In ultra-short pulse laser machining and micro/surface processing, accurate simulation of laser ablation is important for understanding laser-target interaction and improving ablation performance, ...but it remains challenging. This work aims to develop a numerical model to improve the accuracy of the ablation depth calculation. A grid deformation scheme is proposed based on energy conservation and considering contributions to instant material removal from both the electron and lattice subsystems. By incorporating this scheme with the two-temperature model (TTM), a reasonable prediction of the instant target surface profile during laser ablation has been achieved. In the case of single-pulse femtosecond laser ablation of Ti6Al4V, the calculated ablation depth ranges from 0.06 to 0.56 μm for laser energy from 1.0 to 10.0 μJ. For single-pulse picosecond laser ablation of stainless steel, as laser energy increases from 6.0 to 18.5 μJ, the predicted ablation crater deepens accordingly from 40 to 87 nm. In addition, for multi-pulse picosecond laser ablation of stainless steel, a linear dependence of the ablation depth on the pulse number is observed up to a depth of about 803 nm at 6.0 μJ and 20 pulses. In all the above-mentioned cases, the calculation results are in better agreement with experimental measurements than conventional TTM or other material removal schemes, validating the accuracy of the proposed model.
The self‐inclusion behavior of monoester copillar5arenes depends on the position of the ester group, which causes different guest selectivities. Monoester copillar5arenes bearing an acetate chain can ...form stable self‐inclusion complexes in low‐ and high‐concentration solution and exhibit high guest selectivity. However, a monoester copillar5arene bearing a butyrate chain can not form a self‐inclusion complex and exhibits low guest selectivity. Thus, a new class of stable self‐inclusion complexes of copillar5arenes was explored to improve the selectivity of molecular recognition.
Competitive inclusion: Monoester copillar5arenes bearing an acetate chain can form stable self‐inclusion complexes and exhibit high guest selectivity due to decreased binding ability. However, a monoester copillar5arene bearing a butyrate chain can not form a self‐inclusion complex and exhibits strong binding ability but low guest selectivity (see figure).
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
In laser-driven inertial confinement fusion, driving pressure boosting and smoothing are major challenges. A proposed hybrid-drive (HD) scheme can offer such ideal HD pressure performing ...stable implosion and nonstagnation ignition. Here we report that in the hemispherical and planar ablator targets installed in the semicylindrical hohlraum scaled down from the spherical hohlraum of the designed ignition target, under indirect-drive (ID) laser energies of ~43–50 kJ, the peak radiation temperature of 200 ± 6 eV is achieved. And using only direct-drive (DD) laser energies of 3.6–4.0 kJ at an intensity of 1.8 × 10
15
W/cm
2
, in the hemispherical and planar targets the boosted HD pressures reach 3.8–4.0 and 3.5–3.6 times the radiation ablation pressure respectively. In all the above experiments, significant HD pressure smoothing and the important phenomenon of how a symmetric strong HD shock suppresses the asymmetric ID shock pre-compressed fuel are demonstrated. The backscattering and hot-electron energy fractions both of which are about one-third of that in the DD scheme are also measured.
Graphite-like C3N4 hybridized BiOBr photocatalysts have been synthesized through an EG-assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ...(C16mimBr). The as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and photocurrent. The g-C3N4/BiOBr photocatalysts showed high efficiency for the degradation of bisphenol A (BPA) and rhodamine B (RhB) under visible light irradiation. The results assumed that a loading amount of g-C3N4 over BiOBr lead to an increase of the photocatalytic activity under visible light irradiation and showed much higher photocatalytic activity than that of pure BiOBr sample. The enhanced photocatalytic performance could be attributed to the high separation efficiency of the photogenerated electron–hole pairs. The trapping experiments of radicals showed that hole was the main reactive species for the photocatalytic degradation of RhB. A possible mechanism of g-C3N4/BiOBr on the enhancement of visible light performance was proposed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In order to study the laser plasma instabilities (LPIs) in the context of some novel six-side laser-driven indirect designs like the six-cylinder-port hohlraum and the three-axis cylindrical ...hohlraum, where the laser beams inject in hohlraum with a large angle. LPI experiments in cylindrical hohlraum with only outer beams were designed and performed based on the current laser arrangement condition of SGIII laser facility for the first time. Stimulated Brillouin backscatter (SBS) was found to be the dominant instability with high instantaneous reflectivity in experiments. A typical feature was obtained in the time-resolved spectra of SBS, which maintained similar for different laser intensities of the interaction beam. The experimental data are analyzed by the hydrodynamic simulations combined with HLIP code, which is based on the ray-tracing model. By analysis of experimental data, it is argued that the mixture of gas and Au in the region of their interface is important to SBS, which indicates the need for the mixture model between the filled gas and the high Z plasma from hohlraum wall in the hydrodynamic simulations. Nonlinear saturation of SBS as well as the smoothed beam are also discussed here. Our effective considerations of the ions pervasion effect and the smoothed beam provide utilitarian ways for improvement of the current ray-tracing method.
We study theoretically and numerically the acceleration of protons by a combination of laser radiation pressure acceleration and Coulomb repulsion of carbon ions in a multi-ion thin foil made of ...carbon and hydrogen. The carbon layer helps to delay the proton layer from disruption due to the Rayleigh-Taylor instability, to maintain the quasi-monoenergetic proton layer and to accelerate it by the electron-shielded Coulomb repulsion for much longer duration than the acceleration time using single-ion hydrogen foils. Particle-in-cell simulations with a normalized peak laser amplitude of a0 = 5 show a resulting quasi-monoenergetic proton energy of about 70 MeV with the foil made of 90% carbon and 10% hydrogen, in contrast to 10 MeV using a single-ion hydrogen foil. An analytical model is presented to explain quantitatively the proton energy evolution; this model is in agreement with the simulation results. The energy dependence of the quasi-monoenergetic proton beam on the concentration of carbon and hydrogen is also studied.
The first laser–plasma interaction experiment using lasers of eight beams grouped into one octad has been conducted on the Shenguang Octopus facility. Although each beam intensity is below its ...individual threshold for stimulated Brillouin backscattering (SBS), collective behaviors are excited to enhance the octad SBS. In particular, when two-color/cone lasers with wavelength separation 0.3 nm are used, the backward SBS reflectivities show novel behavior in which beams of longer wavelength achieve higher SBS gain. This property of SBS can be attributed to the rotation of the wave vectors of common ion acoustic waves due to the competition of detunings between geometrical angle and wavelength separation. This mechanism is confirmed using massively parallel supercomputer simulations with the three-dimensional laser–plasma interaction code LAP3D.
The results of a commissioning experiment on the SILEX-Ⅱ laser facility (formerly known as CAEP-PW) are reported. SILEX-Ⅱ is a complete optical parametric chirped-pulse amplification laser facility. ...The peak power reached about 1 PW in a 30 fs pulse duration during the experiment. The laser contrast was better than 1010 at 20 ps ahead of the main pulse. In the basic laser foil target interaction, a set of experimental data were collected, including spatially resolved x-ray emission, the image of the coherent transition radiation, the harmonic spectra in the direction of reflection, the energy spectra and beam profile of accelerated protons, hot-electron spectra, and transmitted laser energy fraction and spatial distribution. The experimental results show that the laser intensity reached 5 × 1020 W/cm2 within a 5.8 µm focus (FWHM). Significant laser transmission did not occur when the thickness of the CH foil was equal to or greater than 50 nm. The maximum energy of the accelerated protons in the target normal direction was roughly unchanged when the target thickness varied between 50 nm and 15 µm. The maximum proton energy via the target normal sheath field acceleration mechanism was about 21 MeV. We expect the on-target laser intensity to reach 1022 W/cm2 in the near future, after optimization of the laser focus and upgrade of the laser power to 3 PW.
A monophosphoryl copillar5arene 1 was prepared. The introduction of the phosphoryl group remarkably promoted the binding affinity of 1 with alkanols and alkanediols in comparison with ...1,4-dimethoxypillar5arene. Thus 1 can form a stable 1 : 1 host-guest complex with alkanols in CDCl sub(3).
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IJS, KILJ, NUK, UL, UM, UPUK
![Monoester Copillar[5]arenes...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0947-6539/small "Monoester Copillar[5]arenes: Synthesis, Unusual Self-Inclusion Behavior, and Molecular Recognition")
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