The challenges of using double targets as a novel contrast-enhancement method for laser-driven acceleration

Laser-driven proton acceleration by Target Normal Sheath Acceleration (TNSA) is often performed using thick foil targets. For an efficient acceleration process, the High-Power Laser (HPL) incident on the foil requires sufficient contrast. To meet this requirement, we investigated the use of targets with a spaced bilayer structure consisting of an ultra-thin solid film (nm) in the front, a void of tens of mu m thickness and a foil in the rear, focusing the laser pulse on the foil front surface. Diamond-Like Carbon (DLC) thin films free-standing on Cu substrates were fabricated, characterized, incorporated into carbon-Al double targets, and tested at pulse intensities of similar to 10(20) W/cm(2).