First Name: S.
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Last Name: Reiche
Full Name: S. Reiche
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20 papers
| title: | Current-Enhanced SASE Using an Optical Laser and its Application to the LCLS |
| format: | journal article |
| year: | |
| 6 authors: | | | | | | |
| abstract: | We propose a significant enhancement of the electron peak current entering a SASE undulator by inducing an en- ergy modulation in an upstream wiggler magnet via res- onant interaction with an optical laser, followed by mi- crobunching of the energy-modulated electrons at the ac- celerator exit. This current enhancement allows a reduc- tion of the FEL gain length. The x-ray output consists of a series of uniformly spaced spikes, each spike being tem- porally coherent. The duration of this series is controlled by the laser pulse and in principle can be narrowed down to just a single, -attosecond spike. Given potentially absolute temporal synchronization of the x-ray spikes to the energy-modulating laser pulse, this scheme naturally makes pump-probe experiments available to SASE FEL’s. We also study various detrimental effects related to the high electron peak current . |
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| title: | Spontaneous Radiation Background Calculation for LCLS |
| format: | journal article |
| year: | |
| 1 author: | |
| abstract: | The intensity of undulator radiation, not amplified by the FEL interaction, can be larger than the maximum FEL sig- nal in the case of an X-ray FEL. In the commissioning of a SASE FEL it is essential to extract an amplified signal early to diagnose eventual misalignment of undulator modules or errors in the undulator field strength. We developed a numerical code to calculate the radiation pattern at any position behind a multi-segmented undulator with arbitrary spacing and field profiles. The output can be run through numerical spatial and frequency filters to model the radiation beam transport and diagnostic. In this presentation we estimate the expected back- ground signal for the FEL diagnostic and at what point along the undulator the FEL signal can be separated from the background. We also discusses how much information on the undulator field and alignment can be obtained from the incoherent radiation signal itself. |
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| title: | Generation of GW-level, sub-Angstrom Radiation in the LCLS using a Second-Harmonic Radiator |
| format: | journal article |
| year: | |
| 2 authors: | | |
| abstract: | Electron beams are strongly microbunched near the high-gain free-electron laser (FEL) saturation with a rich harmonic content in the beam current. While the coherent harmonic emission is possible in a planar undulator, the third- harmonic radiation typically dominates with about 1% of the fundamental power at saturation. In this paper, we discuss the second-harmonic radiation in the Linac Coherent Light Source. We show that by a suitable design of an second- stage undulator with its fundamental frequency tuned to the second harmonic of the first undulator, coherent second-harmonic radiation much more intense than the third-harmonic is emitted. Numerical simulations predict that GW-level, sub- Angstrom x-ray pulses can be generated in a relatively short second-harmonic radiator. |
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| title: | VISA IB: Ultra-High Bandwidth, High Gain SASE FEL |
| format: | journal article |
| year: | |
| 15 authors: | | | | | | | | | | | | | | | |
| abstract: | We report the results of a high energy spread SASE FEL experiment, the intermediary experiment linking the VISA I and VISA II projects. A highly chirped beam (1.7 %) was transported, without corrections of longitudinal aberrations in the ATF dogleg, and injected into the VISA undulator. The ouput radiation displayed an uncharacteristicly large bandwidth (12 %) with extremely stable lasing and mea- sured energy of about 2 μJ . Start-to-end simulations re- produced key features of the experiment and provided an insight into the michanisms giving rise to such a high band- width. These analyses have important implications on the VISA II experiment. |
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| title: | SPUR: A new code for the calculation of synchrotron radiation from very long undulator systems |
| format: | conference procceeding |
| conference: | EPAC 2008 |
| year: | 2008 |
| 3 authors: | | | |
| abstract: | The accurate calculation of synchrotron radiation from an undulator is a common problem and numerous codes have been developed that describe the radiation from analytic and measured undulator fields. However, for very long undulator systems there is not a suitable code that can handle the amount of data in a convenient manner and which runs in a practically realisable time limit. The development of a new code, SPontaneous Undulator Radiation (SPUR) [1], is presented which computes the spontaneous radiation from electron beams passing through a system of undulators. The code supports parallel architecture, and uses the HDF5 [2] technology to efficiently handle the multi-dimensional data. The latest developments and benchmarking are presented. |
| keywords: | pbpl_pub |
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| title: | Chicane Radiation Measurements with a Compressed Electron Beam at the BNL ATF |
| format: | journal article |
| year: | 2007 |
| 12 authors: | | | | | | | | | | | | |
| abstract: | |
| keywords: | pbpl |
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| title: | Status of the SPARC-X Project |
| format: | journal article |
| year: | 2007 |
| 97 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | SPARC-X is a two branch project consisting in the SPARC test facility dedicated to the development and test of critical subsystems such as high brightness photoinjector and a modular expandable undulator for SASE-FEL experiments at 500 nm with seeding, and the SPARX facility aiming at generation of high brilliance coherent radiation in the 1.5-13 nm range, based on the achieved expertise. The projects are supported by MIUR (Research Department of Italian Government) and Regione Lazio. SPARC has completed the commissioning phase of the photoinjector in November 2006. The achieved experimental results are here summarized together with the status of the second phase commissioning plans. The SPARX project is based on the generation of ultra high peak brightness electron beams at the energy of 1 and 2 GeV generating radiation in the 1.5-13 nm range. The construction is at the moment planned in two steps starting with a 1 GeV Linac. The project layout including both RF-compression and magnetic chicane techniques has been studied. |
| keywords: | pbpl |
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| title: | Seeded VISA: A 1064 nm Laser-Seeded FEL Amplifier at the BNL ATF |
| format: | journal article |
| year: | 2007 |
| 7 authors: | | | | | | | |
| abstract: | An experimental study of a seeded Free Electron Laser (FEL) using the VISA undulator and a Nd:YAG seed laser will be performed at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory. The study is motivated by the demand for a short Rayleigh length FEL amplifier at 1 micron to allow for high power transmission with min- imal damage of transport optics. Planned measurements include transverse and longitudinal coherence, angular dis- tribution, and wavelength spectrum of the FEL radiation. The effects of detuning the electron beam energy will be studied, with an emphasis on control of the radiation emis- sion angles and increase of the amplifier efficiency. Results of start-to-end simulations are also presented. |
| keywords: | pbpl |
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| title: | Future FEL Studies at the VISA Experiment in the SASE and Seeded Modes |
| format: | journal article |
| year: | 2006 |
| 9 authors: | | | | | | | | | |
| abstract: | The VISA (Visible to Infrared SASE Amplifier) experiment at BNL (Brookhaven National Laboratory) has previously demonstrated saturation at 840 nm in 2001. Further SASE studies, in 2003, have demonstrated an anomalously large bandwidth spread of the FEL spectrum due to off-angle emissions. This paper disseminates the current and future program of the VISA program at BNL. This includes a study of a seeded FEL, using a 1 micron YAG laser as a seed, and the accompanying diagnostics to characterize the radiation. Diagnostics include the double differential spectrometer, a mode converter to investigate the orbital angular momentum of light in the FEL, and an optical pepper-pot for coherence measurements. As usual, start-to-end simulations are presented. |
| keywords: | pbpl |
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| title: | LASER BEAT-WAVE MICROBUNCHING OF RELATIVISTIC ELECTRON BEAM IN THE THZ RANGE |
| format: | journal article |
| year: | 2006 |
| 6 authors: | | | | | | |
| abstract: | Laser-driven plasma accelerators have recently demonstrated a ~1GeV energy gain of self-trapped electrons in a several-centimeter-long plasma channel. Potential staging of such devices will require the external injection of an electron beam prebunched on the scale of 1-10 THz into a plasma accelerating structure or plasma LINAC. Seeded FEL/IFEL techniques can be used for modulation of the electron beam longitudinally on the radiation wavelength scale. However, a seed source in this spectral range is not available. At the UCLA Neptune Laboratory a Laser Beat-Wave (LBW) microbunching experiment has begun. The interaction of the electron beam and the LBW results in ponderomotive acceleration and energy modulation on the THz scale. This stage is followed by a ballistic drift of the electrons, where the gained energy modulation is transferred to the beam current modulation. Then the beam is sent into a 33-cm long undulator, where a coherent start-up of THz radiation takes place, and the THz pulse is used for a bunching analysis. The performance of LBW bunching is simulated and analyzed using a 3D FEL code for the parameters of an existing photoinjector and two-wavelength TW CO2 laser system. |
| keywords: | pbpl |
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| title: | Status of the SPARC Photoinjector |
| format: | journal article |
| year: | 2006 |
| 69 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | The SPARC Project is starting the commissioning of its photo-injector. RF gun, RF sources, RF network and control, power supplies, emittance meter, beam diagnostics and control to measure the RF gun beam have been installed. The photocathode drive laser has been characterized in terms of pulse shape and quality. We will report also about first tests made on RF gun and on the emittance meter device. Additional R&D on X-band and S-band structures for velocity bunching are in progress, as well as studies on new photocathode materials. We will also discuss studies on solenoid field defects, beam based alignments and exotic electron bunch production via blow-out of short laser pulses. |
| keywords: | pbpl |
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| title: | Seeded free-electron and inverse free-electron laser techniques for radiation |
| format: | journal article |
| year: | 2006 |
| 6 authors: | | | | | | |
| abstract: | A comprehensive analysis is presented that describes amplification of a seed THz pulse in a single-pass free-electron laser (FEL) driven by a photoinjector. The dynamics of the radiation pulse and the modulated electron beam are modeled using the time-dependent FEL code, GENESIS 1.3. A 10-ps (FWHM) electron beam with a peak current of 50 –100 A allows amplification of a |
| keywords: | pbpl |
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| title: | Development of a Waveguide FEL Seeded in the 1-3 THz Range for Microbunching Experiment at the Neptune Laboratory |
| format: | journal article |
| year: | 2006 |
| 8 authors: | | | | | | | | |
| abstract: | IFEL and FEL techniques can be used to modulate an electron beam on the scale of the radiation wavelength. However, the lack of a high power radiation source in the 100-300 μm range hinders the progress on THz IFEL microbunching. In this paper, we discuss microbunching of an electron beam using a single-pass FEL seeded with a low power THz pulse generated by frequency mixing of CO2 laser lines in a GaAs nonlinear crystal. A narrowband THz seed source is pumped by a dual beam TEA CO2 laser and can be tuned in the 1-3 THz range. The THz radiation is guided through a hollow waveguide inside the planar FEL undulator driven by a photoinjector. By using a time-dependent FEL code GENESIS 1.3, we optimized the undulator parameters and analyzed the dynamics of the modulated electron beam. By using a ~ 8 MeV electron beam with a peak current of 40 A and a ~1kW THz seed with wavelength 200 μm, the energy modulation up to 1.3% can be achieved in a ~1.8-m long undulator with a constant period of 2.7 cm. At present, the THz seed source is built and fully characterized. The results of transmission measurements for THz waveguides are also discussed. |
| keywords: | pbpl |
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| title: | Observation of Coherent Edge Radiation Emitted by a 100 Femtosecond Compressed Electron Beam |
| format: | journal article |
| year: | 2006 |
| 13 authors: | | | | | | | | | | | | | |
| abstract: | A chicane compressor developed by UCLA for the production of ultra-short, 60 MeV electron beams at the Brookhaven National Laboratory Accelerator Test Facility has been commissioned, and initial beam physics experiments have been performed. These measurements have established the compression of electron beams to the 100 femtosecond (1 kA peak current) regime, via coherent transition radiation (CTR) based measurements. Investigations of coherent edge radiation (CER) include signatures that differentiate it from coherent synchrotron radiation (CSR), such as polarization and far-field angular distribution. Additionally, the radiation wavelength spectrum is determined from autocorrelation measurements. Radiation properties are compared to detailed start-to-end simulations derived from PARMELA and QUINDI (a Lienard-Wiechert code developed at UCLA). Plans for future experiments which further explore the observed wavelength spectra are presented. |
| keywords: | pbpl |
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| title: | Feasibility Study of a Laser Beat-Wave Seeded THz FEL at the Neptune Laboratory |
| format: | journal article |
| year: | 2005 |
| 6 authors: | | | | | | |
| abstract: | |
| keywords: | pbpl |
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| title: | The Development of X-ray Free-Electron Lasers |
| format: | journal article |
| year: | 2004 |
| 2 authors: | | |
| abstract: | We review and discuss the theoretical and experi- mental work that has led to the development of short wavelength free-electron lasers operating as single pass amplifiers, starting from the spontaneous undulator radiation, in the self amplified spontaneous emission mode. This work has led to several projects to build this type of free-electron lasers operating at a wavelength of about 0.1 nm, producing coherent X-ray pulses with an un- precedented brilliance and peak power, and pulse length in the femtosecond range. One such project, the LCLS, is presently under construction and is expected to be operational in 2008. tool to study the properties and structure of matter at the atomic and molecular level for over a century. Using X-rays we have made great progress in understanding the physical properties of materials and living systems. Today, the best sources of X-rays utilize spontaneous synchrotron radiation from relativistic elec- tron beams in storage rings with undulator magnet insertions. The most advanced, so-called third generation sources, are used by thousands of scientists around the world. |
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| title: | Status Report on SPARC Project |
| format: | journal article |
| year: | |
| 96 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | We review the status of FEL source activity of the ongoing SPARC FEL experiment, developed within the framework of a collaboration among ENEA, CNR, INFN, INFM, Sincrotrone Trieste and University of Rome Tor Vergata. The project is aimed at realising a SASE-FEL source, operating in the visible (around 500 nm), with an extended range of tunability down to the VUV (100 nm) by the use of the mechanism of non-linear harmonic generation. The development of the relevant activities foresees the realisation of an advanced 150 MeV photo- injector source, aimed at producing a high brightness electron beams, needed to drive a SASE-FEL experiment, and a 14 m long undulator. We present the status of the design and construction of SPARC FEL device. In particular we discuss the choice of the project parameters, their optimisation and the sensitivity of the SPARC performance to any parameter variation. We will show, using start-to-end simulations, what is the impact of the e- beam and of the undulator parameters on the characteristics of the output laser field and in particular on the amount of the non-linearly generated power at higher harmonics. |
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| title: | The SPARX project: R & D Activity towards X-Ray Sources |
| format: | journal article |
| year: | |
| 79 authors: | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
| abstract: | SPARX is an evolutionary project proposed by a collaboration among ENEA-INFN-CNR-Universita` di Roma Tor Vergata aiming at the construction of a FEL- SASE X-ray source in the Tor Vergata Campus. The first phase of the SPARX project, funded by Government Agencies, will be focused on R&D activity on critical components and techniques for future X-ray facilities as described in this paper. |
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| title: | Terahertz IFEL/FEL Microbunching for Plasma Beatwave Accelerators |
| format: | journal article |
| year: | |
| 9 authors: | | | | | | | | | |
| abstract: | In order to obtain monoenergetic acceleration of electrons, phase-locked injection using electron microbunches shorter than the accelerating structure is necessary. For a laser-driven plasma beatwave accelerator experiment, we propose to microbunch the electrons by interaction with terahertz (THz) radiation in an undulator via two mechanisms– Free Electron Laser (FEL) and Inverse Free Electron Laser (IFEL). Since the high power FIR radiation will be generated via difference frequency mixing in GaAs by the same CO2 beatwave used to drive the plasma wave, electrons could be phase-locked and pre-bunched into a series of microbunches separated with the same periodicity. Here we examine the criteria for undulator design and present simulation results for both IFEL and FEL approaches. Using different CO2 laser lines, electrons can be microbunched with different periodicity 300 –100 μm suitable for injection into plasma densities in the range 1016 – 1017 cm-3, respectively. The requirements on the THz radiation power and the electron beam qualities are also discussed. |
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| title: | Single spike operation in SPARC SASE-FEL |
| format: | conference procceeding |
| conference: | EPAC 2008 |
| year: | |
| 16 authors: | | | | | | | | | | | | | | | | |
| abstract: | The single spike operation regime has been analyzed in the case of the SPARC injector and freeelectron-laser. Four different beams at 50 pC are studied, with different production condition and performance. |
| keywords: | pbpl_pub |
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