The infrared-interfering composite smog material is prepared by a heating and agitating device in aqueous solutions and then sprayed into a cloud chamber for six minutes to form smog using gas-water mixing spray system. The attenuation performances of the smog to visible light, 1.06μm laser, 3-5μm infrared and 8-14μm infrared are evaluated, and compared with those of other testing materials. The results show that the sprayed smog have the best attenuation performances and the longest interfering time to visible light, 1.06μm laser, 3-5μm infrared and 8-14μm infrared. Therefore, the infrared-interfering composite smog material in the form of aqueous solution is the new smoke obscurant materials that are environment-friendly and possess broad application prospects in some aspects such as visible light, laser and infrared countermeasures.
In recent years, the weapon systems of laser and infrared (IR) imaging guidance have been widely used in
modern warfare because of their high precision and strong anti-interference. However, military smoke, a rapid and
effective passive jamming method, can effectively counteract the attack of precision-guided weapons by their scattering
and absorbing effects. The traditional smoke has good visible light (0.4-0.76μm) obscurant performance, but hardly any
effects to other electromagnetic wave bands while the weapon systems of laser and IR imaging guidance usually work in
broad band, including the near-infrared (1-3μm), middle-infrared (3-5μm), far-infrared (8-14μm), and so on. Accordingly,
exploiting new effective obscurant materials has attracted tremendous interest worldwide nowadays. As is known, the
nano-structured materials have lots of unique properties comparing with the traditional materials suggesting that they
might be the perfect alternatives to solve the problems above.
Carbon nanotubes (CNTs) are well-ordered, all-carbon hollow graphitic nano-structured materials with a high
aspect ratio, lengths from several hundred nanometers to several millimeters. CNTs possess many unique intrinsic
physical-chemical properties and are investigated in many areas reported by the previous studies. However, no
application research about CNTs in smoke technology field is reported yet. In this paper, the attenuation performances of
CNTs smoke to laser and IR were assessed in 20m<sup>3</sup> smoke chamber. The testing wavebands employed in experiments are
1.06μm and 10.6μm laser, 3-5μm and 8-14μm IR radiation. The main parameters were obtained included the attenuation
rate, transmission rate, mass extinction coefficient, etc. The experimental results suggest that CNTs smoke exhibits
excellent attenuation ability to the broadband IR radiation. Their mass extinction coefficients are all above 1m2·g-1.
Nevertheless, the mass extinction coefficients vary with the sampling time and smoke particles concentrations, even in
the same testing waveband. With the time going the mass extinction coefficients will increase gradually. Based on the
above results, theoretical calculations are also carried out for further exploitations. In general, CNTs smoke behaves
excellent attenuation ability toward laser and IR under the experimental conditions. Therefore, they have great potentials
to develop new smoke obscurant materials which could effectively interfere with broadband IR radiation including
1.06μm, 10.6μm, 3-5μm and 8-12μm IR waveband.
Many investigations show that almost all detection systems operating in visible light and infrared wave bands are subject to severe performance degradation when they are used in fog. It is necessary to study the influence of fog on the photoelectric sensors so as to find out applicable countermeasures. However, it is hard to get enough meaningful data tested in nature fog. If the forming of fog can be controlled artificially, more credible research methods and experiment conditions will be acquired for studying the electromagnetic wave transmission in fog. In this paper, artificial fog was produced with the fog aerosol specially prepared with oxidant, fuel and bond. Through combustion reaction, the fog aerosol could generate artificial condensation nucleuses, which were provided with fog catalyzing capabilities and able to condense water vapor in air and produce artificial fog within several minutes. Three types of fog aerosols of different oxidant (code-named as NP/KP/LP) were prepared for the experiments. And the influence of oxidant on the photoelectric obscurity performance and the microphysical characteristics of artificial fog were researched. The photoelectric obscurity performance was tested by an IR imaging sensor and an illuminometer sensor, and the microphysical characteristics were tested by the laser granularity system. The experiment results showed that the artificial fog had good photoelectric obscurity and aerosol LP had the best. The attenuation of visible light and infrared wave band (3～5μm) in the fog were above 90%; and the attenuation of infrared wave band (8～14μm) was above 80%. Moreover, the oxidant affected closely the microphysical features of the condensation nucleus, such as the size distribution and number density. It is noticeable that while the size distributions of droplets presented similar trajectories even with different fog aerosols, the coagulation and growth rates of droplets were controlled by the fog catalyzing capabilities of condensation nucleus. Obviously, the maximal droplet concentration and the highest droplet growth rate were obtained form aerosol LP, from which, therefore, the fog catalyzing capability was the best. In conclusion, the oxidant of the fog aerosol greatly affects the catalyzing capabilities of nucleuses and the droplets growth processes, and consequently leads to the difference of photoelectric obscurities.
In recent years, the weapon systems of laser guidance and infrared (IR) imaging guidance have been widely used in modern warfare because of their high precision and strong anti-interference. Notwithstanding, military smoke, as a rapid and effective passive jamming means, can effectively counteract the attack of enemy precision-guided weapons by scattering and absorbability. Conventional smoke has good attenuation capability only to visible light (0.4-0.76 μm), but hardly any effect to other electromagnetic wave band. The weapon systems of laser guidance and IR imaging guidance usually work in broad band, including near IR (1-3 μm), middle IR (3-5 μm), far IR (8-14 μm), and so on. Accordingly, exploiting and using new efficient obscurant materials, which is one of the important factors that develop smoke technology, have become a focus and attracted more interests around the world. Then nano-structured materials that are developing very quickly have turned into our new choice. Hollow nano-structured materials (HNSM) have many special properties because of their nano-size wall-thickness and sub-micron grain-size. After a lot of HNSM were synthesized in this paper, their physical and chemical properties, including grain size, phase composition, microstructure, optical properties and resistivity were tested and analysed. Then the experimental results of the optical properties showed that HNSM exhibit excellent wave-absorbing ability in ultraviolet, visible and infrared regions. On the basis of the physicochemmical properties, HNSM are firstly applied in smoke technology field. And the obscuration performance of HNSM smoke was tested in smoke chamber. The testing waveband included 1.06μm and 10.6μm laser, 3-5μm and 8-14μm IR radiation. Then the main parameters were obtained, including the attenuation rate, the transmission rate, the mass extinction coefficient, the efficiency obscuring time, and the sedimentation rate, etc. The main parameters of HNSM smoke were contrasted in detail with graphite powder smoke agent. The results showed that HNSM smoke possesses better obscuration capability compared with the smoke performance of conventional materials (such as HC, RP, oil, carbon black, and graphite powder). Therefore, they are new smoke obscurant materials which can effectively interfere with broadband electromagnetic radiation, including 1.06 μm and 10.6 μm laser, 3-5 μm and 8-14 μm IR waveband.
A new hollow nanoshell semiconductor was applied for generating smoke screen, and the dispersion and infrared jamming performance were researched. Firstly, the mircostructures and dispersion performance of the screen particles were analized by using SEM and cascade impactor; basing on the findings, the jamming performance of the screen to 8-12μm infrared light, 1.06 μm laser and 10.6 μm laser were examined, and the primary affecting factors and relationships got concluded. The results show that the dispersion performance is favorable as the diameters of more than 70% smoke particles are below 6.1μm; the smoke screen has better and satisfactory jamming performance to IR and laser as within 10 min, the decay rate maintains above 85% to 8-12μm IR and 90% to 1.06μm laser and10.6μm laser.