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Laser Ignition and Flame Temperature for Low-Density Mixtures of Lignite Coal and Pentaerythritol Tetranitrate (Petn)
摘要： We have studied laser ignition (1064 nm, 120 μs) of mixtures of lignite coal (brown coal) particles of size ≤0.1 mm and pentaerythritol tetranitrate (PETN) additives. We established that as the amount of PTEN additives increases in the range 0–50 wt.%, the critical ignition energy density of the mixtures decreases monotonically from 2.9 to 2.0 J/cm2. We used spectral pyrometry to determine that the ?ame temperature for the mixture increases from 1800 K to 2100 K.
关键词： laser ignition,pentaerythritol tetranitrate (PETN),spectral pyrometry,lignite (brown coal),spectroscopy
更新于2025-09-23 15:21:01
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New Method for Studying the Ignition Characteristics of Condensed Systems by Laser Radiation
摘要： A method for determining the characteristics of laser ignition of the condensed systems is presented, which ensures uniform distribution of the heat flux density over the surface during ignition. The method consists in measuring the ignition delay time of a rotating cylindrical sample when the continuous laser heat flux is applied to its end surface. The theoretical estimation of the required angular rotation velocity of the sample is carried out, which ensures averaging with a given error of the radiation flux density on the surface of the sample, as well as the degree of surface cooling due to the convective heat transfer. The experimental results on the pyroxylin sample ignition at the radiant heating by a CO2 laser with and without rotation of the sample are presented.
关键词： pyroxylin,laser ignition,ignition delay time,condensed system,convective heat transfer,angular velocity of rotation
更新于2025-09-23 15:19:57
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Comparison of 1-Propyl-5H-tetrazole and 1-Azidopropyl-5H-tetrazole as Ligands for Laser Ignitable Energetic Materials
摘要： Laser ignitable explosives are potential candidates in future applications for replacing toxic and very sensitive primary explosives, which are used in current devices. In this study, the literature unknown ligand 1-azidopropyl-5H-tetrazole (APT, 1) was synthesized for the first time and applied in energetic coordination compounds (ECC). The complexes are based on different 3d transition metals (Mn2+, Fe2+, Cu2+, and Zn2+) as well as various oxidizing anions (NO3?, ClO4?, ClO3?) and were tested towards their capability as laser ignitable explosives. Furthermore, analogous complexes based on the literature known ligand 1-propyl-5H-tetrazole (PT, 2) were investigated, for comparing the influence of the additional azide group towards the performance of the ECC. Toxicity measurements using Vibrio fischeri and the decreased sensitivities prove their usability as safer laser ignitable explosive with lower toxicities compared to currently used explosives.
关键词： tetrazole ligands,laser ignition,nitrogen heterocycles,structure elucidation,energetic coordination compounds
更新于2025-09-23 15:19:57
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Characterization of Continuousa??Wave Laser Heating Ignition of Ammonium Dinitramidea??Based Ionic Liquids with Carbon Fibers
摘要： Ammonium dinitramide–based energetic ionic liquid propellants (ADN-EILPs) exhibit the advantages of high energy density, low toxicity, and handling safety, and are therefore promising monopropellants. Herein, we characterized the ignition of ADN-EILPs induced by CW laser heating in the presence of carbon fibers, clarifying the effect of laser power and suggesting that ignition reproducibility is influenced by the difference of ADN-EILP osmotic state in carbon fibers or carbon fiber configuration. The observed ignition behavior allowed one to conclude that (i) high-power CW laser heating causes the formation of bubbles on the surface, which disturbs further heating; and (ii) an Arrhenius-type relationship exists between ignition delay and heating rate, suggesting that the strategy of foreshortening ADN-EILP ignition delay by increasing CW laser power has certain limits.
关键词： Carbon fiber,Laser ignition,Ignition delay,Ionic liquid,Ammonium dinitramide (ADN)
更新于2025-09-19 17:13:59
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Pulsed laser irradiation of a nanoparticles sensitised RDX crystal
摘要： The laser initiation of secondary explosives presents tactical, safety and environmental advantages over traditional ignition systems utilising primary explosives. In this paper, direct ignition or initiation by pulsed laser was investigated of cyclotrimethylenetrinitramine (RDX) crystals doped with gold nanoparticles (GNPs) for the first time. A nano-seconds pulsed laser was used for direct irradiation of the crystals at the GNP’s surface-plasmon-resonance wavelength of 532 nm. RDX crystals were recrystallised from a solution containing GNPs and characterised by visual microscopy for surface coating and subsurface doping. A high-speed camera was used to observe and capture the modes of interaction between the GNPs-doped RDX crystals and pulsed laser irradiation with a new classification method. Laser fluence thresholds for ignition and initiation were established. The GNPs sensitized RDX to pulsed laser irradiation at this selected wavelength is 3 orders of magnitude more sensitive than pure RDX. Direct initiation of the GNPs doped RDX crystal at laser fluence of 0.04 J/cm 2 led to the total consumption of a crystal sample, which was unreproducible with pure RDX. The results show that GNPs are effective optical sensitizers for direct initiation of RDX crystal by low-power pulsed laser.
关键词： Gold nanoparticles,Pulsed laser,Explosive,Laser ignition
更新于2025-09-19 17:13:59
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THE TEMPORARY CHARACTERISTICS OF VACUUM DISCHARGE WITH LASER IGNITION
摘要： A study was made of the switching process of a vacuum discharger ignited by a pulsed solid-state laser operating in the Q-switched mode. The dependence of the response time on the energy of the igniting pulse of laser radiation and the thermodynamic characteristics of the target material has been demonstrated. On the basis of the experimental data, it was suggested that under the action of a laser pulse in the erosion products of the electrodes an initial glow discharge is ignited, which, as a result of the development of ionization-superheating instability, undergoes a contraction of the current channel and turns into an arc channel.
关键词： vacuum discharge,laser ignition,switching process,Q-switched mode,glow discharge,arc channel,solid-state laser,thermodynamic characteristics
更新于2025-09-16 10:30:52
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Laser-Induced Ignition and Combustion of Individual Aluminum Particles Below 10 ??m by Microscopic High-Speed Cinematography
摘要： Metal aluminum has been widely used as an ingredient in propellant, gunpowder and thermite, but there is less understanding of the combustion mechanism of aluminum particles from submicron to several microns in diameter. This paper proposes to experimentally investigate the ignition and combustion characteristics of individual aluminum particles below 10 μm. A specific in situ diagnostic experimental apparatus was first designed for directly observing the ignition and combustion behaviors of individual aluminum particles, with a submicrometer spatial resolution and a temporal resolution of tens of microseconds. Direct observation through microscopic high-speed cinematography demonstrated that, when heated by a continuous laser, individual aluminum particles thermally expanded, followed by shell rupture; the molten aluminum core overflowed and evaporated, leading to ignition and combustion. Further results showed that, when the laser power densities were gradually increased (5.88, 7.56 and 8.81 × 105 W/cm2), the durations of thermal expansion, melting and evaporation were shortened. The required time for the aluminum particles to expand to 150% of their initial diameter was shortened (34 s, 0.34 s and 0.0125 s, respectively). This study will be beneficial to further extend the investigation of other individual metal particles and reveal their combustion mechanism by direct observation.
关键词： combustion mechanism,microscopic high-speed cinematography,individual aluminum,laser ignition,submicron particle
更新于2025-09-16 10:30:52
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On the possibility to improve petrol engine operation by laser ignition
摘要： A typical method frequently used for the experimental investigation of engines operation at light load, low speed and different air-fuel ratios by spark timing adjustment was applied to understand in what measure the characteristics of the ignition system could improve the petrol engines performances. In this sense, a Laser Ignition - LI system replacing the original spark ignition system of the engine was mounted and some comparisons between these systems have been made based on engine power, coefficients of variation and combustion duration when 500 consecutive cycles were registered for 2000 rpm engine speed with load equivalent to 2 bar brake mean effective pressure and up to 1.25 relative air-fuel ratios.
关键词： Laser ignition of engines,Laser induced combustion,Passively Q-switched laser,Lean-fuel ignition
更新于2025-09-12 10:27:22
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Experimental investigations of LASER ignition use at spark ignition engine
摘要： In the current global context, due to the impact of pollutant emissions produced by internal combustion engines on the environment, researchers in the automotive industry are designing and implementing new technologies. LASER ignition as a potentially superior ignition source for technical appliances can also be suitable for internal combustion engines. The objective of the paper is the experimental research of LASER ignition use in the spark ignition engine. The experimental results present the influence of LASER ignition on different engine parameters compared to electric spark ignition. The paper also analyses the influence on in-cylinder pressure, heat release rate, heat release law and engine efficiency. The LASER ignition system assures efficient engine operation at lean dosages.
关键词： spark plug,heat release rate,maximum pressure,LASER ignition
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