During the manned space missions, the crucial concerns of the spacecraft safety and thecrew’s health require long term, real-time trace gas monitoring of the cabin atmosphere toprovide early warning of the potentially dangerous events such as overheating of electricwiring insulation, unintended release of chemicals, or malfunctions of the air regenerationsystem. An advanced trace gas monitoring system for Chinese long-term manned spacemissions was discussed. In this paper, a novel design of multi-components trace gas analyzerbased on infrared photoacoustic spectroscopy technology was proposed for monitoring thecabin atmosphere in space missions. The developed instrument consists of the laser sources,photoacoustic cell, ultra-sensitive acoustic measurement unit, mechanical vibration isolationframe, electronic unit and gas exchange unit. The optical source is a combination of a widelytunable pulsed quantum cascade laser (QCL), distribute feedback (DFB) lasers and DFBQCL. Since the photoacoustic system measures the acoustic pressure wave which is directlyrelated to the absorbed energy by gas molecules, it is immune to the background signal andeasily reaches sub-ppm level of detection limits. Different laser source beams are coupledinto the photoacoustic cell using a special device stimulated by multi modulation frequencies.The photoacoustic cell is working in nonresonant mode, and the photo thermal displacementis measured with an interferometer. The experimental results of the prototype analyzer showthat it can measure the target 32 gases in 30 minutes with satisfying detection requirementsfor space missions. Comparing to the current instruments for space missions, the proposedanalyzer, with the same measurement capabilities, less weight (20kg), and lower powerconsumption (50W), is an alternative for trace gas monitoring in spacecraft.
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