Results
Stage I - 2025
- Significant progress was made in developing high repetition rate free-standing targets, consisting of oxygen-free polymer layers decorated with low-density materials (e.g., carbon foam, boron) suspended on honeycomb scaffolds.
- Laser-based deposition techniques, such as Pulsed Laser Deposition (PLD) and Matrix-Assisted Pulsed Laser Evaporation (MAPLE), were optimized.
- MAPLE successfully deposited polypyrrole membranes on frozen water substrates, producing nanostructured free-standing films. Dimethyl sulfoxide yielded smoother PPy layers compared to NMP.
- Spin coating demonstrated polyaniline's ability to form smooth, compact layers (<3 nm roughness), suitable for integration.
- Nanostructured carbon and boron were fabricated via PLD, while photolithography and reactive ion etching (RIE) produced honeycomb scaffolds with 5–12 µm pore sizes.
- At ELI-NP Target Laboratory, tests have been performed for the fabrication of honeycomb scaffold target support, on which the free-standing solid targets will be deposited.
- Tests using Si-based supports have been done, using photolithography technique and Reactive Ion Etching (RIE) system for physical-chemical etching process.
- Results were shared during an ELITE team seminar and submitted for oral presentation at CAMAI 2024.
Stage II - 2025
- Significant advances were achieved in the design, simulation and experimental fabrication of high-repetition-rate free-standing targets.
- Numerical modelling was developed to describe heat transfer, phase change and deformation in ice-supported membranes, allowing a direct comparison between two relevant heating configurations.
- The simulations showed that heating through the polymer induces transient temperature inversion and volume-change-driven deformation during melting, whereas heating through a copper base produces a more uniform thermal field with reduced mechanical stress on the membrane.
- These findings provide guidelines for identifying heating conditions that maintain membrane stability during melting.
- Carbon thin films grown on frozen water were released and transferred onto micro-fabricated silicon honeycomb grids (~15 µm).
- Optical, SEM, AFM and EDX analyses confirmed complete coverage, preservation of structural integrity and chemical purity, with only carbon/oxygen from the membrane and silicon from the support. A mechanical alignment system for sequential positioning of the targets is currently being refined to improve reproducibility and stability under high-repetition-rate irradiation.
- The dissemination and exploitation activities include one published paper (Applied Surface Science 705, 2025), a patent application under legal evaluation, multiple oral/plenary contributions at international conferences, and the Gold Medal distinction at EUROINVENT 2025.