Author: Higo, T.
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THPOR040 Emittance Growth by Misalignments and Jitters in SuperKEKB Injector Linac 3871
 
  • Y. Seimiya, Y. Enomoto, K. Furukawa, T. Higo, T. Kamitani, F. Miyahara, Y. Ohnishi, M. Satoh, T. Suwada, M. Tanaka
    KEK, Ibaraki, Japan
 
  Funding: This work was partly supported by JSPS KAKENHI Grant Number 16K17545.
SuperKEKB injector linac have to transport high-charged beam with low emittance to SuperKEKB ring for high luminosity, 8¥times1035. For the low emittance, photocathode RF gun was adopted as electron source. One of the main reason of the beam emittance blow-up electron linac is generally induced by wakefield in acceleration cavities. A charged beam with a offset from a center of a cavity is affected by the wakefield depending on the offset size in the acceleration cavity and the beam emittance is increased. This emittance blow-up can be eliminated by appropriate steering magnet control so as to cancel the wake effect in the acceleration cavity. We perform particle tracking simulation with some misalignments and beam jitter. Emittance growth by the misalignments and the beam jitter is evaluated in this report.
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR040  
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THPOR041 High Gradient Properties of a CLIC Prototype Accelerating Structure made by Tsinghua University 3874
 
  • X.W. Wu, H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  • T. Higo, S. Matsumoto
    KEK, Ibaraki, Japan
  • W. Wuensch
    CERN, Geneva, Switzerland
 
  A CLIC prototype structure, T24_THU_#1, was recently high-gradient tested at KEK X-band test stand, Nextef. The copper parts of this 24-cell TW structure were delivered from CERN, were bonded and brazed, bench-tested and tuned in Tsinghua University. The aim of this test was not only to verify the cavity high-gradient properties under 100 MV/m but also to study the breakdown phenomenon in high gradient. High power test results were presented and breakdown rate under 100 MV/m was compared to previously-tested CLIC prototype structures. The assembly capability of Tsinghua University for X-band high gradient structures was validated by the good high gradient performance of T24_THU_#1.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR041  
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THPOR043 High Power Test of X-band Single Cell HOM-free Choke-mode Damped Accelerating Structure made by Tsinghua University 3881
 
  • X.W. Wu, H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  • T. Abe, T. Higo
    KEK, Ibaraki, Japan
  • W. Wuensch, H. Zha
    CERN, Geneva, Switzerland
 
  As an alternative design for 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 with different choke dimensions which are working at 11.424 GHz were designed, manufactured and bench tested by accelerator group in Tsinghua University. High power test was carried out on it to study the breakdown phenomenon in high gradient. A single cell structure without choke which almost has the same inner dimension as choke-mode cavity will also be tested to make a comparison and study how the choke affects high-gradient properties.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR043  
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THPOY027 Commissioning Status of SuperKEKB Injector Linac 4152
 
  • M. Satoh, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, Y. Enomoto, S. Fukuda, Y. Funakoshi, K. Furukawa, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Iwase, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, S. Kazama, M. Kikuchi, H. Koiso, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Mimashi, T. Miura, F. Miyahara, T. Mori, A. Morita, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, D. Satoh, Y. Seimiya, T. Shidara, A. Shirakawa, M. Suetake, H. Sugimoto, T. Suwada, M. Tanaka, M. Tawada, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
 
  The SuperKEKB main ring is currently being constructed for aiming at the peak luminosity of 8 x 1035 cm-2s−1. The electron/positron injector linac upgrade is also going on for increasing the intensity of bunch charge with keeping the small emittance. The key upgrade issues are the construction of positron damping ring, a new positron capture system, and a low emittance photo-cathode rf electron source. The injector linac beam commissioning started in the October of 2013. In this paper, we report the present status and future plan of SuperKEKB injector commissioning.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY027  
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