Response of colliding beam-beam system to harmonic excitation due to crab-cavity rf phase modulation

Ohmi, K.; Tomás, Rogelio; Funakoshi, Y.; Calaga, R.; Ieiri, T.; Morita, Yuichi; Nakanishi, Koichi; Oide, K.; Ohnishi, Y.; Sun, Yipeng; Tobiyama, M.; Zimmermann, F.

doi:10.1103/physrevstab.14.111003

Cited by 19 publications

(9 citation statements)

References 3 publications

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“…Future directions of this work also include studies of the effect of different tune distributions on the achieved growth rates in the presence of damper, in particular for the expected distribution due to HOBB effects. Past literature has shown that in the case of dipole kicks or very short bunches, part of the excitation noise is converted in a coherent π-mode oscillation ( [2,4]). This oscillation should be strongly damped by the transverse damper in the case of phase noise-which results in an ensemble displacement of the bunch-but not with amplitude noise.…”

Section: Discussionmentioning

confidence: 99%

“…The effect of momentum kicks on the transverse emittance growth has been studied and measured before. Crab cavity tests at KEK [1] have shown the beam sensitivity to crab cavity rf noise [2]. Contrary to the HiLumi LHC though, these tests were conducted with a lepton beam, which has a very short synchrotron radiation damping time, focused on rf noise with a single spectral line, and were dominated by a π-mode instability.…”

Section: Introductionmentioning

confidence: 99%

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Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

Baudrenghien

Mastoridis

2015

Phys. Rev. ST Accel. Beams

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The high-luminosity LHC (HiLumi LHC) upgrade with planned operation from 2025 onward has a goal of achieving a tenfold increase in the number of recorded collisions thanks to a doubling of the intensity per bunch (2.2e11 protons) and a reduction of β Ã to 15 cm. Such an increase would significantly expedite new discoveries and exploration. To avoid detrimental effects from long-range beam-beam interactions, the half crossing angle must be increased to 295 microrad. Without bunch crabbing, this large crossing angle and small transverse beam size would result in a luminosity reduction factor of 0.3 (Piwinski angle). Therefore, crab cavities are an important component of the LHC upgrade, and will contribute strongly to achieving an increase in the number of recorded collisions. The proposed crab cavities are electromagnetic devices with a resonance in the radio frequency (rf) region of the spectrum (400.789 MHz). They cause a kick perpendicular to the direction of motion (transverse kick) to restore an effective head-on collision between the particle beams, thereby restoring the geometric factor to 0.8 [K. Oide and K. Yokoya, Phys. Rev. A 40, 315 (1989).]. Noise injected through the rf/low level rf (llrf) system could cause significant transverse emittance growth and limit luminosity lifetime. In this work, a theoretical relationship between the phase and amplitude rf noise spectrum and the transverse emittance growth rate is derived, for a hadron machine assuming zero synchrotron radiation damping and broadband rf noise, excluding infinitely narrow spectral lines. This derivation is for a single beam. Both amplitude and phase noise are investigated. The potential improvement in the presence of the transverse damper is also investigated.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

Baudrenghien

Mastoridis

2015

Phys. Rev. ST Accel. Beams

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“…We will not spend much time in this dissertation looking into detail at all the mechanisms that contribute to the reducing factor, or simply restrict the luminosity by setting limits (like the tune shift limits given by beam-beam or space-charge effects) [20,21]. We will simply use as an example of these mechanisms the luminosity degradation due to beam deformations, or the so called hourglass effect, and eventually, we will take a more detailed look at the luminosity degradation due to the crossing angle.…”

Section: Luminosity Degradationmentioning

confidence: 99%

“…), and the total crabbing angle can be built up turn by turn, allowing to lower the voltage per cavity as well as the total number of cavities. However, this scheme can considerably reduce the beam lifetime if it builds up resonant instabilities induced by harmonic excitations[20]. Further complications can derive from the fact that the global scheme requires that the bunches perform transverse oscillations, following the ring's betatron function on the crabbing plane along the machine.…”

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confidence: 99%

Crabbing system for an electron-ion collider

Castilla

2017

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First of all, I would like to sincerely thank my supervisor Dr. Jean Delayen, for all the support and time that he invested in my long journey through my research and studies. To my supervisor Dr. Mauro Napsuciale, for all the trust he has had in me throughout these years, I would not be here without his guidance. I would like to thank the Physics Department at Old Dominion University and the Physics Department at the University of Guanajuato, for all their support, patience, and for all the professors and colleagues from whom I have learnt so much. I am very thankful to CONACYT for all the support. To Dr. Hari Areti and the JSA for all the encouragement and support given to me and my young colleagues. To Dr. Todd Satogata and Dr. Vasiliy Morozov from the Center for Advanced Studies of Accelerator at Jefferson Lab, for all the time and positive attitude that they spent and showed while letting me learn from them, it was really one of the best parts of my research experience. To Joe Preble, Bob Rimmer, Tom Powers, Kirk Davis, and Pete Kushnick from the Superconducting Radiofrequency Institute at Jefferson Lab, for letting me and my colleagues learn from the best and carry out our experimental work without causing too many disasters, I would like to specially thank the amazing technical support of: Chris Dreyfuss, Roland Overton, and of course Danny Forehand, you guys rock! To Terry Grim, Chase Boulware, and Dmitry Gorelov at Niowave, Inc. for their help and work done building and testing the 750 MHz crab cavity. To my thesis committee, for their time and helpful comments. I would like to give special thanks v to my brothers and sisters in arms, my friends and colleagues: Chris Hopper, HyeKyoung Park, Kevin Mitchell, and of course Subashini De Silva, for all the tears, sweat, and blood shed day and night throughout our discussions and experimental work. To Carlos Hernandez-Garcia and his family, for their friendship, inspiration and support, it did not pass unnoticed. Finally and most importantly, to all my friends and family, that in the good and the ill have endured with me and lifted my spirit up, you all occupy a special place in my life. vi

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“…However, it will be added here as a perturbation after considering synchrotron radiation damping and emittance growth from luminosity burn-off. In this study we neglect the possible effects from dynamic aperture [17], beam scraping [18], and beam excitations from power converter noise, flux jumps, or crab cavity noise [15,[19][20][21]. To evaluate the intensity loss from luminosity production the total cross section of the proton is used as a pessimistic approximation.…”

Section: Introductionmentioning

confidence: 99%

Emittance growth from luminosity burn-off in future hadron colliders

Tomás

Keintzel

Papadopoulou

2020

Phys. Rev. Accel. Beams

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Future hadron colliders aim at producing larger integrated luminosities by burning-off an increased fraction of the bunch particles. This burn-off removes particles unevenly in the bunch distribution generating an emittance growth. Analytical equations are derived describing the bunch distribution suffering luminosity burn-off and cooling from synchrotron radiation damping, far from the equilibrium emittance, and possibly including transverse collision offsets. This effect is evaluated for HL-LHC [G. Apollinari et al., Report No. CERN-2017-007-M, 2017], HE-LHC [A. Abada et al., Eur. Phys. J. Spec. Top. 228, 1109 (2019)], and FCC-hh [A. Abada et al., Eur. Phys. J. Spec. Top. 228, 755 (2019).] and included into a step-by-step simulation of the physics fill, together with intrabeam scattering, to evaluate impact on performance.

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Response of colliding beam-beam system to harmonic excitation due to crab-cavity rf phase modulation

Cited by 19 publications

References 3 publications

Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

Transverse emittance growth due to rf noise in the high-luminosity LHC crab cavities

Crabbing system for an electron-ion collider

Emittance growth from luminosity burn-off in future hadron colliders

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