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WEOZSP2 |
Suppression of Crab Cavity Noise Induced Emittance Growth by Transverse Beam Coupling Impedance |
1659 |
SUSPMF068 |
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- N. Triantafyllou, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
- F. Antoniou, H. Bartosik, P. Baudrenghien, X. Buffat, R. Calaga, Y. Papaphilippou
CERN, Meyrin, Switzerland
- T. Mastoridis
CalPoly, San Luis Obispo, California, USA
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Crab Cavities are a key component of the High Luminosity LHC (HL-LHC) upgrade, as they aim to minimize the luminosity reduction caused by the crossing angle. Two superconducting crab cavities were installed in the Super Proton Synchrotron (SPS) at CERN in 2018 to test their operation in a proton machine for the first time. An important point to consider is the increase in transverse emittance induced by noise in the Low-Level RF (LLRF) system. During the first experimental campaign in 2018, the measured emittance growth was found to be a factor of 4 lower than predicted by the available analytical models. In this report, the effects of transverse beam impedance in the presence of CC LLRF noise on transverse emittance growth are presented and the results of the second experimental campaign, which took place in the SPS in 2021, are discussed.
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Slides WEOZSP2 [2.694 MB]
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEOZSP2
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About • |
Received ※ 08 June 2022 — Revised ※ 12 June 2022 — Accepted ※ 14 June 2022 — Issue date ※ 15 June 2022 |
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WEPOPT009 |
Operational Scenario of First High Luminosity LHC Run |
1846 |
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- R. Tomás García, G. Arduini, P. Baudrenghien, R. Bruce, O.S. Brüning, X. Buffat, R. Calaga, F. Cerutti, R. De Maria, J. Dilly, I. Efthymiopoulos, M. Giovannozzi, P.D. Hermes, G. Iadarola, O.R. Jones, S. Kostoglou, E.H. Maclean, N. Mounet, E. Métral, Y. Papaphilippou, S. Redaelli, G. Sterbini, H. Timko, F.F. Van der Veken, J. Wenninger, M. Zerlauth
CERN, Meyrin, Switzerland
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A new scenario for the first operational run of the HL-LHC era (Run 4) has been recently developed to accommodate a period of performance ramp-up to achieve an annual integrated luminosity close to the nominal HL-LHC design. The operational scenario in terms of beam parameters and machine settings, as well as the different phases, are described here along with the impact of potential delays on key hardware components.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOPT009
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About • |
Received ※ 19 May 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 09 July 2022 |
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WEPOTK058 |
Experimental Study of the Transverse Mode Coupling Instability with Space-Charge at the CERN SPS |
2193 |
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- X. Buffat, H. Bartosik
CERN, Meyrin, Switzerland
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Past studies on the Transverse Mode Coupling Instability (TMCI) suggested that it can be suppressed in the presence of space-charge forces. Recent developments in this field show that for higher strength, space-charge forces leads to other types of instabilities. We investigate the characteristics of these instabilities by means of stability threshold measurements at the CERN SPS for various intensities, longitudinal and transverse emittances. These observations are compared to numerical tracking simulations.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK058
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About • |
Received ※ 03 June 2022 — Accepted ※ 15 June 2022 — Issue date ※ 18 June 2022 |
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WEPOTK059 |
Suppression of Emittance Growth by a Collective Force: Van Kampen Approach |
2197 |
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- X. Buffat
CERN, Meyrin, Switzerland
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In hadron synchrotrons, external sources of noise affecting the beam induce emittance growth through the mechanism of decoherence. Active feedbacks are often used to suppress this emittance growth. In the presence of beam-beam interactions, it was shown that coherent modes of oscillations with frequencies shifted outside of the incoherent spectrum significantly enhances the efficiency of the emittance growth suppression by active feedbacks. We show that the same enhancement of the emittance growth suppression may be driven by a beam coupling impedance generating a real tune shift larger than the detuning.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK059
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About • |
Received ※ 03 June 2022 — Accepted ※ 13 June 2022 — Issue date ※ 15 June 2022 |
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WEPOTK062 |
Intrabunch Motion with Both Impedance and Beam-Beam Using the Circulant Matrix Approach |
2209 |
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- E. Métral, X. Buffat
CERN, Meyrin, Switzerland
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In high-intensity high-brightness circular colliders such as the CERN LHC, coherent beam-beam effects and impedance cannot be treated independently. Coherent beam-beam dipole modes can couple with higher order head-tail modes and lead to the transverse mode coupling instability of colliding beams. This mechanism has been analysed in detail in the past through the eigenvalues, which describe the evolution of the beam oscillation mode-frequency shifts. In this contribution, the transverse mode coupling instability of colliding beams is studied using the eigenvectors, which describe the evolution of the intrabunch motion. As this instability exhibits several mode couplings and mode decouplings, the evolution of the intrabunch motion reveals quite some interesting features (such as a propagation of the traveling-wave not only from the head to the tail but also from the tail to the head and similar intrabunch signals for some mode coupling and mode decoupling), which are compared to past predictions in the presence of impedance only.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-WEPOTK062
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About • |
Received ※ 07 June 2022 — Revised ※ 16 June 2022 — Accepted ※ 03 July 2022 — Issue date ※ 06 July 2022 |
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THPOPT035 |
A Second Generation Light Source Aiming at High Power on the Giant Dipole Resonance |
2661 |
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- X. Buffat, L.L. Cuanillon, E.N. Kneubuehler
CERN, Meyrin, Switzerland
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We propose an accelerator concept which could enable nuclear waste transmutation and energy amplification using a second generation light source rather than a high power proton beam. The main parameters of the ring and insertion devices are estimated, targeting a photon beam power of 1 GW with a spectrum that maximizes the potential for nuclear reactions via the Giant Dipole Resonance. The synergies with technologies developed for high energy physics, in particular within the Future Circular Collider study (FCC), are highlighted.
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DOI • |
reference for this paper
※ https://doi.org/10.18429/JACoW-IPAC2022-THPOPT035
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About • |
Received ※ 03 June 2022 — Revised ※ 15 June 2022 — Accepted ※ 16 June 2022 — Issue date ※ 25 June 2022 |
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