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Title: Scattering effects in passive foil focusing of ion beams

A stack of thin, closely spaced conducting foils has been investigated by Lund et al. [ Phys. Rev. ST Accel. Beams 16, 044202 (2013)] as a passive focusing lens for intense ion beams. The foils mitigate space-charge defocusing forces to enable the beam self-magnetic field to focus. In this study, we analyze possible degradation of focusing due to scattering of beam ions resulting from finite foil thickness using an envelope model and numerical simulations with the particle-in-cell code WARP. Ranges of kinetic energy where scattering effects are sufficient to destroy passive focusing are quantified. The scheme may be utilized to focus protons produced in intense laser-solid accelerator schemes. The spot size of an initially collimated 30 MeV proton beam with initial rms radius 200 μm, perveance Q=1.8×10 -2, and initial transverse emittance ϵ x,rms=0.87 mm mrad propagating through a stack of 6.4 μm thick foils, spaced 100 μm apart, gives a 127.5 μm spot with scattering and a 81.0 μm spot without scattering, illustrating the importance of including scattering effects.
Authors:
 [1] ;  [2] ;  [3] ;  [4] ;  [1]
  1. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  2. Michigan State Univ., East Lansing, MI (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. CompX, Del Mar, CA (United States)
Publication Date:
Grant/Contract Number:
FG02-04ER41289; AC52-07NA27344
Type:
Published Article
Journal Name:
Physical Review Special Topics. Accelerators and Beams
Additional Journal Information:
Journal Volume: 18; Journal Issue: 9; Journal ID: ISSN 1098-4402
Publisher:
American Physical Society (APS)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 43 PARTICLE ACCELERATORS
OSTI Identifier:
1215461
Alternate Identifier(s):
OSTI ID: 1221632