Experiment of New Protype Group III-nitride UV Image Converter Tube and Evaluation of Detectable Distance of Missile Approach Warning System with It

A superior ultraviolet image converter tube made of III-nitride semiconductor material was developed for missile approach warning (MAW) system. The Al mole fraction, film thickness and P-type doping level parameters which have the effects on the photoelectric emission performance of photocathode were determined. High resolution X ray diffractometer and ultraviolet spectrometer are used to analyze the structural and optical characteristics of photocathode. A relative flat and high quantum efficiency with small fluctuation in the wavelength range from 220 nm to 270 nm is obtained, the radiation sensitivity is 39.7 mA/W at 266 nm wavelength, and the spectral response begins to fall from 270 nm wavelength. According to the spectral radiation sensitivity and detectable distance model based on signal-to-noise ratio, MODTRAN atmosphere transmittance simulation software is used to calculate the operating range of MAW system with image converter tube by means of iteration solution. The calculated result shows that the operating range of MAW system can be up to 7.1 km.