An Abundance of Extremely Large Clusters as a Target for Intense Laser-Matter Interaction

Abstract

The advent of very intense, short-pulse lasers changed dramatically the field of laser-matter interaction. The interest in new forms of target brought clusters to the forefront as a very promising and unique medium. Here, extremely large Xe or ${\text{CO}}_2$ clusters embedded in an abundance of smaller ones were formed and subsequently irradiated by intense laser pulses ($\lesssim 10^{19}\,{\text{W}}/{\text{cm}}^2$) to demonstrate the specific character of such a medium and its suitability for intense laser-matter interaction. Emission of short-wavelength radiation quantified in the spectral range known as the “water window” constituted the reference for the target performance. The clusters were formed in a double-stream gas-puff equipped with a gas reservoir cooled down to 245 K and backed by a low-to-moderate pressure of $\le 12 \,{\text{bar}}$. The obtained atomic/molecular compounds, mostly of an irregular shape and of an average diameter $\simeq 2.4 \pm 0.5 \,\upmu {\text{m}}$ in the case of Xe and $\simeq 2.0\pm 0.4 \,\upmu {\text{m}}$ for ${\text{CO}}_2$, have been imaged by optical microscopy while the size was determined by the standard scattering method. A scenario explaining the formation of such clusters has been proposed. The interaction results show that a photon/particle source can be copious when based on the developed target technology with an abundance of the extremely large clusters. These clusters enable also the experiments with a single-cluster target.