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Enhanced proton flux in the MeV range by defocused laser irradiation

Green, J. S.; Carroll, D. C.; Brenner, C.; Dromey, B.; Foster, P. S.; Kar, S.; Li, Y. T.; Markey, K.; McKenna, P. and Neely, D., et al. (2010) In New Journal of Physics 12.
Abstract
Thin Al foils (50 nm and 6 mu m) were irradiated at intensities of up to 2x10(19) W cm(-2) using high contrast (10(8)) laser pulses. Ion emission from the rear of the targets was measured using a scintillator-based Thomson parabola and beam sampling 'footprint' monitor. The variation of the ion spectra and beam profile with focal spot size was systematically studied. The results show that while the maximum proton energy is achieved around tight focus for both target thicknesses, as the spot size increases the ion flux at lower energies is seen to peak at significantly increased spot sizes. Measurements of the proton footprint, however, show that the off-axis proton flux is highest at tight focus, indicating that a previously identified... (More)
Thin Al foils (50 nm and 6 mu m) were irradiated at intensities of up to 2x10(19) W cm(-2) using high contrast (10(8)) laser pulses. Ion emission from the rear of the targets was measured using a scintillator-based Thomson parabola and beam sampling 'footprint' monitor. The variation of the ion spectra and beam profile with focal spot size was systematically studied. The results show that while the maximum proton energy is achieved around tight focus for both target thicknesses, as the spot size increases the ion flux at lower energies is seen to peak at significantly increased spot sizes. Measurements of the proton footprint, however, show that the off-axis proton flux is highest at tight focus, indicating that a previously identified proton deflection mechanism may alter the on-axis spectrum. One-dimensional particle-in-cell modelling of the experiment supports our hypothesis that the observed change in spectra with focal spot size is due to the competition of two effects: decrease in laser intensity and an increase in proton emission area. (Less)
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publication status
published
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New Journal of Physics
volume
12
publisher
IOP Publishing Ltd.
external identifiers
  • wos:000281488800001
  • scopus:77956569508
ISSN
1367-2630
DOI
10.1088/1367-2630/12/8/085012
language
English
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yes
id
f2fe37f2-6330-4ba8-b2ae-617cfa3c80a5 (old id 1672267)
date added to LUP
2010-09-23 14:41:56
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2018-05-29 12:02:25
@article{f2fe37f2-6330-4ba8-b2ae-617cfa3c80a5,
  abstract     = {Thin Al foils (50 nm and 6 mu m) were irradiated at intensities of up to 2x10(19) W cm(-2) using high contrast (10(8)) laser pulses. Ion emission from the rear of the targets was measured using a scintillator-based Thomson parabola and beam sampling 'footprint' monitor. The variation of the ion spectra and beam profile with focal spot size was systematically studied. The results show that while the maximum proton energy is achieved around tight focus for both target thicknesses, as the spot size increases the ion flux at lower energies is seen to peak at significantly increased spot sizes. Measurements of the proton footprint, however, show that the off-axis proton flux is highest at tight focus, indicating that a previously identified proton deflection mechanism may alter the on-axis spectrum. One-dimensional particle-in-cell modelling of the experiment supports our hypothesis that the observed change in spectra with focal spot size is due to the competition of two effects: decrease in laser intensity and an increase in proton emission area.},
  author       = {Green, J. S. and Carroll, D. C. and Brenner, C. and Dromey, B. and Foster, P. S. and Kar, S. and Li, Y. T. and Markey, K. and McKenna, P. and Neely, D. and Robinson, A. P. L. and Streeter, M. J. V. and Tolley, M. and Wahlström, Claes-Göran and Xu, M. H. and Zepf, M.},
  issn         = {1367-2630},
  language     = {eng},
  publisher    = {IOP Publishing Ltd.},
  series       = {New Journal of Physics},
  title        = {Enhanced proton flux in the MeV range by defocused laser irradiation},
  url          = {http://dx.doi.org/10.1088/1367-2630/12/8/085012},
  volume       = {12},
  year         = {2010},
}