Author: Urakawa, J.
Paper Title Page
TUBC1 Recent Progress and Operational Status of the Compact ERL at KEK 1359
 
  • S. Sakanaka, M. Adachi, S. Adachi, T. Akagi, M. Akemoto, D.A. Arakawa, S. Araki, S. Asaoka, M. Egi, K. Enami, K. Endo, S. Fukuda, T. Furuya, K. Haga, K. Hara, K. Harada, T. Honda, Y. Honda, H. Honma, T. Honma, K. Hosoyama, K. Hozumi, A. Ishii, X.J. Jin, E. Kako, Y. Kamiya, H. Katagiri, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondou, A. Kosuge, T. Kume, T. Matsumoto, H. Matsumura, H. Matsushita, S. Michizono, T. Miura, T. Miyajima, H. Miyauchi, S. Nagahashi, H. Nakai, H. Nakajima, N. Nakamura, K. Nakanishi, K. Nakao, K.N. Nigorikawa, T. Nogami, S. Noguchi, S. Nozawa, T. Obina, T. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sasaki, K. Satoh, T. Shidara, M. Shimada, K. Shinoe, T. Shioya, T. Shishido, M. Tadano, T. Tahara, T. Takahashi, R. Takai, H. Takaki, T. Takenaka, O. Tanaka, Y. Tanimoto, N. Terunuma, M. Tobiyama, K. Tsuchiya, T. Uchiyama, A. Ueda, K. Umemori, J. Urakawa, K. Watanabe, M. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
    KEK, Ibaraki, Japan
  • E. Cenni
    Sokendai, Ibaraki, Japan
  • R. Hajima, S. Matsuba, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
    JAEA, Ibaraki-ken, Japan
  • J.G. Hwang
    KNU, Deagu, Republic of Korea
  • M. Kuriki
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  • Y. Seimiya
    HU/AdSM, Higashi-Hiroshima, Japan
 
  Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program from the MEXT, and by the MEXT grant for promoting technology for nuclear security.
The Compact Energy Recovery Linac (cERL) is a superconducting test accelerator aimed at establishing technologies for the ERL-based future light source. After its construction during 2009 to 2013, the first CW beams of 20 MeV were successfully transported through the recirculation loop in February 2014*. Then, initial tuning of beams and evaluations of beam properties were carried out. From September to December in 2014, we are constructing a Laser Compton Scattering (LCS) source** which aims at demonstrating technology for the future high-flux quasi-monochromatic gamma-ray source. In the next run of the cERL, which begins at the end of January 2015, we plan such works as an increase in the beam current (from 10 uA to 100 uA), commissioning of the LCS source, and sustained tuning of beams for lower emittance. We will report up-to-date results of these developments.
* N. Nakamura et al., IPAC2014, MOPRO110; S. Sakanaka et al., LINAC14, TUPOL01.
** R. Nagai et al., IPAC2014, WEPRO003.
 
slides icon Slides TUBC1 [2.679 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUBC1  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPWA063 FEL Enhancement by Microbuch Structure Made with Phase-Space Rotation 1570
 
  • M. Kuriki, Y. Seimiya
    HU/AdSM, Higashi-Hiroshima, Japan
  • S. Chen, K. Ohmi, J. Urakawa
    KEK, Ibaraki, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • R. Kato
    ISIR, Osaka, Japan
 
  Funding: This work is partly supported by MEXT/JSPS KAKENHI (Grant-in-Aid for scientic research) 25390126, Japan.
FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. For FEL, enegy chirp made by the emittance exchange and chromaticity made by this chirp should be properly corrected. Simulation results and possible applications are discussed.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA063  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPWA065 Generation of Multi-bunch Beam with Beam Loading Compensation by Using RF Amplitude Modulation in Laser Undulator Compact X-ray (LUCX) 1576
 
  • M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • K. Sakaue, M. Washio
    RISE, Tokyo, Japan
 
  We have developed a compact X-ray source based on inverse Compton scattering between an electron beam and a laser pulse stacked in an optical cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a 3.6 cell photo-cathode rf-gun, a 12cell standing wave accelerating structure and a 4-mirror planar optical cavity. Our aim is to obtain a clear X-ray image in a shorter period of times and the target flux of X-ray is 1.7x107 photons/pulse with 10% bandwidth at present. To achieve this target, it is necessary to increase the intensity of an electron beam to 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches with beam-loading compensation by using the delta T method and the amplitude modulation of RF pulse. The bunch-by-bunch energy difference is within 1.3% peak to peak. We will report the results of the multi-bunch beam generation and acceleration in this accelerator.
This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA065  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPWA066 Development of a High Average Power Laser for High Brightness X-ray Source and Imaging at cERL 1579
 
  • A. Kosuge, T. Akagi, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • R. Hajima, M. Mori, T. Shizuma
    JAEA, Ibaraki-ken, Japan
  • R. Nagai
    JAEA/ERL, Ibaraki, Japan
 
  Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan.
High brightness X-rays via laser-Compton scattering (LCS) of laser photons stored in an optical cavity by a relativistic electron beam is useful for many scientific and industrial applications such as X-ray imaging. The construction of compact Energy Recovery Linac (cERL) is now in progress at KEK to generate low-emittance and high-current electron beams. In order to demonstrate the generation of high brightness LCS X-rays, it is necessary to develop a high average power injection laser and an optical four-mirror ring cavity with two concave mirrors which is used to produce a small spot laser beam inside the cavity. In this presentation, we will show the result of the development of the high average laser system, the LCS X-rays generation, and the X-ray imaging.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA066  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPWA070 CST Simulations of THz Cherenkov Smith-purcell Radiation from Corrugated Capillary 1594
 
  • K. Lekomtsev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  • P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • A. Ponomarenko, A.A. Tishchenko
    MEPhI, Moscow, Russia
 
  Recent advances in generation of femtosecond pre-bunched beams have a potential to generate coherent THz radiation occurring via combination of Smith-Purcell radiation (SPR) and Cherenkov radiation (ChR) generated in a corrugated capillary. This mechanism was studied theoretically *. LUCX accelerator at High Energy Accelerator Research Organisation (KEK) has been upgraded by introducing fs Ti:Sa laser system and it is currently generating short tens of fs electron bunches **. In this report we present EM simulations of Ch.SPR generated in a corrugated channel in infinite dielectric and in a dielectric corrugated capillary. CST PIC solver is used as a simulation tool. It was earlier used for simulation of Transition radiation ***. Intensity dependencies of ChR and SPR peaks as functions of the capillary radius and the corrugation depth are compared with the theoretical investigation *. Output of THz radiation from the dielectric capillary with a radiation reflector is simulated.
* A.A. Ponomarenko et. al, NIMB 309 (2013) 223-226.
** M. Fukuda et. al, NIMA 637 (2011) S67.
*** K.V. Lekomtsev et. al, J. Phys.: Conf. Ser. 517, (2014) 012016.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA070  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPJE002 Demonstration of High-flux Photon Generation from an ERL-based Laser Compton Photon Source 1607
 
  • R. Nagai, R. Hajima, M. Mori, T. Shizuma
    JAEA, Ibaraki-ken, Japan
  • T. Akagi, S. Araki, Y. Honda, A. Kosuge, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
 
  A high-flux photon source from the laser Compton scattering (LCS) by an electron beam in an energy-recovery linac (ERL) is a key technology for a nondestructive assay system to identify nuclear materials. In order to demonstrate accelerator and laser technologies required for a LCS photon generation, a LCS photon source is under construction at the Compact ERL (cERL). The LCS photon source consists of a mode-locked fiber laser and a laser enhancement cavity. Flux monitors and a data aqcuisition system are also under construction. The commissioning of the LCS photon source will be started in February 2015 and LCS photon generation is scheduled in March 2015. The demonstration result of the LCS photon source will be presented in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE002  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPJE011 Laser-Compton Scattering X-ray Source Based on Normal Conducting Linac and Optical Enhancement Cavity 1635
 
  • K. Sakaue, M. Washio
    Waseda University, Tokyo, Japan
  • S. Araki, M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
 
  Funding: Work supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been developing a compact X-ray source via laser-Compton scattering (LCS) at KEK-LUCX (Laser Undulator Compact X-ray source) facility. The LUCX system is based on S-band normal conducting linac with an energy of 30 MeV and optical enhancement cavity for photon target. As a photon target, we invented a burst mode laser pulse storage technique for a normal conducting linac, which enables to store the high power laser pulses at the timing of electron bunchs. The peak storage power exceeds to more than 250 kW with 357 MHz repetition. Electron linac is under operation with multi-bunch mode, 1000 bunches/train with 600 pC charge in each bunches. We have succeeded to produce 1000 pulse/train LCS X-ray train. Combining high repetition rate electron linac and burst mode optical enhancement cavity, more than 109 ph./sec/10%b.w. flux would be possible. In this conference, the introduction of our test facility LUCX, recent expermental results, and future prospective including normal conducting LCS X-ray source will be presented.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE011  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPWI008 RF Gun Based Ultrafast Electron Microscopy 2259
 
  • J. Yang, K. Tanimura, Y. Yoshida
    ISIR, Osaka, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
 
  Ultrafast electron microscopy (UEM) would be a powerful tool for the direct visualization of structural dynamic processes in matter. The resolutions of the observation on femtosecond time scales over sub-nanometer (even atomic) spatial dimensions have long been a goal in science. To achieve such resolutions, we have designed and constructed a femtosecond time-resolved relativistic-energy electron microscopy using a photocathode radio-frequency (RF) electron gun (RF based UEM). The RF gun has successfully generated a high-brightness electron beam with bunch length of 100 fs and emittance of 0.2 mm-mrad, which are essential beam parameters for the achievement of nm-fs space-time resolution in the microscopy. Both the static measurements of both relativistic-energy electron diffraction and image have been succeeded. In this presentation, the activities on RF based UEM are introduced. The requirements and limitations of the beam parameters are reviewed. The concept and design of RF based UEM are reported. Finally, some demonstrations of the relativistic-energy UEM images are reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI008  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWA014 Low Temperature Properties of 20 K Cooled Test Cavity for C-band 2.6-cell Photocathode RF Gun 2519
 
  • T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
    LEBRA, Funabashi, Japan
  • M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  • T.S. Shintomi
    Nihon University, Tokyo, Japan
 
  Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A cryogenic C-band 2.6-cell photocathode RF gun, which operates at 20 K, is under development at Nihon University for future possibility of use in a compact linac-driven X-ray source. The cavity material is 6N8 high purity copper, the RRR of which being expected to be higher than 3000. A 2.6-cell pi-mode test cavity was fabricated for investigation of the properties under low temperature of 20 K*. Ultraprecision machining and diffusion bonding of the cavity were carried out in KEK. The operating frequency of the RF gun cavity is 5712 MHz. The machining dimensions of the test cavity were determined by taking into account the contraction of copper from room temperature to 20 K by approximately 0.33 %. The resonant frequency observed at around 21 K was 5711.761 MHz, which is 185 kHz higher than the expected value that was deduced from the resonant frequency obtained at 23.5 degree C in vacuum and the linear expansion coefficient data for OFC copper by NIST**. The unloaded Q-value of 64500 obtained at 21 K is in agreement with the SUPERFISH calculation when the surface resistance of the RRR=3000 copper was specified with taking the anomalous skin effect into account.
* T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf
/IPAC2014/papers/mopri030.pdf
** http://cryogenics.nist.gov/MPropsMAY/OFHC%20Copper/OFHCCopperrev.htm
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA014  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWA015 RF Input Coupler for 20 K Cooled C-band 2.6-cell Photocathode RF Gun 2522
 
  • T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
    LEBRA, Funabashi, Japan
  • M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  • T.S. Shintomi
    Nihon University, Tokyo, Japan
 
  Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
For future use in a compact linac-driven X-ray source, a cryo-cooled C-band photocathode RF gun is under development. The RF experiment on the basic 2.6-cell test cavity has shown that the unloaded Q-value of the cavity at 20 K can be explained by the surface resistance based on the anomalous skin effect. Since the cavity was intended for preliminary experiments of the low temperature RF properties*, a new test cavity with an RF input coupler has been designed. The basic structure of the accelerating cells has not been changed from the previous cavity. Avoiding an element with a low cooling efficiency such as the inner electrode in a coaxial coupler, a simpler cylindrical input coupler has been designed. The coupler consists of a cylindrical TM01 mode waveguide and a mode converter from a rectangular TE10 mode, with both elements placed on the accelerating axis. The structure and the dimensions of the coupler have been determined using the 3-D simulation code CST Studio so that the resonant frequency of the whole system and the coupling coefficient of the coupler meet the specifications of the RF gun. The new test cavity will be completed early in 2015 at KEK.
* T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf
/IPAC2014/papers/mopri030.pdf
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA015  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPWA017 An Optimization of ILC Positron Source for Electron-Driven Scheme 2529
 
  • Y. Seimiya, M. Kuriki, M. Urano
    HU/AdSM, Higashi-Hiroshima, Japan
  • S. Kashiwagi
    Tohoku University, School of Science, Sendai, Japan
  • T. Okugi, T. Omori, M. Satoh, J. Urakawa
    KEK, Ibaraki, Japan
  • T. Takahashi
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
 
  International Linear Collider is a future accelerator to find new physics behind the electroweak symmetry breaking by precise measurements of Higgs sector, Top quark, and so on. ILC has capacities to reveal new phenomena beyond Standard model, such as Supersymmetry particles and dark matters. In current design of positron source, undulator scheme is adapted as a baseline. In the scheme, positrons are generated from gamma rays through pair-creation process in Ti-alloy target. Generations of the gamma rays by the undulator radiation requires more than 130 GeV electrons. Therefore, a system demonstration of the scheme is practically difficult prior to the real construction. Consequently, it is desirable to prepare a technical backup of this undulator scheme. We study an optimization of positron source based on the conventional electron-driven scheme for ILC. In this scheme, positron beam is generated by several GeV electron beam impinging on W-Re target. Although heavy heat load and destruction of the target is a potential problem, it can be relaxed by stretching the effective pulse length to 60 ms instead of 1 ms, by a dedicated electron linac for the positron production. In this report, a start-to-end simulation of the electron-driven ILC positron source is performed. Beam-loading effect caused by multi-bunch acceleration in the standing wave RF cavity is also considered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA017  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)