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Title: Effect of image charge on the off-axis transport of intense beams in a small aperture quadrupole lattice

This paper investigates the first order image charge effects of circular conducting pipe on an intense off-axis continuous charged particle beam propagating through an alternating-gradient focusing channel. The equations of motion for the centroid and envelopes of slightly off-axis beam are derived and used to determine the equilibrium and stability conditions for the beam transport. The envelope oscillation frequencies of the mismatched beam are obtained by the smooth approximation method and by numerical evaluation of the linearly perturbed envelope equations. Depending on the beam intensity and focusing parameters, it is found that the frequency of the out-of-phase mode of envelope oscillation is reduced due to the presence of the conducting wall. Detailed numerical results for off-axis beam transport in a quadrupole lattice are presented and the stable regimes in the parameter space are determined numerically. It is observed that the unstable region for the envelope evolution with image charge effects depends on beam intensity and external focusing strength and increases with the off centering of the beam.
Authors:
; ;  [1]
  1. Variable Energy Cyclotron Centre, 1/AF, Bidhannagar, Kolkata 700064 (India)
Publication Date:
OSTI Identifier:
22218564
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 20; Journal Issue: 10; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 43 PARTICLE ACCELERATORS; APERTURES; APPROXIMATIONS; BEAM TRANSPORT; CHARGED PARTICLES; EQUATIONS OF MOTION; EQUILIBRIUM; FOCUSING; IMAGES; OSCILLATIONS; PARTICLE BEAMS; PLASMA INSTABILITY; PLASMA WAVES; WALL EFFECTS