Author: Higo, T.
Paper Title Page
TUPAB004 Progress of 7-GeV SuperKEKB Injector Linac Upgrade and Commissioning 1300
 
  • K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funahashi, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimoto, H. Sugimura, T. Suwada, T. Takatomi, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
 
  KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It is being upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of new physics beyond the standard model of elementary particle physics. SuperKEKB asymmetric electron and positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. Electron beams will be generated by a new type of RF gun, that will provide a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 micron to 20 micron in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The recent status of the upgrade and beam commissioning is reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB004  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPAB005 Investigation of Beam Variation and Emittance Growth Simulation With Both Misalignments and the Beam Jitter for SuperKEKB Injector Linac 1304
 
  • Y. Seimiya, K. Furukawa, T. Higo, F. Miyahara, M. Satoh, T. Suwada
    KEK, Ibaraki, Japan
 
  Funding: This work was supported by JSPS KAKENHI Grant Number 16K17545.
The SuperKEKB is e+/e circular collider for high luminosity, 8Â¥times1035 as a target value. For the high luminosity, the injector linac is required to transport low emittance high-charged electron beam and positron beam to the ring. A charged beam with an offset from a center of cavity is affected by the wakefield depending on both the offset size in the cavity and longitudinal particle position in the beam. The wakefield causes emittance growth. This growth can be suppressed by appropriate orbit control so as to cancel the wakefield effect of the cavities in total. On the other hands, the beam variation in 6-dimensional phase space also induces the emittance growth. Emittance growth by both misalignments and 6-dimensional beam jitter was evaluated by particle tracking simulation. Investigation of beam jitter and drift was also performed by correlation analysis between beam position and measured parameter, charge or temperature.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB005  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
TUPAB010 High-Gradient Breakdown Studies of X-Band Choke-Mode Structures 1322
SUSPSIK005   use link to see paper's listing under its alternate paper code  
 
  • X.W. Wu, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
  • T. Abe, T. Higo, S. Matsumoto
    KEK, Ibaraki, Japan
 
  As an alternative design for Compact Linear Collider (CLIC) main accelerating structures, X-band choke-mode damped structures had been studied for several years. However, the performance of choke-mode cavity under high power is still in lack of research. Two standing-wave single-cell choke-mode damped accelerating structures working at 11.424 GHz and one reference structure without choke were designed, manufactured, low-power measured, and tuned by accelerator group at Tsinghua University. High-power test had been done on them to study the breakdown phenomenon in high gradient and how the choke affects high-gradient properties. A max gradient of 75 MV/m were achieved by the choke-mode structure and the choke breakdown limited further increasing of the gradient. Inner surface inspection of the choke-mode structures indicates that the axial part of the choke limits the performance of the structure. Based on this observation, three new choke-mode structures were designed and being manufactured.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB010  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
WEPAB044 Construction and Commissioning of Direct Beam Transport Line for PF-AR 2678
 
  • N. Higashi, S. Asaoka, K. Furukawa, K. Haga, K. Harada, T. Higo, T. Honda, H. Honma, N. Iida, H. Iwase, K. Kakihara, T. Kamitani, M. Kikuchi, Y. Kishimoto, Y. Kobayashi, K. Kodama, K. Kudo, T. Kume, K. Mikawa, T. Mimashi, F. Miyahara, H. Miyauchi, S. Nagahashi, H. Nakamura, N. Nakamura, T. Natsui, K.N. Nigorikawa, Y. Niwa, T. Nogami, T. Obina, Y. Ogawa, M. Ono, T. Ozaki, H. Sagehashi, T. Sanami, M. Sato, M. Satoh, T. Suwada, M. Tadano, T. Tahara, R. Takai, H. Takaki, S. Takasaki, M. Tanaka, Y. Tanimoto, M. Tawada, N. Toge, T. Uchiyama, A. Ueda, Y. Yamada, M. Yamamoto, M. Yoshida
    KEK, Ibaraki, Japan
 
  PF-AR was constructed as an accumulator ring for TRISTAN, and in the KEKB era it has been revitalized as a 6.5 GeV synchrotron radiation source. The injection energy was 3 GeV and the beam was accelerated to 6.5 GeV prior to the user run. The original beam transport line (BT) from the LINAC to the PF-AR shared its upstream part with the the BT line of KEKB High Energy Ring (HER). The injection-mode change from PF-AR to HER or vice versa needs about 10 minutes for the magnet cycling procedure of the shared part. In SuperKEKB, the upgrade of KEKB, the lifetime of HER is about 10 minutes. The mode-switch operation of the BT is, therefore, not allowed for maintaining the highest luminosity of the SuperKEKB. In order to avoid this problem, a new 6.5 GeV BT line dedicated to PF-AR has been constructed. This also enables the top-up injection for the user run. The commissioning of the new BT line has been completed in this March, and now the first user run has been operated successfully.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB044  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)  
 
THPIK068 High Power Test of SINAP X-Band Deflector at KEK 4251
 
  • J.H. Tan, W. Fang, Q. Gu, X.X. Huang, Z.B. Li, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  • T. Higo
    KEK, Ibaraki, Japan
  • D.C. Tong
    TUB, Beijing, People's Republic of China
 
  A crucial RF structure used for bunch length measurement for Shanghai X-ray Free Electron Lasers (SXFEL) at the Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Science [1]. The design, fabrication, measurement and tuning have been completed at SINAP [2], and the high power test was carried out at Nextef of KEK with international collaboration. This paper presents the RF conditioning process and test results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK068  
Export • reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)