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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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2.
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Advances on LHC RF Power Limitation Studies at Injection
/ Timko, Helga (CERN) ; Argyropoulos, Theodoros (CERN) ; Calaga, Rama (CERN) ; Catalán Lasheras, Nuria (CERN) ; Iliakis, Konstantinos (CERN) ; Karlsen-Bæck, Birk Emil (CERN ; Rome U.) ; Karpov, Ivan (CERN) ; Zampetakis, Michail (CERN)
The average power consumption of the main RF system during beam injection in the High-Luminosity Large Hadron Collider is expected to be close to the maximum available klystron power. Power transients due to the mismatch of the beam and the action of control loops will exceed the available power. [...]
2024 - 4 p.
- Published in : JACoW HB 2023 (2024) 567-570
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.567-570
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3.
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Refining the LHC Longitudinal Impedance Model
/ Zampetakis, Michail (CERN) ; Argyropoulos, Theodoros (CERN) ; Brischetto, Ylenia (CERN) ; Calaga, Rama (CERN) ; Giacomel, Lorenzo (CERN) ; Karlsen-Bæck, Birk Emil (INFN, Rome ; Rome U. ; CERN) ; Karpov, Ivan (CERN) ; Mounet, Nicolas (CERN) ; Salvant, Benoit (CERN) ; Timko, Helga (CERN)
Modelling the longitudinal impedance for the Large Hadron Collider (LHC) has been a long-standing effort, especially in view of its High-Luminosity (HL) upgrade. The resulting impedance model is an essential input for beam dynamics studies. [...]
2024 - 4 p.
- Published in : JACoW HB 2023 (2024) 559-562
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.559-562
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4.
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Validation of control loop modeling for power limitation studies with beams for HL-LHC
/ Karlsen-Bæck, B E (CERN ; Rome U.) ; Argyropoulos, T (CERN) ; Calaga, R (CERN) ; Karpov, I (CERN) ; Timko, H (CERN)
For HL-LHC intensities, transient beam loading after injection between the Super Proton Synchrotron (SPS) and the Large Hadron Collider (LHC) is expected to push the RF power in the LHC to the limit of the installed system. A detailed understanding of this process is necessary to minimize beam losses during LHC injection. [...]
2023 - 4 p.
- Published in : JACoW IPAC 2023 (2023) TUPA160
Fulltext: PDF;
In : 14th International Particle Accelerator Conference (IPAC 2023), Venice, Italy, 7 - 12 May 2023, pp.TUPA160
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Detailed characterisation of the LEIR intensity limitations for a Pb ion beam
/ Saá Hernández, Angela (CERN) ; Bartosik, Hannes (CERN) ; Biancacci, Nicolo (CERN) ; Hirlaender, Simon (CERN) ; Moreno, Daniel (CERN) ; Zampetakis, Michail (CERN)
The equilibrium emittance of the Pb beam in the CERN Low Energy Ion Ring (LEIR) results from the interplay of electron cooling and heating processes, as intra-beam scattering and space charge. In this paper we present the measurements of the emittance evolution as a function of intensity, working point and resonance excitation, and compare them with the simulations of the heating processes. [...]
CERN-ACC-2019-109.-
2019 - 4 p.
- Published in : 10.18429/JACoW-IPAC2019-WEPTS042
Preprint: PDF;
In : 10th International Particle Accelerator Conference, Melbourne, Australia, 19 - 24 May 2019, pp.WEPTS042
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6.
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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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7.
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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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8.
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Interplay Between Space Charge, Intra-Beam Scattering, and Synchrotron Radiation Effects
/ Zampetakis, Michail (CERN ; Crete U.) ; Antoniou, Fanouria (CERN) ; Bartosik, Hannes (CERN) ; Papaphilippou, Yannis (CERN)
The objective of this research is to study the interplay of synchrotron radiation, intra-beam scattering, and space charge in the vicinity of excited resonances. In this respect, two modules were developed to simulate intra-beam scattering and synchrotron radiation effects and plugged into pyORBIT to be used together with its space charge module. [...]
Geneva : JACoW, 2021 - 4 p.
- Published in : JACoW IPAC 2021 (2021) 3220-3223
Fulltext: PDF;
In : 12th International Particle Accelerator Conference (IPAC 2021), Online, 24 - 28 May 2021, pp.3220-3223
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9.
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Correlating start-of-ramp losses with beam observables at blat-bottom in the LHC
/ Karlsen-Bæck, Birk Emil (CERN ; Rome U.) ; Salvachua, Belen (CERN) ; Timko, Helga (CERN) ; Zampetakis, Michail (CERN) ; Morales Vigo, Sara (CERN)
Power limitations are expected at injection energy for the main Radio Frequency (RF) system due to the doubled bunch intensity in the High Luminosity (HL-) Large Hadron Collider (LHC) era. One way to overcome these power limitations is to reduce the capture voltage. [...]
2024 - 4 p.
- Published in : JACoW IPAC 2024 (2024) MOPC11
Fulltext: PDF;
In : 15th International Particle Accelerator Conference (IPAC 2024), Nashville, TN, United States, 19 - 24 May 2024, pp.MOPC11
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10.
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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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