Author: Konomi, T.
Paper Title Page
TUPOW036 Recent Developments and Operational Status of the Compact ERL at KEK 1835
  • T. Obina, 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, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, Y. Kondo, T. Konomi, 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. Ozaki, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, S. Sasaki, K. Satoh, Y. Seimiya, 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, N. Yamamoto, Y. Yamamoto, Y. Yano, M. Yoshida
    KEK, Ibaraki, Japan
  • R. Hajima, M. Mori, R. Nagai, N. Nishimori, M. Sawamura, T. Shizuma
    QST, Tokai, Japan
  • M. Kuriki
    Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
  The Compact Energy Recovery Linac (cERL) at KEK is a test accelerator in order to develop key components to realize remarkable ERL performance as a future light source. After the beam commissioning in December 2013, the legal current limit has been increased step-by-step like 1 uA, 10 uA, and 100 uA. Survey for the source of beam losses has been conducted in each step, and the study on beam dynamics and tuning has also been carried out. As a next step, 1 mA operation is scheduled in February 2016. In parallel to the increase in beam current, a laser Compton scattering (LCS) system which can provide high-flux X-ray to a beamline has been successfully commissioned. We report recent progress in various kinds of beam tuning: improvement of electron gun performance, high bunch charge operation, mitigation of beam losses, LCS optics tuning and bunch compression for THz radiation.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW036  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
WEOAA03 Experimental Study on Optical Vortex from a Helical Undulator at UVSOR-III 2036
  • M. Hosaka
    Nagoya University, Nagoya, Japan
  • M. Katoh, N.S. Mirian
    UVSOR, Okazaki, Japan
  • T. Konomi, N. Yamamoto
    KEK, Ibaraki, Japan
  • K. Kuroda
    ISSP, Kashiwa-shi, Japan
  • K. Miyamoto, S. Sasaki
    HSRC, Higashi-Hiroshima, Japan
  A relativistic electron in helical undulator emits an optical vortex which carries orbital angular momentum. Sasaki and McNulty predicted theoretically that higher harmonics of helical undulator is optical vortex* and the experimental verification was made at BESSY** and UVSOR-III***. Further, we have made a systematic study to characterize the optical vortex from a helical undulator at UVSOR-III. Synchrotron radiation in UV region from an optical klystron undulator system consisting of two APPLE-II helical undulators and a buncher was used for the experiment. Patterns resulting from inferences between two undulator radiation carrying different angular momentums were clearly observed. To investigate the optical properties of the radiation, diffraction experiments were carried out. Specific diffraction patterns due to the phase singularity in the radiation center were clearly observed. The experimental results are compared with simulation.
* S. Sasaki, I. McNulty, Phys. Rev. Lett. 100, 124801 (2008)
** J. Bahrdt et al., Phys. Rev. Lett. 111, 034801 (2013)
*** e.g. S. Sasaki et al., presented in SRI2015 (2015)
slides icon Slides WEOAA03 [11.023 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAA03  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
WEPMB013 Long Term Cavity Performance in Compact-ERL Injector Cryomodule 2145
  • E. Kako, T. Konomi, T. Miura, H. Sakai, K. Umemori
    KEK, Ibaraki, Japan
  Degradation of cavity performance due to heavy field emission was observed in three 2-cell cavities after beam operation at 5 MeV for 2 years.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB013  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
WEPMB014 Cavity Performance of the Prototype KEK Superconducting RF Gun 2148
  • T. Konomi, E. Kako, E. Kako, Y. Kobayashi, Y. Kobayashi, K. Umemori, K. Umemori, S. Yamaguchi
    KEK, Ibaraki, Japan
  • R. Matsuda
    Mitsubishi Heavy Industries Ltd. (MHI), Takasago, Japan
  • T. Yanagisawa
    MHI, Hiroshima, Japan
  A superconducting RF (SRF) gun can generate a high current and high energy beam. It has a possibility to achieve requirement from high performance ERL and high repetition FEL. Target values of the L-band KEK SRF gun are that beam repetition is 1.3 GHz, beam current is 100 mA, beam energy is 2 MeV, emittance is 1 mm mrad or less. The number of cell is 1.5. Accelerating energy of 2 MeV corresponds to 42 MV/m of maximum surface field. The photocathode is designed to be illuminated by excitation laser from backside. The SRF gun cavity consists of the 1.5 cell accelerating cavity, cathode plug and choke filter for protecting the heating of cathode plug. To evaluate these parts individually, these parts are added step by step. High gradient test of the accelerating cell without cathode plug and choke filter was done. The surface peak electric field reached 66 MV/m, and this meet the target value 42 MV/m sufficiently. Next high gradient test will be done after adding the choke filter. The choke filter is designed to be simple to wash choke cell easier. In this conference, we will report the design, fabrication and high gradient performance of the SRF gun cavity with choke filter.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB014  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
WEPMB016 Vertical Test Results of Nitrogen Doped SRF Cavities at KEK 2154
  • K. Umemori, H. Inoue, E. Kako, T. Konomi, T. Kubo, H. Sakai, H. Shimizu, M. Yamanaka
    KEK, Ibaraki, Japan
  • H. Hara, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  Recently Nitrogen doping(N-doping) technique was proposed and drastic improvements of Q-values were reported. Since high-Q operation of SRF cavities are very attractive for CW machine, we started investigation on performance of Nitrogen doped SRF cavities. Nitrogen doping systems were prepared on two vacuum furnaces, which have been used for annealing of SRF cavities. Two fine grain single cell cavities have been used for the study. After 800 degree, 3 hours annealing, N-doping were carried out under several Pa of Nitrogen pressure and followed by post annealing. Three kind of different conditions, pressure and duration time, were attempted. After applying EP-2, cavity performances were evaluated by vertical tests. Against our expectations, we observed lower Q-values, at every measurements, than those measured without N-doping. In this presentation, we describe details about N-doping system and parameters and results obtained by vertical tests. Some discussions are also given against our results.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB016  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
WEPMB026 MHI-MS's Production Activities of Superconducting Cavity 2180
  • H. Hara, A. Miyamoto, K. Sennyu, T. Yanagisawa
    MHI-MS, Kobe, Japan
  • E. Kako, T. Konomi, H. Nakai, K. Umemori
    KEK, Ibaraki, Japan
  Mitsubishi Heavy Industries Mechatronics Systems, Ltd. (MHI-MS), a subsidiary of MHI, took over MHI's accelerator business on October 1, 2015, and has been developing the business since that time. MHI-MS has developed manufacturing process of superconducting cavities continuously. In this presentation, recent progress will be reported.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMB026  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
THPOW005 A Study of CsK2Sb Multi-alkali Photocathode by Ultraviolet Photoelectron Spectroscopy at UVSOR 3934
SUPSS022   use link to see paper's listing under its alternate paper code  
  • M. Urano, M. Kuriki, K. Negishi
    HU/AdSM, Higashi-Hiroshima, Japan
  • T. Konomi, Y. Seimiya, N. Yamamoto
    KEK, Ibaraki, Japan
  Photocathode is one of the most important components in the next-generation accelerators, especially based on linear accelerators. Photocathode performance depends not only on electronic state in its bulk material but also on the surface condition. CsK2Sb multi-alkali photocathode is a candidate for the high brightness electron source because of its high quantum efficiency by green laser and its high robustness. We have carried out an UPS (UV Photoelectron Spectroscopy) experiment at UVSOR facility, synchrotron radiation light source in Aichi Japan. We have compared the UPS spectra among several samples, each one has a different quantum efficiency, and try to find physics which decide photocathode's performance. In this case, we focused some characters correlated to the quantum efficiency. I'm going to present a result of this analysis.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW005  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)