Title :
Consequences of the direct space charge effect for dynamic aperture and beam tail formation in the LHC
Author :
RLuggiero, F. ; Zimmermann, F.
Author_Institution :
CERN, Geneva, Switzerland
Abstract :
The direct space charge detuning at the centre of a nominal LHC proton bunch is about 10-3 at injection energy. Owing to their slow synchrotron motion, particles with small betatron amplitudes sample a varying electric charge density within the bunch and thus experience a tune modulation at twice the 66 Hz synchrotron frequency. In conjunction with magnet nonlinearities, such tune modulation may give rise to particle diffusion to large betatron amplitudes and eventually to particle loss. Coherent quadrupole oscillations, caused, e.g., by injection mismatch, resonantly perturb the single-particle motion via the space-charge force, and can cause a rapid growth in the transverse amplitude. Using the results of numerical and analytical investigations, we show that these space-charge effects alone will not affect the LHC performance
Keywords :
colliding beam accelerators; particle beam bunching; particle beam dynamics; particle beam stability; proton accelerators; space charge; synchrotrons; LHC; beam tail formation; betatron amplitude; direct space charge detuning; dynamic aperture; injection mismatch; proton bunch; quadrupole oscillations; space-charge force; transverse amplitude; tune modulation; Amplitude modulation; Apertures; Frequency; Large Hadron Collider; Magnetic modulators; Magnetic resonance; Performance analysis; Protons; Space charge; Synchrotrons;
Conference_Titel :
Particle Accelerator Conference, 1999. Proceedings of the 1999
Conference_Location :
New York, NY
Print_ISBN :
0-7803-5573-3
DOI :
10.1109/PAC.1999.792884