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Proceedings Paper

Theoretical studies of collisionless shocks for laser-acceleration of ions
Author(s): A. Stockem; F. Fiuza; E. Boella; R. A. Fonseca; L. O. Silva; C. Joshi; W. B. Mori
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Paper Abstract

Recently, strong effort has been done in exploring shock acceleration for the generation of highly energetic ion beams, with applications e.g. for medical purposes. The heating of a near-critical density plasma target with a laser, increases the electron temperature and excites ion acoustic waves, which can lead to electrostatic shock formation due to non-linear wave breaking. The higher inertia background ions are reflected and accelerated at the shock potential, showing a quasi-monoenergetic profile. For the first time, its feasibility has been demonstrated experimentally, gaining 20 MeV protons with a very narrow energy spread1 and a predicted scaling up to 200 MeV for lasers with a0 = 10.2 In the quest for high proton energies, optimal conditions for shock formation have to be found. We developed a relativistic model that connects the initial parameters with the steady state shock Mach number, which is based on the Sagdeev approach,3, 4 showing an increase of the ion energy for high upstream electron temperatures and low downstream to upstream density ratios5 and high temperature ratios, which has been confirmed by particle-in-cell simulations. In the context of producing a quasi-monoenergetic beam profile, we studied the enhancement of the Weibel instability in an electrostatic shock setup. Governing parameter regimes for the transition to an electromagnetic shock, which is associated with a broadening of the ion spectrum, were determined analytically and confirmed with simulations.

Paper Details

Date Published: 7 May 2013
PDF: 6 pages
Proc. SPIE 8779, Laser Acceleration of Electrons, Protons, and Ions II; and Medical Applications of Laser-Generated Beams of Particles II; and Harnessing Relativistic Plasma Waves III, 87790B (7 May 2013); doi: 10.1117/12.2018491
Show Author Affiliations
A. Stockem, Univ. Técnica de Lisboa (Portugal)
F. Fiuza, Lawrence Livermore National Lab. (United States)
E. Boella, Univ. Técnica de Lisboa (Portugal)
Politecnico di Torino (Italy)
R. A. Fonseca, Univ. Técnica de Lisboa (Portugal)
Lisbon Univ. Institute Portugal (Portugal)
L. O. Silva, Univ. Técnica de Lisboa (Portugal)
C. Joshi, The Univ. of California, Los Angeles (United States)
W. B. Mori, The Univ. of California, Los Angeles (United States)


Published in SPIE Proceedings Vol. 8779:
Laser Acceleration of Electrons, Protons, and Ions II; and Medical Applications of Laser-Generated Beams of Particles II; and Harnessing Relativistic Plasma Waves III
Eric Esarey; Carl B. Schroeder; Wim P. Leemans; Kenneth W. D. Ledingham; Dino A. Jaroszynski, Editor(s)

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