Keyword: laser
Paper Title Other Keywords Page
MOPLB03 Advances in Beam Tests of Dielectric Based Accelerating Structures wakefield, acceleration, electron, linac 144
 
  • A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • W. Gai
    ANL, Argonne, USA
  • V. Yakimenko
    BNL, Upton, Long Island, New York, USA
 
  Funding: US Department of Energy
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σz = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.
 
slides icon Slides MOPLB03 [1.986 MB]  
 
MOPLB07 Non-destructive Inspections for SC Cavities cavity, target, SRF, cryogenics 156
 
  • Y. Iwashita, Y. Fuwa, M. Hashida, K. Otani, S. Sakabe, S. Tokita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Hayano, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki, Japan
 
  Non-destructive Inspections play important roles to improve yield in production of high-performance SC Cavities. Starting from the high-resolution camera for inspection of the cavity inner surface, high resolution T-map, X-map and eddy current scanner have been developed. We are also investigating radiography to detect small voids inside the Nb EBW seam, where the target resolution is 0.1 mm. We are carrying out radiography tests with X-rays induced from an ultra short pulse intense laser. Recent progress will be presented.  
slides icon Slides MOPLB07 [5.810 MB]  
 
MOPLB12 X-Ray Local Energy Spectrum Measurement on Tsinghua Thomson Scattering X-Ray Source (TTX) scattering, simulation, electron, photon 171
 
  • Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
    TUB, Beijing, People's Republic of China
 
  Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.  
slides icon Slides MOPLB12 [1.311 MB]  
 
MOPB005 High Gradient Operation of 8 GeV C-Band Accelerator in SACLA acceleration, electron, klystron, free-electron-laser 186
 
  • T. Inagaki, C. Kondo, Y. Otake, T. Sakurai
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  SACLA (SPring-8 angstrom compact free electron laser) is the X-ray free electron laser (XFEL) facility. In order to shorten the 8 GeV accelerator length, a C-band (5712 MHz) accelerator was employed. Since the accelerating gradient of C-band accelerating structure is 35 MV/m in nominal, the active accelerator length is 230 m. In total, 64 klystrons, 64 pulse compressors, and 128 accelerating structures are used. In order to withstand the high surface field (~ 100 MV/m), and to reduce the amount of dark current, which decreases the demagnetization effect of undulators, the accelerating structures are carefully fabricated in the factory. After high power RF conditioning of 500 hours, the beam commissioning was started in February 2011. For night time of the commissioning, we continued the RF conditioning. The RF breakdown rate of the structure was steadily decreased. Now we operate the accelerator with the beam energy as much as 8.3 GeV, and the accelerating gradient of 37 MV/m in average. We found the amount of dark current is small enough. So far no trouble occurred in C-band RF components of 64 sets.  
 
MOPB011 Photoinjector of the EBTF/CLARA Facility at Daresbury gun, cavity, vacuum, electron 192
 
  • B.L. Militsyn, D. Angal-Kalinin, C. Hill, S.P. Jamison, J.K. Jones, J.W. McKenzie, K.J. Middleman, B.J.A. Shepherd, R.J. Smith, R. Valizadeh, A.E. Wheelhouse
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • N. Bliss, M.D. Roper
    STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
 
  A description is given of a photoinjector designed for Compact Linear Advanced Research Accelerator (CLARA) and Electron Beam Test Facility (EBTF), which will eventually be used to drive a compact FEL. The photoinjector is based on a 2.5 cell S-band photocathode RF gun operating with a copper photocathode and driven by a third harmonic of Ti: Sapphire laser (266 nm) installed in dedicated thermally stabilized room. The injector will be operated with laser pulses with an energy of up to 2 mJ, a pulse duration of 100 fs and initially a repetition rate of 10 Hz, with the aim of increasing this eventually to 400 Hz. At a field gradient of 100 MV/m provided by a 10 MW klystron the gun is expected to deliver beam pulses with energy of up to 6 MeV. Duration and emittance of electron bunches essentially depend on the bunch charge and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Additional compression of the electron bunches will be provided with a velocity bunching scheme. For thermal stability the low energy part of the injector is mounted on an artificial granite support.  
 
MOPB013 Experimental Results on the PHIL Photo-injector Test Stand at LAL cathode, electron, emittance, gun 198
 
  • R. Roux, F. Blot, J. Brossard, C. Bruni, S. Cavalier, J-N. Cayla, V. Chaumat, M. El Khaldi, A. Gonnin, P. Lepercq, E.N. Mandag, B. Mercier, H. Monard, C. Prevost, V. Soskov, A. Variola
    LAL, Orsay, France
 
  Since the first beam in November 2009 of the alphaX S-band RF gun, upgrades of the beamline have been carried out. Several YAG screens based transverse dimensions monitors have been installed as well as supplementary charge diagnostics. We will present a detailed experimental characterization of the RF gun performances such as emittance measurement using a solenoid scan and energy spread as a function of the RF phase. Most of the accelerator operation and experimental results have been carried out with a copper photo-cathode. PHIL being a test stand for photo-injectors, we have also tested a magnesium photo-cathode with the aim of higher charge per bunch thanks to its higher quantum efficiency. We will report on the results of this experiment. In May 2012, a new RF gun, the PHIN gun, will be installed. This gun which is also a S-band 2,5 cells is a copy of the one that LAL built for the CLIC Test Facility 3 at CERN. In the future, we plan to use this gun to produce a high charge up to 10nC with CsTe photo-cathodes introduced in the gun from a UHV transfer chamber. Preliminary tests and measurements of the beam produced by this gun with a copper photo-cathode will be presented.  
 
MOPB025 1ms Multi-bunch Electron Beam Acceleration by a Normal Conducting RF Gun and Superconducting Accelerator gun, cavity, emittance, cathode 228
 
  • M. Kuriki, S. Hosoda, H. Iijima
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, J. Urakawa, K. Watanabe
    KEK, Ibaraki, Japan
  • G. Isoyama, R. Kato, K. Kawase
    ISIR, Osaka, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • A. Kuramoto
    Sokendai, Ibaraki, Japan
  • K. Sakaue
    RISE, Tokyo, Japan
 
  Funding: Quantum Beam Project by MEXT, Japan
We perform electron beam generation and acceleration of 1 ms long pulse and multi-bunch format at KEK-STF (Superconducting Test Facility). The 1 ms long pulse beam is generated by a normal conducting photo-cathode L-band RF gun. The beam is boosted up to 40 MeV by a super-conducting accelerator. Aim of STF is to establish the super-conducting accelerator technology for ILC (International Linear Collider). The facility is concurrently used to demonstrate high brightness X-ray generation by inverse laser Compton scattering supported by MEXT Quantum Beam project. The RF gun cavity has been fabricated by DESY-FNAL-KEK collaboration. After conditioning process, a stable operation of the cavity up to 4.0 MW RF input with 1 ms pulse was achieved by keeping low dark current. 1 ms pulse generation and acceleration has been confirmed in March 2012. Quasi-monochromatic X-ray generation experiment by Laser-Compton will be carried out at STF from the next coming July. We report the latest status of STF.
 
 
MOPB029 Commissioning of the X-Band Test Area at SLAC gun, cathode, injection, electron 234
 
  • C. Limborg-Deprey, C. Adolphsen, M.P. Dunning, S. Gilevich, C. Hast, R.K. Jobe, D.J. McCormick, A. Miahnahri, T.O. Raubenheimer, A.E. Vlieks, D.R. Walz, S.P. Weathersby
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
The X-Band Test Area (XTA) is being assembled in the NLCTA tunnel at SLAC to serve as a test facility for new X-Band RF guns. The first gun to be tested is an upgraded version of the 5.6 cell, 200 MV/m peak field X-band gun designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA [1]. The XTA beamline is equipped with diagnostics to measure both the longitudinal phase space and the transverse phase space properties of the beam after it has reached 100 MeV. We will review design choices and present some early commissioning results.
[1] A.E. Vlieks, et al. “Recent measurements and plans for the SLAC Compton X-ray source”, SLAC-PUB-11689, 2006. 10pp. Published in AIP Conf. Proc.807:481-490, 2006
 
 
MOPB041 Advances in Beam Tests of Dielectric Based Accelerating Structures wakefield, acceleration, electron, linac 264
 
  • A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • W. Gai
    ANL, Argonne, USA
  • V. Yakimenko
    BNL, Upton, Long Island, New York, USA
 
  Funding: US Department of Energy
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in our recent beam tests of the diamond based accelerating structures of the Ka-band and THz frequency ranges. Wakefield breakdown test of a diamond-loaded accelerating structure has been carried out at the ANL/AWA accelerator. The high charge beam from the AWA linac (~70 nC, σz = 2.5 mm) was passed through a rectangular diamond loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.3 GV/m has been detected on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond has been performed before and after the beam test. Wakefield effects in a 250 GHz planar diamond accelerating structure has been observed at BNL/ATF accelerator as well. We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism.
 
 
MOPB053 Non-destructive Inspections for SC Cavities cavity, target, SRF, cryogenics 294
 
  • Y. Iwashita, Y. Fuwa, M. Hashida, K. Otani, S. Sakabe, S. Tokita, H. Tongu
    Kyoto ICR, Uji, Kyoto, Japan
  • H. Hayano, K. Watanabe, Y. Yamamoto
    KEK, Ibaraki, Japan
 
  Non-destructive Inspections play important roles to improve yield in production of high-performance SC Cavities. Starting from the high-resolution camera for inspection of the cavity inner surface, high resolution T-map, X-map and eddy current scanner have been developed. We are also investigating radiography to detect small voids inside the Nb EBW seam, where the target resolution is 0.1 mm. We are carrying out radiography tests with X-rays induced from an ultra short pulse intense laser. Recent progress will be presented.  
 
MOPB084 Design of a C-band Disk-loaded Type Accelerating Structure for a Higher Pulse Repetition Rate in the SACLA Accelerator. cavity, wakefield, accelerating-gradient, electron 372
 
  • T. Sakurai, T. Inagaki, Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • H. Ego
    JASRI/SPring-8, Hyogo-ken, Japan
 
  The higher pulse repetition rate of the SACLA accelerator provides a higher rate of X-ray laser pulses to expand ability of user experiments, such as simultaneously providing the laser to several beamlines and reducing a measuring time in the experiment. Therefore, we studied on a C-band accelerating structure for a higher pulse rate above 120 pps than that of the present case of 60 pps. The designed structure adopts a TM01-2π/3 mode disk-loaded type with a quasi-constant gradient . Since higher repetition rate operation is inclined to increase a number of vacuum electrical discharges, it is required to reduce the surface electric field in the structure. We designed an ellipsoidal curvature shape around an iris aperture, which reduces the maximum surface field by 20%. Since the higher repetition rate also increases the heat load of the structure, in simulation, we optimized cooling channels to obtain acceptable frequency detuning. As the results of the design, an accelerating gradient of more than 40 MV/m will be expected, when an input RF power of 80 MW is applied to the structure. In this paper, we report the design of the C-band accelerating structure and its rf properties.  
 
MOPB089 X-Ray Local Energy Spectrum Measurement at Tsinghua Thomson Scattering X-Ray Source (TTX) scattering, simulation, electron, photon 383
 
  • Y.-C. Du, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, H. Zha, Z. Zhang
    TUB, Beijing, People's Republic of China
 
  Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.  
 
TU2A02 Overview of SACLA Machine Status electron, undulator, gun, emittance 427
 
  • Y. Otake
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  SACLA of an X-ray free-electron laser has been constructed and was successfully lased at 0.06 nm in 2011. SACLA mainly comprises a low-emittance thermionic electron gun, an 8-GeV linear accelerator using C-band (5712 MHz) cavities and 18 in-vacuum undulators. The concept to develop this machine is compactness compared with the other machine, such as LCLS with the length of more than 1 km. Stable X-ray lasing up to 0.06 nm as also the concept demands extreme stable accelerator components, such as 50 fs temporal stability at a cavity in an injector. We now realized a 700 m compact machine by a low-emittance at the electron gun, an accelerating gradient of more than 35 MV/m with the C-band accelerator, and the short-period undulators. The continuous lasing for more than several days is strongly supported by these stable components and small operator‘s trimming, and also established by reduction of perturbation sources to laser instability. SACLA is regularly operated for user experiments, such as the imaging with extreme amount of data. This presentation introduces the machine performance, the reduction of the perturbation sources and the operation of SACLA.  
slides icon Slides TU2A02 [28.971 MB]  
 
TUPLB10 Non-destructive Real-time Monitor to Measure 3D-bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-seeded EUV-FEL FEL, electron, feedback, optics 467
 
  • H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • M. Aoyama
    JAEA/Kansai, Kyoto, Japan
  • A. Iwasaki, S. Owada
    The University of Tokyo, Tokyo, Japan
  • S. Matsubara, Y. Okayasu, T. Togashi
    JASRI/SPring-8, Hyogo, Japan
  • T. Matsukawa, H. Minamide
    RIKEN ASI, Sendai, Miyagi, Japan
  • E. Takahashi
    RIKEN, Saitama, Japan
 
  Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3-D overlapping electron bunches and higher harmonic generation (HHG) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.  
slides icon Slides TUPLB10 [2.713 MB]  
 
TUPB006 Stability Performance of the Injector for SACLA/XFEL at SPring-8 controls, undulator, cavity, FEL 486
 
  • T. Asaka, T. Hasegawa, T. Inagaki, H. Maesaka, T. Ohshima, Y. Otake, S. Takahashi, K. Togawa
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  To realize the SACLA, it is necessary to obtain stabilities of 10-4 and 50 fs in the amplitude and time of an acceleration voltage, respectively. The achievement of the rf stabilities were almost satisfactory for the target values. Consequently, the 7 GeV beam energy stability was 0.02% (std.) or less. However, there was XFEL power variation caused by a variation of a beam position in a 40 MeV injector section. A periodically changed beam position of 40 μm (std.) was found out at a cycle of 2 s by Fourier transform method using BPM data. The temperatures of all the injector rf cavities are controlled within 28±0.04˚C by a controller using the cooling water. The AC power supplies of the controller to heat the cooling water are operated at 0.5 Hz by pulse width modulation control with alternatively turning on or off. The strong correlation between laser intensity variation and the modulation frequency of the AC power supplies was found out. We are planning to improve the cavity temperature variation in the order of less than 0.01˚C with DC power supplies to establish continuously regulated the cavity temperature. This plan will reduce the XFEL power variation.  
 
TUPB013 Update on the Commissioning Effort at the SwissFEL Injector Test Facility emittance, electron, quadrupole, optics 504
 
  • T. Schietinger
    PSI, Villigen, Switzerland
 
  The SwissFEL Injector Test Facility at the Paul Scherrer Institute is the principal test bed and demonstration plant for the SwissFEL project, which aims at realizing a hard-X-ray Free Electron Laser by 2017. Since the spring of 2012 the photoinjector facility has been running with all RF cavities in full operation, allowing beam characterization at energies around 230 MeV with bunch charges between 10 and 200 pC. We give an overview of recent commissioning efforts with particular emphasis on efforts to optimize the emittance of the uncompressed beam.  
 
TUPB022 A Passive Linearizer for Bunch Compression FEL, electron, linac, emittance 525
 
  • Q. Gu, M. Zhang, M.H. Zhao
    SINAP, Shanghai, People's Republic of China
 
  In high gain free electron laser (FEL) facility design and operation, a high bunch current is required to get lasing with a reasonable gain length. Because of the current limitation of the electron source due to the space charge effect, a compression system is commonly used to compress the electron beam to the exact current needed. Before the bunch compression, the nonlinear energy spread due to the finite bunch length should be compensated; otherwise the longitudinal profile of bunch will be badly distorted. Usually an X band accelerating structure is used to compensate the nonlinear energy spread while decelerating the beam. For UV FEL facility, the X band system is too expensive comparing to the whole facility. In this paper, we present a corrugated structure as a passive linearizer, and the preliminary study of the beam dynamics is also shown.  
 
TUPB080 Non-destructive Real-time Monitor to Measure 3D Bunch Charge Distribution with Arrival Timing to Maximize 3D Overlapping for HHG-Seeded EUV-FEL FEL, electron, feedback, optics 657
 
  • H. Tomizawa, K. Ogawa, T. Sato, M. Yabashi
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • M. Aoyama
    JAEA/Kansai, Kyoto, Japan
  • A. Iwasaki, S. Owada
    The University of Tokyo, Tokyo, Japan
  • S. Matsubara, Y. Okayasu, T. Togashi
    JASRI/SPring-8, Hyogo, Japan
  • T. Matsukawa, H. Minamide
    RIKEN ASI, Sendai, Miyagi, Japan
  • E. Takahashi
    RIKEN, Saitama, Japan
 
  Non-destructive, shot-by-shot real-time monitors have been developed to measure 3D bunch charge distribution (BCD). This 3D monitor has been developed to monitor 3D overlapping electron bunches and higher harmonic generation (HH) pulses in a seeded VUV-FEL. This ambitious monitor is based on an Electro-Optic (EO) multiple sampling technique in a manner of spectral decoding that is non-destructive and enables real-time measurements of the longitudinal and transverse BCD. This monitor was materialized in simultaneously probing eight EO crystals that surround the electron beam axis with a radial polarized and hollow EO-probe laser pulse. In 2009, the concept of 3D-BCD monitor was verified through electron bunch measurements at SPring-8. The further target of the temporal resolution is ~30 fs (FWHM), utilizing an organic EO crystal (DAST) instead of conventional inorganic EO crystals (ZnTe, GaP, etc.) The EO-sampling with DAST crystal is expected to measure a bunch length less than 30 fs (FWHM). In 2011, the first bunch measurement with an organic EO crystal (DAST) was successfully demonstrated in the VUV-FEL accelerator at SPring-8.  
 
WE1A01 ERL-Based Light Source Challenges gun, linac, electron, emittance 714
 
  • Y. Kobayashi
    KEK, Ibaraki, Japan
 
  The challenges of the design and technology for the future Energy Recovery Liancs will be reviewed: electron sources, injector, SCRF cavities and cryomodules, commissioning.  
 
WE1A05 Linac-Based Laser Compton Scattering X-Ray and Gamma-Ray Sources photon, linac, electron, brightness 734
 
  • R. Hajima
    JAEA, Ibaraki-ken, Japan
 
  Laser Compton scattering (LCS) light sources can provide high-energy photons from keV to MeV range. Many research and development projects of linac-based LCS sources are carried on. For the photon energies of tens keV, linac-based LCS sources realize laboratory-size X-ray sources, of which performance can be comparable to synchrotron light sources. Linac-based LCS also realizes unprecedented gamma-ray sources with better monochromaticity than ring-based LCS sources. This talk will review linac-based LCS source in the world.  
slides icon Slides WE1A05 [2.881 MB]  
 
THPB006 Post Acceleration of Laser-generated Proton Bunches by a CH-DTL proton, linac, DTL, cavity 852
 
  • A. Almomani, M. Droba, I. Hofmann, U. Ratzinger
    IAP, Frankfurt am Main, Germany
 
  Laser driven proton beam sources applying the TNSA process show interesting features in terms of energy and proton number per bunch. This makes them attractive as injectors into RF linacs at energies as high as 10 MeV or beyond. The combination shows attractive features like a very high particle number in a single bunch from the source and the flexibility and reliability of the rf linac to match the needs of a specified application. The approach aims on a very short matching section from the source target into the rf linac by one pulsed solenoid lens only. A crossbar H-type (CH - structure) is suggested because of its high acceleration gradient and efficiency at these beam energies. It is intended to realize the first cavity of the proposed CH - linac and to demonstrate the acceleration of a laser generated proton bunch within the LIGHT collaboration at GSI Darmstadt. Detailed beam and field simulations will be presented.  
 
THPB013 Diagnostics Tools for Beam Halo Investigation in SNS Linac emittance, linac, diagnostics, background 873
 
  • A.V. Aleksandrov, W. Blokland, Y. Liu, C.D. Long, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Uncontrolled beam loss is the major concern in operation of a high intensity hadron linac. A low density cloud of particles with large oscillation amplitudes, so called halo, can form around the dense regular beam core. This halo can be direct or indirect cause of beam loss. There is an experimental evidence of halo growing in SNS linac and limiting further reduction of beam loss. A set of tools is being developed for detecting of the halo and investigating its origin and dynamics. The set includes high resolution emittance measurements in the injector, laser based emittance measurements at 1 GeV, and high resolution profile measurements along the linac. We will present our experience with useful measurement techniques and data analysis algorithms as well as current understanding of the halo dynamics in SNS linac.
 
 
THPB037 Iron Beam Acceleration with DPIS rfq, plasma, injection, ion 936
 
  • M. Okamura
    BNL, Upton, Long Island, New York, USA
  • P.J. Jandovitz
    Cornell University, Ithaca, New York, USA
  • T. Kanesue
    IAP, Frankfurt am Main, Germany
  • M. Sekine
    RLNR, Tokyo, Japan
  • T. Yamamoto
    RISE, Tokyo, Japan
 
  Funding: The work supported by US. DOE and RIKEN Japan.
It has been proved that direct plasma Injection Scheme (DPIS) is an efficient way to accelerate high current highly charged state heavy ion beam. More than 50 mA (peak current) of various heavy ion beams can be easily accelerated. However, it was rather difficult to obtain longer pulse especially for highly charged particles. To induce highly charged states ions, a high plasma temperature is required at the laser irradiation point and the high temperature automatically gives a very fast expansion velocity of the plasma. This shortens the ion beam pulse length. To compensate the shorter ion pulse length, we can extend the plasma drift length, but it will dilute the brightness of the plasma since the plasma expands three dimensionally. To avoid the reduction of the brightness, a simple long solenoid was applied to confine the diverging angle of the plasma expansion. In the conference, this new technique will be explained and the latest results of iron beam acceleration will be shown.
 
 
THPB068 First Observation of Photoemission Enhancement from Copper Cathode Illuminated by Z-Polarized Laser Pulse cathode, polarization, gun, focusing 996
 
  • H. Tomizawa, H. Dewa, A. Mizuno, T. Taniuchi
    JASRI/SPring-8, Hyogo, Japan
 
  Since 2006, we have developed a novel photocathode gun gated by laser-induced Schottky-effect. This new type of gun utilizes a laser’s coherency to aim at a compact femtosecond laser oscillator as an IR laser source using Z-polarization on the photocathode. This Z-polarization scheme reduces the laser photon energy (making it possible to excite the cathode with a longer wavelength) by reducing the work function of cathode due to Schottky effect. A hollow laser incidence is applied with a hollow convex lens in a vacuum that is focused after passing the laser beam through a radial polarizer. According to our calculations (convex lens: NA=0.15), a Z-field of 1 GV/m needs 1.26 MW at peak power for the fundamental wavelength (792 nm). In the first demonstration of Z-field emission, enhancement was done with a copper cathode at THG (264 nm). Consequently, we observed 1.4 times enhancement of photoemission at 1.6 GV/m of an averaged laser Z-field on the cathode surface. We report the first observation and analysis of the emission enhancements with this laser-induced Schottky-effect on metal copper photocathodes by comparing radial and azimuthal polarizations of the incident laser pulses.  
 
THPB089 Magnetic Characterization of the Phase Shifter Prototypes Built by CIEMAT for E-XFEL undulator, electron, free-electron-laser, FEL 1029
 
  • I. Moya, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, L.M. Martinez, T. Martínez de Alvaro, E. Molina Marinas, L. Sanchez, S. Sanz, F. Toral, C. Vázquez, J.G.S. de la Gama
    CIEMAT, Madrid, Spain
  • J. Campmany, J. Marcos, V. Massana
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
 
  Funding: Work partially supported by Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009 and project ref. AIC-2010-A-000524
The European X-ray Free Electron Laser (E-XFEL) will be based on a 10 to 17.5 GeV electron linac that will be used in the undulator system to obtain ultra-brilliant X-ray flashes from 0.1 to 6 nanometres for experimentation. The undulator system is formed by undulators and intersections between them, where a quadrupole on top of a precision mover, a beam position monitor, two air coils and a phase shifter are allocated. The function of the phase shifter is to adjust the phase of the electron beam and the radiation when they enter in an undulator according to the different beam energies and wavelengths. CIEMAT is working on the development of the phase shifters, as part of the Spanish in-kind contribution to the E-XFEL project. Several problems reported elsewhere were detected in the first prototype, which did not fulfil the first field integral specification. This paper describes the magnetic measurements realized on the second and third prototypes in the test bench at CELLS, together with the tuning process to decrease the field integral dependence with gap.
 
 
THPB095 Designing of a Phase-mask-type Laser Driven Dielectric Accelerator for Radiobiology electron, acceleration, simulation, vacuum 1041
 
  • K. Koyama
    UTNL, Ibaraki, Japan
  • A. Aimidura, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • Y. Matsumura
    University of Tokyo, Tokyo, Japan
  • T. Natsui, M. Yoshida
    KEK, Ibaraki, Japan
 
  Funding: This work is supported by KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120
In order to estimate the health risk of a low radiation dose, basic processes of the radiobiology should be clarified by shooting a DNA using a spatially and temporary defined particle beam or X-ray. A suitable beam size is as small as a resolving power of an optical microscope of a few hundred nanometers. Photonic crystal accelerators (PCA) are capable of delivering nm-beams of sub-fs pulses because the characteristic length and frequency of PCAs are on the order of the laser light. Since the phase-mask type accelerator has a simpler structure than other types of PCAs, we are designing a phase-mask type laser driven dielectric accelerator. By adopting an unbalanced length of pillar and ditch (grating) of 4:1, a standing wave like acceleration field is produced in a acceleration channel. A pillar height and initial speed of injected electron are determined by analytically. The maximum acceleration gradient of 2 GeV/m is estimated. The required laser power is roughly estimated to be 6.5 GW. The simulation using CST-code also shows similar values to accelerate electrons by the phase-mask type accelerator.
 
 
THPB096 High-power Sources of RF Radiation Driven by Periodic Laser Pulses cavity, electron, radiation, klystron 1044
 
  • S.V. Kuzikov, A.V. Savilov
    IAP/RAS, Nizhny Novgorod, Russia
  • S.V. Kuzikov
    Omega-P, Inc., New Haven, USA
 
  Funding: Supported in part by DoE USA.
A fast, periodic modulation of electron RF sources can be carried out in a form of Q-factor switching by means of fast RF switches, or in a form of I-switching by means of the bunched electron beam. If modulation frequency equals to time which is necessary for RF radiation to travel along the cavity and to come back, the RF oscillator can produce periodic, giant, short pulses which are desirable for many applications in order to avoid a breakdown. The produced RF pulses are phase and frequency locked by modulation shape. The mentioned effects of the phase and frequency locking remain also possible for RF sources operated in a single-mode regime. In last case the modulation frequency should be close to natural single-mode oscillation frequency. For example, one might control operation of a BWO by means of a small periodical modulation of the electron voltage in a drift section in-between a cathode and the corrugated interaction section. The necessary voltage modulation can be provided by means of a DC generator those voltage due to a photoconductivity is externally modulated with definite frequency by laser which irradiates GaAs isolator inserted in-between the electrodes.