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Title: IBS in a CAM-Dominated Electron Beam

Abstract

Electron cooling of the 8.9 GeV/c antiprotons in the Recycler ring requires high-quality dc electron beam with the current of several hundred mA and the kinetic energy of 4.3 MeV. That high electron current is attained through beam recirculation (charge recovery). The primary current path is from the magnetized cathode at high voltage terminal to the ground, where the electron beam interacts with the antiproton beam and cooling takes place, and then to the collector in the terminal. The energy distribution function of the electron beam at the collector determines the required collector energy acceptance. Multiple and single intra-beam scattering as well as the dissipation of density micro-fluctuations during the beam transport are studied as factors forming a core and tails of the electron energy distribution. For parameters of the Fermilab electron cooler, the single intra-beam scattering (Touschek effect) is found to be of the most importance.

Authors:
; ;  [1];  [2]
  1. Fermi National Accelerator Laboratory, P. O. Box 500, Batavia IL 60543 (United States)
  2. Novosibirsk State University, Novosibirsk, 630090 (Russian Federation)
Publication Date:
OSTI Identifier:
20798390
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 821; Journal Issue: 1; Conference: COOL05: International workshop on beam cooling and related topics, Galena, IL (United States), 18-23 Sep 2005; Other Information: DOI: 10.1063/1.2190105; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; ANTIPROTON BEAMS; BEAM CURRENTS; BEAM DYNAMICS; BEAM OPTICS; BEAM TRANSPORT; CATHODES; ELECTRON BEAMS; ELECTRON COOLING; ENERGY SPECTRA; FERMILAB; FLUCTUATIONS; GEV RANGE; SCATTERING

Citation Formats

Burov, A., Nagaitsev, S., Shemyakin, A., and Gusachenko, I. IBS in a CAM-Dominated Electron Beam. United States: N. p., 2006. Web. doi:10.1063/1.2190105.
Burov, A., Nagaitsev, S., Shemyakin, A., & Gusachenko, I. IBS in a CAM-Dominated Electron Beam. United States. doi:10.1063/1.2190105.
Burov, A., Nagaitsev, S., Shemyakin, A., and Gusachenko, I. Mon . "IBS in a CAM-Dominated Electron Beam". United States. doi:10.1063/1.2190105.
@article{osti_20798390,
title = {IBS in a CAM-Dominated Electron Beam},
author = {Burov, A. and Nagaitsev, S. and Shemyakin, A. and Gusachenko, I.},
abstractNote = {Electron cooling of the 8.9 GeV/c antiprotons in the Recycler ring requires high-quality dc electron beam with the current of several hundred mA and the kinetic energy of 4.3 MeV. That high electron current is attained through beam recirculation (charge recovery). The primary current path is from the magnetized cathode at high voltage terminal to the ground, where the electron beam interacts with the antiproton beam and cooling takes place, and then to the collector in the terminal. The energy distribution function of the electron beam at the collector determines the required collector energy acceptance. Multiple and single intra-beam scattering as well as the dissipation of density micro-fluctuations during the beam transport are studied as factors forming a core and tails of the electron energy distribution. For parameters of the Fermilab electron cooler, the single intra-beam scattering (Touschek effect) is found to be of the most importance.},
doi = {10.1063/1.2190105},
journal = {AIP Conference Proceedings},
number = 1,
volume = 821,
place = {United States},
year = {Mon Mar 20 00:00:00 EST 2006},
month = {Mon Mar 20 00:00:00 EST 2006}
}
  • We report on the performance and planned upgrades to the Fermilab Accumulator Stacktail Stochastic Cooling System. The current system has achieved a maximum flux of 16.5e10/hour, limited by the input flux of antiprotons. The upgrades are designed to handle flux in excess of 40e10/hour.
  • An experiment was designed to check theoretical predictions of charge homogenization and emittance growth in nonuniform space-charge--dominated beams due to conversion of field energy into transverse kinetic energy. Five beamlets were masked out of a solid 5-keV electron beam and injected into a periodic solenoidal focusing channel. Phosphor screen images showed that the beamlets merged into a uniform density single beam. Experimental results on merging distance and emittance growth were compared with theory and simulation and good agreement was found.
  • Numerical simulations using the WARP particle-in-cell code are applied to study the evolution of the space-charge-dominated beam in the University of Maryland Electron Ring (1). The self-consistent simulations play a special role because the nonlinear nature of the dynamics makes accurate analytic predictions difficult. Simulations of a matched beam at the nominal design parameters show negligible degradation in beam quality after 10 turns. The role of lattice element nonlinearities on the beam evolution has been investigated. An rms mismatch is shown to lead to bounded oscillations and an acceptable level of emittance growth. A mismatch in the dispersion function, however,more » is shown to lead to a higher levels of emittance growth, and dispersion matching is currently under investigation. {copyright} {ital 1998 American Institute of Physics.}« less
  • Experiments and particle-in-cell simulations demonstrate the appearance of wavelike transverse density variations in a space-charge dominated electron beam. Simulations show how an aperture located near the source gives rise to a nonequilibrium phase-space distribution with strong force imbalance confined to a sheath near the beam edge. Tracking of particles in this sheath, starting near the aperture{close_quote}s edge, reproduces well the onset of the perturbation. The subsequent evolution of the perturbation over about one meter suggests the appearance of a transverse wave. For the parameters investigated, simulations further indicate that the perturbation damps out over a few plasma periods without causingmore » any rms emittance growth. {copyright} {ital 1999} {ital The American Physical Society}« less
  • A continuous electron beam with a correlated emittance will eventually thermalize. Initially, the beam emittance for an intense, high-brightness, space-charge-dominated beam will oscillate, but after a sufficiently long time, it will reach an equilibrium value. The emittance oscillations are due to coherent transverse plasma oscillations in the beam and are a manifestation of periodic energy exchange between potential and kinetic energies. The beam eventually attains an equilibrium emittance, as the beam equipartitions the kinetic and potential energies. This equipartioning is reached as the beam thermalizes due to a form of Landau damping of the radial oscillations at different radial positionsmore » within the beam. Slight differences in the transverse plasma oscillation frequency for different radial positions lead to incoherence in the oscillations. In this paper, we calculate the equilibrium time scales required for equipartioning. We show that the equilibrium emittance scalings and magnitude can be predicted by conservation of energy considerations. In addition, we show that, in the space-charge dominated regime, there is a correspondence between the energy-conservation approach and the kinematic approach. {copyright} {ital 1999} {ital The American Physical Society}« less