scholarly journals Influence of ambient gas pressure on laser induced metal ablation

2010 ◽  
Vol 5 ◽  
pp. 255-259
Author(s):  
Yu. Chivel ◽  
V. Nasonov
Keyword(s):  
Gas Pressure ◽  
Ambient Gas

Deposition of particulate-free thin films by two synchronised laser sources: effects of ambient gas pressure and laser fluence

2004 ◽  
Vol 446 (2) ◽  
pp. 178-183 ◽  
Author(s):  
E. György ◽  
I.N. Mihailescu ◽  
M. Kompitsas ◽  
A. Giannoudakos
Keyword(s):  
Thin Films ◽  
Laser Fluence ◽  
Gas Pressure ◽  
Laser Sources ◽  
Ambient Gas

Experimental and theoretical study of the characteristics of LSPR peaks for metal NPs produced by controlling Ar ambient gas pressure to enhance the efficiency of solar cells

2021 ◽  
pp. 1-6
Author(s):  
Serap Yiğit Gezgin ◽  
Abdullah Kepceoğlu ◽  
Hamdi Şükür Kiliç
Keyword(s):  
Metal Nanoparticles ◽  
Ag Nanoparticles ◽  
Solar Spectrum ◽  
Wavelength Region ◽  
Gas Pressure ◽  
Metal Nanoparticle ◽  
Ag Nanoparticle ◽  
Extinction Cross Section ◽  
Ambient Gas ◽  
Ar Gas

In this study, silver (Ag) nanoparticle thin films were deposited on microscope slide glass and Si wafer substrates using the pulsed-laser deposition (PLD) technique in Ar ambient gas pressures of 1 × 10−3 and 7.5 × 10−1 mbar. AFM analysis has shown that the number of Ag nanoparticles reaching the substrate decreased with increasing Ar gas pressure. As a result of Ar ambient gas being allowed into the vacuum chamber, it was observed that the size and height of Ag nanoparticles decreased and the interparticle distances decreased. According to the absorption spectra taken by a UV–vis spectrometer, the wavelength where the localised surface plasmon resonance (LSPR) peak appeared was shifted towards the longer wavelength region in the solar spectrum as Ar background gas pressure was decreased. This experiment shows that LSPR wavelength can be tuned by adjusting the size of metal nanoparticles, which can be controlled by changing Ar gas pressure. The obtained extinction cross section spectra for Ag nanoparticle thin film was theoretically analysed and determined by using the metal nanoparticle–boundary element method (MNPBEM) toolbox simulation program. In this study, experimental spectrum and simulation data for metal nanoparticles were acquired, compared, and determined to be in agreement.

Numerical Investigation on the Effect of Advanced Breakup Model on Spray Simulation of a Multi-Hole Injector

2018 ◽  
Author(s):  
Srinibas Tripathy ◽  
Sridhar Sahoo ◽  
Dhananjay Kumar Srivastava
Keyword(s):  
Mass Fraction ◽  
Gas Pressure ◽  
Gas Jet ◽  
Computational Time ◽  
Fuel Vapor ◽  
Computational Domain ◽  
Penetration Length ◽  
Spray Penetration ◽  
Ambient Gas ◽  
Vapor Mass

Computational fluid dynamics (CFD) plays a tremendous role in evaluating and visualizing the spray breakup, atomization and vaporization process. In this study, ANSYS Forte CFD tool was used to simulate the spray penetration length and spray morphology in a constant volume chamber at different grid size of a multi-hole injector. An unsteady gas jet model was coupled with Kelvin-Helmholtz (KH) and Rayleigh-Taylor (RT) model for multi-hole spray simulation. The effect of CFD cell size and ambient gas pressure on spray penetration length and spray morphology of fuel vapor mass fraction were investigated for both KH-RT and KH-RT with the unsteady gas jet model. It is found that KH-RT with the unsteady gas jet model shows mesh independent spray penetration length and spray morphology of fuel vapor mass fraction as compared to KH-RT model. This can be explained by the Lagrangian-Eulerian coupling of axial droplet-gas relative velocity is modeled on the principle of unsteady gas jet theory instead of discretizing very fine grid to the computational domain. This reduces the requirement of fine mesh near the nozzle and allows larger time step during spray injection. It is also observed that at higher ambient gas pressure, an aerodynamic force between the droplet and gas intensifies which reduces the overall spray penetration length and fuel vapor mass. The distorted spray morphology of fuel vapor mass fraction was accurately predicted at high ambient gas pressure using the KH-RT with an unsteady gas jet model which results in mesh independent drag predictions. The use of advanced spray model results in the mesh size dependency reduction and accurate drag prediction with less computational time and faster accurate solutions over all conventional spray breakup models.

The concentration and pressure dependent diffusion of carbon dioxide in nitrile rubbers

1992 ◽  
Vol 339 (1655) ◽  
pp. 497-519 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Diffusion Coefficient ◽  
High Pressures ◽  
Ambient Pressure ◽  
Weight Fraction ◽  
Gas Pressure ◽  
Time Dependent ◽  
Initial Increase ◽  
Parametric Function ◽  
Ambient Gas

The paper reports the results of an experimental and associated analytical study of the time dependent adsorption of carbon dioxide gas into two nitrile elastomers. The mass gas sorption has been measured using a device based on a vibrating reed to a weight fraction accuracy of ca . 0.05 % at 47 °C in the ambient gas pressure range 0.1-34 MPa. The experimental method is described and data are provided. These data are used to compute the most effective description of the diffusion process by invoking a number of different diffusion coefficient, D(θ), characteristics, where θ denotes lapsed time, ambient pressure and local ambient gas concentration within the elastomers. The numerical procedures adopted to perform the fitting of the experimental data with various D(θ) characteristics are described and the quality of the fit is assessed. The D(θ) characteristics chosen have no particular physical basis but follow established empirical precedents. The characteristics of the parameters associated with the various D(θ) functions generally indicate that as the gas is embibed with progressively increasing ambient pressures the diffusion coefficient increases. At high pressures the diffusion is arrested and the coefficient decreases. We have associated the initial increase with gas induced plasticization and the eventual decreases with the effect of the hydrostatic component of the ambient gas pressure. The parameter fitting also indicates that the diffusion is arrested with lapsed time which is tentatively associated with time dependent volumetric relaxations. These interpretations apart, the data and analyses clearly indicate that the transport is not simply fickian and a relatively complex parametric function to describe the sensitivity of the diffusion coefficient to time, concentration and pressure is necessary for these systems.

Thermal Conductivity of ZIF-8 Thin-Film under Ambient Gas Pressure

2017 ◽  
Vol 9 (34) ◽  
pp. 28139-28143 ◽  
Author(s):  
Boya Cui ◽  
Cornelius O. Audu ◽  
Yijun Liao ◽  
SonBinh T. Nguyen ◽  
Omar K. Farha ◽  
...  
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Gas Pressure ◽  
Ambient Gas

Silicon and zinc telluride nanoparticles synthesized by low energy density pulsed laser ablation into ambient gases

1999 ◽  
Vol 14 (2) ◽  
pp. 359-370 ◽  
Author(s):  
Douglas H. Lowndes ◽  
Christopher M. Rouleau ◽  
T.G. Thundat ◽  
G. Duscher ◽  
E.A. Kenik ◽  
...  
Keyword(s):  
Laser Ablation ◽  
Energy Density ◽  
Pulsed Laser ◽  
Pulsed Laser Ablation ◽  
Gas Pressure ◽  
Low Energy ◽  
Crystalline Core ◽  
Ambient Gases ◽  
The Mean ◽  
Ambient Gas

The size distributions of Si and ZnTe nanoparticles produced by low energy density ArF (193 nm) pulsed laser ablation into ambient gases were measured as a function of the gas pressure, P, and target-substrate separation, Dts. For both Si and ZnTe, the largest nanoparticles were found closest to the ablation target, and the mean nanoparticle size decreased with increasing Dts. For Si ablation into He, the mean nanoparticle diameter did not increase monotonically with gas pressure but reached a maximum near P = 6 Torr. High resolution Z-contrast transmission electron microscopy and energy loss spectroscopy revealed that ZnTe nanoparticles consist of a crystalline core surrounded by an amorphous ZnO shell; growth defects and surface steps are clearly visible in the crystalline core. A pronounced narrowing of the ZnTe nanocrystal size distribution with increasing Dts also was found. The results demonstrate that the size of laser-ablated nanoparticles can be controlled by varying the molecular weight and pressure of an ambient gas and that nanometer-scale particles can be synthesized. Larger aggregates of both ZnTe and Si having a “flakelike” or “weblike” structure were formed at the higher ambient gas pressures; for ZnTe these appear to be open agglomerates of much smaller (∼10 nm) particles.

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