Pre-plasma formation in experiments using petawatt lasers

Abstract

We used time-resolved shadowgraphy to characterize the pre-plasma formation in solid-target interaction experiments with micrometer-scale accuracy. We performed quantitative measurements of the plasma density for amplified spontaneous emission (ASE) levels ranging from 2 · 10(-7) to 10(-10) backed with 2-dimensional hydrodynamic simulations. We find that ASE levels above 10(-9) are able to create a significant pre-plasma plume that features a plasma canal driving a self-focusing of the laser beam. For ASE levels of 10(-10), no ASE pre-plasma could be detected.

Optimization of plasma mirror reflectivity and optical quality using double laser pulses

“…This fraction of instantaneous intensity relative to that of the main pulse is known as the intensity contrast level. If the contrast level is not sufficiently high the laser will initiate a preplasma expansion [2], altering the initial conditions upon which highly nonlinear ultrashort laser plasma interactions have been shown to sensitively depend, such as in ion acceleration [3][4][5] or harmonic generation [6]. Debate continues over the optimum level of ASE for different experiments but consensus exists in that it should be known and controlled in order to advance the interpretation of experimental laser plasma physics.…”

Electron acceleration at grazing incidence of a subpicosecond intense laser pulse onto a plane solid target

“…In this paper, the generation of hot electrons at grazing incidence of a subpicosecond intense laser pulse onto a plane solid target is analyzed for the parameters of the petawatt high-energy laser for heavy ion experiments (PHELIX) (Bagnoud et al, 2010;Wagner et al, 2014a) using three-dimensional (3D) particle-in-cell (PIC) modeling (Pukhov, 1999) and a wide-range hydro modeling (Povarnitsyn et al, 2012a) of the preplasma expansion under the action of the laser prepulse. Elaboration of wide-range models of the laser-matter interaction is necessary for planning and interpretation of experiments carried out in view of different applications aimed for the development of secondary sources of high energy particles and hard radiation (Morace et al, 2014;Brabetz et al, 2015;Rusby et al, 2015;Vaisseau et al, 2015).…”

A TLD-based ten channel system for the spectrometry of bremsstrahlung generated by laser-matter interaction

“…(8) can be considered as the actual intensities because the preplasma expansion was assumed to be small (some 10 μm according to [17]) compared to the Rayleigh length of the used parabola (Rayleigh length: $ 300 μm).…”