Kinetic and finite ion mass effects on the transition to relativistic self-induced transparency in laser-driven ion acceleration
Konferensbidrag (offentliggjort, men ej förlagsutgivet), 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 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, the threshold density above which hole-boring 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 hole-boring 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.

Författare

Evangelos Siminos

Chalmers, Fysik, Subatomär fysik och plasmafysik

M. Grech

Benjamin Svedung Wettervik

Chalmers, Fysik, Subatomär fysik och plasmafysik

Tünde Fülöp

Chalmers, Fysik, Subatomär fysik och plasmafysik

3rd European Advanced Accelerator Concepts Workshop

Fundament

Grundläggande vetenskaper

Ämneskategorier

Fusion, plasma och rymdfysik

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Skapat

2017-12-29