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Paper Title Other Keywords Page
MOP044 Status of DPIS Development in BNL plasma, ion, target, rfq 169
  • M. Okamura
    BNL, Upton, Long Island, New York
  • T. Kanesue
    Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka
  • J. Tamura
    Department of Energy Sciences, Tokyo Institute of Technology, Yokohama

Direct injection scheme was proposed in 2000 at RIKEN in Japan. The first beam test was done at Tokyo Institute of Technology using a CO2 laser and an 80 MHz 4 vane RFQ in 2001, and further development continued in RIKEN. In 2006, all the experimental equipment was moved to BNL and a new development program was started. We report on our recent activities at BNL including the use of a frozen gas target for the laser source, low charge state ion beam production and a newly developed laser irradiation system.

MOP045 Design Study of a DPIS Injector for a Heavy Ion FFAG ion, rfq, injection, plasma 172
  • M. Okamura, D. Raparia
    BNL, Upton, Long Island, New York
  • K. Ishibashi, T. Kanesue, Y. Yonemura
    Kyushu University, Department of Applied Quantum Physics and Nuclear Engineering, Fukuoka

Direct plasma injection scheme has been developed recently for producing and accelerating intense pulsed heavy ion beams with high charge states. This new method uses a combination of a laser ion source and an RFQ linear accelerator and its repetition rate is determined by the laser system. Fixed field alternating gradient (FFAG) accelerator is being focused as a high repetition synchrotron. An integration of these new techniques enables one to produce a large beam power with heavy ion beams. At Ito campus of Kyushu University, a proton FFAG is being installed. We propose to construct a new injector linac for the FFAG. The planned operating parameters are 100 Hz repetition rate, 20 mA of fully stripped carbon beam and 200 MHz operating frequency for the linac.

MOP060 Quality Improvement of Laser-produced Protons by Phase Rotation and its Possible Extension to High Energies proton, ion, cavity, focusing 214
  • A. Noda, Y. Iwashita, H. Souda, H. Tongu, A. Wakita
    Kyoto ICR, Uji, Kyoto
  • H. Daido, M. Ikegami, H. Kiriyama, M. Mori, M. Nishiuchi, K. Ogura, S. Orimo, A. Sagisaka, A. Yogo
    JAEA/Kansai, Kizu-machi Souraku-gun Kyoto-fu
  • A. Pirozhkov
    JAEA, Ibaraki-ken
  • T. Shirai
    NIRS, Chiba-shi

Funding: This work is supported by Advanced Compact Accelerator project by MEXT of Japanese Government and 21COE of Kyoto University, Center for Diversity and Universality in Physics.
By the phase rotation with the use of rf electric fields created by two gap resonator synchronous to a pulse laser, the energy spread of the laser-produced ions can be reduced*. In addition, owing to the curved structure of the electric field line in the gaps of the phase rotator, radial focusing effect is found also to exist. In order to extend the applicable energy of the phase rotation to the region where such laser produced protons can be directly applied for cancer therapy, multi-gap resonator with higher frequency has been proposed. By controlling the relative phases between the pulse laser and the electric fields in the gaps of phase rotator, we can create peaks in the energy spectrum simultaneously focusing in the radial direction.

* Japanese Journal of Applied Physics (Express Letter), 46 (2007) L717-L720

MOP067 High Gradient Excitation and RF Power Generation Using Dielectric Loaded Wakefield Structures electron, wakefield, gun, klystron 232
  • M.E. Conde, S.P. Antipov, F.J. Franchini, W. Gai, F. Gao, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
    ANL, Argonne
  • C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Dielectric loaded wakefield structures are being developed to be used as high gradient accelerator components. The high current electron beam at the Argonne Wakefield Accelerator Facility was used to excite wakefields in cylindrical dielectric loaded wakefield structures in the frequency range of 8 to 14 GHz, with pulse duration of a few nanoseconds. Short electron bunches (13 ps FWHM) of up to 86 nC drove these wakefields, and accelerating fields as high as 100 MV/m were reached. These standing-wave structures have a field probe near the outer edge of the dielectric to sample the RF fields generated by the electron bunches. Monitoring of the field probe signal serves to verify the absence of electric breakdown. Similar structures were used to extract RF power from the electron beam; however, in this case they were travelling-wave structures, driven by electron bunch trains of up to 16 bunches. RF pulses of up to 40 MW were measured at the output coupler of these structures.

MOP074 Beam Dynamics Simulations of Sub-ps Electron Bunch Produced in a Photo-Injector emittance, simulation, electron, gun 248
  • R. Roux
    LAL, Orsay

A growing number of experiments require low emittance ultra-short electron bunches in the 100 fs range (rms value) for the production of coherent light or the injection in plasma for laser-plasma acceleration. Especially in the last case it is highly desirable to have a compact accelerator; hence a strong experimental activity is carried out to get such a beam directly from a photo-injector. We have performed beam dynamic simulations using the PARMELA code to study the performances of the alphaX photo-injector installed in the University of Strathclyde in UK. This rf gun is aimed to produce electron bunches of 100 pC bunch charge, 100 fs bunch length and 1 mmmrad transverse emittance. We will show the results of systematic parametric studies as a function of charge and laser pulse duration as well as the natural evolution of the beam phase space as a function of the distance from the photo-cathode.

TU104 Laser Acceleration of Quasi-Monoenergetic MeV-GeV Ion Beams acceleration, ion, target, emittance 358
  • J.C. Fernandez
    LANL, Los Alamos, New Mexico

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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TU202 ILC Siting in Moscow Region Near Dubna and ILC Related Activity at JINR site, diagnostics, linac, cryomodule 360
  • G. Shirkov, Ju. Boudagov, Yu.N. Denisov, I.N. Meshkov, A.N. Sissakian, G.V. Trubnikov
    JINR, Dubna, Moscow Region

The report presents the development of investigations on ILC siting in the Dubna region and ILC related activity at JINR. The report will describe the fields of activities ongoing to support the ILC at JINR. In addition, other linear accelerator activities at JINR will be summarized.


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TU301 Positron Beams Propagation in Plasma Wakefield Accelerators plasma, positron, emittance, electron 374
  • P. Muggli
    UCLA, Los Angeles, California

Funding: Work Supported by US Department of Energy
Plasma-based accelerators are one of the emerging technologies that could revolutionize e-/e+ colliders, significantly reducing their size and cost by operating at multi-GeV/m accelerating gradients. Proof-of-principle experiments at SLAC have demonstrated the energy doubling of 42 GeV incoming e- in a plasma only ≈85 cm-long,* corresponding to an unloaded gradient of ≈50 GeV/m. Plasma wakes driven by e+ bunches are different from those driven by e- bunches. The acceleration of e+ in plasmas has been demonstrate,** but the acceleration of high-quality e+ beams is challenging. Measurements show that single e+ bunches suffer halo formation and emittance growth when propagating through dense meter-scale, uniform plasmas.*** Advanced schemes, such as hollow plasma channels, or e+ bunch acceleration on the wake driven by a e bunch, may have to be used in a future plasma-based linear collider. Experimental results obtained with e+ beams in plasmas will be reviewed and compared to those obtained with e- beams. Future experiments including a new scheme to produce a drive e bunch closely followed by a witness e+ bunch appropriate for PWFA experiments will also be discussed.

*I. Blumenfeld et al., Nature 445, 741-744 (15 February 2007).
**B.E. Blue et al., Phys. Rev. Lett. 90, 214801 (2003).
***P. Muggli et al., accepted for publication in Phys. Rev. Lett. (2008).


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TU302 Control, Stability and Staging in Laser Wakefield Accelerators controls, linac, wakefield, plasma 379
  • D. Panasenko
    LBNL, Berkeley, California

Laser driven plasma wakefields have recently accelerated electron beams with quasi-monoenergetic energy distributions and with gradients of ~100 GV/m. Stabilization and optimization of beam quality are now essential. Recent LBNL experiments have demonstrated control of self trapping, resulting in reproducible bunches at 0.5 GeV. Further optimization has been demonstrated using plasma density gradients to control trapping, producing beams with very low absolute momentum spread at low energies. Simulations indicate that use of these beams as an injector greatly improves accelerator performance and experiments are now underway to demonstrate such staging, which will be a crucial technology for laser driven linacs. This talk will cover recent progress in LWFAs to obtain more reproducible, higher quality beams and also cover staging prospects for high energy laser linacs.


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TUP003 Proposal for a 15 MeV Superconducting Electron Linac for the DEINOS Project linac, high-voltage, cavity, electron 386
  • J.-L. Lemaire, P. Balleyguier, J.-L. Flament, D. Guilhem, V. Le Flanchec, M.M. Millerioux, S.J. Pichon
    CEA, Bruyeres-le-Chatel

The design of a 15 MeV, 2 kA peak current, electron accelerator for the DEINOS project is presented. It is dedicated to a new radiographic facility. The accelerator design is based on a dc photo-injector and a rf superconducting linac. Up to twenty electron micro-pulses, 100 ps time duration and 200 nC bench charge are emitted at 352 MHz repetition rate from a CS2Te photocathode and accelerated to 2.5 MeV in the dc diode before injection into a superconducting linac. A general description of the main accelerator components and the beam dynamics simulations are presented.

TUP004 Status of the CTF3 Probe Beam Linac CALIFES linac, alignment, klystron, dipole 389
  • F. Peauger, D. Bogard, G. Cheymol, P. Contrepois, A. Curtoni, G. Dispau, M. Dorlot, W. Farabolini, M. Fontaine, P. Girardot, R. Granelli, F. Harrault, J.L. Jannin, C.L.H. Lahonde-Hamdoun, T. Lerch, P.-A. Leroy, M. Luong, A. Mosnier, F. Orsini, C. Simon
    CEA, Gif-sur-Yvette
  • S. Curt, K. Elsener, V. Fedosseev, G. McMonagle, J. Mourier, M. Petrarca, L. Rinolfi, G. Rossat, E. Rugo, L. Timeo
    CERN, Geneva
  • R. Roux
    LAL, Orsay

The CLIC project based on the innovative Two Beams Acceleration concept is currently under study at CTF3 where the acceleration of a probe beam will be demonstrated. This paper will describe in details the status of the probe beam linac called CALIFES. This linac (170 MeV, 1 A) is developed by CEA Saclay, LAL Orsay and CERN. It will be installed in the new experimental area of CTF3 to deliver short bunches (1.8 ps) with a charge of 0.6 nC to the CLIC 12 GHz accelerating structures. The linac consists in an rf gun triggered by a laser beam, three LIL sections for bunching and acceleration, a beam diagnostic system and a single klystron with a pulse compression cavity and a dedicated rf network. We report new results of beam dynamic simulation considering the new CLIC parameters. We will give an estimation of the energy and phase deviation over the bunch train (140 ns long) by transient calculation of beam loading. Details about the fabrication of the rf gun, the cavity BPM, the HV modulator and the power phase shifter will be described. New results from laser system studies are discussed. The construction of CALIFES and the start of commissioning will be also reported.

TUP033 Lattice Studies for the XFEL-Injector optics, diagnostics, undulator, electron 468
  • Y.A. Kot, V. Balandin, W. Decking, C. Gerth, N. Golubeva, T. Limberg
    DESY, Hamburg

The XFEL injector building has a length of 74.3 metres and is divided by 2.5 m long concrete shielding wall. The section upstream the shielding wall will have a length of 42.3 m and give place for the gun, accelerating module, 3rd harmonic section, laser heater and the beam diagnostics section. At its end the possibility for the beam dump is foreseen so that the tuning of the beam in the injector would become possible without any impact on the subsequent parts of the XFEL. Each of these components sets certain requirements on beam optics which may compete with each other. Downstream the shielding the beam will be vertically displaced by 2.75 m over the distance of 20 m by means of the so called dogleg - a combination of two four cell arcs (8 cell system). Since the vertical displacement takes place there it is important to optimize cells in such an order that the chromatic effects don't impact the beam quality noticeably. In this paper we describe the solution for the beam optics at the XFEL injector.

TUP035 New Experimental Results from PITZ gun, emittance, cathode, cavity 474
  • F. Stephan, J.W. Bähr, C.H. Boulware, H.-J. Grabosch, M. Hänel, Ye. Ivanisenko, M. Krasilnikov, B. Petrosyan, S. Riemann, S. Rimjaem, T.A. Scholz, R. Spesyvtsev
    DESY Zeuthen, Zeuthen
  • G. Asova, L. Staykov
    INRNE, Sofia
  • K. Flöttmann, S. Lederer
    DESY, Hamburg
  • L. Hakobyan, M.K. Khojoyan
    YerPhI, Yerevan
  • F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • P.M. Michelato, L. Monaco, C. Pagani, D. Sertore
    INFN/LASA, Segrate (MI)
  • R. Richter
    BESSY GmbH, Berlin
  • J. Rönsch
    Uni HH, Hamburg
  • A. Shapovalov
    MEPhI, Moscow

Funding: This work was partly supported by the European Community, contracts RII3-CT-2004-506008 and 011935, and by the 'Impuls- und Vernetzungsfonds' of the Helmholtz Association, contract number VH-FZ-005.
The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) was built to develop and optimize high brightness electron sources for Free Electron Lasers (FELs) like FLASH and the European XFEL. In the last shutdown a new RF gun cavity with improved water cooling was installed and conditioned. It is the first rf gun where the surface cleaning was done with dry ice technique instead of high pressure water rinsing and it showed a 10 times lower dark current emission than its precursor gun, even at cathode gradients as high as 60M V/m. In addition, a new photo cathode laser system was installed and will be available for operation in spring 2008. It will allow flat-top temporal laser shapes with 2ps rise/fall time. According to beam dynamics simulations this will further improve the beam quality reported at earlier conferences* and will lead to unprecedented low transverse projected emittance beams at a charge level of 1nC. This contribution will summarize the experimental results from the summer 2008 running period covering transverse projected emittance optimization, thermal emittance from the photocathode, longitudinal phase space and first transverse slice emittance measurements.

* L. Staykov et al., "Measurements of the Projected Normalized Transverse Emittance at PITZ", Proceedings of the FEL 2007, Novosibirsk, Russia, August 2007.


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TUP040 Linear Accelerator for the PSI-XFEL FEL3 Beamline linac, FEL, emittance, gun 483
  • Y. Kim, A. Adelmann, B. Beutner, M.M. Dehler, R. Ganter, T. Garvey, R. Ischebeck, M. Pedrozzi, J.-Y. Raguin, S. Reiche, L. Rivkin, V. Schlott, A. Streun, A.F. Wrulich
    PSI, Villigen

In the planned PSI-XFEL facility, three FEL branches will supply coherent, ultra-bright, and ultra-short XFEL photons at wide wavelength range. FEL branch 1 will use a 6.0 GeV driving linac to generate hard X-rays from 0.1 nm to 0.3 nm, while FEL branch 2 is foreseen for X-rays from 0.3 nm to 1.0 nm. However, FEL branch 3 was designed to supply spatially as well as temporally coherent soft X-rays from 1.0 nm to 10 nm with the High-order Harmonic Generation based seeded HGHG scheme. To reach emittances of 0.2 mm.mrad and to squeeze consequently the whole facility within an 800 m long tunnel, PSI is presently developing an advanced low emittance gun (LEG) based on a 1 MV high gradient pulsed diode and field emission. The advanced LEG will be used to drive FEL branch 1 and 2, while an RF photoinjector will be used to drive the FEL branch 3. In this paper, we describe a CTF3 RF gun based injector, two bunch compressors, two diagnostic sections, and linacs for the PSI-XFEL FEL branch 3.

TUP044 The NPS-FEL Injector Upgrade cathode, gun, injection, FEL 495
  • J.W. Lewellen, W.B. Colson, S.P. Niles
    NPS, Monterey, California
  • A.E. Bogle, T.L. Grimm
    Niowave, Inc., Lansing, Michigan
  • W. Graves
    MIT, Middleton, Massachusetts
  • T.I. Smith
    Stanford University, Stanford, Califormia

Funding: This research is supported by the Office of Naval Research and the Joint Technology Office.
The Naval Postgraduate School (NPS) has begun the design and assembly of the NPS Free-Electron Laser (NPS-FEL). As part of this effort, the original dc gun-based injector system is being refurbished and upgraded. As described in the accompanying paper 'Status of the NPS-FEL' (these Proceedings), the overall NPS-FEL design parameters are for 40 MeV beam energy, 1 nC bunch charge, and 1 mA average beam current, in an energy-recovery linac configuration. As we move towards this configuration, the injector system will be incrementally upgraded to add photocathode capability, have a higher final beam energy, and improve the beam brightness, to meet the demands of the overall experimental program. This paper describes the current status of the injector system, the initial set of experiments planned, and the projected upgrade path.

TUP049 The Electron Bunch Initial Energy Profile on a Seeded Free Electron Laser Performance FEL, electron, undulator, free-electron-laser 509
  • J. Wu, A. Chao
    SLAC, Menlo Park, California
  • J. Bisognano
    UW-Madison/SRC, Madison, Wisconsin

Funding: The work of AWC and JW was supported by the US Department of Energy under contract DE-AC02-76SF00515. The work of JB was supported by National Science Foundation Award No. DMR-0537588.
A single-pass high-gain X-ray free electron laser (FEL) calls for a high quality electron bunch. In particular, for a seeded FEL, and for a cascaded harmonic generation (HG) FEL, the electron bunch initial energy profile uniformity is crucial to preserve an FEL narrow bandwidth. After the acceleration, compression, and transport, the electron bunch energy profile entering the undulator can acquire temporal non-uniformity. During the cascading stages, the electron bunch energy profile is also not uniform temporally entering the next stage. We study the effects of the electron bunch initial energy profile on the FEL performance, cascaded HG FEL or single stage FEL amplifier. Concrete examples are discussed for seeded FEL projects being studied.

TUP052 Status of the NPS Free-Electron Laser FEL, electron, booster, undulator 518
  • J.W. Lewellen, W.B. Colson, S.P. Niles
    NPS, Monterey, California
  • T.I. Smith
    Stanford University, Stanford, Califormia

Funding: This research is supported by the Office of Naval Research and the Joint Technology Office.
The Naval Postgraduate School (NPS) has begun the design and assembly of the NPS Free-Electron Laser (NPS-FEL). The basic NPS-FEL design parameters are for 40 MeV beam energy, 1 nC bunch charge, and 1 mA average beam current, in an energy-recovery linac configuration. The NPS-FEL will make use of portions of the Stanford Superconducting Accelerator (decommissioned in 2007), in particular the injector system, Stanford/Rossendorf-style cryomodules and rf system. The injector will be gradually upgraded to improve beam properties and increase the injection voltage. Each cryomodule contains two, 9-cell TESLA-type 1.3 GHz cavities, each cavity powered by an individual 10 kW cw klystron. NPS has committed to refurbishing a building for the FEL, with approximate interior vault dimensions of 7 m x 20 m x 2.5 m. The building has overall dimensions of 12 m x 49 m and will house the vault, control room, and support equipment. This paper describes the overall goals of the program, initial experimental plans, and progress to date.

TUP053 Experimental Characterization and Optimization of High-brightness Electron Beam at the NSLS SDL emittance, injection, solenoid, electron 521
  • X. Yang, J.B. Murphy, H.J. Qian, S. Seletskiy, Y. Shen, X.J. Wang
    BNL, Upton, Long Island, New York

The Source Development Laboratory (SDL) at the National Synchrotron Light Source (NSLS) is a laser linac facility dedicated for laser seeded FEL and beam physics R&D. The SDL consists of a RF synchronized Ti:sapphire laser, a BNL photocathode RF gun, a four-magnet chicane bunch compressor, and a 300 MeV linac. To further improve the performance of the laser seeded FEL at the NSLS SDL, we have carried out a systematic experimental characterization of the high-brightness electron beam generated by the photocathode RF gun. We will present the experimental studies of both transverse and longitudinal emittance of electron beam as a function of RF gun phase and solenoid magnet for electron beam charge ranging from 350 pC to 1 nC and their influences on FEL output.

TUP065 Demonstration of Multi-Pulse X-ray Generation via Laser-Compton Scattering Using Pulsed-Laser Super-Cavity cavity, electron, photon, linac 545
  • K. Sakaue, M. Washio
    RISE, Tokyo
  • S. Araki, M.K. Fukuda, Y. Higashi, Y. Honda, T. Taniguchi, N. Terunuma, J. Urakawa
    KEK, Ibaraki
  • N. Sasao
    Kyoto University, Kyoto

Funding: Work supported by a Grant-In-Aid for Creative Scientific Research of JSPS (KAKENHI 17GS0210) and a Grant-In-Aid for JSPS Fellows (19-5789)
A compact and high quality X-ray source is required for various field, such as medical diagnosis, drug manifacturing and biological sciences. Laser-Compton based X-ray source that consist of a compact electron storage ring and a pulsed-laser super-cavity is one of the solutions of a compact X-ray source. Pulsed-laser super-cavity has been developed at Waseda University for a compact high brightness X-ray source. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. 357 MHz mode-locked Nd:VAN laser pulses can be stacked stably in a 420 mm long Fabry-Perot cavity with "burst mode", which means stacking of electron beam synchronized amplified pulses in our R&D. In view of this successful result, we have started an X-ray generation experiment using a super-cavity and a multi-bunch electron beam at KEK-LUCX. Recently, the demonstration experiment between the burst mode pulsed-laser super-cavity and the 100bunch multi-bunch electron beam is successfully performed. Development of the super-cavity and the experimental results of X-ray generation will be presented at the conference.

TUP069 Low Energy Photoemission Electron Source for Applications in THz Radiation Production and Time-Resolved Electron Microscopy electron, cathode, radiation, FEL 554
  • N. Vinogradov, P. Piot, C.R. Prokop
    Northern Illinois University, DeKalb, Illinois
  • J.W. Lewellen, J. Noonan
    ANL, Argonne

Funding: Work supported by the Department of Education under contract P116Z010035 with Northern Illinois University.
A simple, inexpensive, and compact low-energy (~20 KeV) photoemission electron source was designed, built and recently commissioned. It uses a commercial ultraviolet photocathode drive laser producing 3 ns RMS pulse. The source will eventually be used to drive a table-top THz radiation source, based on the Smith-Purcell free-electron laser scheme, and could also have potential application to time-resolved electron microcopy. We present experimental measurements of the photoemitted electron beam and numerical simulations of the anticipated parameters. We also discuss the generation of flat beams required to efficiently drive the THz radiation source.

TUP076 Design of a Beam Halo Monitor with a High Dynamic Range photon, radiation, storage-ring, controls 570
  • J. Egberts, S.T. Artikova, C.P. Welsch
    MPI-K, Heidelberg
  • E. Bravin, T. Lefèvre
    CERN, Geneva
  • T. Chapman, M.J. Pilon
    Thermo, Liverpool, New York

A thorough understanding of halo formation and its possible control is highly desirable for essentially all particle accelerators. Limiting the number of particles in the halo region of a beam would allow for minimizing beam losses and maximizing beam transmission, i.e. the experimental output. Measurements based on either optical transition radiation (OTR) or synchrotron radiation (SR) provide an interesting opportunity for high dynamic range measurements of the transverse beam profile, since the signal is linear with the beam charge over a wide range and is routinely used in many diagnostic applications. In this contribution, first results on beam halo measurements obtained from a flexible core masking technique and an innovative CID camera system are summarized.

TUP084 Emittance Measurement Instrument for a High Brilliance H- Ion Beam emittance, ion, diagnostics, rfq 594
  • C. Gabor, C.R. Prior
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • J.K. Pozimski
    STFC/RAL, Chilton, Didcot, Oxon

Funding: Work supported by EU/FP6/CARE (HIPPI) RII3-CT-2003-506395
Among present challenges for beam diagnostics and instrumentation are issues presented by high beam intensity, brightness, resolution and the need to avoid inserting mechanical parts into the beam. This very often means applying non-destructive methods, which avoid interaction between ions and mechanical parts and, furthermore, allow on-line measurements during normal beam operation. The preferred technique for H- beams is the photo-detachment process where (laser) light within the range of 400-1000 nm has a sufficient continuous cross section to neutralize negative ions. The actual diagnostics are then applied to either the neutrals produced or the electrons. The latter are typically used for beam profiles whereas neutrals are more suitable for emittances, and form the subject of the present paper. This provides an overview of the basic features of the diagnostic technique, followed by a more intensive discussion of some experimental and theoretical aspects with emphasis on computing the 4 dimensional emittance using a method called Maximum Entropy (MaxEnt).


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TUP086 Initial Commissioning of a Dual-Sweep Streak Camera on the A0 Photoinjector emittance, cavity, electron, optics 600
  • A.H. Lumpkin, T.W. Koeth, J. Ruan
    Fermilab, Batavia

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Characterization of the micropulse bunch lengths and phase stability of the drive laser and the electron beam continue to be of interest at the Fermilab A0 Photoinjector facility. Upgrades to the existing Hamamatsu C5680 streak camera were identified, and initially a synchroscan unit tuned to 81.25 MHz was installed to provide a method for synchronous summing of the micropulses from the drive laser and the optical transition radiation (OTR) generated by the e-beam. A phase-locked delay box was also added to the system to provide phase stability of ~1 ps over tens of minutes. Initial e-beam measurements identified a significant space-charge effect on the bunch length. Recent measurements with a re-optimized transverse emittance allowed the reduction of the micropulse number from 50 to 10 with 1 nC each to obtain a useful streak image. This increased signal also would facilitate dual-sweep operations of the streak camera to explore macropulse effects. Installation of the recently procured dual-sweep module in the mainframe has now been done. Initial commissioning results and sub-macropulse effects in the beams will be presented as available.

TUP091 Extracting Information Content within Noisy, Sampled Profile Data from Charged Particle Beams: Part II space-charge, diagnostics, brightness 612
  • C.K. Allen, W. Blokland, S.M. Cousineau, J. Galambos
    ORNL, Oak Ridge, Tennessee

Funding: This work was supported by SNS through UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Charged-particle beam diagnostic devices such as wire scanners, wire harps, and laser scanners all provide data sets describing the one-dimensional density distributions of the beam at a particular location; these data are commonly called profile data. We use these data for further computations, usually beam properties such as position and size, but to do so requires a certain level of accuracy in the data. Thus, we must make real world considerations as to its information content. Specifically, we consider noise in the data and the fact that it is sampled. The operation of a typical profile device is outlined in order to create a general model for the data sets. Using signal processing techniques we identify the minimal sampling requirements for maintaining information content. Using Bayesian analysis we identify the most probable Gaussian signal within the data (the mean and standard deviation of the Gaussian signal can then be used for computations). Time permitting we present techniques for direct computation of beam properties using noisy, sampled profile data.

TUP092 Laser-Based Profile and Energy Monitor for H- Beams electron, space-charge, ion, linac 615
  • R. Connolly, J.G. Alessi, S. Bellavia, W.C. Dawson, C. Degen, W. Meng, D. Raparia, T. Russo, N. Tsoupas
    BNL, Upton, Long Island, New York

A beam profile and energy monitor for H- beams based on laser photoneutralization is being developed at Brookhaven National Laboratory for use on the High Intensity Neutrino Source at Fermilab. An H- ion has a first ionization potential of 0.75 eV and can be neutralized by light from a Nd:YAG laser (λ = 1064 nm). To measure beam profiles, a narrow laser beam is stepped across the ion beam removing electrons from the portion of the H- beam intercepted by the laser. A curved axial magnet field channels these electrons into a Faraday cup. To measure the energy spread of the electrons the laser position is fixed and the voltage on a screen in front of the cup is raised in small steps. We deduce the energy spread of the H- beam by deconvolving the electron spectrum into components from beam energy and from space-charge fields. Measurements are reported from experiments in the BNL linac MEBT at 750 keV.


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TUP093 Activities on High Brightness Photo-injectors at the Frascati Laboratories, Italy FEL, linac, emittance, radiation 618
  • 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

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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TUP097 Measurements and Modeling at the PSI-XFEL 500 kV Low-Emittance Electron Source emittance, cathode, electron, simulation 630
  • 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

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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TUP099 Design and Optimization of an S-Band Photoinjector gun, emittance, cavity, solenoid 636
  • J.H. Han
    Diamond, Oxfordshire

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.

TUP100 The Optimization of a DC Injector for the Energy Recovery Linac Upgrade to APS emittance, gun, linac, electron 639
  • Y.-E. Sun, M. Borland, K.C. Harkay, Y.L. Li, H. Shang
    ANL, Argonne

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.

TUP103 Analysis of Halo Formation in a DC Photoinjector cathode, electron, space-charge, emittance 645
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois

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.

TUP105 Simulation of the Upgraded Photoinjector for the 10 kW JLAB IR-FEL emittance, simulation, cavity, FEL 649
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois
  • C. Hernandez-Garcia, S. Zhang
    JLAB, Newport News, Virginia

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.

TUP112 Laser Timing Jitter Measurements at the Fermilab A0 Photoinjector cavity, electron, linac, emittance 664
  • J.K. Keung
    University of Pennsylvania, Philadelphia, Pennsylvania
  • S. Nagaitsev, J. Ruan
    Fermilab, Batavia

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.

WE101 Energy Recovered Linacs electron, linac, emittance, storage-ring 688
  • G.A. Krafft
    JLAB, Newport News, Virginia

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In the last decade, stimulated by the success of the energy recovered free electron lasers, many projects have been initiated exploring the applications and limitations of beam energy recovery in recirculated linear accelerators (linacs). In this talk the performance of many existing energy recovered linacs is briefly reviewed. Looking forward, potential applications of energy recovered linacs such as

  1. recirculated linac light sources,
  2. high energy beam electron cooling devices, and
  3. electron beam sources for high energy colliders have been pursued with varying degrees of effort.
The types of new technology that must be developed for applications, and more broadly, some of the open issues regarding this technology, are discussed in detail. The talk concludes with some thoughts on the future developments in this important, and expanding field.


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WE104 First Tests of the Cornell University ERL Injector cavity, gun, emittance, cathode 699
  • B.M. Dunham, I.V. Bazarov, S.A. Belomestnykh, M.G. Billing, E.P. Chojnacki, Z.A. Conway, J. Dobbins, R.D. Ehrlich, M.J. Forster, S.M. Gruner, G.H. Hoffstaetter, V.O. Kostroun, Y. Li, M. Liepe, X. Liu, D.G. Ouzounov, H. Padamsee, D.H. Rice, V.D. Shemelin, C.K. Sinclair, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, V. Veshcherevich, T. Wilksen
    CLASSE, Ithaca, New York

Funding: Work supported by the National Science Foundation under contract PHY 0131508
Cornell University is planning to build an Energy-Recovery Linac (ERL) X-ray facility. The very small electron-beam emittance would produce an X-ray source that is significantly better than any existing storage-ring based light source. One major difference between an ERL and a typical light source is that the final electron beam emittance, and thus the X-ray beam brightness, is determined by the electron injector rather than the storage ring. We are currently constructing and commissioning an injector for an ERL with the goal of demonstrating the low emittances and high beam power required. The injector is designed to accelerate up to 100 mA cw electron bunches of 77 pC/bunch with an energy of 5 MeV (33 mA at 15 MeV) using 1.3 GHz superconducting cavities. A full suite of diagnostics will allow a complete phase space characterization for comparison with simulations and with the requirements. We will describe the current status of the injector along with results, difficulties and challenges to date.


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THP037 RF Design of a Spoke Resonator for High Power Free-Electron Lasers HOM, electron, free-electron-laser, acceleration 866
  • F.L. Krawczyk, D.C. Nguyen
    LANL, Los Alamos, New Mexico
  • S.J. Cooke
    NRL, Washington, DC
  • B. Rusnak
    LLNL, Livermore, California
  • T.I. Smith
    Stanford University, Stanford, Califormia
  • E.L. Wright
    Beam-Wave Research, Inc., Union City

Funding: Supported by the High-Energy Laser Joint Technology Office
We are investigating spoke resonators that originally were proposed for moderate energy proton acceleration for application in high-average-current free-electron lasers (FEL). This structure holds the promise of alleviating the BBU limitations of conventional rf structures. Spoke resonator have several advantages: 1) strong coupling simplifies the access to higher order modes (HOM), 2) at the same frequency a spoke resonator is about half the size of an elliptical resonator, 3) the spokes provide additional mechanical stability and stiffening , 4) the power and HOM couplers can be attached to the cavity body and do not take up additional space along the length of the accelerator, 5) the presence of the spokes limits the polarizations of the HOMs to two orientations which facilitates the selection of HOM coupler positions. The rf performance of a spoke resonator specifically designed for high-current electron applications (beta=1.0) will be presented and compared with the expected performance of elliptical resonators designed for such applications. Besides the structure's effectiveness for acceleration also HOM properties will be presented.


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THP055 Characteristics of Different Materials on High-Gradient Experiments controls, acceleration, status, klystron 912
  • K. Yokoyama, S. Fukuda, Y. Higashi, T. Higo, N. Kudoh, S. Matsumoto, Y. Watanabe
    KEK, Ibaraki

High-gradient experiments have been performed using a narrow waveguide that has a field of approximately 200 MV/m at an rf power of 100 MW. The study investigates the characteristics of different materials at high-gradient rf breakdown. This paper reports the results of high-gradient experiments and observations of the surface of stainless-steel waveguides.


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THP118 A Femtosecond-Level Fiber-Optics Timing Distribution System Using Frequency-Offset Interferometry klystron, cavity, controls, feedback 1078
  • J.W. Staples, J.M. Byrd, L.R. Doolittle, G. Huang, R.B. Wilcox
    LBNL, Berkeley, California

Funding: This work was supported by the Office of Science, U. S. Department of Energy, under Contract No. DE-AC02-05CH11231.
A fiber-based frequency and timing distribution system based on the principle of heterodyne interferometry has been in development at LBNL for several years. The temporal fiber drift corrector has evolved from an rf-based to an optical-base system, from mechanical correctors (piezo and optical trombone) to fully electronic, and the electronics from analog to fully digital, all using inexpensive commodity fiber components. Short-term optical phase jitter and long-term phase drift are both in the femtosecond range over distribution paths of 2 km and more. The temperature dependence of group and phase velocity correction is measured and applied. We will discuss the results of field tests, integration into various client subsystems and further applications.


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FR102 Commissioning of the LCLS Linac emittance, linac, FEL, electron 1095
  • H. Loos, R. Akre, A. Brachmann, F.-J. Decker, Y.T. Ding, D. Dowell, P. Emma, J.C. Frisch, A. Gilevich, G.R. Hays, P. Hering, Z. Huang, R.H. Iverson, C. Limborg-Deprey, A. Miahnahri, S. Molloy, H.-D. Nuhn, J.L. Turner, J.J. Welch, W.E. White, J. Wu
    SLAC, Menlo Park, California
  • D.F. Ratner
    Stanford University, Stanford, Califormia

Funding: This work was supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515
Construction of the Linac Coherent Light Source (LCLS) X-ray free electron laser at the Stanford Linear Accelerator Center (SLAC) is nearing completion. A new injector and upgrades to the existing accelerator were installed in two phases in 2006 and 2007. We report on the commissioning of the injector, the two new bunch compressors at 250 MeV and 4.3 GeV, and transverse and longitudinal beam diagnostics up to the end of the existing linac at 13.6 GeV. The commissioning of the new transfer line from the end of the linac through the undulator beam line to the main dump is scheduled to start in January 2009 and for the undulator magnets in March 2009 with first light to be expected by May 2009.


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FR104 Review of Advanced Laser Technologies for Photocathode High-Brightness Guns polarization, electron, cathode, gun 1105
  • H. Tomizawa, H. Dewa, H. Hanaki, A. Mizuno, T. Taniuchi
    JASRI/SPring-8, Hyogo-ken

I developed a 3-D pulse shaping system in UV as an ideal laser for yearlong stable photoinjector. At SPring-8, the laser's pulse-energy stability has been improved to 0.7~1.4% at the UV (263 nm) under the laser environmental control included humidity. In addition, the ideal spatial and temporal profiles of an UV-laser pulse are essential to suppress emittance growth in an rf gun. I apply a deformable mirror that automatically shapes the spatial profile with a feedback routine, based on a genetic algorithm, and a pulse stacking system consisting of three birefringence Alpha-BBO crystal rods for temporal shaping at the same time. The 3D shape of the laser pulse is spatially top-hat (flattop) and temporally a square stacked chirped pulse. Using a 3D-shaped laser pulse with diameter of 0.8 mm on the cathode and pulse duration of 10 ps (FWHM), we obtain a normalized emittance of 1.4 pi mm mrad with a beam energy of 26 MeV. To keep the mirror away from beam axis, I developed a new hollow laser incidence with an axicon final focusing. Furthermore, I am developing a laser-induced Schottky-effect-gated photocathode gun using Z-polarization of the laser source with the hollow incidence.


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