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

Persson, Tobias; Tomás, Rogelio; Maclean, Ewen

doi:10.1103/physrevaccelbeams.22.051001

Cited by 1 publication

(1 citation statement)

References 17 publications

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“…Linear coupling can also cause substantial changes to detuning coefficients [23][24][25][26], and plays a significant role in the generation of amplitude-dependent closest tune approach [23,[27][28][29][30][31]. Such coupling-induced distortions of tune-footprint are detrimental to Landau damping of instabilities, as demonstrated in the LHC [32,33].…”

Section: Introductionmentioning

confidence: 99%

New approach to LHC optics commissioning for the nonlinear era

Maclean

Tomás

Carlier

et al. 2019

Phys. Rev. Accel. Beams

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In 2017, optics commissioning strategy for low-β Ã operation of the CERN Large Hadron Collider (LHC) underwent a major revision. This was prompted by a need to extend the scope of beam-based commissioning at high energy, beyond the exclusively linear realm considered previously, and into the nonlinear regime. It also stemmed from a recognition that, due to operation with crossing angles in the experimental insertions, the linear and nonlinear optics quality were intrinsically linked through potentially significant feed-down at these locations. Following the usual linear optics commissioning therefore, corrections for (normal and skew) sextupole and (normal and skew) octupole errors in the high-luminosity insertions were implemented. For the first time, the LHC now operates at top energy with beam-based corrections for nonlinear dynamics, and for the effect of the crossing scheme on beta-beating and dispersion. The new commissioning procedure has improved the control of various linear and nonlinear characteristics of the LHC, yielding clear operational benefits.

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