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Title: Large energy-spread beam diagnostics through quadrupole scans

Abstract

The Facility for Advanced Accelerator and Experimental Tests (FACET) is a new user facility at the SLAC National Accelerator Laboratory, servicing next-generation accelerator experiments. The 1.5% RMS energy spread of the FACET beam causes large chromatic aberrations in optics. These aberrations necessitate updated quadrupole scan fits to remain accurate.

Authors:
; ; ;  [1]
  1. SLAC National Accelerator Laboratory (United States)
Publication Date:
OSTI Identifier:
22075888
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1507; Journal Issue: 1; Conference: 15. advanced accelerator concepts workshop, Austin, TX (United States), 10-15 Jun 2012; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM OPTICS; CHROMATIC ABERRATIONS; FERMILAB ACCELERATOR; PARTICLE BEAMS; QUADRUPOLES; STANFORD LINEAR ACCELERATOR CENTER

Citation Formats

Frederico, Joel, Adli, Erik, Hogan, Mark, and Raubenheimer, Tor. Large energy-spread beam diagnostics through quadrupole scans. United States: N. p., 2012. Web. doi:10.1063/1.4773759.
Frederico, Joel, Adli, Erik, Hogan, Mark, & Raubenheimer, Tor. Large energy-spread beam diagnostics through quadrupole scans. United States. doi:10.1063/1.4773759.
Frederico, Joel, Adli, Erik, Hogan, Mark, and Raubenheimer, Tor. 2012. "Large energy-spread beam diagnostics through quadrupole scans". United States. doi:10.1063/1.4773759.
@article{osti_22075888,
title = {Large energy-spread beam diagnostics through quadrupole scans},
author = {Frederico, Joel and Adli, Erik and Hogan, Mark and Raubenheimer, Tor},
abstractNote = {The Facility for Advanced Accelerator and Experimental Tests (FACET) is a new user facility at the SLAC National Accelerator Laboratory, servicing next-generation accelerator experiments. The 1.5% RMS energy spread of the FACET beam causes large chromatic aberrations in optics. These aberrations necessitate updated quadrupole scan fits to remain accurate.},
doi = {10.1063/1.4773759},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1507,
place = {United States},
year = 2012,
month =
}
  • The Facility for Advanced Accelerator and Experimental Tests (FACET) is a new user facility at the SLAC National Accelerator Laboratory, servicing next-generation accelerator experiments. The 1.5% RMS energy spread of the FACET beam causes large chromatic aberrations in optics. These aberrations necessitate updated quadrupole scan fits to remain accurate.
  • This paper considers an intense nonneutral charged particle beam propagating in the z-direction through a periodic focusing quadrupole magnetic field with transverse focusing force, -{kappa}{sub q}(s)[xe{sub x}-ye{sub y}], on the beam particles. Here, s={beta}{sub b}ct is the axial coordinate, ({gamma}{sub b}-1)m{sub b}c{sup 2} is the directed axial kinetic energy of the beam particles, q{sub b} and m{sub b} are the charge and rest mass, respectively, of a beam particle, and the oscillatory lattice coefficient satisfies {kappa}{sub q}(s+S)={kappa}{sub q}(s), where S is the axial periodicity length of the focusing field. The particle motion in the beam frame is assumed to bemore » nonrelativistic, and the Vlasov-Maxwell equations are employed to describe the collisionless nonlinear evolution of the distribution function f{sub b}(x,y,x{sup '},y{sup '},s) and the (normalized) self-field potential {psi}(x,y,s)=q{sub b}{phi}(x,y,s)/{gamma}{sub b}{sup 3}m{sub b}{beta}{sub b}{sup 2}c{sup 2} in the transverse laboratory-frame phase space (x,y,x{sup '},y{sup '}), assuming a thin beam with characteristic radius r{sub b}<<S. It is shown that collective processes and the nonlinear transverse beam dynamics can be fully simulated in a compact Paul trap configuration in which a long nonneutral plasma column (L>>r{sub p}) is confined axially by applied dc voltages V=const. on end cylinders at z={+-}L, and transverse confinement in the x-y plane is provided by segmented cylindrical electrodes (at radius r{sub w}) with applied oscillatory voltages {+-}V{sub 0}(t) over 90 deg. segments. Here, V{sub 0}(t+T)=V{sub 0}(t), where T=const. is the oscillation period, and the oscillatory quadrupole focusing force on a particle with charge q and mass m near the cylinder axis is -m{kappa}{sub q}(t)[xe{sub x}-ye{sub y}], where {kappa}{sub q}(t){identical_to}8qV{sub 0}(t)/{pi}mr{sub w}{sup 2}. This configuration offers the possibility of simulating intense beam propagation over large distances in a compact configuration which is stationary in the laboratory frame.« less
  • This paper considers an intense non-neutral charged particle beam propagating in the z-direction through a periodic focusing quadrupole magnetic field with transverse focusing force, -{kappa}{sub q}(s)[xe{sub x}-ye{sub y}], on the beam particles. Here, s={beta}{sub b}ct is the axial coordinate, ({gamma}{sub b}-1)m{sub b}c{sup 2} is the directed axial kinetic energy of the beam particles, q{sub b} and m{sub b} are the charge and rest mass, respectively, of a beam particle, and the oscillatory lattice coefficient satisfies {kappa}{sub q}(s+S)={kappa}{sub q}(s), where S is the axial periodicity length of the focusing field. The particle motion in the beam frame is assumed to bemore » nonrelativistic, and the Vlasov-Maxwell equations are employed to describe the nonlinear evolution of the distribution function f{sub b}(x,y,x{sup '},y{sup '},s) and the (normalized) self-field potential {psi}(x,y,s)=q{sub b}{phi}(x,y,s)/{gamma}{sub b}{sup 3}m{sub b}{beta}{sub b}{sup 2}c{sup 2} in the transverse laboratory-frame phase space (x,y,x{sup '},y{sup '}), assuming a thin beam with characteristic radius r{sub b}<<S. It is shown that collective processes and the nonlinear transverse beam dynamics can be simulated in a compact Paul trap configuration in which a long non-neutral plasma column (L>>r{sub p}) is confined axially by applied dc voltages V=const on end cylinders at z={+-}L, and transverse confinement in the x-y plane is provided by segmented cylindrical electrodes (at radius r{sub w}) with applied oscillatory voltages {+-}V{sub 0}(t) over 90 degree sign segments. Here, V{sub 0}(t+T)=V{sub 0}(t), where T=const is the oscillation period, and the oscillatory quadrupole focusing force on a particle with charge q and mass m near the cylinder axis is -m{kappa}{sub q}(t)[xe{sub x}-ye{sub y}], where {kappa}{sub q}(t){identical_to}8qV{sub 0}(t)/{pi}mr{sub w}{sup 2}. (c) 2000 American Institute of Physics.« less
  • A reduction of the velocity spread of a beam of sodium atoms has been observed experimentally as the beam was slowed by an oppositely directed resonant laser beam. Over an effective slowing distance of 20 cm, the longitudinal velocity distribution of the atomic beam was contracted by a factor of 19; correspondingly, the relative-motion temperature of the atoms was lowered to 1.5 K.
  • Two simple methods of characterizing the average energy and energy spread of the electron beam have been developed at the ESRF. Both are based on analysis of the x-ray spectrum from an undulator. The first allows the absolute energy of the electrons to be determined. It is based on the dependence between the harmonics wavelengths and the electron beam energy. The x-ray beam is monochromatized at 21 keV by a silicon crystal in backscattering geometry. By adjusting the magnetic gap, one makes the third harmonic of the radiation from an undulator coincide with the energy selected by the crystal. Themore » main errors come from the uncertainties in the undulator{close_quote}s magnetic field and period. By operating the undulator at low field (K=0.36), an absolute accuracy of 10{sup {minus}3} is reached for the electron energy. The energy spread measurement is performed by analyzing the broadening of the harmonics{close_quote} profile. It is deduced from the measured ratio between the height of the peak of the seventh harmonic at 29 keV and the height of a secondary maximum at lower energy. The measured low current energy spread is 1.1{times}10{sup {minus}3}{plus_minus}20{percent}. It increases with the single bunch current due to turbulent bunch widening. {copyright} {ital 1996 American Institute of Physics.}« less