Buffered high charge spectrally-peaked proton beams in the relativistic-transparency regime
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Author(s)
Type
Journal Article
Abstract
Spectrally-peaked proton beams of high charge (Ep ≈ 8 MeV, ∆E ≈
4 MeV, N ≈ 50 nC ) have been observed from the interaction of an intense laser
(> 1019 Wcm−2
) with ultrathin CH foils, as measured by spectrally-resolved full beam
profiles. These beams are reproducibly generated for foil thicknesses 5-100 nm, and
exhibit narrowing divergence with decreasing target thickness down to ≈ 8
◦
for 5 nm.
Simulations demonstrate that the narrow energy spread feature is a result of buffered
acceleration of protons. The radiation pressure at the front of the target results in
asymmetric sheath fields which permeate throughout the target, causing preferential
forward acceleration. Due to their higher charge-to-mass ratio, the protons outrun a
carbon plasma driven in the relativistic transparency regime.
4 MeV, N ≈ 50 nC ) have been observed from the interaction of an intense laser
(> 1019 Wcm−2
) with ultrathin CH foils, as measured by spectrally-resolved full beam
profiles. These beams are reproducibly generated for foil thicknesses 5-100 nm, and
exhibit narrowing divergence with decreasing target thickness down to ≈ 8
◦
for 5 nm.
Simulations demonstrate that the narrow energy spread feature is a result of buffered
acceleration of protons. The radiation pressure at the front of the target results in
asymmetric sheath fields which permeate throughout the target, causing preferential
forward acceleration. Due to their higher charge-to-mass ratio, the protons outrun a
carbon plasma driven in the relativistic transparency regime.
Date Issued
2016-01-18
Date Acceptance
2015-12-15
Citation
New Journal of Physics, 2016, 18
ISSN
1367-2630
Publisher
IOP Publishing
Journal / Book Title
New Journal of Physics
Volume
18
Copyright Statement
© 2016 IOP Publishing Ltd and Deutsche Physikalische Gesellschaft. Original content from this
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Sponsor
Engineering & Physical Science Research Council (E
Engineering & Physical Science Research Council (E
Science and Technology Facilities Council (STFC)
Grant Number
EP/E035728/1
EP/K022415/1
ST/J002062/1 John Adams Inst
Subjects
Fluids & Plasmas
02 Physical Sciences
Publication Status
Published
Article Number
013038