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Frigola, P.

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MOOAAB02 Experimental Results with the SPARC Emittance-meter 80
  • M. Ferrario, D. Alesini, M. Bellaveglia, S. Bertolucci, R. Boni, M. Boscolo, M. Castellano, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, M. Incurvati, C. Ligi, M. Migliorati, A. Mostacci, E. Pace, L. Palumbo, L. Pellegrino, R. Ricci, C. Sanelli, M. Serio, F. Sgamma, B. Spataro, F. Tazzioli, S. Tomassini, C. Vaccarezza, M. Vescovi, C. Vicario
    INFN/LNF, Frascati (Roma)
  • A. Bacci, S. Cialdi, A. R. Rossi, L. Serafini
    INFN-Milano, Milano
  • L. Catani, E. Chiadroni, A. Cianchi
    INFN-Roma II, Roma
  • A. M. Cook, M. P. Dunning, P. Frigola, J. B. Rosenzweig
    UCLA, Los Angeles, California
  • L. Giannessi, M. Quattromini, C. Ronsivalle
    ENEA C. R. Frascati, Frascati (Roma)
  • P. Musumeci, M. Petrarca
    INFN-Roma, Roma
  The SPARC project foresees the realization of a high brightness photo-injector to produce a 150-200 MeV electron beam to drive a SASE-FEL in the visible light. As a first stage of the commissioning a complete characterization of the photoinjector has been done with a detailed study of the emittance compensation process downstream the gun-solenoid system. For this purpose a novel beam diagnostic device, called emittance meter, has been developed and used at SPARC. This device has allowed to measure the evolution of beam sizes, energy spread and rms transverse emittances at different location along the beamline, in the region where space-charge effects dominate the electron dynamics and the emittance compensation process takes place. In this paper we report our commissioning experience and the results obtained. In particular a comparison between the performances of a Gaussian laser pulse versus a Flat Top laser pulse will be discussed. We report also the first experimental observation of the double emittance minima effect on which is based the optimised matching with the SPARC linac.  
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WEPMS034 Mitigation of Electric Breakdown in an RF Photoinjector by Removal of Tuning Rods in High-Field Regions 2415
  • A. M. Cook, M. P. Dunning, J. B. Rosenzweig, K. M. Serratto
    UCLA, Los Angeles, California
  • P. Frigola
    RadiaBeam, Los Angeles, California
  Funding: United States Department of Energy

The pi-mode resonant frequency of the 1.6 cell SLAC/BNL/UCLA style RF photoinjector electron gun is conventionally tuned using cylindrical copper tuning pieces that extend into the full-cell cavity through holes in the side of the gun. This design begins to fail in many versions of this popular gun design at higher voltage levels, when the cavity undergoes electric breakdown in the vicinity of the tuners. In order to remove the tuners from the region of high electric field, mitigating this problem, the full cell geometry must be changed significantly. We report on a method of accomplishing this, in which we use a mechanical device of custom design to stretch the cavity structure of an existing photoinjector in order to tune the resonant frequency up by over 2 MHz. We present results of testing the modified photoinjector in an RF test bed with both copper and magnesium cathodes, succeeding in putting approximately 8 - 10 MW of RF power into the gun. This is an improvement over the 4 MW routinely achieved in a similar gun using conventional tuning methods installed at the UCLA Neptune laboratory.

THPMS018 High Average Current Betatrons for Industrial and Security Applications 3035
  • S. Boucher, R. B. Agustsson, P. Frigola, A. Y. Murokh, M. Ruelas
    RadiaBeam, Los Angeles, California
  • F. H. O'Shea, J. B. Rosenzweig, G. Travish
    UCLA, Los Angeles, California
  Funding: DOE Grant DE-FG02-04ER84051

The fixed-field alternating-gradient (FFAG) betatron has emerged as a viable alternative to RF linacs as a source of high-energy radiation for industrial and security applications. For industrial applications, high average currents at modest relativistic electron beam energies, typically in the 5 to 10 MeV range, are desired for medical product sterilization, food irradiation and materials processing. For security applications, high power x-rays in the 3 to 20 MeV range are needed for rapid screening of cargo containers and vehicles. In a FFAG betatron, high-power output is possible due to high duty factor and fast acceleration cycle: electrons are injected and accelerated in a quasi-CW mode while being confined and focused in the fixed-field alternating-gradient lattice. The beam is accelerated via magnetic induction from a betatron core made with modern low-loss magnetic materials. Here we present the design and status of a prototype FFAG betatron, called the Radiatron, as well as future prospects for these machines.

TUPMS028 Commissioning of a High-Brightness Photoinjector for Compton Scattering X-Ray Sources 1242
  • S. G. Anderson, C. P.J. Barty, D. J. Gibson, F. V. Hartemann, M. J. Messerly, M. Shverdin, C. Siders, A. M. Tremaine
    LLNL, Livermore, California
  • H. Badakov, P. Frigola, A. Fukasawa, B. D. O'Shea, J. B. Rosenzweig
    UCLA, Los Angeles, California
  Funding: This work was performed under the auspices of the U. S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Compton scattering of intense laser pulses with ultra-relativistic electron beams has proven to be an attractive source of high-brightness x-rays with keV to MeV energies. This type of x-ray source requires the electron beam brightness to be comparable with that used in x-ray free-electron lasers and laser and plasma based advanced accelerators. We describe the development and commissioning of a 1.6 cell RF photoinjector for use in Compton scattering experiments at LLNL. Injector development issues such as RF cavity design, beam dynamics simulations, emittance diagnostic development, results of sputtered magnesium photo-cathode experiments, and UV laser pulse shaping are discussed. Initial operation of the photoinjector is described and transverse phase space measurements are presented.