scholarly journals A Study of the Characteristics of Plasma Generated by Infrared Pulse Laser-Induced Fused Silica

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1009
Author(s):  
Lixue Wang ◽  
Xudong Sun ◽  
Congrui Geng ◽  
Zequn Zhang ◽  
Jixing Cai
Keyword(s):  
Pulse Laser ◽  
Pulse Width ◽  
Laser Energy ◽  
High Energy ◽  
Fused Silica ◽  
Expansion Velocity ◽  
Generation Process ◽  
Experimental Conditions ◽  
Maximum Expansion ◽  
Laser Induced Plasma

When high energy infrared laser pulses are incident on fused silica, the surface of the fused silica is damaged and a laser-induced plasma is produced. Based on the theory of fluid mechanics and gas dynamics, a two-dimensional axisymmetric gas dynamic model was established to simulate the plasma generation process of fused silica induced by a millisecond pulse laser. The results show that the temperature of the central region irradiated by the laser is the highest, and the plasma is first produced in this region. When the laser energy density is 1.0 × 104 J/cm2 and the pulse width is 0.2 ms, the maximum expansion velocity of the laser-induced plasma is 17.7 m/s. Under the same experimental conditions, the results of the simulation and experiment are in good agreement. With an increase in pulse width, the plasma expansion rate gradually decreases.

scholarly journals Laser-Solid Interaction and Dynamics of the Laser-Ablated Materials

1995 ◽  
Vol 388 ◽  
Author(s):  
K. R. Chen ◽  
J. N. Leboeuf ◽  
D. B. Geohegan ◽  
R. F. Wood ◽  
J. M. Donato ◽  
...  
Keyword(s):  
Energy Density ◽  
Laser Energy ◽  
Ablation Rate ◽  
Laser Energy Density ◽  
Expansion Velocity ◽  
Coupled Modeling ◽  
High Background ◽  
Maximum Expansion ◽  
Dynamic Source ◽  
Background Gas

AbstractRapid transformations through the liquid and vapor phases induced by laser-solid interactions are described by our thermal model with the Clausius-Clapeyron equation to determine the vaporization temperature under different surface pressure condition. Hydrodynamic behavior of the vapor during and after ablation is described by gas dynamic equations. these two models are coupled. Modeling results show that lower background pressure results lower laser energy density threshold for vaporization. the ablation rate and the amount of materials removed are proportional to the laser energy density above its threshold. We also demonstrate a dynamic source effect that accelerates the unsteady expansion of laser-ablated material in the direction perpendicular to the solid. a dynamic partial ionization effect is studied as well. a self-similar theory shows that the maximum expansion velocity is proportional to cs/α, where 1 – α is the slope of the velocity profile. Numerical hydrodynamic modeling is in good agreement with the theory. With these effects, α. is reduced. therefore, the expansion front velocity is significantly higher than that from conventional models. the results are consistent with experiments. We further study the plume propagates in high background gas condition. Under appropriate conditions, the plume is slowed down, separates with the background, is backward moving, and hits the solid surface. then, it splits to be two parts when it rebounds from the surface. the results from the modeling will be compared with experimental observations where possible.

NUMERICAL SIMULATION OF FIBER-OPTIC PHOTOACOUSTIC GENERATOR USING NANOCOMPOSITE MATERIAL

2013 ◽  
Vol 21 (02) ◽  
pp. 1350002 ◽  
Author(s):  
YE TIAN ◽  
NAN WU ◽  
KAI SUN ◽  
XIAOTIAN ZOU ◽  
XINGWEI WANG
Keyword(s):  
Fiber Optic ◽  
Laser Energy ◽  
Energy Conversion Efficiency ◽  
High Energy ◽  
Generation Process ◽  
Destructive Testing ◽  
Element Analysis ◽  
Fea Model ◽  
Structure Dimension ◽  
Set Up

Photoacoustic generation using an optical fiber is a promising approach to meet the challenges in most advanced ultrasonic non-destructive testing (NDT) applications. The energy-absorption layer coated on the fiber endface plays an important role in converting the laser energy into heat and exciting the acoustic wave. The selection of the absorption material and the optimization of the structure dimension are the keys for achieving high energy-conversion efficiency. A 2D-axisymmetric finite element analysis (FEA) model was established to simulate the photoacoustic generation process using a newly developed absorption material, polydimethylsiloxane/gold nanoparticle (PDMS/Au NPs) nanocomposites, with different thicknesses and laser pulse durations. The experimental results obtained using a similar set-up show a similar trend predicted by this FEA simulation. The FEA results provide practical clues to the design of the fiber-optic photoacoustic generator.

scholarly journals High Energy Double Peak Pulse Laser Induced Plasma Spectroscopy for Metal Characterization Using a Passively Q-Switched Laser Source and CCD Detector

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3634
Author(s):  
Juri Agresti ◽  
Andrea Azelio Mencaglia ◽  
Salvatore Siano
Keyword(s):  
Pulse Laser ◽  
Yttrium Aluminum Garnet ◽  
Low Cost ◽  
Laser Pulses ◽  
High Energy ◽  
Laser Source ◽  
Plasma Spectroscopy ◽  
Double Peak ◽  
Temporal Separation ◽  
Laser Induced Plasma

Here, the development and testing of a portable double peak pulse laser induced plasma spectroscopy (DPP-LIPS) based on passively Q-switched Nd:YAG (Neodymium-doped Yttrium Aluminum Garnet) laser excitation is reported. The latter delivered structured laser pulses at a repetition rate of up to 20 Hz, including two energy peaks of about 100 mJ each with a relative temporal spacing of about 80 µs. Plasma spectra were collected using a low-cost Czerny–Turner spectrometer equipped with a non-intensified CCD (Charge-Coupled Device) array. Such a DPP-LIPS setup is technologically simpler and cheaper than the usual ones. Despite the relatively large temporal separation between the mentioned laser peaks, significant spectral intensity enhancements with respect to the usual single peak pulse configuration were observed. The amplification factor measured ranged between 2 and 10, depending on the specific emission peaks and the Q-switched configuration, and a consequent significant improvement of the detection limit of trace elements was observed. The instrument was calibrated for the quantitative analysis of copper alloy through systematic measurements carried out on reference samples and was then tested in an example archaeometric characterization of a statuette from the Egyptian Museum of Florence.

scholarly journals Low-Energy Electron Damage to Condensed-Phase DNA and Its Constituents

2021 ◽  
Vol 22 (15) ◽  
pp. 7879
Author(s):  
Yingxia Gao ◽  
Yi Zheng ◽  
Léon Sanche
Keyword(s):  
Condensed Phase ◽  
Genetic Material ◽  
High Energy ◽  
Dna Lesions ◽  
Low Energy ◽  
Experimental Investigations ◽  
Experimental Conditions ◽  
Strand Breaks ◽  
Sequence Of Events ◽  
Wide Range

The complex physical and chemical reactions between the large number of low-energy (0–30 eV) electrons (LEEs) released by high energy radiation interacting with genetic material can lead to the formation of various DNA lesions such as crosslinks, single strand breaks, base modifications, and cleavage, as well as double strand breaks and other cluster damages. When crosslinks and cluster damages cannot be repaired by the cell, they can cause genetic loss of information, mutations, apoptosis, and promote genomic instability. Through the efforts of many research groups in the past two decades, the study of the interaction between LEEs and DNA under different experimental conditions has unveiled some of the main mechanisms responsible for these damages. In the present review, we focus on experimental investigations in the condensed phase that range from fundamental DNA constituents to oligonucleotides, synthetic duplex DNA, and bacterial (i.e., plasmid) DNA. These targets were irradiated either with LEEs from a monoenergetic-electron or photoelectron source, as sub-monolayer, monolayer, or multilayer films and within clusters or water solutions. Each type of experiment is briefly described, and the observed DNA damages are reported, along with the proposed mechanisms. Defining the role of LEEs within the sequence of events leading to radiobiological lesions contributes to our understanding of the action of radiation on living organisms, over a wide range of initial radiation energies. Applications of the interaction of LEEs with DNA to radiotherapy are briefly summarized.

In situ monitoring of isophorone diisocyanate-based flexible polyurethane foams formation

2016 ◽  
Vol 54 (1) ◽  
pp. 37-52 ◽  
Author(s):  
I Eceiza ◽  
L Irusta ◽  
A Barrio ◽  
MJ Fernández-Berridi
Keyword(s):  
Foam Height ◽  
Polyurethane Foams ◽  
In Situ Monitoring ◽  
Generation Process ◽  
Isophorone Diisocyanate ◽  
Experimental Conditions ◽  
Foaming Process ◽  
Foam Generation ◽  
Flexible Polyurethane

Novel isophorone diisocyanate-based flexible polyurethane foams were prepared by the one-step method in a computerized foam qualification system (FOAMAT). The experimental conditions to obtain this type of foams, in relation to the nature and concentration of catalysts as well as the reaction temperature, were established as no data were available in scientific literature. The chemical reactions occurring during the foam generation process were monitored in situ by attenuated total reflectance-FTIR spectroscopy. The kinetics of the foam generation was fitted to an nth order model and the data showed that the foaming process adjusted to a first-order kinetics. The physical changes as pressure, foam height, and dielectric polarization were monitored by the FOAM software (FOAMAT). According to these parameters, the foaming process was divided into four steps: bubble growth, bubble packing, cell opening, and final curing.

scholarly journals Influence of bulk defects on bulk damage performance of fused silica optics at 355 nm nanosecond pulse laser

2017 ◽  
Vol 25 (26) ◽  
pp. 33416 ◽  
Author(s):  
Jin Huang ◽  
Hongjie Liu ◽  
Fengrui Wang ◽  
Xin Ye ◽  
Laixi Sun ◽  
...  
Keyword(s):  
Pulse Laser ◽  
Fused Silica ◽  
Nanosecond Pulse ◽  
Nanosecond Pulse Laser

scholarly journals Improved Phebus laser performances required for precision laser–target experiments

1998 ◽  
Vol 16 (2) ◽  
pp. 253-265 ◽  
Author(s):  
G. Thiell ◽  
R. Bailly-Salins ◽  
J.L. Bruneau ◽  
G. Coulaud ◽  
P. Estraillier ◽  
...  
Keyword(s):  
Laser Energy ◽  
Incident Beam ◽  
High Energy ◽  
Target Chamber ◽  
Laser Target ◽  
Time Resolved ◽  
X Ray ◽  
Target Experiment ◽  
Pointing Precision ◽  
Energy Shots

The Precision Phebus program, started in 1993, emphasizes a series of laser and target experiment objectives on the two-beam Phebus Nd-phosphate glass laser. Recently, three major objectives that are also very important issues for megajoule-class lasers have been met: First, the balance of the incident beam-to-beam 3ω power is shown to be in the range from 5 to 12% for 3-ns, 3ω-shaped pulses of reproducible high-energy shots; second, the smoothing uniformity of the laser energy deposited on the target, that is, the contrast of the spatial beam modulations, can be kept lower than 5%; and, finally, the tight control of the beam targeting leads to a pointing precision of less than 10 μrd on the target at the target chamber center (TCC) and of 80 μrd on X-ray sources located up to 3 cm from the TCC to improve the space- and time-resolved X-ray shadowgraphy techniques performed for target physics experiments such as implosion and hydrodynamical instability studies.

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