面向载人航天的MEMS质谱仪关键技术研究

This project researches the key components of the MEMS mass spectrometer (MS)deeply and systematically, including the ion source, the mass analyzer and the vacuum system. The main purpose of this project is to discover new principles to design the MEMS mass spectrometer to monitor the major atmospheric constituents in the spacecraft cabin in real-time and online, to solve the key scientific and technical issues related to the design of the main components of the MEMS mass spectrometer. The main research contents include: 1) Researching the mechanism of field-emission ion source, designing and fabricating a Micro-field-emission ion source by MEMS technology, which can work under the condition of low vacuum, and has a long life and tunable ionization efficiency; 2) Simulating and optimizing the MEMS-based rectilinear ion trap (RIT) mass analyzer, which can reduce the vacuum system requirements, obtain larger ion capacity and facilitate miniaturization. Completing the fabrication process of the Micro-RIT mass analyzer by MEMS technology; 3) Designing a miniature and mixture vacuum system which contains a variety of vacuum technologies to realize the miniaturization and maintenance-free; 4) Designing the experiments to present a new method and technology to analyze the ion movement characteristics under the condition of the micron scale by the MEMS-MS fabricated above, and to find out the mechanism and characteristics of ions birth, transmission, and analysis. Based on those researches, the research of MEMS mass spectrometer on manned space flight will be completed.

本项目针对MEMS质谱仪涉及到的离子源、质量分析器和真空系统等关键部件进行深入系统研究，探索适于载人航天器舱内空气实时在线监测的MEMS质谱仪设计，解决主要部件设计中涉及到的关键科学和技术问题。主要研究内容包括：1）研究场致发射离子源的机理，进行微型化场致发射离子源的结构和工艺设计，实现可在低真空条件下工作的、长寿命、电离效率可调的微型离子源；2）对可降低真空系统要求、离子容量大且便于微型化的MEMS矩形离子阱质量分析器进行原理仿真与优化设计，完成其工艺研究与加工；3）采用多种真空技术复合使用的方法，设计一种微型复合真空泵系统，实现真空系统的微型化；4）利用所研制的MEMS质谱仪，设计实验对微米尺度条件下离子在质谱分析的整个过程，即离子产生、传输、质量分离中的机理和特性进行研究，探索和建立微米尺度条件下离子运动特性分析的技术和方法。基于上述内容，完成面向载人航天的MEMS质谱仪研究。

载人航天器长期在轨运行期间，由于材料放气、宇航员新陈代谢和泄漏事故等原因，舱内会产生多种微量有害气体。而载人航天航天器客舱是一个封闭的环境，舱内空气污染物对人体健康有很大的危害，因此需要舱内空气实时在线监测的微型气体分析仪器。本项目基于MEMS技术进行了质谱仪微型化的研究，突破了微型离子源、MEMS离子阱质量分析器和微型真空系统等关键部件及其相关技术，研制出原理样机。通过大量实验，证明了该仪器能准确的进行气体检测，检测到的质量下限低于50Th，质量上限高于300Th；检测限低于100ppm。该项目在以下几个方面取得创新：提出了一种MEMS场致电子发射离子源，提高了离子化效率；设计了MEMS矩形离子阱，显著降低了质量分析器的尺寸、重量、功耗；设计了MEMS离子透镜，提高了离子传输效率；研制了一种微型复合真空泵，可实现从大气压至高真空的全气压工作模式。发表学术论文12篇，其中SCI检索12篇；申请发明专利9项，其中6项已授权。本课题研究成果可满足载人航天任务中的气体成分检测需求，并为其他现场气体成分检测场合提供了有力的分析手段。