Synchrotron emission from nanowire-array targets irradiated by ultraintense laser pulses

TL;DR

This study uses 2D particle-in-cell simulations to analyze synchrotron emission from nanowire arrays irradiated by ultraintense femtosecond laser pulses, identifying key radiation mechanisms and optimizing conditions for high-energy photon production.

Contribution

It provides the first detailed numerical analysis of synchrotron emission mechanisms in nanowire-array targets under ultraintense laser irradiation, highlighting optimal parameters for maximum radiation yield.

Findings

Maximum 10% conversion efficiency at 36-50 nm wire width.

Efficient radiation over a broad parameter range compared to uniform plasma.

Enhanced radiation efficiency with a plasma mirror at the backside.

Abstract

We present a numerical study, based on two-dimensional particle-in-cell simulations, of the synchrotron emission induced during the interaction of femtosecond laser pulses of intensities $I=10^{21}-10^{23}\,\mathrm{Wcm}^{-2}$ with nanowire arrays. Through an extensive parametric scan on the target parameters, we identify and characterize several dominant radiation mechanisms, mainly depending on the transparency or opacity of the plasma produced by the wire expansion. At $I=10^{22}\,\mathrm{Wcm}^{-2}$, the emission of high-energy ($>10\,\mathrm{keV}$) photons attains a maximum conversion efficiency of $\sim 10\%$ for $36-50\,\mathrm{nm}$ wire widths and $1\,\mu\mathrm{m}$ interspacing. This maximum radiation yield is similar to that achieved in uniform plasma of same average (sub-solid) density, but nanowire arrays provide efficient radiation sources over a broader parameter range. We examine the variations of the photon spectra with the laser intensity and the wire material. Finally, we demonstrate that the radiation efficiency can be further enhanced by adding a plasma mirror at the backside of the nanowire array.