Rosenzweig, J. B.

Paper	Title	Page
MOPPH022	A Description of Guided FEL Radiation Using Dielectric Waveguide Eigenmodes	65
	A. Gover University of Tel-Aviv, Faculty of Engineering, Tel-Aviv J. B. Rosenzweig, E. Hemsing UCLA, Los Angeles, California
	An analysis of the radiation field of an FEL in terms of eigenmodes of a linear dielectric waveguide is presented.
TUPPH018	Development of Ultra-short Pulse, Single Coherent Spike for SASE X-ray FELs
	P. Musumeci, C. Pellegrini, S. Reiche, J. B. Rosenzweig UCLA, Los Angeles, California
	There is a large interest in the production of high power, ultra-short, one femtoseconds or less, coherent X-ray pulses, for atomic physics and other applications. However the present design of X-ray SASE FELs leads to an X-ray pulse about 100 times longer. Several methods to reduce the bunch length to the 10-1 fs region have been proposed. These methods are based on electron bunch manipulation to cut the lasing part of the bunch to a fraction of the total length, thus reducing the X-ray pulse length. We are considering here a different method, using ultra-short, very low charge electron bunches, with a length of the order or shorter than the FEL cooperation length. In this case the X-ray pulse length after amplification in the undulator is a few times the electron bunch length. Our simulations show that in an LCLS-like case we can obtain coherent, Fourier transform limited, X-ray pulses, consisting of a single spike, with a FWHM of about 0.1 um, corresponding to about 300 as, a peak power of about 5 GW, and an intensity of about 10 uJ.
WEPPH018	A High Brightness X-band Split Photoinjector Concept and Related Technological Challenges	370
	D. Alesini, M. Migliorati, L. Palumbo, B. Spataro, M. Ferrario INFN/LNF, Frascati (Roma) J. B. Rosenzweig UCLA, Los Angeles, California L. Serafini INFN-Milano, Milano
	Future light sources based on high gain free electron lasers, require the production, acceleration and transport up to the undulator entrance of high brightness (low emittance, high peak current) electron bunches. Wake fields effects in accelerating sections and in magnetic bunch compressors typically contribute to emittance degradation, hence the photo-injector design and its operation is the leading edge for high quality beam production. The state of the art photoinjector beam brightness can be in principle brought above the 1015 A/m2 threshold with an X-band gun and a proper emittance compensation scheme. We discuss in this paper an optimized design of a split X-band photoinjector, a convenient matching scheme with the downstream linac, based on the SPARC project experience, and the further technological developments required to reach such an appealing goal.
WEAAU02	Direct Measurement of Phase Space Evolution in the SPARC High Brightness Photoinjector	284
	D. Alesini, M. Bellaveglia, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, M. Incurvati, C. Ligi, L. Pellegrino, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, F. Tazzioli, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario, E. Chiadroni INFN/LNF, Frascati (Roma) A. Bacci INFN/LASA, Segrate (MI) L. Catani, A. Cianchi INFN-Roma II, Roma S. Cialdi, A. R. Rossi, L. Serafini INFN-Milano, Milano L. Giannessi, M. Quattromini, C. Ronsivalle ENEA C. R. Frascati, Frascati (Roma) M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma P. Musumeci, J. B. Rosenzweig UCLA, Los Angeles, California M. Petrarca INFN-Roma, Roma
	The characterization of the transverse phase space for high charge density relativistic electron beams is a fundamental requirement in many particle accelerator facilities, in particular those devoted to fourth-generation synchrotron radiation sources, such as SASE FEL. The main purpose of the SPARC initial phase was the commissioning of the RF photoinjector. At this regard, the evolution of the phase space has been fully characterized by means of the emittance meter diagnostics tool, placed in the drift after the gun exit. The large amount of collected data has shown not only that we can achieve the SPARC nominal parameters, but has also allowed for the first time a detailed reconstruction of the transverse phase space evolution along the drift, giving evidences of the emittance compensation process to occur as predicted by theory and simulations. In particular the peculiar behavior of a flat top longitudinal electron distribution compared to a gaussian distribution has been studied giving important insights for the correct matching with the following linac based on the double emittance minimum effect.
	Slides