Description
In recent years, the continuous emergence of numerous facilities capable of generating highly intense, short-duration (~fs) laser pulses with a high grade of precision and reproducibility has driven growing interest in laser-plasma interaction applications, particularly in proton and ion acceleration through Target Normal Sheath Acceleration (TNSA) mechanism. This technique represents a promising compact alternative to conventional particle accelerators, with potential applications in science, industry, and medicine. However, to make these sources practically available, improvements in maximum particle energy, number of accelerated particles, beam stability, and shot-to-shot reproducibility at high repetition rates are still required.
In this context, one particularly promising solution is represented by the so called Double Layer Targets (DLTs), consisting of a thin solid foil coated with a nanostructured layer placed at the laser-plasma interaction interface. In particular, carbon nanofoam-based DLTs are currently being investigated at the NanoLab of the Politecnico di Milano due to their ability to enhance laser absorption and hot electron generation, thus improving ion acceleration efficiency.
Despite their advantages, DLTs also introduce significant experimental challenges. The nanostructured layer is extremely delicate and may be damaged not only by the laser prepulse, but also by secondary effects such as shock waves, heat propagation, and debris generated during the interaction. This issue becomes particularly critical in high-repetition-rate applications, where cumulative damage in neighbouring region of the shot can reduce the performance of subsequent shots.
The present work investigates the influence of carbon nanofoam density, geometrical thickness, and areal density on its damage resistance. The study combines data from experimental campaigns performed at ELI Beamlines and at the NanoLab of the Politecnico di Milano, highlighting the key role of nanofoam structural properties in the development of robust advanced targets for high-repetition-rate laser-plasma experiments.
