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Title: Long-term, correlated emittance decrease in intense, high-brightness induction linacs

Abstract

Simulations of high-brightness induction linacs often show a slow, long-term emittance decrease as the beam is matched from the electron gun into the linac. Superimposed on this long-term decrease are rapid emittance oscillations. These effects can be described in terms of correlations in the beam{close_quote}s radial phase space. The rapid emittance oscillations are due to transverse plasma oscillations, which stay nearly in phase for different radial positions within the beam. The initial emittance, just after the electron gun, is dominated by nonlinear focusing within the gun introduced by the anode exit hole. Due to the large space-charge force of an intense electron beam, the focusing of the beam through the matching section introduces an effective nonlinear force (from the change in the particles{close_quote} potential energies) which counteracts the nonlinearities from the electron gun, leading to an average, long-term emittance decrease. Not all of the initial nonlinearity is removed by the matching procedure, and there are important consequences both for emittance measurements using solenoid focal length scans and for focusing the electron beam to a target. {copyright} {ital 1999 American Institute of Physics.}

Authors:
 [1]
  1. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Publication Date:
OSTI Identifier:
362684
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 6; Journal Issue: 9; Other Information: PBD: Sep 1999
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION; 43 PARTICLE ACCELERATORS; PLASMA WAVES; COLLECTIVE ACCELERATORS; LINEAR ACCELERATORS; BRIGHTNESS; FOCUSING; ELECTRON GUNS; ELECTRON BEAMS; BEAM DYNAMICS; OSCILLATIONS; THERMIONIC EMISSION

Citation Formats

Carlsten, B.E. Long-term, correlated emittance decrease in intense, high-brightness induction linacs. United States: N. p., 1999. Web. doi:10.1063/1.873621.
Carlsten, B.E. Long-term, correlated emittance decrease in intense, high-brightness induction linacs. United States. doi:10.1063/1.873621.
Carlsten, B.E. Wed . "Long-term, correlated emittance decrease in intense, high-brightness induction linacs". United States. doi:10.1063/1.873621.
@article{osti_362684,
title = {Long-term, correlated emittance decrease in intense, high-brightness induction linacs},
author = {Carlsten, B.E.},
abstractNote = {Simulations of high-brightness induction linacs often show a slow, long-term emittance decrease as the beam is matched from the electron gun into the linac. Superimposed on this long-term decrease are rapid emittance oscillations. These effects can be described in terms of correlations in the beam{close_quote}s radial phase space. The rapid emittance oscillations are due to transverse plasma oscillations, which stay nearly in phase for different radial positions within the beam. The initial emittance, just after the electron gun, is dominated by nonlinear focusing within the gun introduced by the anode exit hole. Due to the large space-charge force of an intense electron beam, the focusing of the beam through the matching section introduces an effective nonlinear force (from the change in the particles{close_quote} potential energies) which counteracts the nonlinearities from the electron gun, leading to an average, long-term emittance decrease. Not all of the initial nonlinearity is removed by the matching procedure, and there are important consequences both for emittance measurements using solenoid focal length scans and for focusing the electron beam to a target. {copyright} {ital 1999 American Institute of Physics.}},
doi = {10.1063/1.873621},
journal = {Physics of Plasmas},
number = 9,
volume = 6,
place = {United States},
year = {1999},
month = {9}
}