Keyword: controls
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MOP08 Recent Progress on Nonlinear Beam Manipulations in Circular Accelerators resonance, emittance, extraction, 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]  
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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, 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]  
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About • Received ※ 15 October 2021 — Revised ※ 17 October 2021 — Accepted ※ 17 January 2022 — Issue date ※ 11 April 2022
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MOP14 The PS Booster Alignment Campaign and a New Tune Control Implementation After the LHC Injectors Upgrade at CERN quadrupole, alignment, focusing, injection 89
  • F. Antoniou, F. Asvesta, H. Bartosik, J.F. Comblin, G.P. Di Giovanni, M. Hostettler, A. Huschauer, B. Mikulec, J.-M. Nonglaton, T. Prebibaj
    CERN, Meyrin, Switzerland
  The CERN PS Booster (PSB) has gone through major upgrades during the Long Shutdown 2 (LS2) and the recommissioning with beam started in December 2020. Two of the aspects leading to improved operation will be described in this paper: a new tune control implementation; and a full re-alignment campaign. The operation of the PSB requires a large range of working points to be accessible along the acceleration cycle. As part of the LIU project, the PSB main power supply was upgraded to raise the extraction energy from 1.4 GeV to 2 GeV, in order to improve the brightness reach of the downstream machines. A new tune control implementation was necessary to take into account saturation effects of the bending magnets and the reconfiguration of the main circuits, as well as the additional complexity of the new H charge exchange injection. The first part of the paper describes the implementation of the new tune control and its experimental verification and optimization. The second part describes the results of the PSB alignment campaign after LS2, giving emphasis to the method developed to perform a combined closed orbit correction through quadrupole alignments.  
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About • Received ※ 18 October 2021 — Revised ※ 19 November 2021 — Accepted ※ 25 March 2022 — Issue date ※ 11 April 2022
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MOP17 End-to-End Longitudinal Simulations in the CERN PS simulation, impedance, cavity, feedback 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.  
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About • Received ※ 16 October 2021 — Revised ※ 19 October 2021 — Accepted ※ 01 April 2022 — Issue date ※ 11 April 2022
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TUEC4 Test of Machine Learning at the CERN LINAC4 linac, electron, target, network 181
  • V. Kain, N. Madysa, P.K. Skowroński, I. Vojskovic
    CERN, Geneva, Switzerland
  • N. Bruchon
    University of Trieste, Trieste, Italy
  • S. Hirlaender, G. Valentino
    University of Malta, Information and Communication Technology, Msida, Malta
  The CERN H linear accelerator, LINAC4, served as a test bed for advanced algorithms during the CERN Long Shutdown 2 in the years 2019/20. One of the main goals was to show that reinforcement learning with all its benefits can be used as a replacement for numerical optimization and as a complement to classical control in the accelerator control context. Many of the algorithms used were prepared beforehand at the electron line of the AWAKE facility to make the best use of the limited time available at LINAC4. An overview of the algorithms and concepts tested at LINAC4 and AWAKE will be given and the results discussed.  
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About • Received ※ 07 October 2021 — Revised ※ 21 October 2021 — Accepted ※ 23 November 2021 — Issue date ※ 19 December 2021
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