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203. Fermi seeded FEL progress report

Author

Svandrlik, M., Allaria, E., Bencivenga, F., Callegari, C., Capotondi, F., Castronovo, D., Cinquegrana, P., Cudin, I., Dal Forno, M., Danailov, M. B., D Auria, G., Monte, R., Ninno, G., Demidovich, A., Di Mitri, S., Diviacco, B., Fabris, A., Fabris, R., Fawley, W. M., Ferianis, M., Ferrari, E., Finetti, P., Froehlich, L., Radivo, P. F., Gaio, G., Luca Giannessi, Kiskinova, M., Loda, G., Lonza, M., Mahne, N., Masciovecchio, C., Parmigiani, F., Penco, G., Plekan, O., Predonzani, M., Principi, E., Raimondi, L., Rossi, F., Rumiz, L., Scafuri, C., Serpico, C., Sigalotti, P., Spampinati, S., Spezzani, C., Sturari, L., Svetina, C., Trovo, M., Vascotto, A., Veronese, M., Visintini, R., Zangrando, D., Zangrando, M., Mahieu, B., Craievich, P., IPAC 2013, M., Svandrlik, E., Allaria, F., Bencivenga, C., Callegari, F., Capotondi, D., Castronovo, P., Cinquegrana, P., Craievich, I., Cudin, G., D'Auria, DAL FORNO, Massimo, M. B., Danailov, R., De Monte, G., De Ninno, A. A., Demidovich, S., Di Mitri, B., Diviacco, A., Fabri, R., Fabri, W. M., Fawley, M., Feriani, Ferrari, Eugenio, P., Finetti, L., Fröhlich, P., Furlan Radivo, G., Gaio, L., Giannessi, M., Kiskinova, G. L., Loda, M., Lonza, B., Mahieu, N., Mahne, C., Masciovecchio, Parmigiani, Fulvio, G., Penco, O., Plekan, M., Predonzani, E., Principi, L., Raimondi, F., Rossi, L., Rumiz, C., Scafuri, C., Serpico, P., Sigalotti, S., Spampinati, C., Spezzani, L., Sturari, C., Svetina, M., Trovò, A., Vascotto, M., Veronese, R., Visintini, D., Zangrando, and M., Zangrando

Subjects
FEL
Abstract

FERMI, the seeded Free Electron Laser (FEL) located at the Elettra laboratory in Trieste, Italy, welcomed in December 2012 the first external users on the FEL-1 line. This line is based on a single stage of High Gain Harmonic Generation (HGHG), seeded by a UV laser, and covers wavelengths between 80 and 20 nm. The photon energy reached more than 300 J. The second FEL line, FEL-2, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, has generated its first coherent photons in October 2012. The latter is the first experimental demonstration of a seeded free electron laser configured as a two-stage cascade operating in the "fresh bunch injection” mode, where the second stage is seeded by the light produced by the first stage. This paper describes the status of the operation and user experiments with FEL-1 and reports about the progress in the commissioning of FEL-2.

205. Status of the fermi@elettra project

Author

Svandrlik, M., Allaria, E., Badano, L., Bassanese, S., Bencivenga, F., Busetto, E., Callegari, C., Capotondi, F., Castronovo, D., Coreno, M., Craievich, P., Cudin, I., Dal Forno, M., Danailov, M. B., D Auria, G., Monte, R., Demidovich, A., Ninno, G., Di Fraia, M., Di Mitri, S., Diviacco, B., Fabris, A., Fabris, R., Fawley, W. M., Ferianis, M., Ferrari, E., Fröhlich, L., Furlan Radivo, P., Gaio, G., Gobessi, R., Grazioli, C., Karantzoulis, E., Kiskinova, M., Lonza, M., Mahieu, B., Masciovecchio, C., Noè, S., Parmigiani, F., Penco, G., Principi, E., Rossi, F., Rumiz, L., Scafuri, C., Spampinati, S., Spezzani, C., Svetina, C., Trovò, M., Vascotto, A., Veronese, M., Visintini, R., Zaccaria, M., Zangrando, D., Zangrando, M., Luca Giannessi, IPAC2012, M., Svandrlik, E., Allaria, L., Badano, S., Bassanese, F., Bencivenga, E., Busetto, C., Callegari, F., Capotondi, D., Castronovo, M., Coreno, P., Craievich, I., Cudin, DAL FORNO, Massimo, M. B., Danailov, G., D'Auria, R., De Monte, A., Demidovich, G., De Ninno, DI FRAIA, Michele, S., Di Mitri, B., Diviacco, A., Fabri, R., Fabri, W. M., Fawley, M., Feriani, Ferrari, Eugenio, L., Fröhlich, P., Furlan Radivo, G., Gaio, R., Gobessi, Grazioli, Cesare, E., Karantzouli, M., Kiskinova, M., Lonza, B., Mahieu, C., Masciovecchio, Noe', Salvatore, Parmigiani, Fulvio, G., Penco, E., Principi, F., Rossi, L., Rumiz, C., Scafuri, S., Spampinati, C., Spezzani, C., Svetina, M., Trovò, A., Vascotto, M., Veronese, R., Visintini, M., Zaccaria, D., Zangrando, M., Zangrando, and L., Giannessi

Subjects
FEL

206. Commissioning and initial operation of FEZRMI@ELETTRA

Author

Di Mitri, S., Allaria, E., Appio, R., Badano, L., Bassanese, S., Bencivenga, F., Borga, A., Bossi, M., Busetto, E., Callegari, C., Capotondi, F., Casarin, K., Castronovo, D., Cinquegrana, P., Cocco, D., Cornacchia, M., Craievich, P., Cucini, R., Cudin, I., Dal Forno, M., D Amico, F., D Auria, G., Danailov, M. B., Delgiusto, P., Demidovich, A., Monte, R., Ninno, G., Diviacco, B., Fabris, A., Fabris, R., Fawley, W., Ferianis, M., Ferrari, E., Ferry, S., Froehlich, L., Furlan Radivo, P., Karantzoulis, E., Kiskinova, M., Gaio, G., Gelmetti, F., Giannessi, L., Gobessi, R., Ivanov, R., Lonza, M., Lutman, A., Mahieu, B., Masciovecchio, C., Menk, R. H., Milloch, M., Musardo, M., Noe, S., Nikolov, I., Parmigiani, F., Pavlovic, L., Emanuele Pedersoli, Penco, G., Petronio, M., Predonzani, M., Principi, E., Quai, E., Quondam, G., Rossi, F., Rumiz, L., Scafuri, C., Serpico, C., Sigalotti, P., Spampinati, S., Spezzani, C., Svandrlik, M., Svetina, C., Trovo, M., Vascotto, A., Veronese, M., Visintini, R., Zaccaria, M., Zangrando, D., Zangrando, M., Wang, D., Alagia, M., Avaldi, L., Coreno, M., Feyer, V., Kivimaki, A., Bolognesi, P., Simone, M., O Keeffe, P., Devetta, M., Mazza, T., Piseri, P., Prince, K., Richter, R., Sergo, R., Stranges, S., Lyamayev, V., Ovcharenko, Y., Sjostrom, M., Biedron, S., and Milton, S.

209. Novel $X$-band transverse deflection structure with variable polarization

Author

Craievich, P., Bopp, M., Braun, H.-H., Citterio, A., Fortunati, R., Ganter, R., Kleeb, T., Marcellini, F., Pedrozzi, M., Prat, E., Reiche, S., Rolli, K., Sieber, R., Grudiev, A., Millar, W. L., Catalan-Lasheras, N., McMonagle, G., Pitman, S., Del Pozo Romano, V., Szypula, K. T., Wuensch, W., Marchetti, Barbara, Assmann, R., Christie, F., Conrad, B., D'Arcy, Richard, Foese, M., Gonzalez Caminal, Pau, Hoffmann, Matthias, Huening, Markus, Jonas, R., Krebs, O., Lederer, S., Marx, Daniel, Osterhoff, J., Reukauff, M., Schlarb, H., Schreiber, Siegfried, Tews, G., Vogt, Mathias, Zubiaurre-Wagner, Antonio De, and Wesch, S.

Subjects
Radio Frequency Calculations and Technology, 3. Good health
Abstract

Physical review accelerators and beams 23(11), 112001 (1-22) (2020). doi:10.1103/PhysRevAccelBeams.23.112001, A collaboration between DESY, PSI and CERN has developed and built an advanced modular $X$-band transverse deflection structure (TDS) system with the new feature of providing variable polarization of the deflecting force. The prototype of the novel $X$-band TDS, the polarizable $X$-band (PolariX) TDS, was fabricated at PSI following the high-precision tuning-free production process developed for the C-band Linac of the SwissFEL project. Bead-pull rf measurements were also performed at PSI to verify, inparticular, that the polarization of the dipole fields does not have any rotation along the structure. The high-power test was performed at CERN and now the TDS is at DESY and has been installed in theFLASHForward beamline, where the first streaking experience with beam has been accomplished. We summarize in this paper the rf design of the TDS and its key components, such as the $X$-band pulse compressor, E-rotator, and phase shifter, the results of the bead-pull measurements and the high power test and finally the rf setup at DESY., Published by American Physical Society, College Park, MD

220. Canaletto and his rivals.

Author

Craievich, Alberto

Abstract

The article reviews the exhibition "Canaletto and His Rivals," which was recently shown at the National Gallery in London, England and will be shown at the National Gallery of Art in Washington, D.C. from February 20, 2011 to May 30, 2011.

Published
2011

222. SAXS Study of Gelation, Aging and Drying of Silica-Polypropyleneglycol Hybrid Materials

Author

Dahmouche, K., Santilli, C. V., Chaker, J. A., Pulcinelli, S. H., and Craievich, A. F.

Abstract

New silica-polypropyleneglycol ormosils (organically modified silicates) with covalent bonds between the organic (polymer) and inorganic (silica) phases have been prepared by the sol-gel process. Their structural evolution during sol formation, sol-gel transition, gel aging and drying has been studied in situby small-angle X-ray scattering (SAXS). The experimental SAXS curves corresponding to sols and gels exhibit features expected from fractal objects. Clusters of size around 55 Å with an initial fractal dimension D = 2.4 are formed in the sol. They are constituted of small primary silica particles chemically crosslinked at the end of the polymer chains. A strong liquid-like spatial correlation between the silica particles develops during drying due to the shrinkage of the polymeric network induced by water and ethanol evaporation. The continuous increase in SAXS intensity during drying, while the interparticle distance remains constant, is a consequence of the progressive growth of the dry fraction of the total volume. After drying, the gel structure consists of a rather compact arrangement of silica particles embedded in the polypropyleneglycol matrix.

Published
1999
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223. Implementation of Radio-Frequency Deflecting Devices for Comprehensive High-Energy Electron Beam Diagnosis

Author

Giuseppe Penco, Massimo Dal Forno, L. Rumiz, Paolo Craievich, Defa Wang, Marco Petronio, L. Sturari, Nicolas Faure, Sandra Biedron, Daniele La Civita, Roberto Vescovo, Simone Di Mitri, D. Castronovo, Craievich, P., Petronio, Marco, Biedron, S. G., Castronovo, D., DAL FORNO, Massimo, Di Mitri, S., Faure, N., La Civita, D., Penco, G., Rumiz, L., Sturari, L., Vescovo, Roberto, and Defa, Wang

Subjects
diagnostic system, optimisation, Electron accelerators, electron beam deflection, high-brightness beams, photon-producing element, free electron laser, Electron, electron beam phase space, radiofrequency deflecting devices, particle beam measurements, longitudinal phase space, law.invention, comprehensive high-energy electron beam diagnosis, electron energie, electron energies, law, next-generation light source, Radio frequency, longitudinal emittance, accelerator RF system, Energy resolution, Cavity resonators, Physics, transverse deflecting cavity structure, particle beam diagnostic, high-brightness beam, photon-producing beam-lines, next-generation light sources, radiofrequency cavitie, VUV wavelength regime, low transverse emittance, photon-producing beam-line, imaging system, linear accelerator, free-electron laser configuration, Wavelength, Cavity resonator, soft X-ray wavelength regime, free electron lasers, radiofrequency deflecting device, optimization, Laser beams, Electron beam, Nuclear and High Energy Physics, accelerator RF systems, accelerator cavities, electron accelerators, electron beams, light sources, particle beam diagnostics, FERMI light source, acceleration process, magnetic spectrometer, radiofrequency cavities, Electron beams, Light sources, Optical beams, free-electron lasers, Electron accelerator, Linear particle accelerator, comprehensive high-energy electron beam diagnosi, Optics, free-electron laser, Light source, Optical beam, oft X-ray wavelength regime, Thermal emittance, Electrical and Electronic Engineering, Laser beam, Spectrometer, business.industry, accelerator cavitie, Laser, acceleration proce, Nuclear Energy and Engineering, Cathode ray, Physics::Accelerator Physics, business
Abstract

In next-generation light sources, high-brightness electron beams are used in a free-electron laser configuration to produce light for use by scientists and engineers in numerous fields of research. High-brightness beams are described for such light sources as having low transverse and longitudinal emittances, high peak currents, and low slice emittance and energy spread. The optimal generation and preservation of such high-brightness electron beams during the acceleration process and propagation to and through the photon-producing element is imperative to the quality and performance of the light source. To understand the electron beam's phase space in the accelerating section of a next-generation light source machine, we employed radio-frequency cavities operating in a deflecting mode in conjunction with a magnetic spectrometer and imaging system for both low (250 MeV) and high (1.2 GeV) electron energies. This high-resolution, high-energy system is an essential diagnostic for the optimization and control of the electron beam in the FERMI light source generating fully transversely and longitudinally coherent light in the VUV to soft x-ray wavelength regimes. This device is located at the end of the linear accelerator in order to provide the longitudinal phase space nearest to the entrance of the photon-producing beam-lines. Here, we describe the design, fabrication, characterization, commissioning, and operational implementation of this transverse deflecting cavity structure diagnostic system for the high-energy (1.2 GeV) regime.

Published
2015

224. Laser heater commissioning at an externally seeded free-electron laser

Author

S. Bassanese, M. Dal Forno, M. Trovo, Simone Spampinati, S. Di Mitri, D. Castronovo, M. B. Danailov, Lars Fröhlich, Enrico Allaria, C. Serpico, Eugenio Ferrari, Marco Veronese, Luigi P. Badano, M. Svandrlik, Alexander Demidovich, Bruno Diviacco, Giuseppe Penco, Luca Giannessi, Sandra Biedron, W. M. Fawley, Paolo Craievich, Stephen V. Milton, Carlo Spezzani, G. De Ninno, Giulio Gaio, Spampinati, S., Allaria, E., Badano, L., Bassanese, S., Biedron, S., Castronovo, D., Craievich, P., Danailov, M. B., Demidovich, A., DE NINNO, Giovanni, Di Mitri, S., Diviacco, B., DAL FORNO, Massimo, Ferrari, Eugenio, Fawley, W. M., Fröhlich, L., Gaio, G., Giannessi, L., Penco, G., Serpico, C., Spezzani, C., Trovò, M., Veronese, M., Milton, S. V., and Svandrlik, M.

Subjects
Physics, Brightness, Nuclear and High Energy Physics, Physics and Astronomy (miscellaneous), business.industry, Astrophysics::High Energy Astrophysical Phenomena, Free-electron laser, Surfaces and Interfaces, Radiation, Laser, Linear particle accelerator, law.invention, Nuclear physics, Optics, law, Extreme ultraviolet, Cathode ray, Physics::Accelerator Physics, lcsh:QC770-798, lcsh:Nuclear and particle physics. Atomic energy. Radioactivity, business, Surfaces and Interface, Fermi Gamma-ray Space Telescope
Abstract

FERMI is the first user facility based upon an externally seeded free-electron laser (FEL) and was designed to deliver high quality, transversely and longitudinally coherent radiation pulses in the extreme ultraviolet and soft x-ray spectral regimes. The FERMI linear accelerator includes a laser heater to control the longitudinal microbunching instability, which otherwise is expected to degrade the quality of the high brightness electron beam sufficiently to reduce the FEL output intensity and spectral brightness. In this paper, we present the results of the FERMI laser heater commissioning. For the first time, we show that optimizing the electron beam heating at an upstream location (beam energy, 100 MeV) leads to a reduction of the incoherent energy spread at the linac exit (beam energy, 1.2 GeV). We also discuss some of the positive effects of such heating upon the emission of coherent optical transition radiation and the FEL output intensity.

Published
2014
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225. Tunability experiments at the FERMI@Elettra free-electron laser

Author

Roberto Gunnella, Roberto Borghes, Erika Giangrisostomi, Enrico Allaria, Ivaylo Nikolov, Adriano Filipponi, M. Di Fraia, Claudio Masciovecchio, Luca Giannessi, Marco Zangrando, W. M. Fawley, Riccardo Cucini, M. Trovo, Filippo Bencivenga, S. Di Mitri, Flavio Capotondi, Giuseppe Penco, Carlo Spezzani, L. Froehlich, Francesco D'Amico, D. Castronovo, S. Di Fonzo, R. Ivanov, Benoît Mahieu, Cristian Svetina, Carlo Callegari, Miltcho B. Danailov, Alessandro Gessini, Marcello Coreno, Lorenzo Raimondi, G. De Ninno, Dario Giuressi, R. Sergo, A. Di Cicco, Daniele Cocco, Bruno Diviacco, Cesare Grazioli, Andrea Battistoni, Alexander Demidovich, Eugenio Ferrari, Emiliano Principi, Paolo Craievich, Paolo Cinquegrana, G. Passos, Nicola Mahne, Emanuele Pedersoli, Paolo Sigalotti, Allaria, E., Battistoni, Andrea, Bencivenga, F., Borghes, R., Callegari, C., Capotondi, F., Castronovo, D., Cinquegrana, P., Cocco, D., Coreno, M., Craievich, P., Cucini, R., D'Amico, F., Danailov, M. B., Demidovich, A., De Ninno, G., Di Cicco, A., Di Fonzo, S., DI FRAIA, Michele, Di Mitri, S., Diviacco, B., Fawley, W. M., Ferrari, Eugenio, Filipponi, A., Froehlich, L., Gessini, A., Giangrisostomi, Erika, Giannessi, L., Giuressi, D., Grazioli, Cesare, Gunnella, R., Ivanov, R., Mahieu, B., Mahne, N., Masciovecchio, C., Nikolov, I. P., Passos, G., Pedersoli, E., Penco, G., Principi, E., Raimondi, L., Sergo, R., Sigalotti, P., Spezzani, C., Svetina, Cristian, Trovò, M., and Zangrando, M.

Subjects
FEL, seeded, tunability, TIMEX, DIPROI, LDM, Fermi, Extreme ultraviolet lithography, General Physics and Astronomy, 02 engineering and technology, 7. Clean energy, 01 natural sciences, Thermopile, law.invention, symbols.namesake, Optics, law, 0103 physical sciences, 010306 general physics, Physics, business.industry, Free-electron laser, 021001 nanoscience & nanotechnology, Laser, Wavelength, Fourier transform, Absorption edge, symbols, RADIATION, 0210 nano-technology, business, Coherence (physics)
Abstract

FERMI@Elettra is a free electron-laser (FEL)-based user facility that, after two years of commissioning, started preliminary users' dedicated runs in 2011. At variance with other FEL user facilities, FERMI@Elettra has been designed to deliver improved spectral stability and longitudinal coherence. The adopted scheme, which uses an external laser to initiate the FEL process, has been demonstrated to be capable of generating FEL pulses close to the Fourier transform limit. We report on the first instance of FEL wavelength tuning, both in a narrow and in a large spectral range (fine- and coarse-tuning). We also report on two different experiments that have been performed exploiting such FEL tuning. We used fine-tuning to scan across the 1s–4p resonance in He atoms, at ≈23.74 eV (52.2 nm), detecting both UV–visible fluorescence (4p–2s, 400 nm) and EUV fluorescence (4p–1s, 52.2 nm). We used coarse-tuning to scan the M4,5 absorption edge of Ge (∼29.5 eV) in the wavelength region 30–60 nm, measured in transmission geometry with a thermopile positioned on the rear side of a Ge thin foil.

Published
2012
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226. Sub-femtosecond time-resolved measurements of electron bunches with a C-band radio-frequency deflector in x-ray free-electron lasers.

Author

Prat E, Malyzhenkov A, and Craievich P

Abstract

Time-resolved diagnostics are fundamental for x-ray free-electron lasers (FELs). Radio-frequency (RF) transverse deflector structures (TDSs) are typically employed to characterize the temporal properties of the electron beams driving FELs. In this article, we present time-resolved measurements with a resolution below one femtosecond using a C-band RF TDS at SwissFEL, the x-ray FEL facility at the Paul Scherrer Institute in Switzerland. The sub-femtosecond resolution is partially achieved due to an optimized optics setup and fits the expected values, showing a good understanding of our models. Measurements with a sub-femtosecond resolution are of crucial importance for ultra-fast x-ray FEL applications., (© 2023 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).)

Published
2023
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227. Simulation studies for characterizing ultrashort bunches using novel polarizable X-band transverse deflection structures.

Author

Marx D, Assmann RW, Craievich P, Floettmann K, Grudiev A, and Marchetti B

Abstract

Transverse deflection structures are useful devices for characterizing the longitudinal properties of bunches in electron accelerators. With efforts to produce ever-shorter bunches for applications such as external injection into novel accelerator structures, e.g. plasma cells or dielectric structures, the applicability of deflection structures to measuring ultrashort bunches has been considered. In this paper, charge-density and bunch-length measurements of femtosecond and subfemtosecond bunches at the ARES linac at the SINBAD facility at DESY are studied with simulations and the limitations discussed in detail. The novel polarizable X-band transverse deflection structure (PolariX-TDS) will allow the streaking of bunches at all transverse angles, making a 3D charge-density reconstruction of bunches possible, in addition to the standard 1D charge-density reconstruction and bunch-length measurements. These various measurements of the charge-density distributions of bunches have been simulated, and it is shown that useful information about ultrashort bunches down to subfemtosecond lengths may be obtained using the setup planned for the ARES linac.

Published
2019
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228. The SwissFEL soft X-ray free-electron laser beamline: Athos.

Author

Abela R, Alarcon A, Alex J, Arrell C, Arsov V, Bettoni S, Bopp M, Bostedt C, Braun HH, Calvi M, Celcer T, Craievich P, Dax A, Dijkstal P, Dordevic S, Ferrari E, Flechsig U, Follath R, Frei F, Gaiffi N, Geng Z, Gough C, Hiller N, Hunziker S, Huppert M, Ischebeck R, Jöhri H, Juranic P, Kalt R, Kaiser M, Keil B, Kittel C, Künzi R, Lippuner T, Löhl F, Marcellini F, Marinkovic G, Ozkan Loch C, Orlandi GL, Patterson B, Pradervand C, Paraliev M, Pedrozzi M, Prat E, Ranitovic P, Reiche S, Rosenberg C, Sanfilippo S, Schietinger T, Schmidt T, Schnorr K, Svetina C, Trisorio A, Vicario C, Voulot D, Wagner U, Wörner HJ, Zandonella A, Patthey L, and Ganter R

Abstract

The SwissFEL soft X-ray free-electron laser (FEL) beamline Athos will be ready for user operation in 2021. Its design includes a novel layout of alternating magnetic chicanes and short undulator segments. Together with the APPLE X architecture of undulators, the Athos branch can be operated in different modes producing FEL beams with unique characteristics ranging from attosecond pulse length to high-power modes. Further space has been reserved for upgrades including modulators and an external seeding laser for better timing control. All of these schemes rely on state-of-the-art technologies described in this overview. The optical transport line distributing the FEL beam to the experimental stations was designed with the whole range of beam parameters in mind. Currently two experimental stations, one for condensed matter and quantum materials research and a second one for atomic, molecular and optical physics, chemical sciences and ultrafast single-particle imaging, are being laid out such that they can profit from the unique soft X-ray pulses produced in the Athos branch in an optimal way., (open access.)

Published
2019
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229. Theoretical and experimental analysis of a linear accelerator endowed with single feed coupler with movable short-circuit.

Author

Dal Forno M, Craievich P, Penco G, and Vescovo R

Abstract

The front-end injection systems of the FERMI@Elettra linac produce high brightness electron beams that define the performance of the Free Electron Laser. The photoinjector mainly consists of the radiofrequency (rf) gun and of two S-band rf structures which accelerate the beam. Accelerating structures endowed with a single feed coupler cause deflection and degradation of the electron beam properties, due to the asymmetry of the electromagnetic field. In this paper, a new type of single feed structure with movable short-circuit is proposed. It has the advantage of having only one waveguide input, but we propose a novel design where the dipolar component is reduced. Moreover, the racetrack geometry allows to reduce the quadrupolar component. This paper presents the microwave design and the analysis of the particle motion inside the linac. A prototype has been machined at the Elettra facility to verify the new coupler design and the rf field has been measured by adopting the bead-pull method. The results are here presented, showing good agreement with the expectations.

Published
2013
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230. Absolute bunch length measurement using coherent diffraction radiation.

Author

Veronese M, Appio R, Craievich P, and Penco G

Abstract

The longitudinal electron beam properties are of crucial importance for many types of frontier accelerators, from storage rings to free electron lasers and energy recovery linacs. For the online control of the machine and its stable operation, nondestructive shot by shot bunch length measurements are needed. Among the various instrumentations proposed and installed in accelerators worldwide, the ones based on the measurement of the coherent radiation power represent the simplest and the more robust tools for operational control. The major limitation of these systems is that they usually can provide only relative bunch length estimation. In this Letter we present a novel experimental methodology to self-calibrate a simple equipment based on diffraction radiation from a gap providing a measurement of the second order moment of the longitudinal distribution. We present the theoretical basis of the proposed approach and validate it through a detailed campaign of measurements.

Published
2013
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