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Proton acceleration by a pair of successive ultraintense femtosecond laser pulses

Ferri, J.; Senje, L. LU ; Dalui, M. LU ; Svensson, K. LU ; Aurand, B. LU ; Hansson, M.; Persson, A. LU ; Lundh, O. LU ; Wahlström, C. G. LU and Gremillet, L., et al. (2018) In Physics of Plasmas 25(4).
Abstract

We investigate the target normal sheath acceleration of protons in thin aluminum targets irradiated at a relativistic intensity by two time-separated ultrashort (35 fs) laser pulses. When the full-energy laser pulse is temporally split into two identical half-energy pulses, and using target thicknesses of 3 and 6 μm, we observe experimentally that the second half-pulse boosts the maximum energy and charge of the proton beam produced by the first half-pulse for time delays below ∼0.6-1 ps. Using two-dimensional particle-in-cell simulations, we examine the variation of the proton energy spectra with respect to the time-delay between the two pulses. We demonstrate that the expansion of the target front surface caused by the first pulse... (More)

We investigate the target normal sheath acceleration of protons in thin aluminum targets irradiated at a relativistic intensity by two time-separated ultrashort (35 fs) laser pulses. When the full-energy laser pulse is temporally split into two identical half-energy pulses, and using target thicknesses of 3 and 6 μm, we observe experimentally that the second half-pulse boosts the maximum energy and charge of the proton beam produced by the first half-pulse for time delays below ∼0.6-1 ps. Using two-dimensional particle-in-cell simulations, we examine the variation of the proton energy spectra with respect to the time-delay between the two pulses. We demonstrate that the expansion of the target front surface caused by the first pulse significantly enhances the hot-electron generation by the second pulse arriving after a few hundreds of fs time delay. This enhancement, however, does not suffice to further accelerate the fastest protons driven by the first pulse once three-dimensional quenching effects have set in. This implies a limit to the maximum time delay that leads to proton energy enhancement, which we theoretically determine.

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published
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Physics of Plasmas
volume
25
issue
4
publisher
American Institute of Physics
external identifiers
  • scopus:85045977717
ISSN
1070-664X
DOI
10.1063/1.5026391
language
English
LU publication?
yes
id
51b8eec3-2535-4d73-a36d-76e3bbff35c1
date added to LUP
2018-05-04 15:50:26
date last changed
2019-04-10 04:07:48
@article{51b8eec3-2535-4d73-a36d-76e3bbff35c1,
  abstract     = {<p>We investigate the target normal sheath acceleration of protons in thin aluminum targets irradiated at a relativistic intensity by two time-separated ultrashort (35 fs) laser pulses. When the full-energy laser pulse is temporally split into two identical half-energy pulses, and using target thicknesses of 3 and 6 μm, we observe experimentally that the second half-pulse boosts the maximum energy and charge of the proton beam produced by the first half-pulse for time delays below ∼0.6-1 ps. Using two-dimensional particle-in-cell simulations, we examine the variation of the proton energy spectra with respect to the time-delay between the two pulses. We demonstrate that the expansion of the target front surface caused by the first pulse significantly enhances the hot-electron generation by the second pulse arriving after a few hundreds of fs time delay. This enhancement, however, does not suffice to further accelerate the fastest protons driven by the first pulse once three-dimensional quenching effects have set in. This implies a limit to the maximum time delay that leads to proton energy enhancement, which we theoretically determine.</p>},
  articleno    = {043115},
  author       = {Ferri, J. and Senje, L. and Dalui, M. and Svensson, K. and Aurand, B. and Hansson, M. and Persson, A. and Lundh, O. and Wahlström, C. G. and Gremillet, L. and Siminos, E. and Dubois, T. C. and Yi, L. and Martins, J. L. and Fülöp, T.},
  issn         = {1070-664X},
  language     = {eng},
  month        = {04},
  number       = {4},
  publisher    = {American Institute of Physics},
  series       = {Physics of Plasmas},
  title        = {Proton acceleration by a pair of successive ultraintense femtosecond laser pulses},
  url          = {http://dx.doi.org/10.1063/1.5026391},
  volume       = {25},
  year         = {2018},
}