Keyword: extraction
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MOP08 Recent Progress on Nonlinear Beam Manipulations in Circular Accelerators resonance, emittance, controls, experiment 52
 
  • F. Capoani, M. Giovannozzi
    CERN, Geneva, Switzerland
  • A. Bazzani
    Bologna University, Bologna, Italy
 
  In recent years, transverse beam splitting by crossing a stable resonance has become the operational means to perform MultiTurn Extraction (MTE) from the CERN PS to the SPS. This method delivers the high-intensity proton beams for fixed-target physics at the SPS. More recently, further novel manipulations have been studied, with the goal of devising new techniques to manipulate transverse beam properties. AC magnetic elements can allow beam splitting to be performed in one of the transverse degrees of freedom. Crossing 2D nonlinear resonances can be used to control the sharing of the transverse emittances. Furthermore, cooling the transverse emittance of an annular beam can be achieved through an AC dipole. These techniques will be presented and discussed in detail, considering future lines of research.  
poster icon Poster MOP08 [5.281 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP08  
About • Received ※ 04 October 2021 — Revised ※ 05 November 2021 — Accepted ※ 13 December 2021 — Issue date ※ 11 April 2022
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MOP11 Controlled Longitudinal Emittance Blow-Up for High Intensity Beams in the CERN SPS emittance, simulation, controls, synchrotron 71
 
  • D. Quartullo, H. Damerau, I. Karpov, G. Papotti, E.N. Shaposhnikova, C. Zisou
    CERN, Geneva, Switzerland
  • D. Quartullo
    Sapienza University of Rome, Rome, Italy
 
  Controlled longitudinal emittance blow-up will be required to longitudinally stabilize the beams for the High-Luminosity LHC in the SPS. Bandwidth-limited noise is injected at synchrotron frequency sidebands of the RF voltage of the main accelerating system through the beam phase loop. The setup of the blow-up parameters is complicated by bunch-by-bunch differences in their phase, shape, and intensity, as well as by the interplay with the fourth harmonic Landau RF system and transient beam loading in the main RF system. During previous runs, an optimization of the blow-up had to be repeated manually at every intensity step up, requiring hours of precious machine time. With the higher beam intensity, the difficulties will be exacerbated, with bunch-by-bunch differences becoming even more important. We look at the extent of the impact of intensity effects on the controlled longitudinal blow-up by means of macro-particle tracking, as well as analytical calculations, and we derive criteria for quantifying its effectiveness. These studies are relevant to identify the parameters and observables which become key to the operational setup and exploitation of the blow-up.  
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poster icon Poster MOP11 [1.121 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP11  
About • Received ※ 15 October 2021 — Revised ※ 17 October 2021 — Accepted ※ 17 January 2022 — Issue date ※ 11 April 2022
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MOP23 Coupled Bunch Instabilities Growth in the Fermilab Booster During Acceleration Cycle booster, emittance, injection, acceleration 140
 
  • C.M. Bhat, N. Eddy
    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.
The Fermilab Booster is an RCS with h=84 and gammaT =5.47 and, during standard operation it accelerates ~4.5E12ppBc from 400 MeV to 8 GeV at 15 Hz. The Booster is being upgraded to handle higher beam intensity >6.7E12ppBc and repetition rate of 20Hz. In the current mode of operation, we perform multi-turn beam injection and capture beam in h=84 system adiabatically. However, we have observed coupled bunch (CB) instabilities in the extracted beam. This issue is expected to worsen at higher beam intensities. In principle, for h=84 one expects 41 modes of oscillations contributing to these CB instabilities. Currently, we have a digital mode damper to mitigate prominent CB modes [1]. We would like to understand at what time in the beam cycle a particular mode is going to originate and how much it contributes at a different time of the cycle. In this regard, we have collected wall current monitor data from injection to extraction and looked for the start of a particular mode of CB instability and its growth for different intensities. This paper presents the results from this study and future plans to mitigate the CB instability in Booster.
[1] Nathan Eddy (private communications, 2020).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP23  
About • Received ※ 17 October 2021 — Accepted ※ 22 November 2021 — Issue; date; ※; 22 January 2022  
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THAC1 Beam Instability Issue and Transverse Feedback System in the MR of J-PARC feedback, simulation, timing, operation 208
 
  • T. Toyama, A. Kobayashi, T. Nakamura, M. Okada, M. Tobiyama
    KEK, Tokai, Ibaraki, Japan
  • Y. Shobuda
    JAEA/J-PARC, Tokai-mura, Japan
 
  In the J-PARC MR, according to the beam power upgrade over 100 kW, beam losses due to transverse collective beam instabilities had started to appear. We had introduced "bunch-by-bunch feedback" system in 2010. Continuing beam power upgrade over 250 kW again caused the transverse instabilities. We introduced "intra-bunch feedback" system in 2014. This has been suppressing those instabilities very effectively. But further beam power upgrade over 500 kW (2.6·10+14 ppp, 8 bunches) needs upgrade of "intra-bunch feedback" system. The current understanding of the transverse instabilities in the MR and the effect of the feedback system are presented from the view points of simplified simulation without the space charge effect and measurements. We are upgrading the system in two steps. The first step is "time-interleaved sampling and kicking" with two feedback systems. The second step is getting the sampling rate twice as much as the current rate, ~110 MHz. Details are explained using simulation.  
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slides icon Slides THAC1 [4.347 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-THAC1  
About • Received ※ 07 October 2021 — Revised ※ 28 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 07 January 2022
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THDC1 Slow Extraction Operation at J-PARC Main Ring operation, timing, experiment, septum 219
 
  • M. Tomizawa, Y. Arakaki, T. Kimura, S. Murasugi, R. Muto, H. Nishiguchi, K. Okamura, Y. Shirakabe, Y. Sugiyama, E. Yanaoka, M. Yoshii
    KEK, Ibaraki, Japan
  • K. Noguchi
    Kyushu University, Fukuoka, Japan
  • F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
 
  A high-intensity proton beam accelerated in the J-PARC main ring (MR) is slowly extracted by using the third integer resonance and delivered to the experimental hall. A critical issue in slow extraction (SX) is a beam loss caused during the extraction. A dynamic bump scheme under an achromatic condition provides extremely high extraction efficiency. We have encountered a beam instability in the debunch formation process, which is estimated to be triggered by a longitudinal microstructure of the beam. To suppress this instability, the beam to the MR has been injected into the RF bucket with a phase offset. A newly developed RF manipulation, 2-step voltage debunch, has successfully pushed up the beam power up to 64.6 kW keeping a high extraction efficiency of 99.5%. A drastic beam loss reduction has been demonstrated in the beam test using a diffuser installed upstream of the first electrostatic septum (ESS1). 8 GeV bunched slow extraction tests for the neutrino-less muon to electron conversion search experiment (COMET Phase-I) have been successfully conducted.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-THDC1  
About • Received ※ 18 October 2021 — Revised ※ 22 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 03 December 2021
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