Beam-beam amplitude detuning with forced oscillations

Tomás, Rogelio; Buffat, Xavier; White, S.; Pieloni, Tatiana; Barranco, J.; Jorge, Patrik Gonçalves

doi:10.1103/physrevaccelbeams.20.101002

Cited by 7 publications

(4 citation statements)

References 17 publications

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“…The beam dynamics with forced oscillations features remarkable differences from that of free oscillations [34][35][36][37]. In presence of an AC dipole the measured β functions differ from the machine β functions.…”

Section: Betatron Oscillations Free or Forcedmentioning

confidence: 82%

Accelerator Operations

Lamont

Wenninger

Steinhagen

et al. 2020

Particle Physics Reference Library

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The cost of building a particle accelerator is a major capital investment. Commissioning should be swift and the subsequent exploitation of a facility must provide an effective return. This return may be difficult to quantify unambiguously but generally acceptable measures of performance can be established. These measures might include: machine availability; integrated luminosity; protons on target; beam hours to users and so on. The role of accelerator operations is to maximize the performance of an accelerator or accelerator complex by: minimizing downtime; maximizing the amount of beam delivered to the users; fully optimizing the quality of beam delivered to the users; and doing it all safely. Accelerators and the control of particles beams have advanced considerably over recent years. There is deep understanding of particle dynamics, innovative measurement techniques, in-depth simulation and modelling, and widespread leverage of Coordinated by M. Lamont.

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Section: Betatron Oscillations Free or Forcedmentioning

confidence: 82%

Accelerator Operations

Lamont

Wenninger

Steinhagen

et al. 2020

Particle Physics Reference Library

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“…In this part we investigate if ADeCTA can be generated in the same way under forced oscillations. Amplitude detuning for forced oscillations is studied in [11,12] up to first order in the strengths of sources of amplitude detuning, while ADeCTA requires higher order approximations. In the following we combine the approaches in [4] and [11,12,30] to study the possible ADeCTA with forced oscillations.…”

Section: A Theorymentioning

confidence: 99%

“…It is well known that the particle motion in the presence of forced oscillations differs from the free motion following a single kick. This has led to methods which account for this difference in the motion when reconstructing the optics parameters [9][10][11][12]. However, these studies stay at linear order in the strength of perturbing components and can therefore not be used to predict the ADeCTA.…”

Section: Introductionmentioning

confidence: 99%

Suppression of amplitude dependent closest tune approach and its behavior under forced oscillations

Persson

Tomás

Maclean

2019

Phys. Rev. Accel. Beams

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An amplitude dependent closest tune approach (ADeCTA) was first observed in the LHC in 2012. This potentially harmful effect can be generated by linear coupling in conjunction with octupoles. In this article we demonstrate experimentally and in simulations a configuration of the octupoles to suppress this recently observed effect. Furthermore, ADeCTA is investigated for the first time with driven oscillations. We show analytically that skew quadrupoles and normal octupoles do not generate ADeCTA for forced oscillations in the same way as for free oscillations. This adds an additional constraint to measure it since the forced oscillations, generated by an ac dipole, are the preferred option for optics measurements in the LHC. The analytical result is confirmed by both measurements and simulations.

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“…The success and reliability of ac dipoles have allowed them to be used for new applications. The LHC ac dipoles have been used to measure the physical aperture of the collider to assist in collimator alignment [19], to measure amplitude detuning in the presence of head-on beam-beam interactions [20] as well as to measure the machine impedance [21]. More recently ac dipoles have been used in lightsources, such as at ESRF [22], PETRA III [23] and ALBA [24].…”

Section: Introductionmentioning

confidence: 99%

First experimental demonstration of forced dynamic aperture measurements with LHC ac dipoles

Carlier

Tomás

Maclean

et al. 2019

Phys. Rev. Accel. Beams

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Diagnostics of nonlinear beam dynamics has become more important for the LHC as it advances into increasingly challenging regimes of operation, as well as for the High Luminosity LHC where machine nonlinearities will have a significantly larger impact. Limitations of traditional excitation methods at top energy, in particular due to machine protection, have pushed the development of safe alternative methods using ac dipoles to characterize the nonlinear content of the LHC. One of the methods that has been proposed is the dynamic aperture under forced oscillation of ac dipoles. This new observable has the potential to help characterize relative changes in the nonlinear content of the machine, improve the understanding of the nonlinear models by comparing to simulations, validate nonlinear optics corrections, and give a qualitative lower bound estimate on the free dynamic aperture. This paper presents the first experimental demonstration of forced dynamic aperture measurements under forced oscillations performed using the LHC ac dipoles, and discusses the benefits of forced dynamic aperture measurements in circular colliders.

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Beam-beam amplitude detuning with forced oscillations

Cited by 7 publications

References 17 publications

Accelerator Operations

Accelerator Operations

Suppression of amplitude dependent closest tune approach and its behavior under forced oscillations

First experimental demonstration of forced dynamic aperture measurements with LHC ac dipoles

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