Electron cloud buildup driving spontaneous vertical instabilities of stored beams in the Large Hadron Collider

Romano, Annalisa; Buffat, Xavier; Iadarola, Giovanni; Rumolo, G.

doi:10.1103/physrevaccelbeams.21.061002

Cited by 13 publications

(12 citation statements)

References 10 publications

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“…chine such as the ones induced by beam-beam effects and non-linear magnets. Additional effects such as electroncloud and magnet imperfections, which have been experimentally observed in the LHC, can potentially introduce additional non-linearities [46]. In this context, the interplay of such mechanisms with the power supply ripples should be further investigated in the future.…”

Section: B Including a Power Supply Noise Spectrum With Multiple Tonesmentioning

confidence: 99%

Tune modulation effects in the High Luminosity Large Hadron Collider

Kostoglou,

Bartosik,

Papaphilippou

et al. 2020

Preprint

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Several transverse noise sources, such as power supply ripples, can potentially act as an important limiting mechanism for the luminosity production of the Large Hadron Collider (LHC) and its future High-Luminosity upgrade (HL-LHC). In the presence of non-linearities, depending on the spectral components of the power supply noise and the nature of the source, such a mechanism can increase the diffusion of the particles in the distribution through the excitation of sideband resonances in the vicinity of the resonances driven by the lattice non-linearities. For the HL-LHC, due to the reduction of the beam size in the Interaction Points (IP) of the high luminosity experiments (IP1 and 5), increased sensitivity to noise effects is anticipated for the quadrupoles of the inner triplets. The modulation that may arise from the power supply ripples will be combined with the tune modulation that intrinsically emerges from the coupling of the transverse and longitudinal plane for off-momentum particles through chromaticity. To this end, the aim of this paper is to study the impact of tune modulation effects on the transverse beam motion resulting from the interplay between quadrupolar power supply ripples and synchro-betatron coupling. A power supply noise threshold for acceptable performance is estimated with single-particle tracking simulations by investigating the impact of different modulation frequencies and amplitudes on the Dynamic Aperture. The excitation of sideband resonances due to the modulation is demonstrated with frequency maps and the higher sensitivity to specific modulation frequencies is explained. Finally, a power supply noise spectrum consisting of several tones is considered in the simulations to determine whether the presence of power supply ripples in the quadrupoles of the inner triplet will limit the luminosity production in the HL-LHC era.

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Section: B Including a Power Supply Noise Spectrum With Multiple Tonesmentioning

confidence: 99%

Tune modulation effects in the High Luminosity Large Hadron Collider

Kostoglou,

Bartosik,

Papaphilippou

et al. 2020

Preprint

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“…Notably, e-clouds can drive transverse head-tail instabilities of the bunches, which cannot be suppressed by conventional transverse feedback systems due to the strong intrabunch motion. These instabilities have hampered the operation of different machines, including, recently, the Large Hadron Collider (LHC) [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Linearized method for the study of transverse instabilities driven by electron clouds

Iadarola

Mether

Mounet

et al. 2020

Phys. Rev. Accel. Beams

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We present a linearized method to study transverse instabilities due to electron clouds. It is based on an accurate and compact characterization of the cloud dipolar and quadrupolar forces, that can be easily obtained from quick single-pass numerical simulations. The long-term stability properties of the bunch are then predicted by solving the linearized Vlasov equation, taking into account the dipolar forces introduced by the e-cloud along the bunch as well as the betatron tune modulation with the longitudinal coordinate due to the e-cloud quadrupolar forces. The method is benchmarked against macroparticle simulations based on the same characterization of the e-cloud and the results are compared against conventional "brute-force" simulations based on the Particle-In-Cell method. The effect of transverse nonlinearities due to the e-cloud, which are neglected by the linearized method, is also analyzed.

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“…Computer-based modeling of electron-cloud formation is a versatile and crucial tool for the design of low cloud density vacuum components and for the optimization of the operation schemes of particle accelerators [29][30][31]. These approaches require precise descriptions of related material properties to be used as input parameters.…”

Section: Introductionmentioning

confidence: 99%

Energy-resolved secondary-electron emission of candidate beam screen materials for electron cloud mitigation at the Large Hadron Collider

Schulte

Hartung

Himmerlich

et al. 2020

Phys. Rev. Accel. Beams

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Energy-resolved secondary electron spectroscopy has been performed on air-exposed standard Cu samples and modified Cu surfaces that are tested and possibly applied to efficiently suppress electron cloud formation in the high-luminosity upgrade of the Large Hadron Collider at CERN. The Cu samples comprise pristine oxygen-free, carbon-coated and laser-structured surfaces, which were characterized prior to and after electron irradiation and rare-gas ion bombardment. Secondary-electron and reflected-electron yields measured with low charge dose of the samples exhibit a universal dependence on the energy of the primary impinging electrons. State-of-the-art models can successfully be used to describe the spectroscopic data. The supplied spectral dependence of electron emission and integrated electron yield as well as the derived parametrization can serve as a basis for forthcoming simulations of electron cloud formation and multipacting.

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Electron cloud buildup driving spontaneous vertical instabilities of stored beams in the Large Hadron Collider

Cited by 13 publications

References 10 publications

Tune modulation effects in the High Luminosity Large Hadron Collider

Tune modulation effects in the High Luminosity Large Hadron Collider

Linearized method for the study of transverse instabilities driven by electron clouds

Energy-resolved secondary-electron emission of candidate beam screen materials for electron cloud mitigation at the Large Hadron Collider

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