FEL08 - List of Authors (Rosenzweig, J. B.)

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Rosenzweig, J. B.

Paper	Title	Page
MOBAU01	Real and Virtual Free-Electron Laser Experiments: From VISA to the Femtosecond Frontier	8
	J. B. Rosenzweig UCLA, Los Angeles, California
	The VISA experiment has been recognized for its role not only in exploring the physics of high-gain SASE free-electron lasers, but in its methodology as well. In VISA, a high degree of correspondence between intricate beam and FEL diagnostics, and detailed start-to-end simulations was developed. These tools worked together to uniquely reveal the underlying microscopic mechanisms that produce complex FEL behavior. We review examples of new and novel physics arising from VISA, and show how they challenged our conceptual and analytical picture of the FEL. We then look next-generation FELs, in which "virtual experiments" must reveal critical physical issues without direct experimental verification. As a relevant context, we take our proposal of using very low-charge beams to produce sub-fs, single-spike FEL pulses. With orders of magnitude lower charge, pulse length, and FEL wavelength beyond current practice, we must face a myriad of challenges enabling this exciting new path for FEL science. We show how simulations identify qualitatively new behavior in the beam/FEL system. The approach to benchmarking these phenomena with new experiments and extended simulation tools are discussed.
MOCAU01	A Virtual Dielectric Eigenmode Expansion of High-Gain FEL Radiation for Study of Paraxial Wave Mode Coupling	167
	E. Hemsing, J. B. Rosenzweig UCLA, Los Angeles, California A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv
	A theoretical approach that uses eigenmodes of a dielectric wave guide to describe the signal field of an FEL is presented. This formulation can provide an efficient characterization of the FEL self-similar eigenmodes and enables a clear descriptive connection to free-space propagation of the input and output radiation. The entire evolution of the radiation wave through the linear gain regime is described with arbitrary initial conditions. By virtue of the flexibility in the expansion basis, this technique can be used to find the direct coupling and amplification of specific modes of interest. A simple transformation converts the derived coupled differential evolution equations into a set of coupled algebraic equations and yields a matrix determinant equation for the FEL eigenmodes. Laguerre-Gaussian modes used as an expansion basis allows investigation of coupling and amplification of optical modes that contain orbital angular momentum, suggesting new regimes of operation for future FELs.
TUBAU04	Generation of Sub-fsec, High Brightness Electron Beams for Single Spike SASE FEL Operation	214
	J. B. Rosenzweig, M. P. Dunning, L. Faillace, A. Fukasawa, E. Hemsing, G. Marcus, A. Marinelli, P. Musumeci, B. D. O'Shea, C. Pellegrini, S. Reiche UCLA, Los Angeles, California M. Boscolo, M. Ferrario, L. Palumbo, B. Spataro, C. Vaccarezza INFN/LNF, Frascati (Roma) L. Giannessi, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) V. Petrillo Istituto Nazionale di Fisica Nucleare, Milano
	We present here the theory and computational modeling of beams in a new regime, where <1 pC beams are strongly velocity bunched at low energy, and then compressed at several GeV to less than a fsec. This regime of operation produces beams with thermally dominated transverse emittance, and mitigates many problems associated with the nC-level operation. These problems include CSR induced instability and intra-undulator wakes. The resulting beams have extremely high brightness, enabling very high gain, efficiency, and single spike operation. We present the scaling laws governing this regime, and the detailed example of the proposed SPARX FEL design.
TUPPH018	Longitudinal Diagnostic for Single-Spike SASE FEL Operation	274
	G. Marcus, G. Andonian, A. Fukasawa, S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California M. Ferrario, L. Palumbo INFN/LNF, Frascati (Roma) L. Giannessi ENEA C. R. Frascati, Frascati (Roma)
	The possibility of ultra-short beam, very low charge, short wavelength FELs at SPARC has been recently investigated. This paper explores the development of a longitudinal diagnostic that will provide the capability to characterize the short wavelength radiation based on the Frequency Resolved Optical Gating (FROG) technique. The paper includes studies of pulses simulated for the SPARC case using GENESIS and reconstructed using the FROG algorithm as well as proposed experimental layouts for the device.
TUPPH021	An Ultra-high Repetition Rate S-band RF Gun	282
	L. Faillace, A. Fukasawa, B. D. O'Shea, J. B. Rosenzweig UCLA, Los Angeles, California P. Frigola RadiaBeam, Marina del Rey L. Palumbo, B. Spataro INFN/LNF, Frascati (Roma)
	We present here a preliminary design, including RF modeling, cooling, and thermal stress and frequency detuning, of an S-band RF gun capable of running near 500 Hz, for application to FEL and inverse Compton scattering sources. The RF design philosophy incorporates many elements in common with the LCLS gun, but the approach to managing cooling and mechanical stress diverges significantly. We examine the new proprietary approach of RadiaBeam Technologies for fabricating copper structures with intricate internal cooling geometries. We find that this approach may enable very high repetition rate, well in excess of the nominal project this design is directed for, the SPARX FEL.
TUPPH023	Quasicrystalline Beam Formation in RF Photoinjectors	285
	J. B. Rosenzweig, M. P. Dunning, E. Hemsing, G. Marcus, A. Marinelli, P. Musumeci UCLA, Los Angeles, California M. Ferrario INFN/LNF, Frascati (Roma)
	The recent observation of coherent optical transition radiation from the beam after the injector line at the LCLS has raised serious questions concerning the present model of beam dynamics in RF photoinjectors. We present here an analysis of what we term quasicrystalline beam formation. In this scenario, the relatively low longitudinal temperature, in combination with strong acceleration and, finally, temporal rearrangement due to bending, allows the longitudinal beam dimension to become more regular, on the microscopic scale of optical wavelengths, than expected from equilibrium statistical properties. This beam distribution then may then display a strong degree of coherence in its optical transition radiation output. We discuss further experimental investigations of this phenomenon.
TUPPH040	A Hybrid Standing Wave-Traveling Wave Photoinjector	334
	A. Fukasawa, H. Badakov, B. D. O'Shea, J. B. Rosenzweig UCLA, Los Angeles, California D. Alesini, L. Ficcadenti, B. Spataro INFN/LNF, Frascati (Roma) L. Palumbo Rome University La Sapienza, Roma
	We present here the RF aspects and beam dynamics study of a hybrid photoinjector, where the cathode section is standing wave, and the section downstream of the third (coupling) cell is traveling wave. This device has strong RF advantages: there is a single feed, mitigating expense, and there is a nearly complete suppression of reflected power during the SW section fill. This, critically, allows one to scale these devices to higher field and frequency, which should dramatically improve beam brightness. Further, the beam dynamics are fundamentally changed, as the TW section acts as a velocity buncher. Thus one may produce low emittance, >kA beams at 20-30 MeV from such a device. We discuss here results of detailed beam dynamics simulations, RF design and initial cold-testing, and preparations for high power testing.
TUPPH012	Single spike experiments with the SPARC SASE FEL	258
	M. Ferrario, M. Boscolo, L. Palumbo, C. Vaccarezza INFN/LNF, Frascati (Roma) G. Andonian, E. Hemsing, G. Marcus, S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California A. Bacci, I. Boscolo, F. Castelli, S. Cialdi, V. Petrillo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano L. Giannessi, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) M. Serluca INFN-Roma, Roma
	We describe in this paper a possible experiment with the existing SPARC photoinjector to test the generation of sub-picosecond high brightness electron bunches able to produce single spike radiation pulses at 500 nm with the SPARC self-amplified spontaneous emission free-electron laser (SASE-FEL). The main purpose of the experiment will be the production of short electron bunches as long as few SASE cooperation lengths and to validate scaling laws to foresee operation at shorter wavelength in the future operation with SPARX. We present in this paper start to end simulations of the expected FEL performance and discuss the layout of the machine, including the diagnostics to measure the FEL pulse length and other aspects of FEL performance. The experience gained from this experiment, will help in the configuration of the VUV and X-ray FEL SPARX to obtain FEL pulses below 10 fs.
TUPPH048	Recent Results of the SPARC Project	359
	M. Ferrario, D. Alesini, M. Bellaveglia, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, A. Marcelli, B. Marchetti, M. Migliorati, A. Mostacci, E. Pace, L. Palumbo, L. Pellegrino, R. Ricci, U. Rotundo, C. Sanelli, F. Sgamma, B. Spataro, F. Tazzioli, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario INFN/LNF, Frascati (Roma) A. Bacci, I. Boscolo, F. Broggi, F. Castelli, S. Cialdi, C. De Martinis, D. Giove, C. Maroli, V. Petrillo, A. R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano M. Bougeard, B. Carré, D. Garzella, M. Labat, G. Lambert, H. Merdji, P. Salieres, O. Tchebakoff CEA, Gif-sur-Yvette L. Catani INFN-Roma II, Roma A. Cianchi Università di Roma II Tor Vergata, Roma F. Ciocci, G. Dattoli, M. Del Franco, A. Dipace, A. Doria, G. P. Gallerano, L. Giannessi, E. Giovenale, G. L. Orlandi, S. Pagnutti, A. Petralia, M. Quattromini, C. Ronsivalle, E. Sabia, I. P. Spassovsky, V. Surrenti ENEA C. R. Frascati, Frascati (Roma) M.-E. Couprie SOLEIL, Gif-sur-Yvette A. Marinelli, J. B. Rosenzweig UCLA, Los Angeles, California M. Mattioli, M. Petrarca, M. Serluca INFN-Roma, Roma J. Rossbach Uni HH, Hamburg
	The SPARC project foresees the realization of a high brightness photo-injector to produce a 150-200 MeV electron beam to drive 500 nm FEL experiments in various configurations. The SPARC photoinjector is also the test facility for the recently approved VUV FEL project named SPARX. The second stage of the commissioning, that is currently underway, foresees a detailed analysis of the beam matching with the linac in order to confirm the theoretically prediction of emittance compensation based on the “invariant envelope” matching , the demonstration of the “velocity bunching” technique in the linac and the characterisation of the spontaneous emission radiation in the SPARC undulators. In this paper we report the experimental results obtained so far.