Research Of Influence Of Oxidant On The Photoelectric Obscurity Of Artificial Fog

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 similar to 5 mu m) in the fog were above 90%; and the attenuation of infrared wave band (8 similar to 14 mu m) 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.