Beam Dynamics in Linacs
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MOP03 Longitudinal Emittance Measurements at PIP2IT 27
 
  • M. El Baz
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • J.-P. Carneiro, B.M. Hanna
    Fermilab, Batavia, Illinois, USA
 
  The PIP-II particle accelerator is a new upgrade to the Fermilab accelerator complex, featuring an 800-MeV H superconducting linear accelerator that will inject the beam into the present Fermilab Booster. A test accelerator known as PIP-II Injector Test (PIP2IT) has been built to validate the concept of the front-end of PIP-II. One of the paramount challenges of PIP2IT was to demonstrate a low longitudinal emittance at the end of the front end. Having a low longitudinal emittance is crucial in order to ensure the stability of the beam in the accelerator. We present a longitudinal emittance calculation at 14.3 MeV at the SSR1-8 cavity in the High Energy Transport line (HEBT). The signal is collected by a Fast Faraday Cup (FFC) at the end of HEBT and recorded by a high-bandwidth oscilloscope.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP03  
About • Received ※ 02 November 2021 — Revised ※ 05 November 2021 — Accepted ※ 03 February 2022 — Issue date ※ 04 February 2022
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MOP04 Status of the JAEA-ADS Superconducting LINAC Design 30
 
  • B. Yee-Rendón, Y. Kondo, F. Maekawa, S.I. Meigo, J. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  The Japan Atomic Energy Agency (JAEA) is working in the research and development of an Accelerator Driven Subcritical System (ADS) for the transmutation of nuclear waste. To this end, JAEA is designing a 30-MW cw proton linear accelerator (linac) with a beam current of 20 mA. The JAEA-ADS linac starts with a Normal Conducting (NC) up to an energy of 2.5 MeV. Then, five Superconducting (SC) sections accelerate the beam up to 1.5 GeV. The biggest challenge for this ADS linac is the stringent reliability required to avoid thermal stress in the subcritical reactor, which is higher than the achieved in present accelerators. For this purpose, the linac pursues a strong-stable design that ensures the operation with low beam loss and fault-tolerance capabilities to continue operating in case of failure. This work presents the beam dynamics results toward achieving high reliability for the JAEA-ADS linac.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP04  
About • Received ※ 30 September 2021 — Revised ※ 15 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 05 January 2022
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MOP05 Reduction of the Beam Jitter at the PIP2IT Test Accelerator 35
 
  • A.V. Shemyakin, G.W. Saewert, A. Saini
    Fermilab, Batavia, Illinois, USA
 
  Funding: This manuscript has been authored by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy, Office of Science, Office of High Energy Physics.
Analysis of the beam position monitor (BPM) signals at the H test linear accelerator PIP2IT showed that a large portion of the signals scatter comes from the beam jitter. BPM position measurements of the jitter modes were compared with beam motion responses to perturbations excited by driving various beamline parameters in a low frequency sinusoidal manner. The main contributor to the jitter was found to be a low frequency noise in the input reference to the ion source high voltage (HV) power supply. Filtering the HV power supply reference signal decreased the rms scatter in BPM readings by a factor of 2-3.
 
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slides icon Slides MOP05 [0.852 MB]  
poster icon Poster MOP05 [0.852 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP05  
About • Received ※ 30 September 2021 — Revised ※ 19 October 2021 — Accepted ※ 04 March 2022 — Issue date ※ 11 April 2022
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WEBC1
Envelope Instabilities and Their Mitigation in High Intensity Hadron Beams  
 
  • J. Qiang
    LBNL, Berkeley, California, USA
 
  The envelope instabilities driven by space-charge effects in high intensity hadron beams can cause beam emittance growth, size blow up and potential particle loss inside an accelerator. In this talk, we will discuss about the mechanism of the envelope instabilities, the parameters that result in the envelope instabilities, and potential methods to mitigate these instabilities.  
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WEBC2
H-minus and Light-Ion Linacs Upgrade Plan for Production of Critical Isotopes at BNL  
 
  • D. Raparia
    BNL, Upton, New York, USA
 
  To increase medical isotopes production at BNL, an energy upgrade to existing 200 MeV H linac and new light ion linac to accelerate light ions (m/q ~ 2.3) is proposed. H beam from the BLIP beam line will be diverted to existing radiation effect facility (REF) tunnel. The final energy of 600 MeV for H can be achieved by installing couple cavity linac (CCL) in the REF and Neutral Beam Time of Flight (NBTF) tunnel. The add on accelerator can provide beam of 200 to 600 MeV on the target with the maximum beam power of 120 kW. The Light ion linac tunnel will be built parallel to the NBTF tunnel with the same target building as H target building. The light ion linac will accelerate light ion (m/q ~ 2.3 ) to 60 MeV/amu with 200 micro-appear of average current.  
slides icon Slides WEBC2 [11.630 MB]  
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WEBC4
Beam Physics for the SPIRAL2 Linac Commissioning  
 
  • A.K. Orduz, R. Ferdinand, J.-M. Lagniel, G. Normand
    GANIL, Caen, France
  • D.U. Uriot
    CEA-DRF-IRFU, France
 
  Commissioning of the SPIRAL2 linac began as soon as the French Nuclear Safety Authority authorisation was obtained on 8 July 2019, first with the settings of the medium energy line MEBT (between the RFQ and the linac, including the tuning of the bunch selector), then with the linac settings. The settings of the MEBT, linac and high-energy lines (HEBT) to the beam dump and to the Neutron For Science (NFS) experiment room were validated during the two six-month commissioning periods. Stable operation with a 16 kW proton beam (10% of the nominal) has been achieved, showing that the conditions are already met (beam loss control) to be able to operate at maximal power (160 kW proton, 200 kW deuteron). The various stages of commissioning and the results obtained are presented.  
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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 ※ https://doi.org/10.18429/JACoW-HB2021-THBC1  
About • Received ※ 09 November 2021 — Revised ※ 16 November 2021 — Accepted ※ 23 November 2021 — Issue date ※ 27 November 2021
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THBC2
Mitigation of 4th Order Resonance and Envelope Instability by Beam Angular Momentum  
 
  • D. Jeon
    IBS, Daejeon, Republic of Korea
  • Y.L. Cheon, 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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FRPS2
Summary WG-B  
 
  • Y. He
    IMP/CAS, Lanzhou, People’s Republic of China
  • P.N. Ostroumov
    FRIB, East Lansing, Michigan, USA
  • D.C. Plostinar
    ESS, Lund, Sweden
 
  Summary of the Working Group B (Beam Dynamics in Linacs)  
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