High Power Laser Science and Engineering, Volume. 10, Issue 1, 010000e3(2022)

Fabrication of micrometre-sized periodic gratings in free-standing metallic foils for laser–plasma experiments

C. C. Gheorghiu1, M. Cerchez2, E. Aktan2, R. Prasad2, F. Yilmaz2, N. Yilmaz2, D. Popa1, O. Willi2, and V. Leca1、*
Author Affiliations
  • 1Extreme Light Infrastructure – Nuclear Physics, Horia Hulubei National Institute for Physics and Nuclear Engineering, 077125 Magurele, Romania
  • 2Institut für Laser- und Plasmaphysik, Heinrich-Heine-Universität, 40225 Düsseldorf, Germany
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    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.

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    1 Introduction

    Micro-structured 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] and 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] and 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[1214] or improve the physical parameters of the electron and ion beams[1517]. The modulations of the target surface induced by the laser pulse itself[18] or by target engineering are effective methods to maximize the laser energy coupling since various absorption mechanisms, for example, vacuum heating[19], are sensitive to the laser field structure at the target surface[20]. Relativistic laser driven plasmas generated by solid targets have been shown to support the generation of intense radiation beams of energy over a wide range, from terahertz to X-ray. 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]. Recently, experimental and numerical results indicate that nano-structured targets enable the control of the electron bunch dynamics and, consequently, the properties of the emitted electromagnetic radiation[23].

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    C. C. Gheorghiu, M. Cerchez, E. Aktan, R. Prasad, F. Yilmaz, N. Yilmaz, D. Popa, O. Willi, V. Leca. Fabrication of micrometre-sized periodic gratings in free-standing metallic foils for laser–plasma experiments[J]. High Power Laser Science and Engineering, 2022, 10(1): 010000e3

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    Paper Information

    Category: Research Articles

    Received: Mar. 19, 2021

    Accepted: Dec. 6, 2021

    Published Online: Jan. 19, 2022

    The Author Email: V. Leca (victor.leca@eli-np.ro)

    DOI:10.1017/hpl.2021.57

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