Simulation and Measurement of the Laser Induced Breakdown in Air and Argon for Nanosecond Order Pulses

2012 ◽  
Author(s):  
Yongjun Choi ◽  
Chuandong Zhou ◽  
Peter Stoltz ◽  
Sachin Joshi ◽  
Azer Yalin
Keyword(s):  
Impact Ionization ◽  
Focal Spot ◽  
Laser Energy ◽  
Fluid Dynamic ◽  
Ambient Pressure ◽  
Laser Pulses ◽  
Focal Region ◽  
Laser Propagation ◽  
Laser Induced Breakdown ◽  
Photon Ionization

The interest in lasers for engine ignition is the possibility of higher efficiency and reduction of pollutants compared with conventional spark plugs. The interest in this area is to understand the laser energy needed for breakdown and ignition in order to better design practical systems. To support such development, the laser induced breakdown of air is simulated by the use of a two-dimensional computational fluid-dynamic model for 10 and 46 ns laser pulses for several pressures and focal spot sizes. The simulation includes the laser propagation, multi-photon ionization, impact ionization, electrons heating and energy loss. The dependence of breakdown irradiance on pulse duration, ambient pressure, and dimensions of the focal region is investigated and compared with experimental results.

scholarly journals Passage of laser light through a hole-plasma shutter

1994 ◽  
Vol 12 (3) ◽  
pp. 445-454 ◽  
Author(s):  
K. Mašek ◽  
B. Králiková ◽  
J. Krása ◽  
L. Láska ◽  
K. Rohlena ◽  
...  
Keyword(s):  
Focal Spot ◽  
Laser Light ◽  
Laser Energy ◽  
Laser Pulses ◽  
Hole Diameter ◽  
Simple Analytical Model ◽  
Iodine Laser ◽  
Temporal Shape ◽  
Foil Target ◽  
Laser Focal Spot

The interaction of a plasma produced by irradiation of perforated foils with laser pulses was studied. The laser beam of the first harmonics of the iodine laser (λ = 1.315 μm) system PERUN was focused by anf/2 optics (f = 20 cm) on a hole in the foil target of high-Z material. The laser energy and the temporal shape of the pulses were monitored both before and behind the hole. Foils of two different materials (Pb, Cu) were used, and a series of hole diameters 2rH ranging from 100 μm to 500 μm were tested. The diameter of the laser focal spot 2r0 was about 150 μm. For hole diameters smaller than 300 μm, a shortening of the laser pulse was observed, demonstrating the effect of plasma shutter. The pulse shortening, which depends on the hole diameter, corresponds to the reduction in the pulse energy passing through the hole. An analysis of the experimental data is based on hydrodynamic computations, and the physics of the process is illustrated by a simple analytical model.

CO2 laser induced gas breakdown in preionized argon

1980 ◽  
Vol 58 (2) ◽  
pp. 153-163
Author(s):  
J. Santiago ◽  
A. M. Robinson
Keyword(s):  
Co2 Laser ◽  
Electric Discharge ◽  
Laser Pulses ◽  
Cascade Model ◽  
Focal Region ◽  
Model Yield ◽  
Laser Induced Breakdown ◽  
Uv Photons ◽  
Gas Breakdown ◽  
Good Agreement

CO2 laser induced breakdown of argon is investigated as a function of pressure and preionization. The gas is preionized by uv photons from an electric discharge. By varying the time between the discharge and laser pulses, initial densities in the focal region vary from 109 cm−3 to 1012 cm−3. Numerical calculations of the breakdown process based on a cascade model yield thresholds which are in good agreement with measurements.

Characterization of Amethysts from Sukamara, Central Kalimantan, Using Laser-Induced Breakdown Spectroscopy (LIBS)

2020 ◽  
Vol 1 (2) ◽  
pp. 5-8
Author(s):  
Komang Gde Suastika, Heri Suyanto, Gunarjo, Sadiana, Darmaji
Keyword(s):  
Emission Intensity ◽  
Laser Energy ◽  
Emission Spectra ◽  
Atomic Emission ◽  
Laser Induced Breakdown Spectroscopy ◽  
Chemical Formula ◽  
Central Kalimantan ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown

Abstract - Laser-Induced Breakdown Spectroscopy (LIBS) is one method of atomic emission spectroscopy using laser ablation as an energy source. This method is used to characterize the type of amethysts that originally come from Sukamara, Central Kalimantan. The result of amethyst characterization can be used as a reference for claiming the natural wealth of the amethyst. The amethyst samples are directly taken from the amethyst mining field in the District Gem Amethyst and consist of four color variations: white, black, yellow, and purple. These samples were analyzed by LIBS, using laser energy of 120 mJ, delay time detection of 2 μs and accumulation of 3, with and without cleaning. The purpose of this study is to determine emission spectra characteristics, contained elements, and physical characteristics of each amethyst sample. The spectra show that the amethyst samples contain some elements such as Al, Ca, K, Fe, Gd, Ba, Si, Be, H, O, N, Cl and Pu with various emission intensities. The value of emission intensity corresponds to concentration of element in the sample. Hence, the characteristics of the amethysts are based on their concentration value. The element with the highest concentration in all samples is Si, which is related to the chemical formula of SiO2. The element with the lowest concentration in all samples is Ca that is found in black and yellow amethysts. The emission intensity of Fe element can distinguish between white, purple, and yellow amethyst. If Fe emission intensity is very low, it indicates yellow sample. Thus, we may conclude that LIBS is a method that can be used to characterize the amethyst samples.Key words: amethyst, impurity, laser-induced, breakdown spectroscopy, characteristic, gemstones

Un-Shocked High Amplitude Standing Waves in Wave-Shaped Resonators

2012 ◽  
Author(s):  
Dion Savio Antao ◽  
Bakhtier Farouk
Keyword(s):  
Numerical Study ◽  
Fluid Dynamic ◽  
Ambient Pressure ◽  
Standing Waves ◽  
High Amplitude ◽  
Prime Mover ◽  
Non Linear ◽  
Resonator System ◽  
Cylindrical Resonators ◽  
Linear Nature

A numerical study of non-linear, high amplitude standing waves in non-cylindrical circular resonators is reported here. These waves are shock-less and can generate peak acoustic overpressures that can exceed the ambient pressure by three/four times its nominal value. A high fidelity compressible computational fluid dynamic model is used to simulate the phenomena in cylindrical and arbitrarily shaped axisymmetric resonators. A right circular cylinder and frustum of cone are the two geometries studied. The model is validated using past numerical and experimental results of standing waves in cylindrical resonators. The non-linear nature of the harmonic response of the frustum of cone resonator system is investigated for two different working fluids (carbon dioxide and argon) operating at various values of piston amplitude. The high amplitude non-linear oscillations demonstrated can be used as a prime mover in a variety of applications including thermoacoustic cryocooling.

scholarly journals Dependence of laser accelerated protons on laser energy following the interaction of defocused, intense laser pulses with ultra-thin targets

2011 ◽  
Vol 29 (3) ◽  
pp. 345-351 ◽  
Author(s):  
C.M. Brenner ◽  
J.S. Green ◽  
A.P.L. Robinson ◽  
D.C. Carroll ◽  
B. Dromey ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Focal Spot ◽  
Laser Pulse Energy ◽  
Laser Energy ◽  
Spot Size ◽  
Proton Flux ◽  
Focal Spot Size ◽  
Order Of Magnitude ◽  
Laser Focal Spot ◽  
Accelerated Protons

AbstractThe scaling of the flux and maximum energy of laser-driven sheath-accelerated protons has been investigated as a function of laser pulse energy in the range of 15–380 mJ at intensities of 1016–1018 W/cm2. The pulse duration and target thickness were fixed at 40 fs and 25 nm, respectively, while the laser focal spot size and drive energy were varied. Our results indicate that while the maximum proton energy is dependent on the laser energy and laser spot diameter, the proton flux is primarily related to the laser pulse energy under the conditions studied here. Our measurements show that increasing the laser energy by an order of magnitude results in a more than 500-fold increase in the observed proton flux. Whereas, an order of magnitude increase in the laser intensity generated by decreasing the laser focal spot size, at constant laser energy, gives rise to less than a tenfold increase in observed proton flux.

scholarly journals Laser-induced breakdown of argon gas near a metal surface

1992 ◽  
Vol 10 (1) ◽  
pp. 109-116 ◽  
Author(s):  
V. Kumar ◽  
R. K. Thareja
Keyword(s):  
Metal Surface ◽  
Laser Energy ◽  
Thermionic Emission ◽  
Argon Gas ◽  
Photoelectric Emission ◽  
Laser Induced Breakdown

Laser-induced breakdown of argon gas near a metal surface is studied. It is observed that the threshold laser energy required to break down argon gas is reduced in the presence of a metal surface. Photoelectric emission from the metal surface dominates the thermionic emission to reduce the threshold laser energy for breakdown.

Post-solitons and electron vortices generated by femtosecond intense laser interacting with uniform near-critical-density plasmas

2021 ◽  
Author(s):  
Dong-Ning Yue ◽  
Min Chen ◽  
Yao Zhao ◽  
Pan-Fei Geng ◽  
Xiao-Hui Yuan ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Critical Density ◽  
Laser Pulses ◽  
Intense Laser ◽  
Nonlinear Structures ◽  
Particle In Cell ◽  
Laser Propagation ◽  
Laser Driver ◽  
Linearly Polarized ◽  
Dimensional Simulation

Abstract Generation of nonlinear structures, such as stimulated Raman side scattering waves, post-solitons and electron vortices, during ultra-short intense laser pulse transportation in near-critical-density (NCD) plasmas are studied by using multi-dimensional particle-in-cell (PIC) simulations. In two-dimensional geometries, both P- and S- polarized laser pulses are used to drive these nonlinear structures and to check the polarization effects on them. In the S-polarized case, the scattered waves can be captured by surrounding plasmas leading to the generation of post-solitons, while the main pulse excites convective electric currents leading to the formation of electron vortices through Kelvin-Helmholtz instability (KHI). In the P-polarized case, the scattered waves dissipate their energy by heating surrounding plasmas. Electron vortices are excited due to the hosing instability of the drive laser. These polarization dependent physical processes are reproduced in two different planes perpendicular to the laser propagation direction in three-dimensional simulation with linearly polarized laser driver. The current work provides inspiration for future experiments of laser-NCD plasma interactions.

scholarly journals Preparation and Characterization of Lead Oxide Nanoparticles by Laser Ablation as Antibacterial Agent

2017 ◽  
Vol 14 (4) ◽  
pp. 801-807
Author(s):  
Baghdad Science Journal
Keyword(s):  
Laser Ablation ◽  
Lead Oxide ◽  
Laser Energy ◽  
Laser Pulses ◽  
Diffusion Method ◽  
Lead Target ◽  
Oxide Nanoparticles ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

In this work, lead oxide nanoparticles were prepared by laser ablation of lead target immersed in deionized water by using pulsed Nd:YAG laser with laser energy 400 mJ/pulse and different laser pulses. The chemical bonding of lead oxide nps was investigated by Fourier Transform Infrared (FTIR); surface morphology and optical properties were investigated by Scanning Electron Microscope (SEM) and UV-Visible spectroscopy respectively, and the size effect of lead oxide nanoparticles was studied on its antibacterial action against two types of bacteria Gram-negitive (Escherichia coli) and Gram-positive (Staphylococcusaurus) by diffusion method. The antibacterial property results show that the antibacterial activity of the Lead oxide NPs was inversely proportional to the size of the nanoparticles in both Gram-negative and Gram-positive, and also it has been found that Gram-positive bacteria possess have greater sensitivity and less resistance to the lead oxide nanoparticles compared with Gram-negative bacteria.

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