DYNAMIC APERTURE EXTRAPOLATION IN THE PRESENCE OF TUNE MODULATION

Citation
M. Giovannozzi et al., DYNAMIC APERTURE EXTRAPOLATION IN THE PRESENCE OF TUNE MODULATION, Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 57(3), 1998, pp. 3432-3443
Citations number
41
Categorie Soggetti
Physycs, Mathematical","Phsycs, Fluid & Plasmas
ISSN journal
1063651X
Volume
57
Issue
3
Year of publication
1998
Part
B
Pages
3432 - 3443
Database
ISI
SICI code
1063-651X(1998)57:3<3432:DAEITP>2.0.ZU;2-4
Abstract
In hadron colliders, such as the Large Hadron Collider (LHC) to be bui lt at CERN, the long-term stability of the single-particle motion is m ostly determined by the field-shape quality of the superconducting mag nets. The mechanism of particle loss may be largely enhanced by modula tion of betatron tunes, induced either by synchrobetatron coupling (vi a the residual uncorrected chromaticity), or by unavoidable power supp ly ripple, This harmful effect is first investigated in a simple dynam ical system model, the Henon map with modulated Linear frequencies. Th en a realistic accelerator model describing the injection optics of th e LHC lattice is analyzed. Orbital data obtained with long-term tracki ng simulations (10(5)-10(7) turns) are post-processed to obtain the dy namic aperture. It turns out that the dynamic aperture can be interpol ated using a simple empirical formula, as it decays proportionally to a power of the inverse logarithm of the number of turns. Furthermore, the extrapolation of tracking data at 10(5) turns gives reliable estim ates of the dynamic aperture for 10(7) turns, which represent the expe cted duration of the LHC injection plateau.