Modeling of helicopter-borne tunable TEA CO2 DIAL system employment for detection of methane and ammonia leakages

The characteristics of a helicopter-borne lidar based on tunable TEA CO2 la ser and its third harmonic designed for remote detection of methane and amm onia leakages from pipelines are analyzed numerically. The spectral range n ear 3 mu m was shown to be most promising for remote sensing of methane emi ssions. Parameters of radiation of the tunable pulse-periodic mini-TEA CO2 laser and generators of harmonics to be utilized in the helicopter-borne di fferential absorption lidar are estimated. Emissions of different gas inten sities are analyzed for possible detectability at a distance of up to 1 km, The use of the third harmonic of the TEA CO2 laser allows methane emission s from a pipeline to be detected and measured with mean measurement error f rom 10% to 15% for methane concentrations varying from the background level to the explosion-hazardous one,The optimal pair and possibilities of the a mmonia remote; sensing on the base of the first harmonic of TEA CO2 laser w ere determined as well. (C) 2000 Elsevier Science B.V. All rights reserved.