Nonlinear chromaticity correction with sextupole families [particle accelerator]

Verdier, A.

doi:10.1109/pac.1995.505715

Cited by 3 publications

(2 citation statements)

References 5 publications

(7 reference statements)

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“…This initial oscillation of the horizontal emittance can be explained by a dispersion and smaller betatron mismatch induced by space-charge. The dispersion and second order dispersion both satisfy differential equations similar to the one of a closed-orbit distortion due to dipole field errors, explicitly [20]:…”

Section: Influence Of Dispersionmentioning

confidence: 99%

Systematic studies on the effect of linear lattice optics for space-charge limited beams

Fitterer

Carli

Molodozhentsev

et al. 2015

Phys. Rev. ST Accel. Beams

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The HL-LHC (High Luminosity LHC) project aims to an increase of the luminosity of the LHC by a factor of 10. In order to realize this ambitious goal, the LHC itself has to undergo a major upgrade accompanied by an extensive upgrade of the complete injector complex referred to as LHC injector upgrade (LIU). In the framework of the LIU project, a new rapid cycling synchrotron (RCS) as an alternative to the energy upgrade of the existing PS Booster has been proposed. Motivated by the optics studies conducted for this RCS, the more general question of the influence of the linear optics on the machine performance has been raised. In this paper, we want to investigate this question by comparing different lattices with the final aim of identifying lattice characteristics advantageous under strong space-charge effects.

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Section: Influence Of Dispersionmentioning

confidence: 99%

Systematic studies on the effect of linear lattice optics for space-charge limited beams

Fitterer

Carli

Molodozhentsev

et al. 2015

Phys. Rev. ST Accel. Beams

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“…Three families are used for the vertical plane where the phase advance is 60 and two families are used for the horizontal plane where the phase advance is 90 . Detailed specifications concerning sextupole families are given in another paper at this conference [1]. The basic motivation to use more than two sextupole families is to compensate the off-momentum mismatch of the low-insertions.…”

Section: Introductionmentioning

confidence: 99%

Measurement of chromatic effects in LEP

Brandt

Castro

Cornelis

et al.

Proceedings Particle Accelerator Conference

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The chromaticity produced by the insertions and the lattice of LEP is corrected in the FODO lattice of the arcs which has horizontal and vertical phase advances of 90 0 and 60 0 for the LEP optics presently used. This is done with two horizontal and three vertical sextupole families. To check this correction scheme the non-linear chromaticities have been measured by observing the betatron tunes as a function of RF-frequency, i.e. of momentum deviation. The differences between the results and the expected effects of the sextupoles are interpreted in terms of octupole and decapole components in the dipole magnets. To check the distribution around the ring of the chromaticities and their corrections the betatron phase advances have been measured as a function of momentum deviation. This was done by observing an excited betatron oscillation for 1024 turns in all beam position monitors for different RF-frequencies. The results clearly show the negative chromaticity produced in the straight sections and its correction in the arcs. The parasitic sextupole components are found to be spread uniformly in the arcs within the measurement errors. Under this condition one finds that they have a negligible effect on the dynamic aperture.

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Theory of a feedback to cure transverse mode coupling instability

Karliner

Popov

2005

Nuclear Instruments and Methods in Physics Research Section A:

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In the present paper an attempt is made to develop an advanced transverse feedback theory capable to clarify the conditions, at which the resistive feedback can cure the TMC instability. The hollow beam model is used for analysis because of its simplicity. As it appeared an important role can play chromaticity. Negative chromaticity combined with resistive feedback as from theory follows can increase the TMC instability threshold by several times. In any case, the basic results obtained with the hollow beam model may be then corrected using more complicated one.©Bgklblml y^_jghc nbabdb bf =B ;m^d_jZ KH J:G 3 _______________________________________________________________

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Nonlinear chromaticity correction with sextupole families [particle accelerator]

Abstract: The correction of the non-linear chromaticity with sextupoles families is explained by means of a simple perturbation theory. The advantages and limitations of such systems are shown, as well as the constraints they put on machine optics.

Cited by 3 publications

References 5 publications

Systematic studies on the effect of linear lattice optics for space-charge limited beams

Systematic studies on the effect of linear lattice optics for space-charge limited beams

Measurement of chromatic effects in LEP

Theory of a feedback to cure transverse mode coupling instability

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