Abstract
Abstract Engineered targets are expected to play a key role in future high-power laser experiments calling for joined, extensive knowledge in materials properties, engineering techniques and plasma physics. In this work, we propose a novel patterning procedure of self-supported 10 μm thick Au and Cu foils for obtaining micrometre-sized periodic gratings as targets for high-power laser applications. Accessible techniques were considered, by using cold rolling, electron-beam lithography and the Ar-ion milling process. The developed patterning procedure allows efficient control of the grating and foil surface on large area. Targets consisting of patterned regions of 450 μm × 450 μm, with 2 μm periodic gratings, were prepared on 25 mm × 25 mm Au and Cu free-standing foils, and preliminary investigations of the micro-targets interacting with an ultrashort, relativistic laser pulse were performed. These test experiments demonstrated that, in certain conditions, the micro-gratings show enhanced laser energy absorption and higher efficiency in accelerating charge particle beams compared with planar thin foils of similar thickness.
Highlights
Microstructured foils have been intensively exploited in the last several years as targets for applications of ultra-high-power lasers in nuclear physics[1], proton radiography[2] or cancer therapy[3]
The inverse pole figure (IPF) map suggests that this process induces the orientation, to the direction, reverting to the initial crystalline orientations of the as-received foils
We investigated the acceleration of proton beams via the target normal sheath acceleration (TNSA) mechanism on the rear side of a thin grating irradiated at normal incidence
Summary
Microstructured foils have been intensively exploited in the last several years as targets for applications of ultra-high-power lasers in nuclear physics[1], proton radiography[2] or cancer therapy (hadrontherapy)[3]. Theoretical and experimental studies have shown that by irradiating structured and engineered targets including gratings[4,5], nanowires[6,7], nanoparticles[8], nano-channels[9,10] or flat-top cones[11] with high intensity laser pulses, novel processes and surface effects can be excited, which can enhance the radiation yield over a broad spectral range[12,13,14] or improve the physical parameters of the electron and ion beams[15,16,17]. The electron bunches can be generated periodically during every laser cycle at the vacuum-plasma interface and their dynamics is relevant for the emission of electromagnetic radiation[21,22]. Experimental and numerical results indicate that nano-structured targets enable the control of the electron bunch dynamics and, the properties of the emitted electromagnetic radiation[23]
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