photocathode RF gun with a high quantum efficiency photocathode is the most natural candidate to provide this performance. The development of a 1/2 cell superconducting photoinjector designed to operate at a current of 0.5 amperes and beam energy of 2 MeV and its photocathode system are the subjects covered in this paper. The main issues are the photocathode and its insertion mechanism, the power coupling and High Order Mode damping. This technology is being developed at BNL for DOE nuclear physics applications such as electron cooling at high energy and electron ion colliders.
	Slides

WEBAU04	Single-Shot Longitudinal Bunch Profile Measurements at FLASH Using Electro-Optic Detection: Experiment, Simulation, and Validation	laser, electron, simulation, polarization	310
	V. R. Arsov, E.-A. Knabbe, B. Schmidt, P. Schmüser, B. Steffen DESY, Hamburg G. Berden, A. F.G. van der Meer FOM Rijnhuizen, Nieuwegein W. A. Gillespie, P. J. Phillips University of Dundee, Nethergate, Dundee, Scotland S. P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire A. MacLeod UAD, Dundee
	At the superconducting linac of FLASH at DESY, we have installed an electro-optic experiment for single shot, non-destructive measurements of the longitudinal electric charge distribution of individual electron bunches. The profile of the electric bunch field is electro-optically encoded onto a stretched Ti:Sa laser pulse. In the decoding step, the profile is retrieved from a cross-correlation of the encoded pulse with a 35 fs laser pulse, obtained from the same laser. At FLASH, sub-100 fs electron bunches have been measured during FEL operation with a resolution of better than 50 fs. The electro-optic encoding process in gallium phosphide as well as the decoding step in a frequency doubling BBO crystal were numerically simulated using bunch shapes simultaneously measured with a transverse-deflecting rf structure as input data. In this contribution, we present electro-optically measured profiles and compare them with the simulation.
	Slides

WEBAU05	Magnetic Measurements, Tuning and Fiducialization of LCLS Undulators at SLAC	undulator, alignment, background, quadrupole	314
	V. Kaplounenko, A. W. Weidemann, Z. R. Wolf, Yu. I. Levashov SLAC, Menlo Park, California
	A new Magnetic Measurement Facility (MMF) has been built at Stanford Linear Accelerator Center (SLAC) to measure, tune and fiducialize undulators for Linac Coherent Light Source (LCLS) project. Climate controlled MMF utilizes two magnetic measurement benches and a large Coordinate Measurement Machine (CMM) and provides a throughput of one undulator segment a week. Magnetic measurement, tuning and fiducialization process is being presented and first tuning results are discussed.
	Slides

WEPPH008	Measurements of Projected Emittances at FLASH	emittance, undulator, electron, lattice	338
	F. Loehl, E. Prat DESY, Hamburg K. Honkavaara Uni HH, Hamburg
	FLASH is a SASE FEL user facility at DESY (Hamburg) operating with photon wavelengths in the range from vacuum ultraviolet to soft x-rays. Although the slice emittance is a more appropriate parameter to characterize the SASE process, the projected emittance provides a useful measure of the electron beam quality. At FLASH the projected emittance is measured at three location along the linac: in the injector (130 MeV), after the collimator (full electron beam energy), and in the undulator section. The transverse beam shape is measured with OTR monitors and wire scanners. The multi-monitor method is used to determine the emittance. In this paper we describe the measurement set-up and procedure and report recent results and planned upgrades.

WEPPH015	Modeling of a Laser Heater for Fermi@Elettra	laser, undulator, electron, emittance	362
	S. Di Mitri, S. Spampinati ELETTRA, Basovizza, Trieste
	To cure the microbunching instability in the FERMI@elettra FEL a laser heater is proposed. The one-dimensional model of the instability predicts a large energy modulation building up the electron beam travels through the linac. According to analytical studies and simulations the longitudinal Landau damping provided by the laser heater is expected to help in suppressing the formation of such a modulation. The efficiency of the beam heating is studied as function of the transverse laser-electron beam mismatch in the laser heater undulator in case of a realistic transverse beam profile.

WEPPH029	Development of the Longitudinal Phase-Space Monitor for the L-band Electron Linac at ISIR, Osaka University	electron, photon, radiation, vacuum	409
	T. Igo, G. Isoyama, S. Kashiwagi, M. Morio, R. Kato ISIR, Osaka
	The correlation between longitudinal positions of electrons in a bunch and their energies has a critical effect on the temporal evolution of SASE, and various methods are being developed to measure the longitudinal phase-space profile. We are developing a system to measure the longitudinal phase-space distribution of electrons by a combination of a bending magnet, a profile monitor, and a streak camera at the Institute of Scientific and Industrial Research (ISIR), Osaka University. In the preliminary experiments using a profile monitor utilizing optical transition radiation (OTR), it was confirmed that the monitor had higher momentum resolution than the presently used momentum analyzer consisting of a slit and a current meter. However, we could not obtain the sufficient number of photons to obtain the phase-space image since, in addition to a low photon yield, the angular distribution of OTR emitted by the electron beam in the energy region of 10 – 20 MeV, with which THz-SASE and THz-FEL experiments are conducted at this laboratory, is too large to concentrate it efficiently on a streak camera. In order to increase the number of photons, we try to use silica aerogel as a radiator of the profile monitor by following the example of PITZ. We will present an outline of the phase-space monitor we are developing and its experimental results. R. Kato et al, FEL’06, Berlin, Germany, August 2006, THPPH041, p.676, http://www.jacow.org.** J. Roensch et al, FEL’06, Berlin, Germany, August 2006, THPPH019, p.597, http://www.jacow.org

WEPPH030	Development of a Precise Timing System for the ISIR L-Band Linac at Osaka University	laser, gun, electron, single-bunch	413
	T. Igo, G. Isoyama, R. Kato, M. Morio, S. Suemine, S. Kashiwagi ISIR, Osaka
	We are developing a free electron laser (FEL) in the infrared region and also conducting SASE experiment in the same wavelength region using the L-band linear accelerator at the Institute of Scientific and Industrial Research (ISIR), Osaka University. In order to conduct such studies, stable operation of the linac is critical, so that we have developed a highly precise and flexible timing system for stable generation of the high intensity electron beam with the energy region of 10^-30 MeV. In the timing system, a rubidium atomic clock producing 10 MHz rf signal is used as a time base for a synthesizer which is used as the master oscillator for generating the acceleration frequency of 1.3 GHz. The 1.3 GHz signal from the master oscillator is directly counted down to produce the clock signal of the timing system at 27 MHz and the four rf signals for the linac and laser used in the beam line. The start signal for the linac is precisely synchronized with the 27 MHz clock signal. To make an arbitrary delayed timing signal, a standard digital delay generator is used to make a gate signal for a GaAs rf switch, which slices out one of the 27 MHz clock pulses to generate the delayed timing signal. Any timing signal can be made at an interval of 37 ns and the timing jitter of the delayed signal is less than 2 ps (rms). We will report the new timing system and its performance in detail.

WEPPH032	Electron-Linac Based Femtosecond THz Radiation Source at PAL	radiation, electron, simulation, target	421
	J. Choi, Y. G. Jung, C. Kim, H.-G. Kim, S.-C. Kim, I. S. Ko, W. W. Lee, B. R. Park, H. S. Suh, I. H. Yu, H.-S. Kang PAL, Pohang, Kyungbuk
	A 60-MeV electron linac for intense femto-second THz radiation is under construction at PAL, which is the beamline construction project to be completed by 2008. To get intense femto-second THz radiation up to 100 cm^-1, the electron beam should be compressed down to below 100 fs. The linac will use an S-band photocathode RF-gun as an electron beam source, two S-band accelerating structures to accelerate the beam to 60 MeV, a chicane-type bunch compressor to get femto-second electron bunch, and an optical transition radiation (OTR) target as a radiator. The PARMELA code simulation result shows that the 0.2 nC beam can be compressed down to a few tens of femto-seconds, and even the higher charge of 0.5nC to about one hundred femto-seconds. Also, the linac will be able to provide a femto-second electron beam for electron pulse radiolysis and compton-scattering experiment for fs X-ray.

THAAU01	Experience and Plans of the JLAB FEL Facility as a User Facility	laser, free-electron-laser, electron, radiation	491
	M. D. Shinn Jefferson Lab, Newport News, Virginia
	Jefferson Lab’s IR Upgrade FEL building was planned from the beginning to be a user facility, and includes an associated 600 sq. m area containing seven laboratories. The high average power capability (multikilowatt-level) in the near-infrared (1-3 microns), and many hundreds of watts at longer wavelengths, along with an ultrafast (~ 1 ps) high PRF (10’s MHz) temporal structure makes this laser a unique source for both applied and basic research. In addition to the FEL, we have a dedicated laboratory capable of delivering high power (many tens of watts) of broadband THz light. After commissioning the IR Upgrade, we once again began delivering beam to users in 2005. In this presentation, I will give an overview of the FEL facility and its current performance, lessons learned over the last two years, and a synopsis of current and future experiments.
	Slides

FRAAU02	Status of the FEL Test Facility at MAX-lab	laser, gun, electron, emittance	513
	M. Abo-Bakr, J. Bahrdt, K. Goldammer BESSY GmbH, Berlin M. Brandin, F. Lindau, D. Pugachov, S. Thorin, S. Werin MAX-lab, Lund A. L'Huillier Lund University, Division of Atomic Physics, Lund
	An FEL test facility is built on the existing MAX-lab linac system in collaboration between MAX-lab and BESSY. The goal is to study and analyse seeding, harmonic generation, beam compression and diagnostic techniques with the focus of gaining knowledge and experience for the MAX IV FEL and the BESSY FEL projects. The test facility will in the first stage be using the 400 MeV linac beam to generate the third harmonic at 90 nm from a 266 nm Ti:SA seed laser. The optical klystron is installed and magnetic system, gun and seed laser systems are currently being finalised. Start-to-end simulations have been performed and operation modes for bunch compression defined. The linac and beam transport system is already in operation. We report the status and layout of the project, the issues to be addressed, the solutions for bunch compression and operation. We also report on the prospects of extending the seeding to HHG laser systems.
	Slides

FRAAU04	Re-Commissioning of the Far-Infrared Free Electron Laser for Stable and High Power Operation after the Renewal of the L-Band Linac at ISIR, Osaka University	klystron, wiggler, electron, controls	521
	T. Igo, S. Kashiwagi, R. Kato, M. Morio, G. Isoyama ISIR, Osaka
	We have been developing a far-infrared FEL since late 1980s based on the 40 MeV, L-band electron linac at the Institute of Scientific and Industrial Research (ISIR), Osaka University. The first lasing was obtained at 32~40 um in 1994 and since then we progressively modified the FEL system and continued experiment in between to expand the wavelength region toward the longer wavelength. We finally obtained lasing at 150 um in 1998. We could not obtain power saturation because the macropulse duration is 2 us, though the RF pulse is 4 us long, due to a long filling time of the acceleration tube of the L-band linac and the number of amplification times is limited to 50 only. The linac was constructed approximately 30 years ago and it was not suitable for stable and high power operation of FEL, so that we suspended the development of the FEL. In 2002, we had an opportunity to remodel the linac largely for higher stability and reproducibility of operation. We also added a new operation mode for FEL in which the macropulse duration can be extended to 8 us. I took time to remodel the linac and commission it, but finally the operation mode for FEL is being commissioned and we are resuming the FEL again after the long suspension. We will report the progress and the current status of the re-commissioning of the FEL.
	Slides