60 research outputs found
Numerical Calculations of Wake Fields and Impedances of LHC Collimators' Real Structures
The LHC collimators have very complicated mechanical designs including
movable jaws made of higly resistive materials, ferrite materials, tiny RF
contacts. Since the jaws are moved very close to the circulating beams their
contribution in the overall LHC coupling impedance is dominant, with respect to
other machine components. For these reasons accurate simulation of collimators'
impedance becomes very important and challenging. Besides, several dedicated
tests have been performed to verify correct simulations of lossy dispersive
material properties, such as resistive wall and ferrites, benchmarking code
results with analytical, semi-analytical and other numerical codes outcomes.
Here we describe all the performed numerical tests and discuss the results of
LHC collimators' impedances and wake fields calculations.Comment: Invited Talk at ICAP 2015, Shanghai, China, 11 pages, 11 figure
Beam-Beam Interaction in Novel, Very High Luminosity Parameter Regimes
In order to achieve luminosities significantly higher than in existing
machines, future storage-ring based colliders will need to operate in novel
parameter regimes combining ultra-low emittance, large Piwinski angle and high
bunch charge; implementation of techniques such as a "crab waist" will add
further challenges. Understanding the beam-beam interaction in these situations
will be essential for the design of future very high luminosity colliders.
Recent developments in modeling tools for studying beam-beam effects, capable
of investigating the relevant regimes, will be discussed and examples,
including tests with crab waist collisions in DAFNE, will be presented.Comment: Invited Talk at 1st International Particle Accelerator Conference
(IPAC10), Kyoto, Japan, May 23-28, 2010. 5 pages, 7 figure
Numerical Calculations of Wake Fields and Impedances of LHC Collimators' Real Structures
The LHC collimators have very complicated mechanical designs including
movable jaws made of higly resistive materials, ferrite materials, tiny RF
contacts. Since the jaws are moved very close to the circulating beams their
contribution in the overall LHC coupling impedance is dominant, with respect to
other machine components. For these reasons accurate simulation of collimators'
impedance becomes very important and challenging. Besides, several dedicated
tests have been performed to verify correct simulations of lossy dispersive
material properties, such as resistive wall and ferrites, benchmarking code
results with analytical, semi-analytical and other numerical codes outcomes.
Here we describe all the performed numerical tests and discuss the results of
LHC collimators' impedances and wake fields calculations
Single Bunch Instabilities in FCC-ee
FCC-ee is a high luminosity lepton collider with a centre-of-mass energy from 91 to 365 GeV. Due to the machine parameters and pipe dimensions, collective effects due to electromagnetic fields produced by the interaction of the beam with the vacuum chamber can be one of the main limitations to the machine performance. In this frame, an impedance model is required to analyze these instabilities and to find possible solutions for their mitigation. This paper will present the contributions of specific machine components to the total impedance budget and their effects on the beam stability. Single bunch instability thresholds will be estimated in both transverse and longitudinal planes
Coupling impedances and collective effects for FCC-ee
A very important issue for the Future Circular Collider (FCC) is represented by collective effects due to the selfinduced electromagnetic fields, which, acting back on the beam, could produce dangerous instabilities. In this paper we will focus our work on the FCC electron-positron machine: in particular we will study some important sources of wake fields, their coupling impedances and the impact on the beam dynamics. We will also discuss longitudinal and transverse instability thresholds, both for single bunch and multibunch, and indicate some ways to mitigate such instabilities
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