Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2020, Vol. 31 ›› Issue (3): 23 doi: 10.1007/s41365-020-0735-7


Optimization of the S-band side-coupled cavities for proton acceleration

Hao-Yun Li, Xin-Miao Wan, Wei Chen, Chen-Hui Shi, Zhi-Hui Li   

  1. The Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610065, China
  • Received:2019-12-10 Revised:2020-01-19 Accepted:2020-01-20
  • Contact: Zhi-Hui Li
  • Supported by:
    This work was supported by the National Natural Science Foundation of China (Nos. 11375122 and 11875197).
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Hao-Yun Li, Xin-Miao Wan, Wei Chen, Chen-Hui Shi, Zhi-Hui Li. Optimization of the S-band side-coupled cavities for proton acceleration.Nuclear Science and Techniques, 2020, 31(3): 23     doi: 10.1007/s41365-020-0735-7

Abstract: The proton beam with energy around 100 MeV has seen wide applications in modern scientific research and in various fields. However, proton sources in China fall short for meeting experimental needs owing to the vast size and expensive traditional proton accelerators. The Institute of Nuclear Science and Technology of Sichuan University proposed to build a 3 GHz side-coupled cavity linac (SCL) for re-accelerating a 26 MeV proton beam extracted from a CS-30 cyclotron to 120 MeV. We carried out investigations into several vital factors of S-band SCL for proton acceleration, such as optimization of SCL cavity geometry, end cell tuning, and bridge coupler design. Results demonstrated that the effective shunt impedance per unit length ranged from 22.5 to 59.8 MΩ/m throughout the acceleration process, and the acceleration gradient changed from 11.5 to 15.7 MV/m when the maximum surface electric field was equivalent to Kilpatrick electric field. We obtained equivalent circuit parameters of the biperiodic structures and applied them to the end cell tuning; results of the theoretical analysis agreed well with the 3D simulation. We designed and optimized a bridge coupler based on the previously obtained biperiodic structure parameters, and the field distribution un-uniformness was < 1.5% for a two-tank module. The radio frequency power distribution system of the linac was obtained based on the preliminary beam dynamics design.

Key words: Proton beam, Side-coupled cavity linac, Accelerating cavity, Biperiodic structure, Bridge coupler