Author: Konomi, T.
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MOPMP009 Effect of Initial Parameters on the Super Flat Beam Generation with the Phase-Space Rotation for Linear Colliders 442
 
  • M. Kuriki, R. Tamura
    HU/AdSM, Higashi-Hiroshima, Japan
  • H. Hayano, X.J. Jin, T. Konomi, Y. Seimiya, N. Yamamoto
    KEK, Ibaraki, Japan
  • S. Kashiwagi
    Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • J.G. Power
    ANL, Argonne, Illinois, USA
  • K. Sakaue
    The University of Tokyo, The School of Engineering, Tokyo, Japan
  • M. Washio
    RISE, Tokyo, Japan
  
  Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI) Kiban B.
Linear collider is a concept to realize e+e− collision beyond the limitation of the ring colliders by the synchrotron radiation. To obtain an enough luminosity, eg. 1.0·10+34 cm-2sec-1, the beam is focused down to nano-meter size with a high aspect ratio. This super flat beam is useful to improve the luminosity and to compensate the beam-beam effect, eg. Beamstrahlung. In a conventional design, the super-flat beam is produced by radiation damping in a storage ring. We propose to produce this super-flat beam with phase-space rotation techniques. We employ both Round to Flat Beam Transformation and Transverse to Longitudinal Emittance eXchange, the super flat beam can be generated by controlling the space-charge effect which spoiled the performance. We present the RFBT performance with respect to the initial conditions, i.e. beam size, initial emittance, solenoid field (strength and profile), etc. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP009  
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019  
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TUPGW036 1 mA Stable Energy Recovery Beam Operation with Small Beam Emittance 1482
 
  • T. Obina, D.A. Arakawa, M. Egi, T. Furuya, K. Haga, K. Harada, T. Honda, Y. Honda, T. Honma, E. Kako, R. Kato, H. Kawata, Y. Kobayashi, Y. Kojima, T. Konomi, H. Matsumura, T. Miura, T. Miyajima, S. Nagahashi, H. Nakai, N. Nakamura, K. Nakanishi, K.N. Nigorikawa, T. Nogami, F. Qiu, H. Sagehashi, H. Sakai, S. Sakanaka, M. Shimada, M. Tadano, T. Takahashi, R. Takai, O.A. Tanaka, Y. Tanimoto, T. Uchiyama, K. Umemori, M. Yamamoto
    KEK, Ibaraki, Japan
  • R. Hajima, R. Nagai, M. Sawamura
    QST, Tokai, Japan
  • N. Nishimori
    National Institutes for Quantum and Radiological Science and Technology (QST), Sayo-cho, Japan
  
  A compact energy-recovery linac (cERL) have been operating since 2013 at KEK to develop critical components for ERL facility. Details of design, construction and the result of initial commissioning are already reported*. This paper will describe the details of further improvements and researches to achieve higher averaged beam current of 1 mA with continuous-wave (CW) beam pattern. At first, to keep the small beam emittance produced by 500 kV DC-photocathode gun, tuning of low-energy beam transport is essential. Also, we found some components degrades the beam quality, i.e., a non-metallic mirror which disturbed the beam orbit. Other important aspects are the measurement and mitigation of the beam losses. Combination of beam collimator and tuning of the beam optics can improve the beam halo enough to operate with 1 mA stably. The cERL has been operated with beam energy at 20 MeV or 17.5 MeV and with beam rep-rate of 1300 MHz or 162.5 MHz depending on the purpose of experiments. In each operation, the efficiency of the energy recovery was confirmed to be better than 99.9 %.
* S. Sakanaka, et.al., Nucl. Instr. and Meth. A 877 (2017)197, https://doi.org/10.1016/j.nima.2017.08.051
 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW036  
About • paper received ※ 14 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019  
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TUPRB037 Experimental Demonstration of Vector Beam Generation With Tandem Helical Undulators 1766
 
  • S. Matsuba
    HSRC, Higashi-Hiroshima, Japan
  • M. Fujimoto, M. Katoh
    UVSOR, Okazaki, Japan
  • M. Hosaka
    Nagoya University, Nagoya, Japan
  • K. Kawase
    QST, Tokai, Japan
  • T. Konomi, N. Yamamoto
    KEK, Ibaraki, Japan
  • A. Miyamoto
    Toshiba, Yokohama, Japan
  • S. Sasaki
    ANL, Argonne, Illinois, USA
  
  Vector beam is a light beam with spatially modulated polarization state across the beam. Particular examples of vector beam are radial and azimuthal polarization which have donut-shaped intensity and radially and azimuthally oriented linear polarization state. Vector beam has long been interest in the laser community and it is well known that vector beam can be created by superposing two optical vortex beams which have spiral wave fronts. It has been demonstrated that optical vortex beam can be generated from a helical undulator as harmonics. Therefore, we propose a scheme to generate vector beam by superposing two optical vortex beams from two helical undulators in tandem, based on the principle of the ’crossed undulator’. The experiment was carried out at UVSOR BL1U. In this paper, we describe the principle and the experimental details.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB037  
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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