Speaker
Manuel Blanco
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P2.2039.pdf
Suitability and robustness of triangular nanostructured targets for proton
acceleration
M. Blanco1 , M.T. Flores-Arias1 , M. Vranic2
1 Photonics4Life Research group, Applied Physics Department, Faculty of Physics,
Universidade de Santiago de Compostela, Santiago de Compostela, Spain
2 GoLP/IPFN, Instituto Superior Técnico, University of Lisbon, Lisbon, Portugal
Proton acceleration via the target normal sheath acceleration (TNSA) mechanism has became
a promising tool for future and current technologies where accelerated ions with energies in the
MeV range are needed. The possibility of achieving these energies with table-top femtosec-
ond laser sources and thin foils makes this technology cheaper for some applications than the
traditional particle acceleration methods.
A current challenge for TNSA is to improve the properties of the proton beam without in-
creasing the laser peak power. To that end several proposals for target engineering have been
made, such as manipulating the target thickness, growing a low density foam on top of the tar-
get, nanostructuring the rear surface or the front surface of the target. The latter has proven to
be a very efficient method to enhance the laser energy absorption and thus the transfer of energy
from the laser to the electrons, having as a product more energetic protons in the accelerated
beam. This method to increase the energy of the protons has demonstrated to be extremely ef-
ficient for triangular nanostructures, where nearly a 100% of the laser energy can absorbed by
the plasma if the proper conditions are met [1].
In this contribution we present the results from realistic three-dimensional particle-in-cell
(PIC) simulations of triangular nanostructured targets, in order to give a realistic estimate of the
outcome of such an experiment, and be able to estimate the expected number and corresponding
energies of the accelerated protons. We also address the robustness of this acceleration method
by analyzing how the laser energy absorption is affected by deviations of the setup from the
assumed ideal situation, such as changes in the laser peak intensity, changes in the ion species,
the existence of irregularities in the nanostructures, or the existence of a pre-plasma at the target
front surface. Our findings demonstrate, on one hand, that the very high absorption percentages
achieved are robust with respect to non-ideal target manufacturing, but on the other hand, that
very high contrast laser pulses are needed to preclude the formation of a pre-plasma region.
References
[1] M. Blanco, M.T. Flores-Arias, C. Ruiz and M. Vranic, New J. Phys 19, 033004 (2017)
