LHC Beam Diffusion Dependence on RF Noise: Models And Measurements

Conference · Tue Sep 14 04:00:00 EDT 2010 · Conf.Proc.C100523:TUPEA062,2010

OSTI ID:992885

Mastorides, T.; Rivetta, C.; Fox, J. D.; Van Winkle, D.; Baudrenghien, P.; Butterworth, A.; Molendijk, J.

Radio Frequency (RF) accelerating system noise and non-idealities can have detrimental impact on the LHC performance through longitudinal motion and longitudinal emittance growth. A theoretical formalism has been developed to relate the beam and RF loop dynamics with the bunch length growth [1]. Measurements were conducted at LHC to validate the formalism, determine the performance limiting RF components, and provide the foundation for beam diffusion estimates for higher energies and intensities. A brief summary of these results is presented in this work. During a long store, the relation between the energy lost to synchrotron radiation and the noise injected to the beam by the RF accelerating voltage determines the growth of the bunch energy spread and longitudinal emittance. Since the proton synchrotron radiation in the LHC is very low, the beam diffusion is extremely sensitive to RF perturbations. The theoretical formalism presented in [1], suggests that the noise experienced by the beam depends on the cavity phase noise power spectrum, filtered by the beam transfer function, and aliased due to the periodic sampling of the accelerating voltage signal V{sub c}. Additionally, the dependence of the RF accelerating cavity noise spectrum on the Low Level RF (LLRF) configurations has been predicted using time-domain simulations and models [2]. In this work, initial measurements at the LHC supporting the above theoretical formalism and simulation predictions are presented.

• Research Organization: SLAC National Accelerator Laboratory (SLAC)
• Sponsoring Organization: US DOE Office of Science (DOE SC)
• DOE Contract Number: AC02-76SF00515
• OSTI ID: 992885
• Report Number(s): SLAC-PUB-14248
• Conference Information: Journal Name: Conf.Proc.C100523:TUPEA062,2010
• Country of Publication: United States
• Language: English

Related Subjects

43 PARTICLE ACCELERATORS
Accelerators
ACCPHY
ACCSYS
BEAM DYNAMICS
BEAM EMITTANCE
DIFFUSION
LINEAR COLLIDERS
PERFORMANCE
PROTONS
RF SYSTEMS
SYNCHROTRON RADIATION
TRANSFER FUNCTIONS