Speaker
Description
In high power laser-solid target interaction experiments, usually a flat target is used to accelerate ions, create X-ray emission, neutrons, or other particles. If on top of the flat target surface nanostructures are added, the surface area is larger, resulting in a better coupling of the laser pulse with the target. Therefore, the laser absorption and conversion efficiency of the laser energy to accelerated particle energy is increased, leading to better proton acceleration (in terms of energy and particle numbers), x-ray emission, and high energy density matter creation. Highly ordered metallic nanotubes and nanowires were fabricated at ELI-NP Target Laboratory by electrochemical methods. The raw material is an aluminum plate which is pre-processed by polishing, rolling, and thermal treatment, and then anodized to obtain a porous alumina template in which the metallic structures are grown by electrodeposition from Watts bath containing the metals salts (e.g. nickel chloride and nickel sulfate for nickel nanostructures). The template is then dissolved, and the structures liberated. The diameter of the wires/tubes varies from 100 to 400 nm, with distances between them of 100-300nm and length of few microns on a very thin substrate (from 300nm to microns thick). The nanostructured thin films of a few cm2 areas are then cut into pieces and mounted on frames to be used in high power laser experiments. Nickel nanowires and nanotubes were shoot in 3 different laser configurations: at ILIL PW laser in Pisa, at ELI-NP 1 PW user experiment, and in Gemini laser from Rutherford Appleton Laboratory, where proton acceleration and x-ray emission were measured in comparison with flat targets. Preliminary data analysis showed that there is an increased efficiency of the laser energy absorption on these types of nanostructured targets, as compared to flat surface targets.
