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G. Marcus

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Last Name: Marcus

Full Name: G. Marcus

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7 papers
title: FEMTOSECOND X-RAY PULSE GENERATION WITH AN ENERGY CHIRPED ELECTRON BEAM
format: conference proceeding
conference: FEL 2015 37th
year: 2015
7 authors: C. Emma | C. Pellegrini | Y. Ding | G. Marcus | A. Lutman | Z. Huang | A. Marinelli
abstract: We study the generation of short (sub 10 fs) pulses in the X-ray spectral region using an energy chirped electron beam in a Self Amplified Spontaneous Emission Free Electron Laser (SASE FEL) and a self-seeding monochromator [1-4]. The monochromator filters a small bandwidth, short duration pulse from the frequency chirped SASE spectrum. This pulse is used to seed a small fraction of the long chirped beam, hence a short pulse with narrow bandwidth is amplified in the following undulators. We present start-to-end simulation results for LCLS operating in the soft X-ray self-seeded mode with an energy chirp of 1% over 30 fs and a bunch charge of 150 pC. We show the possibility to generate 5 fs pulses with a bandwidth 0.3 eV. We also assess the possibility of further shortening the pulse by utilizing one more chicane after the self-seeding stage and shifting the radiation pulse to a “fresh” part of the electron beam. Experimental study on this short pulse seeding mode has been planned at the LCLS.
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title: Time-domain measurement of a self-amplified spontaneous emission free-electron laser with an energy-chirped electron beam and undulator tapering
format: journal article
publisher: Applied Physics Letters
year: 24 Sep 2012
2 authors: Gabriel Marcus | J.B. Rosenzweig
abstract: We report, with an unequivocal time-domain measurement, that an appropriately chosen undulator taper can compensate for an electron beam longitudinal energy-chirp in a free-electron laser amplifier, leading to the generation of single-spike radiation close to the Fourier limit. The measurements were taken using the frequency-resolved optical gating technique by employing an advanced transient-grating diagnostic geometry. The reconstructed longitudinal radiation characteristics are compared in detail to prediction from time-dependent three-dimensional simulations.
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title: Self-Amplified Spontaneous Emission Free-Electron Laser with an Energy-Chirped Electron Beam and Undulator Tapering
format: journal article
publisher: Physical Review Letters
year: 8 April 2011
41 authors: L. Giannessi | A. Bacci | M. Bellaveglia | F. Briquez | M. Castellano | E. Chiadroni | A. Cianchi | F. Ciocci | M.E. Couprie | L. Cultrera | G. Dattoli | D. Filippetto | M. Del Franco | G. Di Pirro | M. Ferrario | L. Ficcadenti | F. Frassetto | A. Gallo | G. Gatti | M. Labat | Gabriel Marcus | M. Moreno | A. Mostacci | E. Pace | A. Petralia | V. Petrillo | L. Poletto | M. Quattromini | J.V. Rau | C. Ronsivalle | J.B. Rosenzweig | A.R. Rossi | V. Rossi Albertini | E. Sabia | M. Serluca | S. Spampinati | I. Spassovsky | B. Spataro | V. Surrenti | C. Vaccarezza | C. Vicario
abstract: We report the first experimental implementation of a method based on simultaneous use of an energy chirp in the electron beam and a tapered undulator, for the generation of ultrashort pulses in a self-amplified spontaneous emission mode free-electron laser (SASE FEL). The experiment, performed at the SPARC FEL test facility, demonstrates the possibility of compensating the nominally detrimental effect of the chirp by a proper taper of the undulator gaps. An increase of more than 1 order of magnitude in the pulse energy is observed in comparison to the untapered case, accompanied by FEL spectra where the typical SASE spiking is suppressed.
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title: Gain length fitting formula for free-electron lasers with strong space-charge effects
format: journal article
publisher: Physical Review Accelerators and Beams
year: 2011
3 authors: G. Marcus | E. Hemsing | J.B. Rosenzweig
abstract: We present a power-fit formula, obtained from a variational analysis using three-dimensional free-electron laser theory, for the gain length of a high-gain free-electron laser’s fundamental mode in the presence of diffraction, uncorrelated energy spread, and longitudinal space-charge effects. The approach is inspired by the work of Xie [Nucl. Instrum. Methods Phys. Res., Sect. A 445, 59 (2000)], and provides a useful shortcut for calculating the gain length of the fundamental Gaussian mode of a free-electron laser having strong space-charge effects in the 3D regime. The results derived from analytic theory are in good agreement with detailed numerical particle simulations that also include higher-order space-charge effects, supporting the assumptions made in the theoretical treatment and the variational solutions obtained in the single-mode limit.
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title: Breaking the Attosecond, Angstrom and TV/m Field Barriers with Ultrafast Electron Beams
format: conference proceeding
conference: AAC 2010 14th
year: 2010
17 authors: J.B. Rosenzweig | G. Andonian | P. Bucksbaum | A. Fukasawa | M. Ferrario | M. Hogan | E. Hemsing | P. Krejcik | G. Marcus | A. Marinelli | P. Muggli | P. Musumeci | B. O'Shea | F. O'Shea | C. Pellegrini | D. Schiller | G. Travish
abstract: Recent initiatives at UCLA concerning ultra-short, GeV electron beam generation have been aimed at achieving sub-fs pulses capable of driving X-ray free-electron lasers (FELs) in single-spike mode. This scheme uses very low charge beams, which may allow existing FEL injectors to produce few-100 attosecond pulses, with very high brightness. Towards this end, recent experiments at the Stanford X-ray FEL (LCLS, first of its kind, built with essential UCLA leadership) have produced ~2 fs, 20 pC electron pulses. We discuss here extensions of this work, in which we seek to exploit the beam brightness in FELs, in tandem with new developments at UCLA in cryogenic undulator technology, to create compact accelerator/undulator systems that can lase below 0.15 Å, or be used to permit 1.5 Å operation at 4.5 GeV. In addition, we are now developing experiments which use the present LCLS fs pulses to excite plasma wakefields exceeding 1 TV/m, permitting a table-top TeV accelerator for frontier high energy physics applications. We discuss the experimental issues associated with this initiative.
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title: Short period, high field cryogenic undulator for extreme performance x-ray free electron lasers
format: journal article
publisher: APS
year: 13 July 2010
8 authors: F.H. O'Shea | Gabriel Marcus | J. B. Rosenzweig | Michael Scheer | Johannes Bahrdt | Raphael Weingartner | Andreas Gaupp | Florian Gruner
abstract: Short period, high field undulators can enable short wavelength free electron lasers (FELs) at low beam energy, with decreased gain length, thus allowing much more compact and less costly FEL systems. We describe an ongoing initiative to develop such an undulator based on an approach that utilizes novel cryogenic materials. While this effort was begun in the context of extending the photon energy regime of a laser-plasma accelerator based electron source, we consider here implications of its application to sub-fs scenarios in which more conventional injectors are employed. The use of such low-charge, ultrashort beams, which has recently been proposed as a method of obtaining single-spike performance in x-ray FELs, is seen in simulation to give unprecedented beam brightness. This brightness, when considered in tandem with short wavelength, high field undulators, enables extremely high performance FELs. Two examples discussed in this paper illustrate this point well. The first is the use of the SPARX injector at 2.1 GeV with 1 pC of charge to give 8 GW peak power in a single spike at 6.5 � with a photon beam peak brightness greater than 1035??photons/(s?mm2?mrad2??0.1%??BW), which will also reach LCLS wavelengths on the 5th harmonic. The second is the exploitation of the LCLS injector with 0.25 pC, 150 as pulses to lase at 1.5 � using only 4.5 GeV energy; beyond this possibility, we present start-to-end simulations of lasing at unprecedented short wavelength, 0.15 �, using 13.65 GeV LCLS design energy.
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title: Observation of coherent terahertz edge radiation from compressed electron beams
format: journal article
publisher: PRSTAB
year: 3 March 2009
9 authors: G. Andonian | A.M. Cook | M. Dunning | E. Hemsing | Gabriel Marcus | A. Murokh | S. Reiche | D. Schiller | J.B. Rosenzweig
abstract: Coherent radiation emitted from a compressed electron bunch as it traverses the sharp edge regions of a magnetic chicane has been investigated at the Brookhaven National Laboratory Accelerator Test Facility. Electron beam measurements using coherent transition radiation interferometry indicate a 100 fs rms bunch accompanied by distinct distortions in energy spectrum due to strong self-fields. These self-fields are manifested in emitted high power THz radiation, which displays signatures of the phenomenon known as coherent edge radiation. Radiation characterization studies undertaken include spectral analysis, far-field intensity distribution, polarization, and dependence on the electron bunch length. The observed aspects of the beam and radiation allow detailed comparisons with start-to-end simulations.
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