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TU104 |
Laser Acceleration of Quasi-Monoenergetic MeV-GeV Ion Beams
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358 |
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- J.C. Fernandez
LANL, Los Alamos, New Mexico
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Laser interactions with thin solid targets can produce sheath fields of tens of TV/m, which have been used to accelerate ions to several MeV with ps pulse lengths, high currents, and low transverse emittance. While previous results have had 100% energy spread, recent experiments using foils coated with a few monolayers have produced quasi-monoenergetic beams with 17% energy spread near 3 MeV. Such beams may be of interest as injectors or sources. Simulations show the potential for acceleration to hundreds of MeV or GeV energies using very thin foils.
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Slides
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TUP093 |
Activities on High Brightness Photo-injectors at the Frascati Laboratories, Italy
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618 |
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- R. Boni, D. Alesini, M. Bellaveglia, C. Biscari, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, L. Cultrera, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, L. Ficcadenti, D. Filippetto, V. Fusco, A. Gallo, G. Gatti, A. Ghigo, B. Marchetti, A. Marinelli, C. Marrelli, M. Migliorati, A. Mostacci, E. Pace, L. Palumbo, L. Pellegrino, R. Ricci, U. Rotundo, C. Sanelli, M. Serio, 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. Salières, O. Tchebakoff
CEA, Gif-sur-Yvette
- L. Catani, A. Cianchi
INFN-Roma II, Roma
- F. Ciocci, G. Dattoli, M. Del Franco, A. Dipace, A. Doria, G.P. Gallerano, L. Giannessi, E. Giovenale, A. Lo Bue, G.L. Orlandi, S. Pagnutti, A. Petralia, M. Quattromini, C. Ronsivalle, P. Rossi, E. Sabia, I.P. Spassovsky, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma)
- M.-E. Couprie
SOLEIL, Gif-sur-Yvette
- M. Mattioli, M. Petrarca, M. Serluca
INFN-Roma, Roma
- J.B. Rosenzweig
UCLA, Los Angeles, California
- J. Roßbach
DESY, Hamburg
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Funding: Work partially supported by the EU Commission in the sixth framework program. Contract No. 011935 EUROFEL and MIUR(Research Department of Italian Government).
An intense activity on high brilliance photo-injectors for SASE-FEL experiments and facilities, is being carried out, since 2003, in the research site of the INFN Frascati Laboratory, Rome, in collaboration with CNR and ENEA. The SPARC project, a 150 MeV photo-injector, is currently in advanced phase of commissioning. The electron beam, which drives a 530 nm FEL experiment, is being characterized in terms of emittance, energy spread, peak current. The matching with the linac confirmed the theoretical prediction of emittance compensation based on the invariant-envelope matching. The demonstration of the velocity-bunching technique is in progress too. The SPARC photo-injector is the test facility for the soft-X FEL project named SPARX, that is based on the generation of ultra high peak brightness electron beams at the energies of 1.2 and 2.4 GeV generating radiation in the 1.5-13 nm range. SPARX will be realized in the Tor-Vergata University campus. In this paper we report the experimental results obtained so far with SPARC and the design status of the SPARX project.
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Slides
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TUP094 |
Development of a Photocathode RF Gun for an L-Band Electron Linac
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621 |
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- G. Isoyama, S. Kashiwagi, R. Kato
ISIR, Osaka
- H. Hayano, T. Muto, J. Urakawa
KEK, Ibaraki
- M. Kuriki
HU/AdSM, Higashi-Hiroshima
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Funding: This research is partly supported by the accelerator support program to universities conducted by the High Energy Accelerator Research Organization in Japan.
We have begun a three-year project to develop a photocathode rf electron gun for the 40 MeV L-band linac at ISIR, Osaka University in collaboration with KEK. The L-band linac with an rf frequency of 1.3 GHz is equipped with a thermionic electron gun and it can accelerate a high-intensity single-bunch electron beam with charge up to 91 nC/bunch. Because the large emittance of ~100 pi mm x mrad is a limiting factor in the experiments, it is required to develop a new electron gun capable of providing an electron beam with much lower emittance. Since a group at the Accelerator Laboratory of KEK is developing a photocathode rf electron gun in the L-band for the International Linear Collider Project, we have joined the group to learn how to develop such an rf gun and also to obtain support from KEK. In this first year, characteristics of the rf gun will be measured at KEK for ILC fabricated by FNAL. We plan to optimize the structure of the rf gun for ISIR with computer simulation. We will report the plan and progress to develop a photocathode rf gun for the L-band linac.
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TUP095 |
Development of a Cs-Te Cathode RF Gun at Waseda University
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624 |
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- Y. Kato, A. Fujita, Y. Hama, T. Hirose, C. Igarashi, A. Masuda, A. Murata, T. Nomoto, K. Sakaue, T. Suzuki, M. Washio
RISE, Tokyo
- H. Hayano, T. Takatomi, N. Terunuma, J. Urakawa
KEK, Ibaraki
- Y. Kamiya
University of Tokyo, Tokyo
- S. Kashiwagi
ISIR, Osaka
- M. Kuriki
HU/AdSM, Higashi-Hiroshima
- R. Kuroda
AIST, Tsukuba, Ibaraki
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Funding: Work supported by MEXT High Tech Research Project HRC707, JSPS Grant-in-Aid for Scientific Research (B)(2) 16340079
At Waseda University, we have been developing a high quality electron source based on photo-cathode rf gun which has a Cs-Te cathode with high quantum efficiency. Until now, at the Waseda University we have succeeded the soft X-ray generation via inverse-Compton scattering and pulse radiolysis system for studying the early processes of radiation chemistry with electron beams generated by copper cathode rf gun. Cs-Te rf gun is expected to generate higher charge electron bunches with a low emittance than a copper cathode because of its high quantum efficiency and also the high-quality multi-bunch electron beams. That enables us to extend the range of electron beam parameters for our application experiments. However, a Cs-Te cathode has a short life compared with a copper, so it has to be exchanged occasionally, thus we have developed a new rf-gun cavity which can be attached the compact cathode load-lock system. Moreover, we improved the design of an existing rf-gun cavity for the reduction of the dark current and the higher electric field. In this conference, the performance of the improved cavity and the result of electron beam generation experiments will be reported.
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TUP096 |
RF Gun Development with Improved Parameters
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627 |
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- V.V. Paramonov, Y.Z. Kalinin
RAS/INR, Moscow
- K. Flöttmann
DESY, Hamburg
- M. Krasilnikov, T.A. Scholz, F. Stephan
DESY Zeuthen, Zeuthen
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During development and operation of DESY L-band rf gun cavities, desires for further improvements were formulated. The next step of development is based on the proven advantages of existing cavities, but includes significant changes. The L-band 1.6 cell rf gun cavity is intended for operation in pulse mode with electric fields at the cathode of up to 60 MV/m, rf pulse length of ~1 ms and average rf power higher than existing gun cavities. In the new design the cell shape is optimized to have the maximal surface electric field at the cathode and lower rf loss power. The cavity cells are equipped with rf probes. Cooling circuits are designed to combine cooling efficiency with operational flexibility. In the report, the main design ideas and simulation results are described.
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TUP097 |
Measurements and Modeling at the PSI-XFEL 500 kV Low-Emittance Electron Source
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630 |
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- T. Schietinger, A. Adelmann, Å. Andersson, M. Dietl, R. Ganter, C. Gough, C.P. Hauri, R. Ischebeck, S. Ivkovic, Y. Kim, F. Le Pimpec, S.C. Leemann, K.B. Li, P. Ming, A. Oppelt, M. Paraliev, M. Pedrozzi, V. Schlott, B. Steffen, A.F. Wrulich
PSI, Villigen
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Paul Scherrer Institute (PSI) is presently developing a low emittance electron source for the PSI-XFEL project. The electron gun consists of an adjustable diode configuration subject to pulses of 250 ns (FWHM) with amplitude up to 500 kV from an air-core transformer- based high-voltage pulser. The facility allows high gradient tests with different cathode configurations and emission processes (field emission and photo emission). In the first stage, the beamline is only made up of focussing solenoids followed by an emittance monitor. Selected beam characterization measurements, from photo-cathode operation driven by a 266 nm UV laser system delivering 4 uJ energy during 6.5 ps (FWHM), are presented and compared to the results of 3D particle tracking simulations.
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Slides
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TUP098 |
Lienard-Wiechert Potentials and Method of Images in RF Free Electron Laser Photoinjector
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633 |
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- R.M. Jones
UMAN, Manchester
- W. Salah
The Hashemite University, Zarka
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Based on Lienard-Weichert method of retarded potentials and the potential due to the image of charges on the cathode, a rigorous relativistic description of the beam transport inside the rf-photoinjector is presented. The velocity dependent effects are explicitly taken into account in a complete analytical description. Simulations are presented for parameters of the ELSA photo-cathode.
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TUP099 |
Design and Optimization of an S-Band Photoinjector
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636 |
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- J.H. Han
Diamond, Oxfordshire
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Many X-ray Free Electron Laser (XFEL) projects are under construction or are being proposed. A photoinjector with low transverse emittance is one of the key elements for successful XFEL operation. For the last two decades, photoinjectors have been developed to reach the XFEL requirement, typically with a normalised emittance of 1 mm mrad for a 1 nC bunch and high peak current. Here, we make a further numerical optimization of an S-band photoinjector to achieve 0.5 mm mrad for 1 nC bunch in a structure that should permit high repetition rates to be achieved. Optimizations for alternative operation conditions with lower charge and lower emittance are also shown.
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TUP100 |
The Optimization of a DC Injector for the Energy Recovery Linac Upgrade to APS
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639 |
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- Y.-E. Sun, M. Borland, K.C. Harkay, Y.L. Li, H. Shang
ANL, Argonne
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Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
An energy recovery linac based light source is a potential revolutionary upgrade to the Advanced Photon Source (APS) at Argonne National Laboratory. The concept relies on several key research areas, one of which is the generation of ultra-low emittance, high-average-current electron beams. In this paper, we present our investigation of a dc-gun-based system for ultra-low emittance bunches in the 20 pC range. A parallel multi-objective numerical optimization is performed in multi-parameter space. Parameters varied include experimentally feasible drive-laser shapes, the dc gun voltage, and the thermal energy of the emitted photo-electrons. Our goal is to deliver a 10 MeV, 20 pC bunch at the entrance of the linac with an emittance of 0.1 μm or lower, rms bunch length of 2 to 3 ps, and energy spread no larger than 140 keV. We present the machine parameters needed to generate such an injector beam, albeit without a merger.
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TUP101 |
Photocathode R&D Program at LBNL
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642 |
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- W. Wan, C.E. Coleman-Smith, C.M.R. Greaves, H.A. Padmore, E. Pedersoli, A. Polyakov
LBNL, Berkeley, California
- G. Ferrini, M. Montagnese, S. Pagliara, F. Parmigiani
Università Cattolica-Brescia, Brescia
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Funding: US Deparment of Energy
The photocathode R&D program at Lawrence Berkeley National Laboratory is presented, including the status of the lab and experimental results. We will also present experimental result obtained at Brescia Italy and theoretical work on predicting minimum thermal emittance from metal cathodes and emittance growth due to stochastic Coulomb interaction.
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TUP103 |
Analysis of Halo Formation in a DC Photoinjector
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645 |
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- D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois
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Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
We discovered, by modeling the AES/JLab direct-current photoinjector with several beam-simulation codes, that nominal injector settings would create a large diffuse beam halo as a consequence of the internal space-charge force in the beam. The injector-induced halo is sensitive to the injector settings, but if the settings are judiciously chosen, it can be largely circumvented. We present an exploration of the parameter space for the AES/JLab photoinjector. Measurement of beam halo will be a crucial aspect of commissioning this machine.
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TUP104 |
A High-Brightness Low-Energy Photoinjector Option for the Fermilab Electron Accelerator Facility
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648 |
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- P. Piot, D. Mihalcea
Northern Illinois University, DeKalb, Illinois
- M. Church, S. Nagaitsev, Y.-E. Sun
Fermilab, Batavia
- I.V. Pogorelov
LBNL, Berkeley, California
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Funding: Work supported by Fermi Research Alliance LLC. Under DE-AC02- 07CH11359 with the U.S. DOE and by the Department of Education under contract P116Z010035 with Northern Illinois University
Fermilab is currently constructing a GeV-scale electron accelerator test facility. The accelerator will serve as a backbone for several Fermilab R&D programs, e.g., to test subsystem associated to project-X, ILC and the muon collider program. It is also anticipated that this facility will support beam physics and accelerator R&D programs such as testing of novel acceleration techniques, beam diagnostics and radiation sources concepts. In this paper we describe a possible option for the electron injector based on a photoemission rf gun. Optimization and performance studies of this ~50 MeV photoinjector are performed with various tracking programs (Astra, GPT, Impact-T, Impact-Z). We explore the performances of the magnetic bunch compressor which is extremely challenging at 50 MeV due to strong phase space dilution via collective effects (space charge and coherent synchrotron radiation). We also investigate the generation of flat beams with very high transverse emittance ratio using a round-to-flat beam transformer.
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TUP105 |
Simulation of the Upgraded Photoinjector for the 10 kW JLAB IR-FEL
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649 |
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- D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois
- C. Hernandez-Garcia, S. Zhang
JLAB, Newport News, Virginia
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Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
The photoinjector of the JLab 10 kW IR FEL was recently upgraded: a new photocathode drive laser was commissioned and the booster section was replaced with 7-cell cavities. In this paper we present numerical simulation and optimization of the photoinjector perform with ASTRA, IMPACT-T and IMPACT-Z beam dynamics codes. We perform these calculations for two operating voltage of the dc gun: the nominal 350 keV and the planned 500 keV operating points.
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TUP106 |
Simulation of Field-Emission Cathodes for High Current Electron Injectors
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652 |
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- D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois
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Funding: Work supported by the Department of Defense under contract N00014-06-1-0587 with Northern Illinois University
From the prospect of the high average current electron injectors, the most important advantage of the field-emission cathodes is their capability to generate very large current densities. Simulation of field-emission cathodes is complicated by the large range of spatial dimensions: from sub-micron scale, for a single field-emission tip, to millimeter scale, for a field-emitter array. To overcome this simulation challenge our numerical model is split in two steps. In the first step, only electrons emitted by a single tip are considered. In the second step, the beams originating from many single emitting tips are merged together to mimic the field-emitter array configuration. We present simulation results of injector based on field array emitters cathodes.
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TUP108 |
Initial RF Measurements of the CW Normal-Conducting RF Injector
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656 |
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- D.C. Nguyen, G.O. Bolme, F.L. Krawczyk, F.A. Martinez, N.A. Moody, K.A. Young
LANL, Los Alamos, New Mexico
- L.M. Young
AES, Medford, NY
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Funding: This work is supported by ONR and HEL-JTO.
The LANL/AES 2.5-cell, normal-conducting radio-frequency (NCRF) injector has been fabricated. This room-temperature injector can be used to generate cw electron beams with average current greater than 100 mA and beam energy up to 2.5 MeV prior to injection into an energy-recovery linac. PARMELA simulations show the effectiveness of emittance compensation in generating high-brightness electron beams at relatively low accelerating gradients. We present the initial measurement results of the rf, accelerator and vacuum properties of the NCRF injector and the associated ridge-loaded waveguides. The impact of these rf measurement results on the planned thermal and electron beam tests will also be discussed.
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TUP110 |
Modeling of a Low Frequency SRF Electron Gun for the Wisconsin FEL
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658 |
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- R.A. Legg
UW-Madison/SRC, Madison, Wisconsin
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Funding: This work is supported by the University of Wisconsin-Madison and MIT, and by the US NSF under award No. DMR-0537588
The Wisconsin FEL project is a 2.2 GeV, HHG seeded, FEL designed to provide six individual beamlines with photons from 5 to 900 eV. The FEL requires electron bunches with 1 kA peak bunch current and less than 1 mm*mrad transverse slice emittance. To meet those requirements a low frequency, SRF electron gun is proposed which uses "blow-out" mode bunches*. Blow-out mode produces ellipsoidal bunches which are easily emittance compensated**. They also have a very smooth density and energy distribution. Results of the modeling of the injector and a diagnostic beamline will be presented.
* O.J. Luiten, et al., Phys. Rev. Lett., 93, 094802-1 (2004) ** C. Limborg-Deprey, P. Bolton, NIM-A, 557 (2006) 106-116
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TUP111 |
Longitudinal Bunch Lengthening Compensation in a High Charge RF Photoinjector
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661 |
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- S. Pei, C. Adolphsen
SLAC, Menlo Park, California
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Funding: Work supported by DOE contract DE-AC02-76SF00515
In high charge rf photo-injectors, due to the strong longitudinal space charge, bunch lengthening can readily occur. This paper presents beam dynamics studies of such bunch lengthening and methods to compensate it. With these methods, not only can the bunch length be preserved, but it can be shortened at the photo-injector exit.
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TUP112 |
Laser Timing Jitter Measurements at the Fermilab A0 Photoinjector
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664 |
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- J.K. Keung
University of Pennsylvania, Philadelphia, Pennsylvania
- S. Nagaitsev, J. Ruan
Fermilab, Batavia
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The Fermilab A0 Photoinjector is a 16 MeV high-intensity, low emittance electron linac used for advanced accelerator R&D. To achieve a high quality beam here it is important to maintain a stable laser in terms of both intensity and timing. This paper presents our measurement of the laser timing jitter, which is the random late or early arrival of the laser pulse. The seed laser timing jitter has been measured to less than 200 fs, by examining the power spectrum of the signal of a fast photodiode illuminated by it. The pulsed and pumped laser timing jitter has been measured with limited resolution to less than 1.4 ps, by examining the phase of a cavity impulsively excited by the signal from a fast photodiode illuminated by the laser pulse.
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TUP113 |
Emittance Exchange at the Fermilab A0 Photoinjector
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667 |
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- T.W. Koeth
Rutgers University, The State University of New Jersey, Piscataway, New Jersey
- L. Bellantoni, H.T. Edwards, R.P. Fliller, A.S. Johnson, A.H. Lumpkin, J. Ruan, R. Thurman-Keup
Fermilab, Batavia
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Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
An experiment has been developed at the Fermilab A0 Photoinjector Lab to demonstrate the exchange of longitudinal emittance with the horizontal emittance. Our apparatus consists of a 3.9 GHz TM110 deflecting rf cavity placed between two magnetic dogleg channels. The first dogleg generates the needed dispersion to appropriately position the off-momentum electrons in the TM110 cavity. The TM110 cavity reduces the momentum spread and imparts a time dependent transverse kick. The second dogleg finishes the exchange and yields the exchange of the emittances. We report on the measurement of the exchange beamline matrix elements as well as an inital report on measuring the exchange emittances directly.
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Slides
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TUP117 |
Development of Ultra-Low Emittance Injector for Future X-Ray FEL Oscillator
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676 |
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- P.N. Ostroumov, K.-J. Kim
ANL, Argonne
- P. Piot
Northern Illinois University, DeKalb, Illinois
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Funding: This work was supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC-02-06CH11357.
An XFELO proposed recently* requires a continuous sequence of electron bunches with ultra-low transverse emittance less than 0.1 mm-mr, a bunch charge of 40 pC, an rms energy spread of 1.4 MeV, repeating at a rate between 1 MHz to 100 MHz. The bunches are to be compressed to an rms lengths less than 2 ps at the final energy of 7 GeV. Following the successful commissioning of the pulsed injector based on a thermionic gun** we discuss a concept for ultra-low emittance injector to produce 100 MHz CW electron bunches. The electron beam is extracted by ~1MV rf voltage using low frequency ~100 MHz room temperature rf cavity. The injector also includes a chicane and slits to form a short ~1 nsec bunch, a pre-buncher a booster buncher to form low longitudinal emittance of the bunched beam, an accelerating section to ~50 MeV using higher harmonic cavities, and an rf cosine-wave chopper to form any required bunch repetition rate between 1 MHz and 100 MHz. The results of initial optimizations of the beam dynamics with the focus on extracting and preserving ultra-low emittance will be presented.
*K.-J. Kim, Y. Shvyd'ko, and S. Reiche, to be published in Physical Review Letters (2008) **K. Togawa, et al., Phys. Rev. STAB 10, 020703 (2007)
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TH201 |
Charge State Boosters for Radioactive Ion Acceleration
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745 |
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- F. Ames
TRIUMF, Vancouver
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For the post acceleration of radioactive ions produced at ISOL facilities the increase of the charge state is essential to reduce the A/q requirements of the accelerators. Many of those existing or proposed facilities are relying on the performance of charge state boosters of EBIS or ECRIS type. Although, in principle both types of sources can be used in pulsed or continuous mode operation an EBIS is better suited for pulsed beams whereas an ECRIS is most efficient in a continuous mode. The present state of the art with respect to existing data of both sources will be presented and potential future developments will be discussed. Latest results from the on line commissioning of a PHOENIX ECRIS charge breeder at ISAC will be presented.
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Slides
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