Probing ultrafast dynamics in a solid-density plasma created by an intense femtosecond laser

Amitava Adak,Prashant Kumar Singh,G Ravindra Kumar,P Brijesh,Gourab Chatterjee,Amit D Lad,Dave Blackman,A P L Robinson,John Pasley

doi:10.1088/1742-6596/688/1/012001

Abstract

We report a study on the dynamics of a near-solid density plasma using an ultraviolet (266 nm) femtosecond probe laser pulse, which can penetrate to densities of ∼ 1022 cm-3, nearly an order of magnitude higher than the critical density of the 800 nm, femtosecond pump laser. Time-resolved probe-reflectivity from the plasma shows a rapid decay (picosecond- timescale) while the time-resolved reflected probe spectra show red shifts at early temporal delays and blue shifts at longer delays. This spectral behaviour of the reflected probe can be explained by a laser-driven shock moving inward and a subsequent hydrodynamic free expansion in the outward direction.

Highlights

Ultra-intense lasers can create extremely hot, high-density plasma while interacting with a solid
We investigate the temporal dynamics of a highly dense electron layer(ne = 1022 cm−3 ) inside a plasma created on an aluminium-coated BK7 glass target by a laser at relativistic light intensities
Doppler spectrometry of the reflected probe enables the observation of the ultrafast motion of its critical surface inside the hot dense plasma

Summary

Introduction

Ultra-intense lasers can create extremely hot, high-density plasma while interacting with a solid. A lot of experimental and theoretical studies have been performed in recent decades for the basic understanding of intense short-pulse-laser matter interaction[3] and for applications like particle acceleration[4, 5]. We investigate the temporal dynamics of a highly dense electron layer(ne = 1022 cm−3 ) inside a plasma created on an aluminium-coated BK7 glass target by a laser at relativistic light intensities. Doppler spectrometry of the reflected probe enables the observation of the ultrafast motion of its critical surface (high density layer) inside the hot dense plasma. Published under licence by IOP Publishing Ltd doi:10.1088/1742-6596/688/1/012001

Experiment

Results & Discussions

Simulation

Conclusions