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2002 Fiscal Year Final Research Report Summary

Development of Superconducting Cavities for Future Synchrotron Light Sources and Electron-Positron Colliders

Research Project

Project/Area Number 12440074
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field 素粒子・核・宇宙線
Research InstitutionKEK, High Energy Accelerator Research Organization

Principal Investigator

FURUYA Takaaki  KEK, High Energy Accelerator Research Organization Accelerator Lab., Associate Professor, 加速器研究施設, 助教授 (70156975)

Co-Investigator(Kenkyū-buntansha) MITSUNOBU Shinii  KEK, High Energy Accelerator Lab., Professor, 加速器研究施設, 教授 (50100821)
EZURA Eizi  KEK, High Energy Accelerator Lab., Professor, 加速器研究施設, 教授 (60044749)
KUROKAWA Shin-ichi  KEK, High Energy Accelerator Lab., Professor, 加速器研究施設, 教授 (90044776)
AKAI Kazunori  KEK, High Energy Accelerator Lab., Associate Professor, 加速器研究施設, 助教授 (10184061)
FUKUMA Hitoshi  KEK, High Energy Accelerator Lab., Associate Professor, 加速器研究施設, 助教授 (40150007)
Project Period (FY) 2000 – 2002
Keywordssuperconducting / cavities / KEKB / collider / HOM / ferrite / coupler / synchrotron
Research Abstract

Superconducting (SC) RF cavities provide a high accelerating field gradientin constant wave operation, which is several times higher than that achieved by conventional normal conducting (NC) cavities. This superior performance has a clear advantage in the application to high intensity electron (positron) storage rings, where the less number of cavities is desired so as to reduce the total higher order mode (HOM) impedance and to avoid beam instabilities.
KEKB is an electron and positron collider for B meson physics, in which extreme high intensity beams of 1.1 A and 2.6 A are accumulated and collided each other to achieve a luminosity of 10^<34> cm^<-2>S^<-1>. To keep such a high intensity beam, new SC cavities based on a HOM damping scheme using ferrite absorbers have been developed and commissioned in the electron ring (HER). The mission of this research projefct is to make clear the performance of the SC cavities and also to establish the operation technology of SC cavities in high c … More urrent use.
The important results will be summarized as follows.
1) During this research project, the beam intensity has gradually been improved and finally reached the full current of 1.1 A. This result demonstrates that the new SC cavity with ferrite absorbers is quite useful as an RF cavity for high intensity storage accelerators in various fields.
2) The cavity has a strong interaction with the beam in such a high intensity operation. As a result, just a small movement of the beam disturbs the cavity voltage and causes a trip of the cavities. Tfte analysis study of all the trips showed clearly that 90 % of die trips were caused by the instabilities and the loss of the beam. On the other hand, the SC cavity itself was quite stable, and tripped once or twice per month that was caused by discharging.
3) The study of an input coupler demonstrated that multipacting discharging happened on the wall of outer conductor, which was in agreement with a simulation result under a DC bias voltage between the conductors.
4) RF power absorbed by ferrite dampers has been measured and analyzed under various beam intensity and bunch configurations. The results show that the power caused by wide-range HOMs is dominant, and that the ferrite dampers sufficiently damps the Q of all the HOMs in th cavity so as not to introduce the beam instabilities. Because of an operation mode of higher bunch current, absorbed power has already reached two times higher than the design level.
Besides these results, the study of a cavity shape of 500MHz gave a solution of the SC cavity in synchrotron light source rings. As a result this research project has made clear the feasibility of SC cavities in high current use. Less

  • Research Products

    (12 results)

All Other

All Publications (12 results)

  • [Publications] K.Akai et al.: "RF System for the KEK B-Factory"Nuclear Instruments and Methods in Physics Research. A499. 45-65 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Akai et al.: "Commissioning of KEKB"Nuclear instruments and Methods in Physics Research. A499. 191-227 (2003)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K.Akai et al.: "Protection of Hardware Components with High-current Beam against RF Trips in KEKB"Proc. of the 8^<th> European Particle Accelerator Conference. June 3-7. 2112-2114 (2002)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] T.Furuya et al.: "Operation Status of the KEKB Superconducting Damped Cavity"Proc. of the 10^<th> Workshop on RF Superconductivity. 599-601 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] Y.Kijima et al.: "Conditioning of Input Couoplers for KEKB Superconducting Cavities"Proc. of the 10^<th> Workshop on RF Superconductivity. 505-569 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] R.Noer at al.: "Secondary Electron Yield of Nb RF Cavity Surface"Proc. of the 10^<th> Workshop on PF Superconductivity. 400-402 (2001)

    • Description
      「研究成果報告書概要(和文)」より
  • [Publications] K. Akai, et. al: "RF System for the KEK B-Factory"Nuclear Instruments and Methods in Physics Research. A 499. 45-65 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Akai, et.al.: "Commissioning of KEKB"Nuclear Instruments and Methods in Physics Research. A499. 191-227 (2003)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] K. Akai, K. Ebihara, T. Furuya, M. Suetake: "Protection of Hardware of Components with High-current Beam against RF trips in KEKB"Proceeding of the 8th European Particle Accelerator Conference. 2112-2114 (2002)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] T. Furuya, et.al.: "Operation Status of the KEKB Superconducting Damped Cavity"Proceedings of the 10^<th> Workshop on RF Superconductivity. 599-610 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] Y. Ftijima, G. Katano, T. Furuya, S. Mitsunobu: "Conditioning of Input Couplers for KEKB Superconducting Cavities"Proceedings of the 10^<th> Workshop on RF Superconductivity. 505-569 (2001)

    • Description
      「研究成果報告書概要(欧文)」より
  • [Publications] R. Noel, S. Mitsunobu, Y. Kijima, T. Higuchi, K. Saito: "Secoridary Electron Yield of Nb Cavity Surfaces"Proceeding of the 10^<th> Workshop on RF Superconductivity. 400-402 (2001)

    • Description
      「研究成果報告書概要(欧文)」より

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Published: 2004-04-14  

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