THB —  WGB - Beam Dynamics in Linacs   (07-Oct-21   10:30—11:00)
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THBC1 Beam Acceleration with the Upgraded Riken Heavy-Ion Linac 231
  • T. Nishi, M. Fujimaki, N. Fukunishi, H. Imao, O. Kamigaito, T. Nagatomo, N. Sakamoto, A. Uchiyama, T. Watanabe, Y. Watanabe, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  The performance of RIKEN heavy-ion linac (RILAC) has been upgraded with a new ECR ion source and superconducting linac booster (SRILAC). It is expected to play a major role in the synthesis of super-heavy elements (SHE), development of the technologies for production of medical radioisotopes, and as a powerful injector to RI Beam Factory. In this talk, I will report on the beam delivery for the SHE experiment that started in June 2020, especially on how to adjust the optics based on the measured beam emittance. We would also like to compare the simulated beam acceleration in RILAC with the measured emittance.  
DOI • reference for this paper ※  
About • Received ※ 09 November 2021 — Revised ※ 16 November 2021 — Accepted ※ 23 November 2021 — Issue date ※ 27 November 2021
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Mitigation of 4th Order Resonance and Envelope Instability by Beam Angular Momentum  
  • D. Jeon
    IBS, Daejeon, Republic of Korea
  • Y.L. Cheonpresenter, M. Chung, S.H. Moon
    UNIST, Ulsan, Republic of Korea
  For modern high-intensity linear accelerators, the well-known envelope instability and recently reported fourth-order particle resonance impose a fundamental operational limit: zero-current phase advance (sig0)<90deg. In particular, it has been discovered that the fourth-order particle resonance is always excited and manifested predominantly over the envelope instability along the drift-tube linac when sig0>90deg and sig<90deg. In this study, we present a novel method to mitigate the space-charge driven fourth-order resonance by introducing a new concept of ‘spinning beam’. Motivated by classical mechanics on the stability of spinning flying objects, ‘spinning beam’ has non-zero average canonical angular momentum under axisymmetric system. From the analytical and numerical simulation studies, we found that spinning beams have an intrinsic characteristic that can suppress the impact of the fourth-order resonance on emittance growth and the following envelope instability. Unlike other approaches to suppress the coherent instabilities, we have demonstrated beam spinning as a possible control knob for mitigating the fourth-order resonance to surpass the linac operational limit.  
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