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Laser Ablation - From Fundamentals to Applications || Nanosecond Laser Ablation: Mathematical Models, Computational Algorithms, Modeling
摘要： The basic mathematical models, computational algorithms, and results of mathematical modeling of various modes of laser action on metals are considered. It is shown that for mathematical description and analysis of the processes of laser heating, melting, and evaporation of condensed media, various theoretical approaches are used: continuum, kinetic, atomistic, etc. Each of them has its own field of applicability, its advantages, and disadvantages. Mathematical description of ns-laser ablation is usually carried out within the framework of continuum approach in the form of hydrodynamic models that take into account reaction of irradiated material to varying density, pressure, and energy both in the target and in the vapor-gas medium. Within the framework of continuum approach, a multiphase, multifront hydrodynamic model and computational algorithm were constructed that were designed for modeling ns-PLA of metal targets embedded in gaseous media. It is shown that proposed model and computational algorithm allow to carry out the simulation of interrelated mechanisms of heterogeneous and homogeneous evaporation of metals manifested as a series of explosive boiling. Modeling has shown that explosive boiling in metals occurs due to the presence of a near-surface temperature maximum. It has been established that in ns-PLA, exposure regimes can be realized in which a phase explosion is the main mechanism of material removal. The verification of reliability of obtained results was carried out by comparing experimental data and calculations with atomistic models.
关键词： explosive boiling,phase explosion,hydrodynamic model,laser action,nanosecond pulse,mathematical modeling,subsurface temperature maximum
更新于2025-09-12 10:27:22
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Design on Program-Controlled Initiation System of the SCB explosive devices Based on Optical Fiber Communication
摘要： A control system for Semiconductor Bridge explosive devices is designed based on optical fiber Communication, which can make the explosive devices perform better in the complex electromagnetic environment. By the combination of programmable bus controller, ignition unit and the optical fiber communication, the ignition of the explosive devices in chronological order could be realized. After the system design was completed, the major function and anti-electromagnetic interference capability were tested. The results indicated that the system had remote-control ability, high reliability, high security and good electromagnetic compatibility. The system can be used in more complicated electromagnetic environment than the conventional initiating explosive devices.
关键词： programmable bus controller,ignition unit,electromagnetic compatibility,Semiconductor Bridge explosive devices,optical fiber communication
更新于2025-09-12 10:27:22
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The Effect of Metal Film Thickness on Ignition of Organic Explosives with a Laser Pulse
摘要： The results of numerical ignition simulation of pentaerythritol tetranitrate (PETN), cyclotrimethylene trinitramine (RDX), cyclotetramethylene tetranitramine (HMX) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) by aluminium (Al) and molybdenum (Mo) films heated by nanosecond laser pulses in a three-layer system: glass–metal–explosive material (EM) are presented. Influence of metal film thickness on the time of EM ignition delay was considered. A non-linier dependence of time of delay of ignition of EM from thickness of a metal film is shown. The greatest critical thicknesses of Al and Mo metallic films at which ignition of EM is still possible were determined. It was established that the greater the thickness of the metal film and heat resistance of EM, the greater the heat reserve needed in EM ignition film. It was established that the ignition delay time of EM increases in the sequence of PETN, RDX, HMX and TATB.
关键词： TATB,Al film,simulation,explosive,laser ignition,HMX,Mo film,PETN,RDX
更新于2025-09-12 10:27:22
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Controlled Detonation Synthesis of Nano Fe-based Oxides/ SiO2 Core-shell Composite Particles
摘要： Controlled detonation of emulsion Explosive and Hexogen (a kind of high explosive, for short, RDX) was performed to prepare Fe-based oxides/SiO2 nanoparticles. XRD (X-ray diffraction), TEM (Transmission electron microscope) and VSM (Vibrating sample magnetometer) experiments were performed to characterize and investigate the ingredients and phase structure of the granules, morphology, and distribution of the particles and the magnetism of the powders respectively. Results indicated that Fe/Urea complex detonation via emulsion explosives was advantageous to prepare Fe-based oxides/SiO2 core-shell powders, the inner FeO/Fe core was properly coated by a silica outer shell with the core size of around 50nm and shell thickness of around 5~10nm. And most of the raw detonation dust were converted into SiO2 coating Fe particles with the remained core-shell structure after proper thermal treatment. Raw powders obtained by RDX detonation presented weaker magnetism than that via emulsion explosives detonation, but which was substantially improved after thermal treatment.
关键词： Controlled detonation,Fe-based oxides/SiO2,Emulsion explosive,Core-shell Structure
更新于2025-09-12 10:27:22
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Effect of Decomposition of CuO Film on Ignition of Organic Explosives by a Laser Pulse
摘要： This work presents experimental results of the PETN ignition in a three-layer system: glass – copper oxide (CuO) – explosive materials (EM) and results of numerical simulations of the ignition of PETN, RDX, HMX, and TATB with a CuO film heated by a YLS-150 fiber laser with a pulse duration of 20 ms. In the numerical simulations, the endothermic reaction of decomposition of the CuO film and decomposition reaction of EM were taken into account. It has been established that the endothermic effect of the CuO decomposition reaction increases the dynamic ignition delay time of EM. The expression for an estimation of width of a reaction layer in EM at heating by a constant heat stream is obtained. Calculations have shown that the dynamic threshold of ignition of organic explosives by laser pulse in a three-layer system (glass – CuO – EM) has a minimum for the thickness of the copper oxide film of 5 mm. The density of the critical ignition energy of an explosive laser pulse increases in the sequence of PETN, RDX, HMX, and TATB. The calculated dependence of the PETN dynamic ignition delay time on the thickness of the CuO film is consistent with the experimental data.
关键词： PETN,explosive,RDX,TATB,copper oxide,HMX,laser ignition,simulation
更新于2025-09-11 14:15:04
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[IEEE 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Greifswald, Germany (2018.9.23-2018.9.28)] 2018 28th International Symposium on Discharges and Electrical Insulation in Vacuum (ISDEIV) - Simulation of the Explosion of a Surface Microprotrusion during a Radio Frequency Breakdown
摘要： The explosion of a surface microprotrusion under the action of a radio frequency electromagnetic field has been numerically simulated. It has been demonstrated that the microexplosion and the subsequent crater formation occur in much the same way as they do in the case of a dc field. The results obtained support the hypothesis that a dc vacuum breakdown and a breakdown initiated by an rf wave incident on a metal surface proceed by the same mechanism.
关键词： explosive emission,MHD modeling,radio frequency breakdown
更新于2025-09-10 09:29:36
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[IEEE 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Odessa (2018.9.4-2018.9.7)] 2018 9th International Conference on Ultrawideband and Ultrashort Impulse Signals (UWBUSIS) - Application of the Industry 4.0 Paradigm to the Design of a UWB Radiolocation System for Humanitarian Demining
摘要： The modern world is characterized by the pervasive use of computers, sensors, robotics, and Internet connectivity. This represents a new industrial revolution, dubbed Industry 4.0. In this paper, we discuss the application of the Industry 4.0 paradigm to creating a robotic search-and-detection platform intended for humanitarian demining. This is based on the combination and interaction of two microwave radars - including a UWB multi-sensor array, and a holographic imager - as well as 3-D optical cameras, remote navigation, and GPS tracking. The concepts introduced by Industry 4.0 represent an important opportunity for the scientific community to adopt new approaches in the design and use of UWB radar systems, and how data from these systems can be shared, archived, and processed in a decentralized manner accessible to the worldwide community
关键词： holographic radar,unexploded ordnance (UXO),computer simulations,georadar,landmine,Industry 4.0,ultra-wide-band (UWB) radar,humanitarian demining,improvised explosive device (IED),robotic platform,detection
更新于2025-09-09 09:28:46
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Porous Halide Perovskite–Polymer Nanocomposites for Explosive Detection with a High Sensitivity
摘要： A porous halide perovskite–polymer nanocomposite is developed using a freeze-drying process. Such a composite shows strong fluorescence quenching after exposure to explosive nitroaromatics, nitroamines, and nitrate esters with a sensitivity of a few nanograms. In addition, this composite is robust against moisture and solvents, showing negligible change in fluorescence intensities after submersion in water, alcohol, and acid, base, and salt solutions. Transient absorption spectroscopy studies further disclose that the explosive chemical introduces more trap states into the perovskite that contributes to fluorescence quenching of the perovskite.
关键词： explosive detection,TNT,perovskite,composites
更新于2025-09-09 09:28:46
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Investigation of explosive electron emission sites on surface of polished cathodes in vacuum
摘要： The field enhancement effect of the surface microstructures of electrodes with two different surface treatments is evaluated, on the basis of observations made by a 3-D laser microscope. The maximum field enhancement factor of the micro-protrusions on the surface after turning or mirror polishing is about 1-5.8. The vacuum gap breakdown strength of the mirror polished electrodes is 1-1.4 times higher than that of the turned electrodes, because the surface grooves are removed. Experiments to test the breakdown strength of 2.5 cm vacuum gaps with the electrodes after the treatments were carried out and the experimental results were found to correspond to the analysis. The results also revealed that it is not enough to induce explosive electron emission and vacuum breakdown just by the field enhancement at the micro-protrusions and grooves. Moreover, the emission sites of mirror polished cathode made of titanium alloy and stainless steel after vacuum breakdown were observed by a scanning electron microscope and an energy dispersive spectrometer. The results show that the proportion of carbon atoms in the damaged area of the stainless steel cathode surface is as high as 40-70%, and most of the pits located at the grain boundaries, which suggests that grain boundaries have important effects on the electron emission and vacuum breakdown.
关键词： explosive electron emission,grain boundary,field-induced electron emission,vacuum breakdown
更新于2025-09-04 15:30:14