Kinetic and finite ion mass effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
Artikel i vetenskaplig tidskrift, 2017

We study kinetic effects responsible for the transition to relativistic self-induced transparency in the interaction of a circularly-polarized laser-pulse with an overdense plasma and their relation to hole-boring (HB) and ion acceleration. It is demonstrated using particle-in-cell simulations and an analysis of separatrices in single-electron phase-space, that ion motion can suppress fast electron escape to the vacuum, which would otherwise lead to transition to the relativistic transparency regime. A simple analytical estimate shows that for large laser pulse amplitude the time scale over which ion motion becomes important is much shorter than usually anticipated. As a result of enhanced ion mobility, the threshold density above which HB occurs decreases with the charge-to-mass ratio. Moreover, the transition threshold is seen to depend on the laser temporal profile, due to the effect that the latter has on electron heating. Finally, we report a new regime in which a transition from relativistic transparency to HB occurs dynamically during the course of the interaction. It is shown that, for a fixed laser intensity, this dynamic transition regime allows optimal ion acceleration in terms of both energy and energy spread.

separatrices

hole-boring

relativistic transparency

laser plasma interaction

Hamiltonian

near critical plasmas

Författare

Evangelos Siminos

Chalmers, Fysik, Subatomär fysik och plasmafysik

M Grech

Le Commissariat à l’Énergie Atomique et aux Énergies Alternatives (CEA)

Benjamin Svedung Wettervik

Chalmers, Fysik, Subatomär fysik och plasmafysik

Tünde Fülöp

Chalmers, Fysik, Subatomär fysik och plasmafysik

New Journal of Physics

1367-2630 (ISSN)

Vol. 19 123042- 123042

Fundament

Grundläggande vetenskaper

Ämneskategorier

Fusion, plasma och rymdfysik

DOI

10.1088/1367-2630/aa8e66