Design And Research Of IR Active Decoy

Since the 1970s infrared technology obtained a comprehensive development and breakthroughs. Various types of infrared technology, such as target detection systems, tracking and guidance, have played an increasingly important role. It is very important that military targets are seriously threatened by infrared-guided missiles. During the Vietnam War the United States started to equip the army with infrared decoy. then, other countries equipped their armies one after the other. At present, infrared decoy has become the most widely used in infrared countermeasure equipment. Up to now, the fourth generation of infrared decoy had been developed. The first generation of infrared decoy mainly rely on the infrared radiation of the combustion, the second generation generated infrared radiation by heating, the third generation utilized Xenon lights as the infrared radiation sources, and the fourth generation utilized the modulated laser as the radiation source.This paper mainly research the infrared decoy, and design an infrared decoy based on the deeply study of infrared decoy at home and abroad.In this paper, by comparing with every generation infrared decoy, first of all we researched 3-5um laser using to the fourth generation of infrared decoy. According to the literatures I had consulted, I summarize the development of quantum cascade laser and inter-band cascade lasers, and discuss the materials and structure that the two types of lasers used. By referring to lots of literatures, we discover that the technology of 3-5um laser is not mature. This laser radiation is not very satisfactory such as radiant power, stability, 3-5 um band coverage. The efficiency of frequency conversion is very low. Therefore we use electric heating method which between the third generation and the second generation.The main content of the paper is to design a decoy matching the spectrum of the plane radiate by using electric heating to generate infrared radiation. The choosing of the high emitting rate and high power conversion efficiency materials is also one aspect of the study. In the design, we choose carbon fiber, whose radiation characteristics approach to which of absolute blackbody. There have very good mechanical and calorific characteristics. We confirm its characteristics by measuring mechanical and calorific properties. During the measure, we used steady state calorimeter method to measure some parameters of carbon fiber at room temperature, such as the total hemispheroidal emissivity and the normal spectral reflectance. According to the compensation principle we determine the potential drop of the carbon fiber. Furthermore, the questions of measuring the carbon fiber's hot resistance and the temperatureθare resolved.Because carbon fiber exist strong phenomenon of oxidation at a high temperature, we package carbon fiber in order to gain the vacuum environment, because the vacuum environment can prevent from heat loss and reduce response time. We choose corundum materials as package just because the materials are high hardness, tensile strength through verification of test, hardly damaged and high transmittance. The experiment showed that the transmittance of corundum whose thickness is 2mm can reach 90% though adding AR coating.In order to reduce collision damage, the paper adopt the shock absorption design, and calculate their best size, radiating angle, length of external structure, relations between the length and damping coefficient of spring. In order to reduce heat radiation losses caused by outer structure, we add anti-film in the outer layer structure to make the outer layer of the reflection coefficient of up to 97 percent. The design adopt a drag-type structure, we can provide constant power to the infrared decoy through the wires, which can increase the decoy protection time.Finally, the product device can achieve the following performances through experimental verification.We product a small sample, the independently design the test system in actual test. Input signal conditioning is supplied by the steady power, we measure some datum such as the voltage, current, temperature, radiation, heat loss for the calculation. In order to reduce the heat diffused during measuring, and gain the more accurate data, during the experiments a separate heat cover is needed, we can measure some points we added in the test, then process the data though compensation analysis. Finally we gain the good experimental data. The power output of plane is 24 V, 2000W at actual circumstances. The device can achieve the following performances: the actual temperature at full load can exceed 1200 K, the surface load exceed 36000 W / m2. Ignoring surface radiation, effective radiation can reach 2200 W /sr, response time is less than 0.5 S, as the vacuum devices can prevent from carbon fiber's oxidation in high-temperature. According to the literatures, the theoretical life is more than 1,000 hours. Because plane take-off speed less than 20m/s, the collision will not damage the device with this structural design. The performance parameters satisfy requirements.Finally, this device also can be used infrared target.In process of missile tests,it to be served as target of missiles through simulated the radiation signals of target aircraft. Thereby reducing costs of tests.