Trying to bring the topic of laser-driven ion acceleration from the realm of fundamental science into concrete engineering applications, a team of people works in synergy integrating different, advanced kinds of expertise in materials engineering, nanotechnology, laser-plasma physics and computational science. Each goal is addressed as explained below.

Design and production of innovative targets for laser-driven ion acceleration

The well-consolidated experience in novel materials synthesis and characterization of the NanoLab – Politecnico di Milano – is exploited for the manufacturing of targets for laser-induced ion acceleration experiments, with a focus on the promising Double Layer Target (DLT) concept. Targets with non-conventional properties (like ultra-low density and nano-engineered surface) are produced by means of the (nanosecond) Pulsed Laser Deposition (PLD, see image below), a highly flexible technique that allows to grow nanostructured materials with tailored properties on solid substrates. Targets are characterized mainly through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDXS); Raman spectroscopy measurements are also performed.

Other innovative Physical Vapor Deposition techniques are also exploited, taking advantage of the new laboratory equipment acquired thanks to the ENSURE funding: a femtosecond PLD system and a High Power Impulse Magnetron Sputtering (HiPIMS), which can extend the ability to obtain materials with desired properties. Specifically, they can work together to manifacture the DLT target: the fs-PLD is suitable for the production of the low-density layer, while the HiPIMS is apt at substrate manufacturing.

All these techniques are employed for the production of advanced targets (for example with ultra-low thickness, variable density, heterogeneous controlled composition) to identify an optimal solution for ion acceleration.

Theoretical investigations of novel laser-driven ion acceleration mechanisms and interaction of laser-generated ions with matter

Analytical descriptions and numerical simulations are developed for the investigation of three main topics: new regimes of laser-matter interaction, optimized ion acceleration mechanisms and laser-based ions interacting with matter. These studies regard both basic issues of the underlying physics as well as complex features that arise in real experiments for example due to the non-conventional properties of matter. The open source, massively parallel Particle-In-Cell (PIC) code piccante is used to perform large-scale simulations of laser-plasma interaction mainly on the computer clusters hosted at CINECA, Bologna, Italy. MonteCarlo codes (specifically Geant4 and Fluka) are exploited for the simulation of propagation and interaction of laser-ion beams with matter, especially useful in light of potential applications. The two different tools can be suitably integrated to simulate the whole physical phenomena, from laser-plasma interaction to ion beam generation to their subsequent interaction with matter.

New experimental campaigns of laser-driven ion acceleration

For the development of this part of the project, the experimental work on innovative targets and the theoretical work is oriented to the design, proposal, realization and interpretation of ion acceleration experiments. They are performed on some of the currently available top-class latest generation laser systems, thanks to different collaborations with international groups working on these facilities.

Applications of laser-driven ions for nuclear and materials engineering

The investigation of the possible use of the laser-driven ion beams for nuclear and materials science and engineering is developed starting from the theoretical and experimental knowledge obtained from the other activities, thanks to which the properties of the ion beams in present and future regimes together with the possible solutions in the preparation of advanced targets can be ascertained. This represents the starting point from which two main aspects are investigated both theoretically and experimentally: the generation of ion-driven exotic-nuclei/secondary particle sources and material irradiation and characterization using such particle beams.