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

Gheorghiu, C. C.; Cerchez, M.; Aktan, E.; Prasad, R.; Yılmaz, Fatih; Yilmaz, N.; Popa, D.; Willi, O.; Leca, V.

doi:10.1017/hpl.2021.57

Cited by 16 publications

(4 citation statements)

References 62 publications

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“…[78,79] To comprehend the absorption mechanism, the equivalent circuit theory has been broadly utilized. [80][81][82][83][84] Representing periodic patterns through the resistance-inductance-capacitance (RLC) circuit model, where the equivalent impedance (Z u ) can be described in Equation (1) [85][86][87]…”

Section: Design Principles and Methods Of Absorbersmentioning

confidence: 99%

“…[ 78,79 ] To comprehend the absorption mechanism, the equivalent circuit theory has been broadly utilized. [ 80–84 ] Representing periodic patterns through the resistance–inductance–capacitance (RLC) circuit model, where the equivalent impedance (

Z_{\text{u}}

) can be described in Equation () [ 85–87 ]

\textrm{ } Z_{\text{u}} = R + j \omega L + \frac{1}{j \omega C}

where R , C , and L are the equivalent resistance, capacitance, and inductance of periodic patterns, respectively. For dielectric spacers supported by a grounding plane, the equivalent impedance (

Z_{t}

) is expressed as [ 88 ]

$$Z_{t} = j Z_{0} \sqrt{\frac{\left(\mu\right)_{r}}{\left(\epsilon\right)_{r}}} tan \left(\right.

…”

Section: Design and Preparation Of Masmentioning

confidence: 99%

See 1 more Smart Citation

Research Progress in Tunable Metamaterial Absorbers

Liu,

Li,

Fang

et al. 2023

Advanced Photonics Research

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Since the initial discovery of metamaterial absorbers (MAs), they generate significant interest across the electromagnetic device industry due to their capacity to attain subwavelength magnitudes, adaptable design, and almost complete absorption. In recent years, there has been a growing focus on incorporating active materials into MAs, making it a current focal point of investigation. In the past few years, MAs have seen the integration of various active materials and configurations thanks to continuous exploration and innovation. Herein, comprehensive and systematic research on different tuning methods of MAs is reviewed, highlighting innovative materials and unique designs to accurately control the electromagnetic absorption characteristics of MAs. Key parameters, such as the operating frequency and relative tuning range, are summarized and compared to provide guidance for optimization design. Finally, the challenges of tunable MAs and their future prospects are also summarized.

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Section: Design Principles and Methods Of Absorbersmentioning

confidence: 99%

Z_{\text{u}}

) can be described in Equation () [ 85–87 ]

\textrm{ } Z_{\text{u}} = R + j \omega L + \frac{1}{j \omega C}

where R , C , and L are the equivalent resistance, capacitance, and inductance of periodic patterns, respectively. For dielectric spacers supported by a grounding plane, the equivalent impedance (

Z_{t}

) is expressed as [ 88 ]

$$Z_{t} = j Z_{0} \sqrt{\frac{\left(\mu\right)_{r}}{\left(\epsilon\right)_{r}}} tan \left(\right.

…”

Section: Design and Preparation Of Masmentioning

confidence: 99%

Research Progress in Tunable Metamaterial Absorbers

Liu,

Li,

Fang

et al. 2023

Advanced Photonics Research

View full text Add to dashboard Cite

show abstract

“…Currently, the processes [1]. With the advent of laser-plasma accelerators, proton beams with energies of up to 100 MeV have been experimentally produced [5] via hybrid schemes involving radiation pressure acceleration [6] and target normal sheath acceleration (TNSA) [7][8][9]. Meanwhile, other mechanisms of laserproton acceleration, such as the breakout afterburner [10,11] and collision-less shock acceleration (CSA) [12][13][14], have also been studied.…”

Section: Introductionmentioning

confidence: 99%

Enhanced polarized proton acceleration driven by femtosecond laser pulses irradiating a micro-structured solid–gas target

Yan¹,

Wu²,

Geng³

et al. 2023

Plasma Phys. Control. Fusion

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Herein, we propose a scheme based on collision-less shock acceleration (CSA) involving the use of composite targets comprising a micro-structured foil and pre-polarized gas for obtaining high-energy polarized proton beams. Femtosecond laser pulses irradiate a microwire-array (MWA) target and efficiently heat the dense plasma, which moves toward the dilute plasma. Shocks are then introduced in the pre-polarized gas and accelerate upstream spin-polarized protons to relativistic velocities. Based on particle-in-cell simulations with added spin dynamics, protons with energies of 30–300 MeV are produced, and the polarization rate of protons in the high-energy region exceeds 90%. The simulations demonstrate an evident increase in the temperature and number of hot electrons owing to the presence of MWA structures, which increase both the longitudinal electric field strength associated with the shock and the energy of the reflected protons. During CSA, the bipolar magnetic field driven by hot-electron currents demonstrates a weak effect on the polarization level of the accelerated protons, resulting in a high polarization rate. The relationship between the energy of the polarized proton beam and the hot-electron temperature enables an optimization of the micro-structured target or other target components to enhance proton quality via the CSA process.

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“…Recent numerical and experimental studies have shown that creating nano- and microstructures, as well as patterns on the front surface of the targets, leads to an enhanced laser energy absorption and, hence, an improved conversion efficiency from laser energy into the resulting ion beam energy [ 21 ]. A number of surface structures have been proposed to this end, such as gratings [ 22 , 23 ], nanowires [ 24 ], nanobrushes [ 25 ], carbon foam [ 26 ], nanospheres [ 27 , 28 ] or nanoparticles [ 29 ]. When used as targets in high-power laser experiments, increasing the effective surface area of thin films through the use of specific growth methods can be an effective way of improving their laser energy absorption capabilities.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Control of Structure and Composition for Nanocrystalline Fe Thin Films Grown by Oblique Angle RF Sputtering

et al. 2022

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The use of Fe films as multi-element targets in space radiation experiments with high-intensity ultrashort laser pulses requires a surface structure that can enhance the laser energy absorption on target, as well as a low concentration and uniform distribution of light element contaminants within the films. In this paper, (110) preferred orientation nanocrystalline Fe thin films with controlled morphology and composition were grown on (100)-oriented Si substrates by oblique angle RF magnetron sputtering, at room temperature. The evolution of films key-parameters, crucial for space-like radiation experiments with organic material, such as nanostructure, morphology, topography, and elemental composition with varying RF source power, deposition pressure, and target to substrate distance is thoroughly discussed. A selection of complementary techniques was used in order to better understand this interdependence, namely X-ray Diffraction, Atomic Force Microscopy, Scanning and Transmission Electron Microscopy, Energy Dispersive X-ray Spectroscopy and Non-Rutherford Backscattering Spectroscopy. The films featured a nanocrystalline, tilted nanocolumn structure, with crystallite size in the (110)-growth direction in the 15–25 nm range, average island size in the 20–50 nm range, and the degree of polycrystallinity determined mainly by the shortest target-to-substrate distance (10 cm) and highest deposition pressure (10−2 mbar Ar). Oxygen concentration (as impurity) into the bulk of the films as low as 1 at. %, with uniform depth distribution, was achieved for the lowest deposition pressures of (1–3) × 10−3 mbar Ar, combined with highest used values for the RF source power of 125–150 W. The results show that the growth process of the Fe thin film is strongly dependent mainly on the deposition pressure, with the film morphology influenced by nucleation and growth kinetics. Due to better control of film topography and uniform distribution of oxygen, such films can be successfully used as free-standing targets for high repetition rate experiments with high power lasers to produce Fe ion beams with a broad energy spectrum.

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

Cited by 16 publications

References 62 publications

Research Progress in Tunable Metamaterial Absorbers

Research Progress in Tunable Metamaterial Absorbers

Enhanced polarized proton acceleration driven by femtosecond laser pulses irradiating a micro-structured solid–gas target

Nanoscale Control of Structure and Composition for Nanocrystalline Fe Thin Films Grown by Oblique Angle RF Sputtering

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