0_6948 Porous materials known as foams have attracted a considerable interest in the field of laser-plasma interaction. In the framework of Inertial Confinement Fusion (ICF) research, low-Z (i.e. plastic) foams have been proposed as outer layer in a fusion target with the purpose of smoothing laser beam inhomogeneities, increasing the laser absorption and enhancing the ablation pressure [1,2]. Most of ICF experiments reported in literature involve plastic foams produced by chemical methods, whose internal structure is made of structural elements (e.g. filaments and membranes) and voids characterized by a length scale in the micrometer range or larger. Therefore, the potential advantages of a target structuring at a length scale comparable to (or shorter than) the laser wavelength is a largely unexplored topic.   Moreover, while recent studies indicate that ablators of mid-Z elements – such as carbon – have the potential to mitigate Laser Plasma Instabilities and increase the performance of the target in both indirect-drive and direct-drive schemes [3,4], the behavior of low-density carbon foam in ICF experiments is essentially unknown. In this contribution we report about the behavior of nanostructured carbon foams produced with the Pulsed Laser Deposition (PLD) technique [5] under the action of a high-power nanosecond-long laser beam, at conditions relevant for ICF. PLD carbon nanofoams have already been exploited in the field of ultra-intense, ultra-short laser-plasma interaction as the near-critical layer in double-layer targets for ion acceleration [6,7]. These nanofoams also represent a promising candidate material for ICF targets, since they potentially combine benefits coming from the use of a mid-Z element and from their internal structure at the sub-micrometer scale.    
We consider two different set of carbon nanofoams, characterized by different morphology (fractal-like and tree-like) and average density (~ 6 mg/cm³ and 18 mg/cm³, respectively). The samples have been irradiated by the main beam of the ABC facility, at a wavelength of 1054 nm, with a time duration of 3 ns and a maximum intensity on the target of about 10¹⁴ W/cm². Multiple diagnostics for characterizing the plasma behavior have been used, including optical streak camera, interferometry, shadowgraphy, visible spectroscopy and charged particles detectors.

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[2] M. Cipriani et al., High Pow. Laser Sci. Eng., 9 (2021) e40 
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[5] A. Maffini et al., App. Surf. Sci. 599 (2022) 153859 
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[7] I. Prencipe et al., New Journ. Phys., 23 (2021) 093015