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beam-beam-effects

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TU1PBI01 Fully 3D Multiple Beam Dynamics Processes Simulation for the Tevatron simulation, proton, dipole, emittance 630
 
  • E.G. Stern, J.F. Amundson, P. Spentzouris, A. Valishev
    Fermilab, Batavia
 
 

Extensive work has been done to create an accurate model of beam dynamics at the Fermilab Tevatron. This talk will present validation and results from the development of a simulation of the machine including multiple beam dynamics effects. The essential features of the simulation include a fully 3D strong-strong beam-beam particle-in-cell Poisson solver, interactions among multiple bunches and both head-on and long-range beam-beam collisions, coupled linear optics and helical trajectory consistent with beam orbit measurements, chromaticity and resistive wall impedance. The individual physical processes are validated against measured data where possible, and analytic calculations elsewhere. The simulation result discussion will focus on the effects of increasing beam intensity with single and multiple bunches on the impedance of the beams.

 

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WE3PBI03 LHC Beam-Beam Compensation Studies at RHIC electron, simulation, proton, collider 1899
 
  • W. Fischer, R. Calaga, R. De Maria, Y. Luo, N. Milas, C. Montag, G. Robert-Demolaize
    BNL, Upton, Long Island, New York
  • H.J. Kim, T. Sen
    Fermilab, Batavia
 
 

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH1-886


Long-range and head-on beam-beam effects are expected to limit the LHC performance with design parameters. To mitigate long-range effects current carrying wires parallel to the beam were proposed. Two such wires are installed in RHIC where they allow studying the effect of strong long-range beam-beam effects, as well as the compensation of a single long-range interaction. The tests provide benchmark data for simulations and analytical treatments. To reduce the head-on beam-beam effect electron lenses were proposed for both the LHC and RHIC. We present the experimental long-range beam-beam program and report on head-on compensations studies at RHIC, which are primarily based on simulations.

 

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WE6PFP018 Optimization of the LHC Separation Bumps Including Beam-Beam Effects simulation, emittance, optics, luminosity 2522
 
  • S.M. White, H. Burkhardt, S.D. Fartoukh, T. Pieloni
    CERN, Geneva
 
 

The LHC beams will cross each other and experience perturbations as a result of the beam-beam effect at the interaction points, which can result in emittance growth and halo creation. The beam-beam force is approximately linear for small offsets and highly non-linear for larger offsets with peaks in growth close to 0.3 and 1.5 σ separation. We present a study of the process of going into collisions in the LHC and use simulations to investigate on possible emittance blow-up. We analyze how the crossing scheme can be optimized to minimize the collapsing time of the separation bumps for given hardware constraints.

 
WE6PFP028 Recent Experience with Electron Lens Beam-Beam Compensation at the Tevatron electron, proton, luminosity, gun 2552
 
  • V. Kamerdzhiev, G.F. Kuznetsov, G.W. Saewert, V.D. Shiltsev, A. Valishev
    Fermilab, Batavia
 
 

Tevatron Electron Lenses (TEL) have reliably demonstrated correction of the bunch-to-bunch tune shift induced by long-range beam-beam interactions. The second and most important intended application of TEL is compensation of the nonlinearity of head-on beam-beam force. We report on the first studies of head-on beam-beam compensation with the second generation Gaussian profile TEL. We evaluate the effect of TEL on beam life time and emittance and compare the observed results with simulations.

 
WE6PFP029 Tevatron Electron Lens Upgrade electron, gun, proton, pick-up 2555
 
  • V. Kamerdzhiev, G.W. Saewert
    Fermilab, Batavia
 
 

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-07CH11359


A novel high voltage modulator had been under development for 1.5 years. It was completed tested on the bench and became a part of the TEL2 system in October 2008. The modulator is used to drive the electron gun anode. We provide technical details on the stacked transformer modulator, analyze its performance and discuss the design challenges. The results of the beam studies made possible by the new high voltage modulator are reported.

 
WE6PFP034 Electron Lens for Beam-Beam Compensation at LHC electron, simulation, proton, emittance 2567
 
  • A. Valishev, V.D. Shiltsev
    Fermilab, Batavia
 
 

Funding: Work supported by the United States Department of Energy under Contract No. DE-AC02-07CH11359


Head-on beam-beam effect may become a major performance limitation for the LHC in one of the upgrade scenarios. Given the vast experience gained from the operation of Tevatron electron lenses, a similar device provides significant potential for mitigation of beam-beam effects at the LHC. In this report we present the results of simulation studies of beam-beam compensation and analyze potential application of electron lense at LHC and RHIC.

 
WE6PFP037 3D Strong-Strong Simulations of Wire Compensation of Long-Range Beam-Beam Effects at LHC emittance, simulation, lattice, luminosity 2576
 
  • J. Qiang
    LBNL, Berkeley, California
 
 

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.


In this paper, we report on studying wire compensation of long-range beam-beam effects using a fully 3D strong-strong beam-beam model. The simulations include two head-on collisions with 0.3 mrad crossing angle and 64 long-range beam-beam collisions near IP 1 and IP5. We found that using conducting wires with appropriate current level will compensate the tail emittance growth due to long-range beam-beam effects. The random fluctuation of current level should be controlled below 0.1% level for a good compensation. Lowering the long-range beam-beam separations by 20% together with wire compensation will improve the luminosity by a few percentage. Further reducing the beam-beam separations causes significant beam blow-up and decrease of luminosity.

 
WE6PFP039 Emittance Growth due to Beam-Beam Effects with a Static Offset in Collision in the LHC emittance, proton, luminosity, simulation 2582
 
  • T. Pieloni
    PSI, Villigen
  • W. Herr
    CERN, Geneva
  • J. Qiang
    LBNL, Berkeley, California
 
 

Under nominal operational conditions, the LHC bunches experience small unavoidable offset at the collision points caused by long range beam-beam interactions. Although the geometrical loss of luminosity is small, one may have to consider an increase of the beam transverse emittance, leading to a deterioration of the experimental conditions. In this work we evaluate and understand the dynamics of beam-beam interactions with static offsets at the collision point. A study of the emittance growth as a function of the offset amplitude in collisions is presented. Moreover, we address the effects coming from the beam parameters such as the initial transverse beam size, bunch intensity and tune.

 
FR1PBC04 Recent Tevatron Operational Experience collider, proton, antiproton, luminosity 4230
 
  • A. Valishev, G. Annala, D.S. Bollinger, B.M. Hanna, A. Jansson, T.R. Johnson, R.S. Moore, D.A. Still, C.-Y. Tan, X. Zhang
    Fermilab, Batavia
 
 

Funding: Work supported by the United States Department of Energy under Contract No. DE-AC02-07CH11359


Over the past year Tevatron has been routinely operating at initial luminosity over 3·1032. The high luminosity regime highlighted several issues that became the focus for operational improvements. In this report we summarize the experience in such areas as mitigation of particle losses, maintaining orbit and optics stability, and identification of aperture restrictions.

 

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