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Effects of cavity pre-detuning on RF power transients at injection into the LHC
/ Karlsen-Baeck, B E (CERN ; Rome U.) ; Argyropoulos, T (CERN) ; Butterworth, A (CERN) ; Calaga, R (CERN) ; Karpov, I (CERN) ; Timko, H (CERN) ; Zampetakis, M (CERN)
At injection into the Large Hadron Collider (LHC), the radiofrequency (RF) system is perturbed by beam-induced voltage resultingin strong RF power transients and the instant detuning of thecavities. The automatic tuning system, however, needs time for themechanical compensation of the resonance frequency to takeplace. [...]
2024 - 8 p.
- Published in : JINST 19 (2024) T04005
Fulltext: PDF;
In : 68th ICFA Advanced Beam Dynamics workshop on high-Intensity and High-Brightness Hadron Beams (HB 2023), CERN, Geneva, Switzerland, 9 - 13 Oct 2023, pp.T04005
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2.
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Effects of Cavity Pre-Detuning on RF Power Transients at Injection into the LHC
/ Karlsen-Bæck, Birk Emil (CERN ; Rome U.) ; Argyropoulos, Theodoros (CERN) ; Butterworth, Andrew (CERN) ; Calaga, Rama (CERN) ; Karpov, Ivan (CERN) ; Timko, Helga (CERN) ; Zampetakis, Michail (CERN)
At injection into the LHC, the RF system is perturbed by beam-induced voltage resulting in strong RF power transients and the instant detuning of the cavities. The automatic tuning system, however, needs time for the mechanical compensation of the resonance frequency to take place. [...]
2024 - 4 p.
- Published in : JACoW HB 2023 (2024) 530-533
Fulltext: PDF;
In : 68th ICFA Advanced Beam Dynamics workshop on high-Intensity and High-Brightness Hadron Beams (HB 2023), CERN, Geneva, Switzerland, 9 - 13 Oct 2023, pp.530-533
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3.
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Interplay of Space Charge, Intra-Beam Scattering and Synchrotron Radiation in the CLIC Damping Rings
/ Zampetakis, Michail (CERN ; Crete U.) ; Antoniou, Fanouria (CERN) ; Asvesta, Foteini (CERN) ; Bartosik, Hannes (CERN) ; Papaphilippou, Yannis (CERN)
Future ultra-low emittance rings for electron/positron colliders require extremely high beam brightness and can thus be limited by collective effects. In this paper, the interplay of effects such as synchrotron radiation, intra-beam scattering (IBS) and space charge in the vicinity of excited betatron resonances is assessed. [...]
arXiv:2308.02196.-
2024-06-01 - 20 p.
- Published in : Phys. Rev. Accel. Beams: 27 (2024) , no. 6, pp. 064403
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Consequences of longitudinal coupled-bunch instability mitigation on power requirements during the HL-LHC filling
/ Karpov, I (CERN) ; Baudrenghien, P (CERN) ; Medrano, L E Medina (CERN) ; Timko, H (CERN)
During the filling of the Large Hadron Collider (LHC), it is desirable to keep the RF cavity voltage constant both in amplitude and phase to minimize the emittance blow-up and injection losses. To have a constant voltage and to minimize power consumption, a special beam-loading compensation scheme called half-detuning is used in the LHC, for which the cavity fundamental resonant frequency needs to be de-tuned from the RF frequency by an appropriate value. [...]
2020 - 6 p.
- Published in : 10.23732/CYRCP-2020-009.312
Fulltext: PDF;
In : ICFA mini-Workshop on Mitigation of Coherent Beam Instabilities in Particle Accelerators (MCBI 2019), Zermatt, Switzerland, 23 - 27 Sep 2019, pp.312-317 (CERN-2020-009)
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6.
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Beam gas curtain monitor: Vacuum studies for LHC integration and operation
/ Castro Sequeiro, C (CERN) ; Ady, M (CERN) ; Bregliozzi, G (CERN) ; Chatzigeorgiou, N (CERN) ; Churchman, A R (CERN) ; Kersevan, R (CERN) ; Lefevre, T (CERN) ; Mazzoni, S (CERN) ; Pigny, G (CERN) ; Rossi, A (CERN) et al.
A beam gas curtain (BGC) monitor has been designed to obtain information about the relative position between the LHC proton beam and the hollow electron lens electron beam through a minimally invasive process. Its working principle relies on intersecting the path of both beams with a supersonic gas curtain, introduced transversely into the LHC beamline, to produce a fluorescence signal. [...]
2024 - 10 p.
- Published in : Phys. Rev. Accel. Beams 27 (2024) 043201
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7.
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Chapter 4: RF systems
/ Calaga, R (CERN) ; Baudrenghien, P (CERN) ; Capatina, Ofelia (CERN) ; Jensen, Erk (CERN) ; Montesinos, Eric (CERN)
The HL-LHC beams are injected, accelerated, and stored to their nominal energy of 7 TeV by the existing 400 MHz superconducting RF system of the LHC.
A novel superconducting RF system consisting of eight cavities per beam for transverse deflection (aka crab cavities) of the bunches will be used to compensate the geometric loss in luminosity due to the non-zero crossing angle and the extreme focusing of the bunches in the HL-LHC.
Due to doubling of the beam currents in the HL-LHC era, an optimal detuning scheme (aka full- detuning) is required to cope with the transient beam loading effects. A modulation of the klystron and cavity phase make the phase of bunches with respect to the RF clock to progressively slip along the bunch train, but then recover during the abort gap. [...]
2020 - 22 p.
- Published in : 10.23731/CYRM-2020-0010.65
Fulltext: PDF;
In : High-Luminosity Large Hadron Collider (HL-LHC): Technical design report, pp.65-86
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8.
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Beam-based commissioning of a novel X-band transverse deflection structure with variable polarization
/ González Caminal, P (DESY) ; Christie, F (DESY) ; D'Arcy, R (DESY) ; Jaster-Merz, S M (DESY) ; Assmann, R (DESY) ; Burkart, F (DESY) ; Conrad, B (DESY) ; Dinter, H (DESY) ; Foese, M (DESY) ; Herrmann, J (DESY) et al.
Longitudinal electron-beam diagnostics play a critical role in the operation and control of x-ray free-electron lasers, which rely on parameters such as the current profile, the longitudinal phase space, or the slice emittance of the particle distribution. On the one hand, the femtosecond-scale electron bunches produced at these facilities impose stringent requirements on the resolution achievable with the diagnostics. [...]
2024 - 19 p.
- Published in : Phys. Rev. Accel. Beams 27 (2024) 032801
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Electrical Simulations of the SIS100 Superconducting Dipole and Quadrupole Circuits: Transients, Earthing and Failure Modes
/ Szwangruber, P B (Darmstadt, GSI) ; Raginel, V (Darmstadt, GSI) ; Delkov, D (Ilmenau Tech. U.) ; Ravaioli, E (CERN) ; Plyusnin, V (Darmstadt, GSI) ; Michna, M (Gdansk Tech. U.) ; Wilk, A (Gdansk Tech. U.) ; Wołoszyk, M (Gdansk Tech. U.) ; Freisleben, W (Darmstadt, GSI) ; Dziewiecki, M (Darmstadt, GSI) et al.
The 100 Tm superconducting synchrotron SIS100 is the main accelerator of the international Facility for Antiproton and Ion Research (FAIR) currently under advanced construction in Darmstadt, Germany. The SIS100 dipole circuit which creates the magnetic field required to bend the beam, consists of 108 dipoles distributed over six arc sections of the ring. [...]
2024 - 5 p.
- Published in : IEEE Trans. Appl. Supercond. 34 (2024) 4903805
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Space charge driven beam loss for cooled beams and mitigation measures in the CERN Low Energy Ion Ring
/ Bartosik, Hannes (CERN) ; Hancock, Steven (CERN) ; Huschauer, Alexander (CERN) ; Kain, Verena (CERN)
The performance of the CERN Low Energy Ion Ring (LEIR) with electron cooled lead ion beams is presently limited by losses, which occur during RF capture and the first part of acceleration. Extensive experimental studies performed in 2015 indicate that the losses are caused by the interplay of betatron resonances and the direct space charge detuning, which is significantly enhanced during bunching. [...]
2016 - 6 p.
- Published in : 10.18429/JACoW-HB2016-TUAM5X01
Fulltext: PDF;
In : 57th ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, Malmö, Sweden, 3 - 8 Jul 2016, pp.TUAM5X01
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