FEL 2007 - List of Keywords (free-electron-laser)

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

free-electron-laser

Paper	Title	Other Keywords	Page
MOPPH003	VOLC: Volume Free Electron Laser Simulation Code	electron, simulation, radiation, laser	14
	S. Sytova Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk
	First lasing of Volume Free Electron Laser (VFEL) in mm wavelength range was obtained recently. Мulti-wave volume distributed feedback where electromagnetic waves and electron beam spread angularly one to other in a spatially-periodic target is the VFEL distinctive feature. Mathematical model and numerical methods for VFEL nonlinear stage simulation were proposed** and implemented in computer code VOLC that means "VOLume Code". It was developed on the basis of multiple Fortran codes created in 1991-2006 years. VOLC allows to simulate different geometries of two- and three-wave VFEL in amplifier and oscillator regimes. Electron beam is modelled by averaging over initial phases of electrons. Dimensionality is 2D (one spatial coordinate and one phase space coordinate) plus time. All numerical results obtained using VOLC are in good agreement with analytical predictions of VFEL theory. Different roots to chaos in VFEL were investigated using VOLC. Some successful simulations of VFEL experimental setup at INP were carried out. A description of VOLC possibilities and representative numerical results are presented. * V. G. Baryshevsky et al., NIMA483 (2002) 21. V. G. Baryshevsky, NIMA445 (2000) 281. * K. Batrakov, S. Sytova, Computational Mathematics and Mathematical Physics 45 (2005) 666.

MOPPH010	Three-Dimensional Analysis of the Surface Mode Supported by a Reflection Grating	electron, electromagnetic-fields, laser, polarization	38
	K.-J. Kim ANL, Argonne, Illinois V. Kumar RRCAT, Indore (M. P.)
	In a Smith-Purcell Free-Electron Laser (SP-FEL), the electron beam interacts with the surface mode supported by a metallic reflection grating to produce coherent radiation. All the previous analyses of SP-FEL had considered the localization of the surface mode only in the direction perpendicular to the grating surface and assumed translational invariance along the direction of grooves of the grating. In this paper, we include the localization of the surface mode along the direction of grooves and study the three-dimensional structure of the surface mode in order to include diffraction effects in the analysis of SP-FELs. Full three-dimensional Maxwell-Lorentz equations are derived for the self-consistent nonlinear analysis of SP-FELs.

MOPPH012	Conservation Laws in Quasilinear Theory of Raman Free-Electron Laser	electron, space-charge, plasma, laser	46
	A. Chakhmachi AEOI, Tehran B. Maraghechi AUT, Tehran
	A quasilinear theory of the free-electron laser, in Raman regime, is presented to establish that conservation laws on number, energy, and momentum are upheld. A high density electron beam is assumed so that the space-charge potential is no longer negligible. A sufficiently broad band spectrum of waves is assumed so that saturation will be due to the quasilinear spread of the beam electrons. Otherwise, for the single mode excitation, saturation will be due to the electron trapping in the space-charge potential. It is shown that the quasilinear slow variation of the background distribution function is in the form of the diffusion equation in momentum space. An expression for the time evolution of the spectral energy density is derived. Conservation laws to the quasilinear order (second order) are derived and are proved to be satisfied. Results of the present investigation may be used to study the quasilinear saturation of free-electron laser in the presence of the space-charge wave.

MOPPH017	1D Linear Intensity Spiking Evolution in a Single Shot of a SASE FEL	radiation, electron, undulator, laser	54
	V. Petrillo Universita' degli Studi di Milano, Milano L. Serafini, C. Maroli INFN-Milano, Milano
	The analysis is based on the 1D Maxwell-Lorentz equations which are reduced to the usual averaged linear equation in the limit of vanishingly small radiation field A(z,t) and average length lm. It is shown that if this equation is solved with initial shot noise conditions in which the widths of the spikes and the average distance between successive spikes are both uniformly smaller than the cooperation length Lc, it may lead to large amplitude coherent signals. The intensity spiking RMS relative amplitude decreases from the 100% values it has at t=0, down to values of the order or less than 0.1% in time intervals from ten to twenty gain times.

MOPPH019	Optimized Designs for CAEP IR Free-electron Laser	coupling, simulation, laser, electron	58
	Y. H. Dou, X. J. Shu IAP, Beijing
	The characteristics of CAEP IR free-electron laser are estimated and the optimized designs of the resonator parameters such as radius of output hole, the size of mirror, the resonator length is carried out using our 3D FEL oscillator code. Based on the appropriate parameters, the saturated power, output power, gain and construction of optical modes are calculated.

MOPPH025	Three-dimensional Theory of the Cerenkov Free-Electron Laser	electron, laser, radiation, feedback	73
	C. A. Brau, H. L. Andrews Vanderbilt University, Nashville, Tennessee
	We present an analytical theory for the operation of a Cerenkov free-electron laser which includes diffraction of the optical mode in the direction transverse to the electron beam. Because the width of the optical mode depends on the gain, the usual cubic dispersion relation is replaced by a 5/2-power dispersion relation, however, only two of these roots are allowed. These two roots both have positive real parts, indicating that they are slow waves. For a narrow electron beam, the optical mode is much wider than the beam, thus reducing the gain by an order of magnitude from that predicted by the two dimensional theory. In the limit of a wide electron beam, the two dimensional theory is recovered.

MOPPH026	Three-Dimensional Theory of the Smith-Purcell Free-Electron Laser	electron, laser, radiation, synchrotron	77
	H. L. Andrews, C. A. Brau, J. D. Jarvis Vanderbilt University, Nashville, Tennessee
	We present an analytic theory for the operation of a Smith-Purcell free-electron laser (SPFEL) that includes transverse diffraction of the optical beam. For the case of an infinitely wide electron beam, this theory agrees with previous two-dimensional analyses. When the electron beam is narrow compared to the mode, the gain (amplifier regime) is substantially reduced by diffraction, while its dependence on the beam current is increased due to gain guiding. A 5/2-power dispersion relation replaces the conventional cubic dispersion relation. Additionally, the constituent waves of the laser mode are found to have different transverse decay rates. An estimate of the start current (oscillator regime) of the device is obtained by satisfying the appropriate boundary conditions on the beam axis.

MOPPH028	On NMR probing of the kinetics of a free-electron laser-induced chemical exchange	resonance, laser	81
	S. P. Babailov Nikolaev IIC, Novosibirsk
	Determination of the quantum yields of photochemical reactions (in particular, molecular photoisomerization reactions) is an efficient application of NMR spectroscopy,. We are proposed a combined approach for study the kinetics of photo-induced chemical exchange (PICE) reactions (see Scheme), which involves a free-electron laser (FEL) and NMR spectroscopy. Scheme hv A↔B Continuous and pulse IR-irradiation of the chemical system in the presence of PICE can be achieved using FEL. Based on the analytical equations derived in the work we consider the time-dependent dynamics of variation of the instant NMR line shape for two-site chemical exchange. If one induce an abrupt increase in the rate constant of chemical exchange (for example, by quickly heating the system or PICE), then the NMR line shape will change with time, ultimately reaching another new steady state. Our calculations show that there are beats and oscillations (on the NMR line shape) damped with time. The information about the time-dependent instant line shapes provides possibility to predict the real kinetics of PICE. Prospective objects are molecular conformers and spin isomers. So, FEL can be used in the setup for PICE studies in combination with a NMR spectrometer. S. P. Babailov, E. M. Glebov, et al., Concepts in Magn. Reson., 2006, 8, 571. ** S. P. Babailov, Russ. Chem. Bull., Int. Ed., 2006, 10, 1631.

MOPPH030	Terahertz Imaging and Radioscopy with 160x120 Microbolometer 90 fps Camera	radiation, laser, electron, controls	83
	A. L. Aseev, M. A. Dem'yanenko, D. G. Esaev, I. V. Marchishin ISP, Novosibirsk G. N. Kulipanov, N. Vinokurov, B. A. Knyazev BINP SB RAS, Novosibirsk
	Uncooled micromolometer camera for IR and THz high-speed imaging has been developed. The 160x120 focal plane array consists of resistive vanadium oxide elements on a silicon nitride bridge. The element size is 48x48 micron at 51 micron array period. We describe device fabrication process and focal plane array operational characteristics. The camera was used as a recorder in quasi-optical systems with Novosibirsk terahertz free electron laser as a radiation source. Radioscopy of the objects, which are of interest for biology and security applications, has been demonstrated. The recording rate up to 90 frames per second has been obtained.

MOPPH031	Spectroscopy and Spectrally Resolved Radioscopy of Biological Substances Using Terahertz Free Electron Laser Radiation	radiation, laser, diagnostics, electron	86
	V. V. Gerasimov NSU, Novosibirsk A. M. Gonchar ICG SB RAS, Novosibirsk B. A. Knyazev BINP SB RAS, Novosibirsk
	High average power and monochromacity of terahertz Novosibirsk free electron laser are favorable for the development of time and space resolved spectroscopic and radioscopic techniques for study of highly absorbing substances, in particular, biological ones. To study highly absorbing objects we applied a homemade attenuated total reflection spectrometer, which enables operation in both conventional and imaging mode. By measuring the reflection coefficients for p- and s-polarized radiation, the real (n) and imaginary (k) parts of refractive index can be derived. Using a microbolometer matrix (see the paper by Esaev et al. at this conference), imaging radioscopy of the samples containing amino acids and DNA had been performed. The methods developed were applied also for examination of bones of intact and senescence-accelerated mice that, probably, would lead to study osteoporosis development.

MOPPH033	Diffraction Optical Elements and Optical Systems with a High Power Monochromatic Terahertz Source	radiation, focusing, laser, electron	93
	H. J. Cha, Y. U. Jeong KAERI, Daejon V. S. Cherkassky, L. A. Merzhievsky, S. A. Zhigach NSU, Novosibirsk A. V. Fanova, B. A. Knyazev, G. N. Kulipanov, N. Vinokurov, I. A. Polskikh BINP SB RAS, Novosibirsk
	We have developed reflective diffraction optical elements (DOE) for focusing radiation of terahertz free electron lasers (FEL). Metal-dielectric Fresnel zone plates and metallic kinoform "lenses" were fabricated and tested using FEL radiation. A microbolometer camera (see the paper by Esaev et al. at this conference) sensitive to THz radiation had been applied for recording both terahertz beam caustic and terahertz images. Diffraction efficiency of a kinoform lens appears to be about unity. Quality of images obtained with the kinoform lens was studied. The lens was used as a key element for a Toepler optical system, which were used for studying condense matter non-uniformities and deformations. The experiments were performed at Novosibirsk and KAERI FELs.

MOPPH036	First Experiences with the FIR-FEL at ELBE	electron, laser, undulator, radiation	97
	P. Michel, W. Seidel, G. Staats, J. Teichert, R. Wuensch, U. Lehnert FZD, Dresden
	We show the design and the parameters of operation of the long-wavelength (U100) FEL of ELBE. First lasing has been shown in August, 2006. Since then, the laser has undergone thorough commissioning and is available for user experiments since fall, 2006. Besides in-house users 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. At the beginning of 2007 lasing in the full designed wavelength range from 20μm to 200μm was demonstrated. The laser power typically reaches several W in CW operation but drops for very long wavelengths depending on the size of the used outcoupling hole. However, there exists a serious problem with small gaps in the providable wavelength spectrum. We attribute this behaviour to the transmission characteristics of the overmoded partial waveguide used from the undulator entrance to the first mirror.

MOPPH042	Losses in Optical Resonator of Novosibirsk Terahertz Free Electron Laser: Theory and Experiment	coupling, laser, electron, radiation	107
	V. V. Kubarev BINP SB RAS, Novosibirsk
	Design of optical resonator of Novosibirsk terahertz free electron laser (NovoFEL)was made on base simple analitical theory discribed in paper. Direct comparison of the theory and many experiments on NovoFEL is presented. Kubarev V. V. Babinet principle and diffraction losses in laser resonators. Quantum Electronics 30(9)824-826(2000).

MOPPH073	Thermal and Non-thermal Laser Cutting Utilizing Advanced Industrial Lasers and ERL-FELs	laser, electron, linac, 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.

TUAAU05	Modelling Mirror Aberrations in FEL Oscillators Using OPC	undulator, laser, simulation, radiation	207
	K.-J. Boller, J. G. Karssenberg, P. J.M. van der Slot Mesa+, Enschede
	Thermal distortion in mirrors used in high average power FEL oscillators, like the JLAB FEL and the 4GLS VUV-FEL, will influence the mode quality and affect the FEL performance. In order to quantify these effects, these distortions needs to be characterised. Mirror aberrations are generally described using Zernike polynomials and also in case of thermal distortions, it has been shown that these polynomials can be used to describe the mirror distortion. The Optical Propagation Code (OPC)* is a general optical propagation package in the paraxial approximation, that works together with gain codes like Medusa and Genesis 1.3 to model FEL oscillators. We have extended OPC to include phase masks, that can either be generated by an external program or internally using Zernike polynomials. This allows OPC to model mirror aberrations. We will present a few examples, illustrating the capabilities of OPC. * Nucl. Instrum. Meth. A407 (1998)401** J. Appl. Phys. 100, 093106 (2006)
	Slides

TUPPH011	Analytical Studies of Transverse Coherence Properties of X-ray FELs	radiation, electron, undulator, emittance	240
	E. Schneidmiller, M. V. Yurkov, E. Saldin DESY, Hamburg
	We describe analytically the process of formation of transverse coherence in X-ray SASE FELs.

WEPPH005	Magnet Sorting for the European XFEL Hybrid Undulator - Comparing Study	undulator, electron, controls, laser	326
	B. Faatz, J. Pflueger, Y. Li DESY, Hamburg
	Current permanent magnet material quality is insufficient to obtain field qualities in undulators, which satisfy FEL requirements. Therefore position and orientation of magnets have to be carefully chosen in order to obtain mutual cancellation of field errors. In this paper we compare two different sorting schemes, simulated annealing and a straight forward paring method. They are applied to a 5m prototype structure built for the European XFEL facility. The algorithms of these two methods are described in detail and the sorting results and the expected field qualities are carefully compared.

WEPPH012	Investigations on the Thermal Emittance of Cs2Te Photocathodes at PITZ	emittance, cathode, electron, laser	350
	G. Asova, J. W. Baehr, C. H. Boulware, H.-J. Grabosch, M. Hänel, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, B. Petrosyan, S. Rimjaem, J. Roensch, T. A. Scholz, L. Staykov, F. Stephan, S. Lederer DESY Zeuthen, Zeuthen K. Boyanov INRNE, Sofia L. H. Hakobyan YerPhI, Yerevan R. Richter BESSY GmbH, Berlin A. Shapovalov MEPhI, Moscow
	The main objective of the Photo Injector Test facility at DESY in Zeuthen (PITZ) is the production of electron beams with minimal transverse emittance. The lower limit of this property of electron beams produced with a photocathode in an RF-gun is determined by the thermal emittance. To understand this crucial parameter for high performance FEL’s, measurements under RF operation conditions for Cesium Telluride (Cs2Te) photocathodes are done. Results for various accelerating gradients and the dependence on the laser spot size in the cathode plane are presented and discussed in this work.

WEPPH023	Beam Properties from S-band Energy Compensated Thermionic RF Gun and Linac for KU-FEL	electron, emittance, gun, klystron	386
	K. Masuda, H. Ohgaki, S. Sasaki, T. Shiiyama, H. Zen, T. Kii Kyoto IAE, Kyoto
	Energy degradation arising from back-bombardment effect was quite serious problem for using a thermionic RF gun as injector of FEL device. Thus we have developed energy compensation technique, which keeps cavity voltage as constant by controlling input RF power to the RF gun. We have successfully extracted electron beam with constant energy from the thermionic RF gun with the energy compensation technique. However, PFN tuning of the Klystron modulator and time-varying beamloading would affect macro-pulse properties; energy spread, emittance, phase mismatch between RF gun and accelerator, etc. Thus we have estimated effects to the beam properties by using the 1D thermal conduction model* and PARMERA, and also evaluated these properties experimentally. The estimated and measured results were not so serious for KU-FEL system. We will discuss the comparison between the experimental results and the calculation results in this conference. * N. Okawachi, et al., Proc. of the FEL 2006, pp.664-667 (2006)** T. Kii, et al., Nucl. Instr. and Meth. A 483 310-314 (2002)

WEPPH028	Development of a Compact Cherenkov Free-Electron Laser Operating Terahertz Wave Range	electron, radiation, vacuum, cathode	406
	M. R. Asakawa, N. M. Miyabe Kansai University, Osaka A. Ikeda, M. Kusaba, Y. Tsunawaki OSU, Daito, Osaka
	We designed a compact Cherenkov Free-Electron Laser(CFEL) device capable of delivering mW-level output power at frequencies of up to THz from 10GHz to 1 THz. CFEL has the advantage of generating higher frequencies at lower electron beam energy. Due to lower electron beam CFEL device is compact. Our CFEL device consists of a waveguide partially filled with two lined parallel dielectric slabs through which a relativistic electron beam propagates. We call this structure "double-slab". In our device, the electron beam is generated using the Spindt cathode. We used a super conducting magnet to compress and guide the electron beam along the dielectric slabs. Assuming a dielectric slab thickness of 0.65mm,length of 11cm and electron beam energy 50keV ,the output power generated by the device was numerically calculated to be mW-level at 46GHz. Currently , we are conducting the POP experiment at millimeter wave range.

WEPPH043	The UCSB MM-FEL Injection Locking System	injection, laser, electron, coupling	445
	S. Takahashi, G. J. Ramian UCSB, Santa Barbara, California
	An Injection locking system has been implemented on UCSB's Millimeter Wave FEL at 240 GHz. It it is based on a VDI varactor multiplier source and a Keating quasi-optical isolator. Its purpose is to stabilize lasing and suppress mode beating by always forcing lasing to occur at a single frequency on one specific longitudinal mode. Theoretical and experimental results are presented.

THAAU01	Experience and Plans of the JLAB FEL Facility as a User Facility	laser, electron, radiation, linac	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

THAAU03	Experimental Study of Volume Free Electron Laser Using a "Grid" Photonic Crystal with Variable Period	electron, radiation, laser, feedback	496
	V. G. Baryshevsky, N. A. Belous, V. A. Evdokimov, A. Gurinovich, A. S. Lobko, A. V. Oskin, P. F. Safronov, P. V. Molchanov Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk
	Electrodynamical properties of a crystal-like artificial periodic structure (photonic crystal) formed by a periodically strained metallic threads were studied both theoretically and experimentally,. In the present paper operation of Volume Free Electron Laser using a "grid" photonic crystal with variable period is experimentally studied. Dependence of the generation threshold on photonic crystal length is investigated along with the frequency characteristics of generated radiation. Baryshevsky V. G. et al. NIM section B. Vol252 (2006) P.92-10¹ ** Baryshevsky V. G. et al. Proc. of the 28th FEL Conference PP.331-338
	Slides

THBAU01	Research Highlights from FLASH	laser, electron, radiation, vacuum	499
	J. Feldhaus, R. Treusch DESY, Hamburg
	The Free electron LASer in Hamburg (FLASH) has started regular user operation in summer 2005, providing XUV radiation pulses with pulse energies in the 10 - 100 μJ range and pulse durations of 10 - 50 fs. The science programme at FLASH covers a broad range of novel applications including fundamental studies on atoms, ions, molecules and clusters, creation and characterisation of warm dense matter, diffraction imaging of nanoparticles, spectroscopy of bulk solids and surfaces, investigation of surface reactions and spin dynamics, and the development of advanced photon diagnostics and experimental techniques. So far, 16 science projects have been pursued involving approximately 200 scientists from 11 countries. Some of the research highlights will be presented.
	Slides