Infrared Extinction Calculations of Smokescreen Particles by Moment Method

A moment-method-based infrared extinction model of rotating smokescreen particles is applied to perform calculations entailing three graphite particles including flakes, spheres, and cylinders, mainly focusing on the relationship between extinction ability and particle parameters, such as shape, diameter, and thickness. The calculations suggest that extinction is attributed to absorption when the particle size is small and attributed to scattering when the particle size is large. Flakes exhibit the best infrared extinction performance. When flakes become thinner, their extinction abilities are enhanced. Flakes with 100 nm thickness and 1.5–2.1 μm radius exhibit outstanding extinction performance in the 1–10 μm infrared wavelength range, with an average infrared extinction coefficient as high as 5.0 m²/g.