FEL 2006 - List of Keywords (diagnostics)

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

diagnostics

Paper	Title	Other Keywords	Page
MOAAU05	The First Lasing of 193 nm SASE, 4th Harmonic HGHG and ESASE at the NSLS SDL	laser, electron, undulator, linac	18
	X. J. Wang, J. B. Murphy, J. Rose, Y. Shen, T. Tsang, T. Watanabe BNL, Upton, Long Island, New York
	After successfully achieving SASE lasing at 198 nm on April 20, 2006, we have also observed the first 4th harmonic High Gain Harmonic Generation (HGHG) with a 795 nm seed laser. We will report the progress and experimental characterization of the 198 nm SASE and 4th harmonic HGHG.
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MOPPH073	An Enhanced GINGER Simulation Code with Harmonic Emission and HDF5 IO Capabilities	radiation, simulation, undulator, vacuum	218
	W. M. Fawley LBNL, Berkeley, California
	GINGER* is an axisymmetric, polychromatic (r-z-t) FEL simulation code originally developed in the mid-1980's to model the performance of single-pass amplifiers. Over the past 15 years GINGER's capabilities have been extended to include more complicated configurations such as undulators with drift spaces, dispersive sections, and vacuum chamber wakefield effects; multi-pass oscillators; and multi-stage harmonic cascades. Its coding base has been tuned to permit running effectively on platforms ranging from desktop PC's to massively parallel processors such as the IBM-SP. Recently, we have made significant changes to GINGER by replacing the original predictor-corrector field solver with a new direct implicit algorithm, adding harmonic emission capability, and switching to the HDF5 IO library** for output diagnostics. In this paper, we discuss some details regarding these changes and also present simulation results for a number of test cases ranging from LCLS SASE emission to performance of the FERMI@ELETTRA two-stage, harmonic cascade. * http://www-ssrl.slac.stanford.edu/lcls/technotes/LCLS-TN-04-3.pdf (also LBNL-49625-Rev. 1) ** http://hdf.ncsa.uiuc.edu/HDF5/

TUBAU05	Technical Aspects of the Integration of the Optical Replica Synthesizer for the Diagnostics of Ultra-short Bunches into FLASH at DESY	laser, electron, undulator, vacuum	296
	P. van der Meulen, N. X. Javahiraly, M. Larsson FYSIKUM, AlbaNova, Stockholm University, Stockholm E. Saldin, H. Schlarb, E. Schneidmiller, A. Winter, M. V. Yurkov DESY, Hamburg V. G. Ziemann UU/ISV, Uppsala
	Recently, Saldin et al.* introduced a novel scheme to characterise ultra-short electron bunches in a FEL. The method is based on producing an 'optical copy' of the electron bunch, which can then be easily analysed using well-known non-linear optical techniques. To this end, a near-IR laser beam is overlapped with the electron beam in the first undulator of an optical klystron. In the following dispersive section the laser-induced energy modulation is transformed into a density modulation . The modulated electron bunch then produces a strong optical pulse in the second undulator. Analysis of this near-IR pulse (the optical copy) then provides information about the length, the slice emittance and the slice energy spread of the original electron bunch. We discuss the implementation of such a measurement set-up at the VUV-FEL at DESY and investigate the influence of various parameters on the performance of the device. Topics we address include the electron beam optics of the undulators, quadrupoles and the dispersive chicane, as well as the requirements for the seed laser pulses. The detection and analysis of the near-IR pulse and an extension to the XUV-FEL are also covered. * E. Saldin, et al. "A simple method for the determination of the structure of ultrashort relativistic electron bunches," Nucl. Inst. and Methods A 539 (2005) 499.
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TUPPH015	Remote Controlled IR-Diagnostic Station for the FEL at Rossendorf	plasma, laser, radiation, electron	341
	W. Seidel, S. Friebel, R. Jainsch, M. Justus, K.-W. Leege, D. Proehl, D. Stehr, H. Weigelt, S. Winnerl, D. Wohlfarth FZR, Dresden
	The remote controlled diagnostic station delivers a small amount of the IR radiation by means of a system of relocatable mirrors and beam splitters to the spectrometer and to various power detectors working in different power ranges. Furthermore, a long wavelength MCT detector is integrated in the diagnostic station for gain and loss measurement in the whole wavelength range of the U27-FEL. The average radiation power available for the users can be reduced by a remote controlled attenuator. To characterize the optical micropulse duration we have built a non-collinear background-free autocorrelator as a part of the diagnostic station. By using a CdTe single-crystal for second-harmonic generation a broad wavelength coverage is obtained. Certain experiments require high pulse energies but moderate or low average power. For such experiments the repetition rate of the Rossendorf FEL can be reduced from 13 MHz to 1 kHz, in the future also to 1 Hz, by a semiconductor plasma switch excited with a synchronized Nd:YAG amplifier. This system is under commissioning and we will report on first results. Submitted as a poster to the FEL 2006 conference.

TUPPH056	Comparative Study of Digital and Analog Synchronization Techniques for Lasers in Accelerators	laser, feedback, resonance, controls	459
	A. Winter DESY, Hamburg W. J. Jalmuzna Warsaw University of Technology, Institute of Electronic Systems, Warsaw
	Laser systems play an important role in present and future light sources. These lasers need to be synchronized very precisely to the accelerator RF. One aproach is using an analog controller, which offers low-noise performance and has been demonstrated to achieve sub-50 fs stability. A digital controller based on a high-performance FPGA on the other hand offers great flexibility, for instancethe possibility to implement notch filters to evade the limitations of piezo resonances. This paper presents results obtained with both approaches.

TUPPH067	Commissioning of a New Emittance Measurement System at PITZ	emittance, electron, booster, gun	474
	L. Staykov, J. W. Baehr, H.-J. Grabosch, S. Khodyachykh, S. A. Korepanov, M. Krasilnikov, A. Oppelt, B. Petrosyan, J. R. Roensch, F. Stephan DESY Zeuthen, Zeuthen G. Asova, I. Tsakov INRNE, Sofia
	The goal of the Photo Injector Test facility in Zeuthen (PITZ) is to test and optimize high brightness electron sources suitable for FEL's like FLASH and XFEL. Such sources are characterized by very low emittance at high bunch charge. The Emittance Measurement SYstem (EMSY) described in this paper uses YAG and OTR screens to measure the transverse beam size and thin Tungsten slits to measure the divergence of the beam. It has been optimized to measure emittance for a beam of 1 nC in the energy range 5 - 30 MeV. EMSY was developed in a cooperation between DESY Zeuthen and INRNE Sofia. It was installed in the PITZ tunnel in the beginning of June and commissioning and first measurements were done.

THPPH018	Single-Shot Longitudinal Diagnostics with THz Radiation at the Free-Electron Laser FLASH	radiation, electron, free-electron-laser, laser	594
	H. Delsim-Hashemi, J. Rossbach, P. Schmüser Uni HH, Hamburg O. Grimm, H. Schlarb, B. Schmidt DESY, Hamburg A. F.G. van der Meer FOM Rijnhuizen, Nieuwegein
	The longitudinal charge distribution in the electron bunches has a strong impact on the lasing process in a SASE-type FEL. The investigation of the longitudinal charge distribution in the electron bunches with very high resolution and on a bunch-by-bunch basis is enabled by a novel spectrometer which is based on diffraction gratings and multichannel signal detection. Measurements of coherent transition radiation with this spectrometer in both the scanning mode and the single-shot mode are presented. Structures in the electron bunches as short as 10 fs have been observed. Correlations between the measured FEL pulse energies and the signals in different wavelength channels of the single-shot spectrometer have been established. These data will be utilized to fine-tune the parameters of the bunch compression system at FLASH in order to optimize the gain in the SASE process.

THPPH021	Design Consideration of the RF Deflector to Optimize the Photo Injector at PITZ	emittance, simulation, kicker, single-bunch	605
	S. A. Korepanov, S. Khodyachykh, M. Krasilnikov, A. Oppelt, F. Stephan DESY Zeuthen, Zeuthen V. V. Paramonov RAS/INR, Moscow
	In order to optimize photo injectors for Free Electron Laser (FEL) applications, a detailed characterization of the longitudinal and transverse phase space of the electron beam provided by the Photo Injector Test Facility at DESY in Zeuthen (PITZ) is required. Design considerations of the RF deflecting cavity for transverse slice emittance and longitudinal phase space measurements are presented in the paper.

THPPH029	The Diagnostics of the FERMI@Elettra Bunch Compressors	electron, radiation, dipole, feedback	629
	M. Veronese, S. Di Mitri, M. Ferianis ELETTRA, Basovizza, Trieste
	Bunch compressors are key components of the single pass Linac based seeded FEL FERMI@ELETTRA. Assuring their stable operation, to reliably produce sub-psec electron bunches, requires multiple non-destructive diagnostics. Most of these diagnostics provide the error signals to the feedback systems used to stabilize the energy and the peak current of the electron bunch which are crucial parameters for optimum FEL operation. The different operation regimes foreseen for FERMI* call for a flexible set-up, for both the bunch compressors and the associated diagnostics. In this paper we present the adopted diagnostics for the measurement of position, energy and energy spread; both "energy" BPM, in between BC, and OTR screen plus wire scanner will be used. The design of a relative bunch length monitor needed for the determination of the optimal compression and for peak current stabilization is presented as well. The scheme is based on non-invasive techniques, namely the detection of the coherent synchrotron radiation (CSR) from the last bending of the BC plus the coherent diffraction radiation (CDR) from a downstream slit. Finally, a technique for the bunch phase measurement is presented. * Study of the Electron Beam Dynamics in the FERMI @ ELETTRA Linac, M. Cornacchia, et al., Proc. of EPAC 2006 Conf., Scotland, UK (June 2006), to be published.

THPPH031	Commissioning of the SPARC Photo-Injector	laser, gun, controls, emittance	637
	M. Bellaveglia, D. Alesini, S. Bertolucci, M. E. Biagini, R. Boni, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, S. Guiducci, M. Incurvati, C. Ligi, M. Migliorati, A. Mostacci, L. Palumbo, L. Pellegrino, M. A. Preger, R. Ricci, C. Sanelli, F. Sgamma, B. Spataro, F. Tazzioli, C. Vaccarezza, M. Vescovi, C. Vicario INFN/LNF, Frascati (Roma) A. Bacci, I. Boscolo, F. Broggi, S. Cialdi, D. Giove, M. Mauri, A. R. Rossi, L. Serafini INFN-Milano, Milano L. Catani, E. Chiadroni, A. Cianchi, S. Tazzari INFN-Roma II, Roma L. Giannessi, M. Quattromini, A. Renieri, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) M. Mattioli, P. Musumeci, M. Petrarca INFN-Roma, Roma A. Perrone INFN-Lecce, Lecce J. B. Rosenzweig UCLA, Los Angeles, California
	The SPARC project is born to perform R&D activity headed to realize SASE-FEL experiments at 500nm and higher harmonic generation. The project foresees the realization of a high brightness photo-injector able to produce a 150-200MeV electron beam to drive FEL process inside a dedicated 14m long undulator. The machine is going to be assembled at LNF and its final configuration is made up of an RF gun, driven by a Ti:Sa laser, injecting into three SLAC type accelerating sections. Nowadays we are working in a photo-injector test phase, aiming to characterize the main hardware components and to investigate the behavior of the e-beam dynamics in the first meters of drift. To do this we utilize the emittance-meter, a home designed diagnostic device placed just after the RF gun, able to move 1.2 meters along the longitudinal axis to measure beam parameters. In this paper we report a more accurate description of the project, the status of the single systems constituting the machine and the most important results we obtained in the e-meter phase.

THPPH055	Nonintercepting Beam Size and Position Monitor Using ODR for X-Ray FELs	quadrupole, radiation, polarization, dipole	710
	A. H. Lumpkin, W. Berg, N. Sereno, B. X. Yang, C. Yao ANL, Argonne, Illinois D. W. Rule NSWC, West Bethesda, Maryland
	Interest in nonintercepting (NI) beam size and position diagnostics in the undulators of x-ray free-electron lasers (XFELs) is driven by the requirement of beam-emittance matching, as well as by the need to minimize radiation damage to the undulator's permanent magnets from scattered beam produced by the insertion of converter screens. For these reasons, our investigations on optical diffraction radiation (ODR) as NI relative beam size and position diagnostics are particularly relevant to XFELs. We report the extensions of our studies at 7-GeV beam energy to aspects of the vertical and horizontal polarization components of the ODR near-field and far-field images. The near-field, vertically polarized data are particularly interesting since the vertical field lines at the metal more directly reflected the actual beam sizes. Although our experiments to date are with larger beams and impact parameters of 1-2 mm, our analytical model indicates that this technique scales with beam size and has sensitivity at the 20- to 50-micron regime with an impact parameter, d = 5 times σ-y =100 microns. This is the x-ray FEL intraundulator beam size regime.

THPPH056	Initial Search for 9-keV XTR from a 28-GeV Beam at SPPS*	wiggler, radiation, photon, background	714
	A. H. Lumpkin ANL, Argonne, Illinois J. B. Hastings SLAC, Menlo Park, California D. W. Rule NSWC, West Bethesda, Maryland
	The potential to use x-ray transition radiation (XTR) as a beam diagnostic and coherent XTR (CXTR) as a gain diagnostic in an x-ray FEL was proposed previously. At that time we noted that the unique configuration of the SLAC Sub-picosecond Photon Source (SPPS) with its known x-ray wiggler source, a special three-element x-ray monochromator, x-ray transport line, and experimental end station with x-ray detectors made it an ideal location for an XTR feasibility experiment. A test of XTR intensity with respect to the x-rays emitted by the SPPS wiggler was proposed. The three-element monochromator was first adjusted to transport 9-keV or 1.3-Angstrom x rays from the SPPS wiggler source to the camera. The expected source strength in the bandpass of the monochromator was about 2x10⁷ photons per 3 nC electron pulse, and our calculated XTR intensity was about 10³ photons. We first successfully imaged the SPPS x-ray beam with the ANDOR x-ray CCD by using an Al-foil attenuation of 4x10³. The wiggler gap was then opened, and x-ray images recorded with the Ti foils out for background evaluation and with the Ti foils inserted to search for XTR. Initial images will be presented.

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

THCAU01	Overview on Diagnostics for X- and XUV-FELs	radiation, laser, electron, emittance	761
	B. Schmidt DESY, Hamburg
	Controlling and optimizing the SASE process of X-FELs and XUV-FELs requires detailed knowledge and information about the parameters of the driving electron beam which are of critical influence on the laser performance. Due to the very high peak current, collective phenomena have to be carefully measured and controlled while integral (projected) parameters are of limited use. This necessitates the development of a variety of diagnostics tools to monitor the electron bunch parameters in detailedness beyond the capabilities of conventional systems. Longitudinal bunch structures can be derived from time domain methods like electro optic techniques or using transverse deflecting RF-structures, and from frequency domain methods using coherent radiation. The talk will report on recent developments with special emphasis on single shot and online monitoring capabilities in this field. Other topics will be new concepts and experience in measuring the projected and time-sliced emittance of the beam, high precision beam position monitors and sub-picosecond beam phase and arrival time monitor systems.
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FRAAU01	Photon Optics at SCSS	radiation, photon, undulator, optics	785
	M. Yabashi, T. Ishikawa RIKEN Spring-8 Harima, Hyogo S. Goto, T. Hirono, H. Kimura, H. Ohashi, S. Takahashi, K. Tamasaku JASRI/SPring-8, Hyogo-ken
	Developments of x-ray optics for the SCSS project are summarized. The optics has two important roles: beam handling (conditioning) and diagnostics. For the former issue, our R&D program for improving qualities of optical components (diamond monochromator, total-reflection mirror, beryllium windows, etc.) are presented. For the latter, a new spectrometer will be introduced. M. Yabashi et al., PRL (in press)
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FRAAU03	Wave-Front Observations at FLASH	alignment, optics, focusing, laser	794
	M. Kuhlmann, E. Plönjes, K. I. Tiedtke, S. Toleikis DESY, Hamburg P. Mercere SOLEIL, Gif-sur-Yvette P. Zeitoun LOA, Palaiseau
	During the first user operation of the Free-Electron Laser in Hamburg (FLASH) wavefront measurements have been recorded in the vacuum-ultraviolet region using a Hartmann sensor (by Imagine Optic). The Hartmann principle is based on a pinhole array, which divides the incoming beam into a large number of sub-rays monitored in intensity and position of individual spots. The identification of the local slope of the incident wavefront makes the aberrations from a perfect spherical wavefront visible. Ray tracing in upstream direction accesses the beam focal point in size and position. The intense and coherent vacuum-ultraviolet FEL beam leads to unique requirements for the wavefront sensor setup. We report an optimized setup to observe the metrology of flat and curved mirrors at FLASH beamlines. The effects of solid and gaseous filters are selectively described in the wavelength regime of 10nm to 32nm. The use of wavefront measurements to provide reliable machine parameter is discussed. The wavefront sensor proved to be a valuable tool to observe the FEL beam quality and the performance of optical elements, filters and diagnostic tools.
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