Keyword: simulation
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MOIPI1 1 MW J-PARC RCS Beam Operation and Further Beyond injection, operation, resonance, experiment 1
 
  • H. Hotchi
    KEK, Tokai, Ibaraki, Japan
  • H. Harada, N. Hayashi, M. Kinsho, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
    JAEA/J-PARC, Tokai-mura, Japan
 
  The J-PARC RCS have recently established a 1 MW beam operation with low fractional beam loss of the order of 10-3. In this talk, our approaches to beam loss issues that we faced in the course of beam power ramp-up are reviewed. Our recent efforts to further beam power ramp-up beyond 1 MW are also presented.  
slides icon Slides MOIPI1 [2.210 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOIPI1  
About • Received ※ 04 October 2021 — Revised ※ 18 October 2021 — Accepted ※ 10 November 2021 — Issue date ※ 22 November 2021
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MOAC3 Development of an Injection-Painted Self-Consistent Beam in the Spallation Neutron Source Ring injection, emittance, space-charge, target 7
 
  • A.M. Hoover
    UTK, Knoxville, Tennessee, USA
  • N.J. Evans
    ORNL RAD, Oak Ridge, Tennessee, USA
  • T.V. Gorlov, J.A. Holmes
    ORNL, Oak Ridge, Tennessee, USA
 
  A self-consistent beam maintains linear space charge forces under any linear transport, even with the inclusion of space charge in the dynamics. Simulation indicates that it is possible to approximate certain self-consistent distributions in a ring with the use of phase space painting. We focus on the so-called Danilov distribution, which is a uniform density, rotating, elliptical distribution in the transverse plane and a coasting beam in the longitudinal plane. Painting the beam requires measurement and control of the orbit at the injection point, and measuring the beam requires re- construction of the four-dimensional (4D) transverse phase space. We discuss efforts to meet these requirements in the Spallation Neutron Source (SNS) ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOAC3  
About • Received ※ 18 October 2021 — Revised ※ 21 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 02 March 2022
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MOCC3 First Experience of Crystal Collimators During LHC Special Runs and Plans for the Future collimation, background, operation, proton 12
 
  • M. D’Andrea, V. Avati, R. Bruce, M.E.J. Butcher, M. Deile, M. Di Castro, H. Garcia Morales, S. Jakobsen, J. Kašpar, I. Lamas Garcia, A. Masi, A. Mereghetti, D. Mirarchi, S. Redaelli, B. Salvachua, P. Serrano Galvez, M. Solfaroli Camillocci
    CERN, Geneva, Switzerland
  • B.S. Dziedzic, K.M. Korcyl
    IFJ-PAN, Kraków, Poland
  • Yu.A. Gavrikov
    PNPI, Gatchina, Leningrad District, Russia
  • K.H. Hiller
    DESY Zeuthen, Zeuthen, Germany
  • N. Turini
    UNISI, Siena, Italy
 
  Bent crystals can deflect charged particles by trapping them within the potential well generated by neighboring crystalline planes and forcing them to follow the curvature of the crystal itself. This property has been extensively studied over the past decade at the CERN accelerator complex, as well as in other laboratories, for a variety of applications, ranging from beam collimation to beam extraction and in-beam fixed target experiments. In 2018, crystal collimators were operationally used for the first time at the Large Hadron Collider (LHC) during a special high-beta* physics run with low-intensity proton beams, with the specific goal of reducing detector background and achieving faster beam halo removal. This paper describes the preparatory studies carried out by means of simulations, the main outcomes of the special physics run and plans for future uses of this innovative collimation scheme, including the deployment of crystal collimation for the High-Luminosity LHC upgrade.  
slides icon Slides MOCC3 [2.138 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOCC3  
About • Received ※ 03 October 2021 — Accepted ※ 22 November 2021 — Issue; date; ※; 13 January 2022  
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MOP03 Longitudinal Emittance Measurements at PIP2IT cavity, emittance, MEBT, cryomodule 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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MOP09 HL-LHC Beam Dynamics with Hollow Electron Lenses electron, optics, emittance, operation 59
 
  • P.D. Hermes, R. Bruce, R. De Maria, M. Giovannozzi, A. Mereghetti, D. Mirarchi, S. Redaelli
    CERN, Geneva, Switzerland
  • G. Stancari
    Fermilab, Batavia, Illinois, USA
 
  Each of the two proton beams in the High-Luminosity Large Hadron Collider (HL-LHC) will carry a total energy of 720 MJ. One concern for machine protection is the energy stored in the transverse beam tails, estimated to potentially reach up to 5% of the total stored energy. Several failure scenarios could drive these tails into the collimators, potentially causing damage and therefore severely affecting operational efficiency. Hollow Electron Lenses (HEL) were integrated in the HL-LHC baseline to mitigate this risk by depleting the tails in a controlled way. A hollow-shaped electron beam runs co-axially to the hadron beam over about 3 m, such that halo particles at large amplitudes become unstable, while core particles ideally remain undisturbed. Residual fields from e-beam asymmetries can, however, induce emittance growth of the beam core. Various options for the pulsing of the HEL are considered and are compared using two figures of merit: halo depletion efficiency and core emittance growth. This contribution presents simulations for these two effects with different HEL pulsing modes using the final HL-LHC optics, that was optimized at the location of the lenses.  
poster icon Poster MOP09 [0.970 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP09  
About • Received ※ 06 October 2021 — Revised ※ 02 November 2021 — Accepted ※ 22 November 2021 — Issue date ※ 19 January 2022
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MOP10 Closed Form Formulas of the Indirect Space Charge Wake Function for Axisymmetric Structures impedance, space-charge, vacuum, coupling 65
 
  • N. Mounet, E. Dadiani, E. Métral, C. Zannini
    CERN, Geneva, Switzerland
  • A. Rahemtulla
    EPFL, Lausanne, Switzerland
 
  Indirect space charge contributes significantly to the impedance of non ultrarelativistic machines such as the LEIR, PSB and PS, at CERN. While general expressions exist in frequency domain for the beam coupling impedance, the time domain wake function is typically obtained numerically, thanks to an inverse Fourier transform. An analytical expression for the indirect space charge wake function, including the time dependence as a function of particle velocity, is nevertheless highly desirable to improve the accuracy of time domain beam dynamics simulations of coherent instabilities. In this work, a general formula for the indirect space charge wake function is derived from the residue theorem. Moreover, simple approximated expressions reproducing the time and velocity dependence are also provided, which can even be corrected to recover an exact formula, thanks to a numerical factor computed once for all. The expressions obtained are successfully benchmarked with a purely numerical approach based on the Fourier transform.  
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poster icon Poster MOP10 [1.939 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP10  
About • Received ※ 30 September 2021 — Revised ※ 28 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 30 January 2022
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MOP11 Controlled Longitudinal Emittance Blow-Up for High Intensity Beams in the CERN SPS emittance, controls, synchrotron, extraction 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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MOP12 Understanding of the CERN-SPS Horizontal Instability with Multiple Bunches impedance, octupole, injection, kicker 77
 
  • C. Zannini, H. Bartosik, M. Carlà, K.S.B. Li, E. Métral, G. Rumolo, B. Salvant
    CERN, Geneva, Switzerland
  • L.R. Carver
    ESRF, Grenoble, France
  • M. Schenk
    EPFL, Lausanne, Switzerland
 
  At the end of 2018, an instability with multiple bunches has been consistently observed during high intensity studies at the CERN-SPS. This instability could be a significant limitation to achieve the bunch intensity expected after the LHC Injector Upgrade (LIU). Therefore, a deep understanding of the phenomena is essential to identify the best mitigation strategy. Extensive simulation studies have been performed to explore the consistency of the current SPS model, give a possible interpretation of the instability mechanism and outline some possible cures.  
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poster icon Poster MOP12 [1.454 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP12  
About • Received ※ 07 October 2021 — Revised ※ 20 October 2021 — Accepted ※ 28 December 2021 — Issue date ※ 11 April 2022
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MOP15 Threshold for Loss of Longitudinal Landau Damping in Double Harmonic RF Systems impedance, damping, synchrotron, dipole 95
 
  • L. Intelisano, H. Damerau, I. Karpov
    CERN, Meyrin, Switzerland
 
  Landau damping is a natural stabilization mechanism to mitigate coherent beam instabilities in the longitudinal phase space plane. In a single RF system, binominal particle distributions with a constant inductive impedance above transition (or capacitive below) would lead to a vanishing threshold for the loss of Landau damping, which can be avoided by introducing an upper cut-off frequency to the impedance. This work aims at expanding the recent loss of Landau damping studies to the common case of double harmonic RF systems. Special attention has been paid to the configuration in the SPS with a higher harmonic RF system at four times the fundamental RF frequency, and with both RF systems in counter-phase (bunch shortening mode). Refined analytical estimates for the synchrotron frequency distribution allowed to extend the analytical expression for the loss of Landau damping threshold. The results are compared with semi-analytical calculations using the MELODY code, as well as with macroparticle simulations in BLonD.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP15  
About • Received ※ 16 October 2021 — Revised ※ 19 October 2021 — Accepted ※ 05 February 2022 — Issue date ※ 11 April 2022
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MOP17 End-to-End Longitudinal Simulations in the CERN PS impedance, cavity, feedback, controls 106
 
  • A. Lasheen, H. Damerau, K. Iliakis
    CERN, Meyrin, Switzerland
 
  In the context of the LHC Injector Upgrade (LIU) project, the main longitudinal limitations in the CERN PS are coupled bunch instabilities and uncontrolled emittance blow-up leading to losses at injection into the downstream accelerator, the SPS. To complement beam measurements, particle tracking simulations are an important tool to study these limitations. However, to avoid excessive runtime, simulations are usually targeting only a fraction of the cycle assuming that bunches are initially matched to the RF bucket. This ignores all initial perturbations that could seed an instability. Simulations were therefore performed along the full PS cycle by using the BLonD tracking code optimized with advanced parallelization schemes. They include beam manipulations with several RF harmonics (batch compression, merging, splittings), controlled emittance blow-up, a model of the beam coupling impedance covering a wide frequency range, as well as beam and cavity feedbacks. A large number of macroparticles is required as well as arrays to store beam induced voltage spanning several revolutions to account for long range wakefields.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP17  
About • Received ※ 16 October 2021 — Revised ※ 19 October 2021 — Accepted ※ 01 April 2022 — Issue date ※ 11 April 2022
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MOP19 Optimised Transverse Painting Schemes for the New 160 MeV H Injection System at CERN injection, operation, emittance, resonance 118
 
  • E. Renner, S.C.P. Albright, F. Antoniou, F. Asvesta, H. Bartosik, C. Bracco, G.P. Di Giovanni, B. Mikulec, T. Prebibaj, F.M. Velotti
    CERN, Meyrin, Switzerland
 
  A major aspect of the LHC Injectors Upgrade (LIU) project at CERN is the Proton Synchrotron Booster (PSB) connection to the newly built Linac4 and the related installation of a new 160 MeV H charge exchange injection. This contribution presents the first operational experience with the new injection system and its flexibility of applying horizontal phase space painting to tailor different beams to the respective user-defined brightness targets. The presented measurement and multi-particle simulation results focus on the optimisation of the required transverse injection settings to reduce losses when producing high-intensity beams, i.e. for the ISOLDE experiment. In this context, feasibility studies towards applying numerical optimisation algorithms for improving and efficiently adapting the respective injection settings online are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP19  
About • Received ※ 17 October 2021 — Revised ※ 19 October 2021 — Accepted ※ 20 November 2021 — Issue date ※ 12 April 2022
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MOP20 Space Charge Resonance Analysis at the Integer Tune for the CERN PS resonance, space-charge, quadrupole, optics 124
 
  • F. Schmidt, F. Asvesta
    CERN, Meyrin, Switzerland
 
  In the context of the LHC Injectors Upgrade (LIU) project, a series of studies have been performed in order to better understand the beam brightness limitations imposed by resonances and space charge effects. Space charge simulations using the analytic (frozen) space charge solver as implemented in the MAD-X code conducted for the CERN Proton Synchrotron (PS) show that a particle approaching the integer tune of Qx = 6 demonstrates a resonant behavior. The analysis of the single particle transverse motion reveals the excitation of a second order resonance. The interplay of the space charge effect and the optics perturbation in the regime of the integer tune on this excitation was further investigated. The simulations were complemented with the analysis of the resonance driving terms coming from the space charge potential derived in a classical perturbative approach.  
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poster icon Poster MOP20 [5.934 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP20  
About • Received ※ 05 October 2021 — Revised ※ 20 October 2021 — Accepted ※ 24 December 2021 — Issue date ※ 12 April 2022
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MOP21 3D Symplectic Space Charge Implementation in the Latest Mad-X Version emittance, space-charge, experiment, optics 129
 
  • F. Schmidt, A. Latina, H. Renshall
    CERN, Meyrin, Switzerland
  • Y.I. Alexahin
    Fermilab, Batavia, Illinois, USA
 
  In 2018 as part of a collaboration between CERN and FNAL, the space charge (SC) implementation has been upgraded in a test version of MAD-X. The goal has been to implement the 3D symplectic SC kick together with a number of new features and benchmark it with earlier MADX-SC versions. Emphasis has given to the use of the Sigma Matrix approach that allows to extend MAD-X optics calculations. In the meantime, significant effort has been made to fully debug and optimize the code and in particular to achieve a speed-up of the simulations by a factor of 2. The code has been ported to the latest MAD-X version, the elaborated set-up procedures have been automated and a user manual has been written.  
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poster icon Poster MOP21 [1.236 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-MOP21  
About • Received ※ 05 October 2021 — Revised ※ 21 October 2021 — Accepted ※ 11 November 2021 — Issue date ※ 12 April 2022
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TUAC1 Self-Consistent Long-Term Dynamics of Space Charge Driven Resonances in 2D and 3D resonance, space-charge, emittance, synchrotron 160
 
  • A. Oeftiger, I. Hofmann
    GSI, Darmstadt, Germany
  • O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
 
  Understanding the 3D collective long-term response of beams exposed to resonances is of theoretical interest and essential for advancing high intensity synchrotrons. This study of a hitherto unexplored beam dynamical regime is based on 2D and 3D self-consistent particle-in-cell simulations and on careful analysis using tune spectra and phase space. It shows that in Gaussian-like beams Landau damping suppresses all coherent parametric resonances, which are of higher than second order (the "envelope instability"). Our 3D results are obtained in an exemplary stopband, which includes the second order coherent parametric resonance and a fourth order structural resonance. They show that slow synchrotron oscillation plays a significant role. Moreover, for the early time evolution of emittance growth the interplay of incoherent and coherent resonance response matters, and differentiation between halo and different core regions is essential. In the long-term behavior we identify a progressive, self-consistent drift of particles toward and across the resonance, which results in effective compression of the initial tune spectrum. However, no visible imprint of the coherent features is left over, which only control the picture during the first one or two synchrotron periods. An intensity limit criterion and an asymptotic formula for long-term rms emittance growth are suggested. Comparison with the commonly used non-self-consistent "frozen space charge" model shows that in 3D this approximation yields a fast and useful orientation, but it is a conservative estimate of the tolerable intensity.
HB’21 talk on "Effect of Space Charge on Bunch Stability and Space Charge Compensation Schemes" based on this APS PR-AB published contribution.
 
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slides icon Slides TUAC1 [2.836 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-TUAC1  
About • Received ※ 11 October 2021 — Revised ※ 04 November 2021 — Accepted ※ 05 November 2021 — Issue date ※ 23 November 2021
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WEDC1 Study on the Injection Beam Commissioning and Painting Methods for CSNS/RCS injection, target, timing, MMI 191
 
  • M.Y. Huang, S. Wang, S.Y. Xu
    IHEP, Beijing, People’s Republic of China
 
  Funding: Work supported by National Natural Science Foundation of China (Project Nos. 12075134 and U1832210 )
In this paper, firstly, the beam commissioning of the injection system for CSNS/RCS will be studied, including: timing adjustment of the injection pulse powers, injection beam parameter matching, calibration of the injection painting bumps, measurement of the painting distribution, injection method adjustment, application of the main stripping foil, optimization of the injection beam loss and radiation dose, etc. Secondly, the painting methods for the CSNS/RCS will be studied, including: the fixed-point injection method, anti-correlated painting method and correlated painting method. The results of the beam commissioning will be compared with the simulation results. Combining with other precise optimizations, the beam power on the target has successfully reached the design value of 100kW and the stable operation of the accelerator has been achieved.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-WEDC1  
About • Received ※ 10 October 2021 — Revised ※ 19 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 05 January 2022
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WEDC2 Acceleration of the High Current Deuteron Beam Through the IFMIF-EVEDA RFQ: Confirmation of the Design Beam Dynamics Performances rfq, emittance, MMI, proton 197
 
  • L. Bellan, L. Antoniazzi, M. Comunian, E. Fagotti, M.G. Giacchini, F. Grespan, M. Montis, A. Palmieri, A. Pisent, M. Poggi
    INFN/LNL, Legnaro (PD), Italy
  • T. Akagi, K. Kondo, K. Masuda, M. Sugimoto
    QST, Aomori, Japan
  • B. Bolzon, N. Chauvin
    CEA-IRFU, Gif-sur-Yvette, France
  • P. Cara, F. Scantamburlo
    IFMIF/EVEDA, Rokkasho, Japan
  • Y. Carin, H. Dzitko
    F4E, Germany
  • D. Jimenez-Rey, I. Podadera
    CIEMAT, Madrid, Spain
  • J. Marroncle
    CEA-DRF-IRFU, France
  • I. Moya
    Fusion for Energy, Garching, Germany
 
  The Linear IFMIF Prototype Accelerator (LIPAc) is a high intensity D+ linear accelerator; demonstrator of the International Fusion Material Irradiation Facility (IFMIF). In summer 2019 the IFMIF/EVEDA Radio Frequency Quadrupole (RFQ) accelerated its nominal 125 mA deuteron (D+) beam current up to 5 MeV, with >90% transmission for pulses of 1 ms at 1 Hz, reaching its nominal beam dynamics goal. The paper presents the benchmark simulations and measurements performed to characterize the as-built RFQ performances, in the low and high perveance regime. In this framework, the commissioning strategy with a particular focus on the reciprocal effects of the low-medium energy transfers lines and the RFQ is also discussed. In the last part of the paper, the future commissioning outlooks are briefly introduced.  
slides icon Slides WEDC2 [2.696 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-HB2021-WEDC2  
About • Received ※ 05 October 2021 — Revised ※ 20 October 2021 — Accepted ※ 22 November 2021 — Issue date ※ 27 January 2022
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THAC1 Beam Instability Issue and Transverse Feedback System in the MR of J-PARC feedback, timing, extraction, 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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