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MOBAU02 | Technology Challenges Towards Short-Wavelength FELs | electron, undulator, radiation, space-charge | 9 | |||||
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Since the very first proposal of high-gain FELs for the X-ray wavelength regime it was obvious that realization of such a device, potentially rewarding revolutionary science opportunities, would impose extraordinary challenges in terms of accelerator physics and technology. The talk will review the major steps that had to be taken to finally construct an FEL user facility for soft X-rays. Also, a few issues will be pointed out that are to be addressed in order to make full profit of the FEL principle at X-ray wavelengts.
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MOPPH048 | ARC-EN-CIEL Project Electron Beam Dynamics | electron, linac, focusing, quadrupole | 118 | |||||
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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.
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MOPPH052 | Output Performance of the STARS HGHG Demonstrator at BESSY | undulator, radiation, laser, electron | 130 | |||||
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BESSY is planning to construct a free-electron laser facility (STARS) to demonstrate cascaded high-gain harmonic generation (HGHG) FELs. A 325MeV superconducting linear accelerator will drive two HGHG-stages, where the second stage is seeded by the radiation from the first stage. Such a cascading of the HGHG scheme, originally pioneered by L. H. Yu, allows a reduction of the STARS output wavelength down to the few 10nm range. This paper describes the expected performance of the facility, the achievable wavelength range, the harmonic content of the radiation, the potential of super-radiant pulses and first considerations about the stability of the source.
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MOPPH055 | Measurements of the Projected Normalized Transverse Emittance at PITZ | gun, booster, cathode, laser | 138 | |||||
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The main objective of the Photo Injector Test facility at DESY in Zeuthen (PITZ) is the production of electron beams with minumum transverse emittance at 1 nC bunch charge. PITZ consists of a photo cathode RF gun, solenoids for the compensation of space charge induced emittance growth and a booster cavity. In order to study the emittance evolution along the beam line three Emittance Measurement SYstems (EMSY's) were installed downstream of the booster cavity. In a first operation periode in October 2006 the emittance was measured for moderate gun gradients of about 40 MV/m. A new gun cavity is presently installed at PITZ and conditioning up to a gradient of 60 MV/m is ongoing. In this work we present recent results from measurements of the normalized projected transverse emittance of the electron beam. The emittance is measured using the so called single slit technique. Data are presented for different gun and booster gradients, solenoid strengths and initial beam size at the cathode.
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MOPPH058 | Status of the SPARX Project | linac, undulator, radiation, simulation | 142 | |||||
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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.
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MOPPH061 | Design of the PAL Test FEL Machine | linac, undulator, simulation, electron | 149 | |||||
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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.
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MOPPH062 | Features of the PAL-XFEL Design | undulator, electron, radiation, brightness | 152 | |||||
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The PAL-XFEL design has been revised since the previous conference. The 2nd bunch compressor has been moved to a higher energy to eliminate the space charge effect and the total linac energy has been increased from 3.7 GeV to 4.0 GeV. Details and reasons of these design revisions are explained in this paper.
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MOPPH064 | A Project of SC ERL at KAERI | sextupole, electron, undulator, dipole | 160 | |||||
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A project of an ERL at Korea Atomic Energy Research Institute is described. The ERL will be connected to the existing machine without any modification. It consists of two 180° bents and two straight sections: one is for an FEL, another for a Compton X-ray source. One can choose the regime controlling the lenses. The total ERL is isochronous to avoid any problem with longitudinal beam instability. It will be possible to control both Sx and Sy transormation matrix elements independently to suppress longitudinal beam instability and allow the increase of beam current. Sextuples will be installed in bents to suppress chromatic aberration. This design provides operation in FEL regime with high electron efficiency in the range of electron energies 1222 MeV.
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TUBAU02 | Status of SCSS & X-ray FEL Project in Japan | electron, gun, undulator, cathode | 216 | |||||
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Staus of SCSS project after the first lasing last year will be reported. The X-ray FEL, which uses 8 GeV C-band, is under construction, whose status will be reported.
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TUBAU03 | STARS an FEL to Demonstrate Cascaded HGHG | radiation, linac, electron, laser | 220 | |||||
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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.
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TUBAU04 | Towards a Low Emittance X-ray FEL at PSI | electron, acceleration, cathode, simulation | 224 | |||||
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The Paul Scherrer Institute (PSI) in Switzerland aims at building a compact and cost-effective X-ray FEL facility for the wavelength range 0.1 - 10 nm. Based on the generation of very low emittance beams, it consists of a low-emittance electron gun (LEG) followed by high-gradient acceleration, and advanced accelerator technology for preserving the initial low emittance during further acceleration and bunch compression. In order to demonstrate the feasibility of the concept and the emittance preservation, a 250 MeV test facility will be built. This machine has been designed to be used as injector for the X-ray FEL at a later date. The accelerator design of the 250 MeV linac will be presented in the paper together with the status of the LEG and high gradient acceleration.
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TUPPH002 | High Order Mode Analyses for the Rossendorf SRF Gun | gun, resonance, coupling, focusing | 228 | |||||
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High Order Modes (HOM) excited by the beam in a superconducting RF gun (SRF gun) could destroy the quality of the electron beam. This problem is studied on the base of frequency domain description by considering of the equivalent RLC circuit contour for each HOM, periodical excited by a pulsed current source. Expression for the voltage, the field amplitude and the phase of the excited HOM has been obtained. The equations for the coupling impedances of monopole TM-HOM and TE-HOM in the RF gun cavity has been derived. In this calculation the change of the particle velocity due to acceleration is taken into account. Resonance frequencies, coupling impedances, unloaded and external quality factors, excitation voltages and field distributions for each HOM including trapped HOM are calculated for Rossendorf SRF gun up to the frequency of 7.5 GHz, using the complex field solver CLANS. The dependence of the calculated parameters from a cavity deformation has been studied. The influence of the seven most dangerous HOM on the beam quality has been estimated by particle tracking using the ASTRA code.
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TUPPH006 | FEL Potential of the High Current ERLs at BNL | electron, linac, gun, simulation | 232 | |||||
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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.
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* 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). |
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TUPPH011 | Analytical Studies of Transverse Coherence Properties of X-ray FELs | radiation, electron, undulator, free-electron-laser | 240 | |||||
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We describe analytically the process of formation of transverse coherence in X-ray SASE FELs.
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TUPPH012 | Compact X-ray Free-Electron-Laser Based on an Optical Undulator | laser, undulator, radiation, electron | 244 | |||||
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The interaction between a very high brightness electron beam and a relativistically intense optical laser pulse produces X rays via coherent Thomson back scattering with FEL collective amplification. The phenomenon is, however, very selective, so that the characteristics of both electron and laser beam must satisfy tight requirements in terms of beam current, emittance, energy spread and laser amplitude stability within the pulse. The three-dimensional equations governing the radiation phenomena have been studied in both linear and non linear regime and solved numerically for the particularly interesting values of wavelengths of 1 Ang, 1 nm and 12 nm. The performance of the collective Thomson source has been compared with that of an equivalent static undulator. A set of scaling laws ruling the phenomenon is also presented. The possibility of using an electron beam produced via LWFA in the bubble regime is investigated.
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TUPPH019 | Simulations for the LCLS Injector | simulation, laser, cathode, gun | 260 | |||||
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The commissioning of the LCLS Injector has started this year. The electron beam quality for producing high power SASE X-rays is very challenging to reach. In this paper, we will describe comparisons between simulations made with multi-particle tracking code and electron beam measurements performed on the LCLS injector.
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WEAAU01 | Commissioning Results of the SLAC LCLS Gun | laser, cathode, gun, radiation | 276 | |||||
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The beam quality and operational requirements for the Linac Coherent Light Source (LCLS) currently being constructed at SLAC are exceptional, requiring the design of a new s-band RF photocathode gun for the electron source. Two guns (Gun1 and Gun2) have been fabricated and tested at high RF power. Gun1 was installed March 17, 2007 and began providing beams for the LCLS injector commissioning on April 5, 2007. Gun2 is reserved as a backup gun. The results and analysis of the guns performance in the LCLS injector will be presented.
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WEAAU02 | Direct Measurement of Phase Space Evolution in the SPARC High Brightness Photoinjector | simulation, laser, brightness, gun | 284 | |||||
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The characterization of the transverse phase space for high charge density relativistic electron beams is a fundamental requirement in many particle accelerator facilities, in particular those devoted to fourth-generation synchrotron radiation sources, such as SASE FEL. The main purpose of the SPARC initial phase was the commissioning of the RF photoinjector. At this regard, the evolution of the phase space has been fully characterized by means of the emittance meter diagnostics tool, placed in the drift after the gun exit. The large amount of collected data has shown not only that we can achieve the SPARC nominal parameters, but has also allowed for the first time a detailed reconstruction of the transverse phase space evolution along the drift, giving evidences of the emittance compensation process to occur as predicted by theory and simulations. In particular the peculiar behavior of a flat top longitudinal electron distribution compared to a gaussian distribution has been studied giving important insights for the correct matching with the following linac based on the double emittance minimum effect.
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WEAAU04 | Superconducting Photoinjector for High-Power Free Electron Lasers | gun, electron, cathode, linac | 290 | |||||
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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.
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WEBAU01 | Adaptive 3-D UV-laser Pulse Shaping System to Minimize Emittance for Photocathode RF Gun | laser, electron, cathode, controls | 298 | |||||
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We developed an adaptive 3-D shaping (both temporal (1D) and spatial (2D)) short pulse (80 fs~40 ps) UV-laser system as an ideal light source for yearlong stable generation of a low emittance electron beam with a high charge (1~2 nC/pulse). In its current form, the lasers pulse-energy stability has been improved to 0.2~0.3% (rms; 10 pps, 0.4 TW in femtosecond operation) at the fundamental wavelength and 0.7~1.4% at the third-harmonic generation. Such improvement reflects an ability to stabilize the laser system in a humidity-controlled clean room. The pulse-energy stability of a mode-locked femtosecond oscillator has been continuously held to 0.3% (p-p) for 10 months, 24 hours a day. In addition, the ideal spatial and temporal profiles of a shot-by-shot single UV-laser pulse are essential to suppress emittance growth in an RF gun. We apply a deformable mirror that automatically shapes the spatial UV-laser profile with a feedback routine, based on a genetic algorithm, and a pulse stacker for temporal shaping at the same time. The 3D shape of the laser pulse is spatially top-hat (flattop) and temporally a square stacked pulse. Using a 3D-shaped laser pulse with a diameter of 0.8 mm on the cathode and pulse duration of 10 ps (FWHM), we obtain a minimum normalized emittance of 1.4 π mm mrad with beam energy of 26 MeV.
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WEPPH008 | Measurements of Projected Emittances at FLASH | undulator, electron, linac, lattice | 338 | |||||
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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.
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WEPPH009 | Recent Measurements of the Longitudinal Phase Space at PITZ | gun, booster, simulation, electron | 342 | |||||
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The Photo Injector Test facility at DESY in Zeuthen (PITZ) was built to test and optimize electron guns for short wavelength Free-Electron Lasers (FELs) like FLASH and XFEL at DESY in Hamburg. For a detailed analysis of the behaviour of the electron bunch, the longitudinal phase space and it projections can be measured behind the gun cavity. The electric field at the photo cathode was increased from 40 MV/m to 60 MV/m, to optimize the transverse emittance. The momentum distributions for different gradients and gun phases will be presented. The determination of the field balance from the momentum distribution will be discussed. In order to study emittance conservation, a booster cavity and additional diagnostics were installed. The evolution of the longitudinal phase space in the booster cavity will be investigated. Measurements of the momentum distribution and longitudinal distribution behind the booster cavity will be discussed.
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WEPPH011 | Photocathode Laser Pulse Diagnostics at PITZ | laser, cathode, diagnostics, electron | 346 | |||||
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The main objective of the Photo Injector Test facility at DESY in Zeuthen (PITZ) is the development of electron sources that meet the requirements for existing and future FELs such as FLASH or the European XFEL. The goal is the minimization of the transverse emittance of the produced electron bunches. In this respect one of the key issues is the cathode laser system, which should provide longitudinal and transversal flat-top pulses with an excellent long-term stability. In this work we present the full system of laser diagnostics that is currently used at PITZ to monitor the laser pulse parameters.
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WEPPH012 | Investigations on the Thermal Emittance of Cs2Te Photocathodes at PITZ | cathode, electron, laser, free-electron-laser | 350 | |||||
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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 FELs, 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.
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WEPPH013 | Status and Perspectives of the PITZ Facility Upgrade | gun, cathode, diagnostics, booster | 354 | |||||
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The Photo Injector Test facility at DESY in Zeuthen (PITZ) has been established to develop and optimize electron sources that cover requirements of FEL facilities such as FLASH and the European XFEL. A major upgrade of the facility is ongoing in steps, in parallel to the commissioning of the extended setup and first experiments. The new setup towards the final design mainly includes a photo cathode RF gun, a post acceleration booster cavity and several diagnostic systems. In order to fulfil the high brightness electron source characterization, the diagnostic systems will consist of three emittance measurement systems, two high-energy dispersive arms, an RF deflecting cavity and a longitudinal phase space tomography module as well as bunch length diagnostics. In this paper, results of the commissioning of the new RF gun, which has been installed and conditioned at PITZ in spring and summer of 2007, the current PITZ status and details of the future facility upgrade will be presented.
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WEPPH015 | Modeling of a Laser Heater for Fermi@Elettra | laser, undulator, electron, linac | 362 | |||||
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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.
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WEPPH018 | A High Brightness X-band Split Photoinjector Concept and Related Technological Challenges | gun, brightness, electron, klystron | 370 | |||||
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Future light sources based on high gain free electron lasers, require the production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake fields effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, hence the photo-injector design and its operation is the leading edge for high quality beam production. The state of the art photoinjector beam brightness can be in principle brought above the 1015 A/m2 threshold with an X-band gun and a proper emittance compensation scheme. We discuss in this paper an optimized design of a split X-band photoinjector, a convenient matching scheme with the downstream linac, based on the SPARC project experience, and the further technological developments required to reach such an appealing goal.
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WEPPH023 | Beam Properties from S-band Energy Compensated Thermionic RF Gun and Linac for KU-FEL | electron, gun, free-electron-laser, klystron | 386 | |||||
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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.
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* 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) |
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WEPPH024 | Numerical Evaluation of Oscillator FEL with Multi-Bunch Photo-Cathode RF-gun in Kyoto University | electron, gun, undulator, laser | 390 | |||||
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An infrared FEL (4-13 micro-m) facility to develop new energy materials is constructed in Institute of Advanced Energy, Kyoto University. The electron beam of 40 MeV has been successfully accelerated by a linac system which consists of a 4.5-cell thermionic RF gun*. However, due to severe back-bombardment effect, there still needs several efforts to extend the macro-pulse duration to obtain a stable FEL. Upgrade from the present thermionic RF gun to a photocathode RF gun has been planned in KU-FEL**, because a photocathode RF gun is free from the back-bombardment and can generate a high brightness electron beam. A multi-bunch photo-cathode RF gun system has been developed*** and will be installed into the KU-FEL linac. Thus a design work on the new linac system from the gun to the FEL has been performed by using PARMELA and GENESIS. The evaluated peak current is about 4 times and the expected FEL gain is about 10 times as high as those with the present system. The required laser system will be discussed in this conference, as well.
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* H. Ohgaki, et al., NIM A, vol.528, pp.366-370 (2004).** H. Ohgaki, et al., Proc. of the FEL 2004, pp.454-457 (2004).*** K. Hirano, et al., NIM A, vol. 560, pp.233-239 (2006). |
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WEPPH026 | Design Study of the Triode-Type Thermionic RF Gun | cathode, gun, coupling, electron | 398 | |||||
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We use a 4.5-cell RF gun with a thermionic cathode as the injector for our KU-FEL facility, having taken its advantageous features compared with photocathode guns, such as high averaged current, low cost and easy operation, while we suffer from the limited macro-pulse duration and peak current by the back-bombardment effect. To mitigate these adverse effects, we proposed the triode-type thermionic RF gun with an additional small cavity providing the accelerating phase nearby the cathode independent of the main cavity phase*. Results from PIC simulations show that the back-bombardment power can be reduced drastically by more than 80%, and in addition the peak current of the output electron beam will be improved greatly by supplying a moderate RF power of tens kW to the RF triode structure. The RF system of up to 100 kW capabilities has been prepared and tested. Also the prototype design of the triode-type thermionic RF gun was completed. The cavity parameters, namely the quality factor, shunt impedance, and the coupling coefficient with the RF feed coaxial cable were designed taking into account both the available maximum field on the cathode and the phase and amplitude stability against the expected variations of the beam loading and cavity temperature. We will also present PIC simulation prediction on the output beam characteristics promising the first FEL lasing.
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* K. Masuda, et al., Proceedings of the 2006 FEL conference, (2006) |
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WEPPH027 | Beam Diagnostics for the First Lasing of the KU-FEL | gun, electron, simulation, undulator | 402 | |||||
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Mid-IR FEL (4-13μm) device for energy science has been constructed in Institute of Advanced Energy, Kyoto University and the electron beam of 40MeV has been successfully accelerated*. The transverse phase space distribution and the corresponding emittance of the electron beam were measured by using a tomographic method**. As the result, normalized emittance was around 3 pi mm mrad. An FEL gain calculation*** shows that the peak current of 10A is the minimum value for the FEL amplification, and that of 40A is required to achieve the FEL saturation. Therefore the bunch compression experiment has been carried out to shorten the micro-bunch length by 2 ps in KU-FEL. The 180 deg. arc section was used for the bunch compression. We will report the result of the emittance measurement and of the bunch compression experiment in the conference.
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* H. Ohgaki, et al., NIM A, vol.528, pp.366-370 (2004).** H. Zen, et al., Proc. of the FEL 2006, pp.592-595(2006)*** M. Nakano, et al., Proc. of the FEL 2006, pp.660-664 (2006). |
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WEPPH031 | Development of A Low Emittance DC Gun for Smith-Purcell BWO FEL | gun, cathode, simulation, electron | 417 | |||||
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An electron DC gun capable for producing very low emittance beam is under developed at Laboratory of Nuclear Science, Tohoku University. The DC gun employs a high voltage of 50 kV to extract electrons, which is suitable to drive Smith-Purcell backward wave oscillator free electron laser (BWO FEL). A result of numerical simulation using a 3-D finite deference time domain (FDTD) method shows the BWO FEL oscillation at the terahertz wavelength region maybe achieved by using the electron beam with an emittance around 0.1 mmmrad. Average power is expected to be more than 100 W per square mm. In addition to which a very small cathode of LaB6 single crystal is employed for the gun, the geometrical structure is optimized to produce the lower emittance beam. A numerical calculation of the elctro-static model for the DC gun to solve equilibrated beam envelope predicts a normalized beam emittance of 0.2 mmmrad will be realized at the beam current of a couple of hundreds mA. Particularly by applying special bias voltage between the cathode and the wehnelt, the transverse distribution of electrons is possibly becoming to be an ideal Kapchinskij-Vladimirskij (K-V) beam, so that the space charge effect will be minimized. The paper will present the status of the development of the low emittance DC gun and various simulation result of the terahertz BWO FEL oscillation.
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WEPPH037 | Coherence of Space Charge Vibrarion and Parameters of Electron Guns | gun, electron, space-charge, cathode | 432 | |||||
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Space charge effect always determines the motion of particles in electron guns. Coherence of space charge vibration leads to oscillation of the emittance along a gun or a charge affected beamline. This phenomenon is closely related to a technique known as emittance compensation. These phenomena together with others (non-coherent) have been considered in the paper. The optimal parameters of guns and the expected emittance of the beam from the optimal ones have been estimated and scaled.
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FRAAU02 | Status of the FEL Test Facility at MAX-lab | laser, gun, electron, linac | 513 | |||||
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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.
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