Density bump formation in a collisionless electrostatic shock wave in a laser-ablated plasma

TL;DR

This paper investigates the formation of a density bump in a collisionless electrostatic shock wave within laser-ablated plasma, combining experimental observations and numerical simulations to understand the underlying particle dynamics.

Contribution

It provides a detailed physical interpretation of the density bump formation, linking experimental results with simulation insights into ion behavior during laser ablation.

Findings

Density bump consists of transit particles from dense plasma and background ions.

Simulations reveal ion acceleration and wave interactions at the shock front.

Experimental and numerical results agree on the origin of the density bump.

Abstract

The emergence of a density bump at the front of a collisionless electrostatic shock wave have been observed experimentally during the ablation of an aluminium foil by a femtosecond laser pulse. We have performed numerical simulations of the dynamics of this phenomena developing alongside the generation of a package of ion-acoustic waves, exposed to a continual flow of energetic electrons, in a collisionless plasma. We present the physical interpretation of the observed effects and show that the bump consists of transit particles, namely, the accelerated ions from the dense plasma layer, and the ions from the diluted background plasma, formed by a nanosecond laser prepulse during the ablation.