基于等动量加速与场发射电子源的空间用微型飞行时间质谱计研究

For the scientific goals of future deep space explorations in our country, this project aims to develop miniature time-of-flight mass spectrometer with small size, light load, low power consumption, and high mass resolution. Traditional time-of-flight mass spectrometer (TOF-MS) is based on the principle of equal energy acceleration. Instead, this project puts forward a new-concept TOF-MS on the basis of equal momentum acceleration principle. Introduction of such a new concept is expected to greatly expand the mass number range of TOF-MS instruments, and significantly improve their mass resolution power. The key technology to attain this goal is to accelerate the gas ions using high-voltage pulses with short duration. Based on our previous accumulations in this area, in order to further compress the equipments’ volume and reduce their power consumption, this project is planned to use field-emission based ionization source, mainly to solve the instability and short-life problems of field emission cathode by using our novel patented technologies. We will learn from the NASA and ESA on their advanced experiences in developing miniature TOF-MS instruments for space applications in recent years, adopting coaxial structure in the main structure of the instrument, namely, the ionization source, ion reflector, and the ion detector are in coaxial structure. We will also use a large number of MEMS techniques in order to suppress the volume and mass of the instrument in the main structure, electronic control unit, and the other structural units. This project will develop momentum analyzer-based miniature TOF-MS prototype instruments with the key specifications meeting or exceeding the international advanced levels, then manage to apply these instruments in the institutes specialized in space technology researches, and at last exploit new application prospect in the fields such as environmental monitoring.

针对我国深空探测科学目标，本项目拟研制小体积、轻质量、低功耗、高分辨的空间用微型飞行时间质谱计。传统的飞行时间质谱计（TOF-MS）基于等能量加速原理。与此不同，在多年积累基础上，我们提出基于等动量加速原理的TOF-MS概念，预期将大大扩展仪器的质量数范围，明显提升仪器的分辨本领。其关键在于对离子的高压短脉冲加速。为减小仪器体积和功耗，还将采用场发射电离源方案，并采用全新的专利技术解决场发射阴极的不稳定和短寿命问题。仪器的主体结构借鉴NASA和ESA空间用微型TOF-MS的经验，采用电离源、离子反射镜、离子探测器三者同轴结构。大量采用MEMS工艺技术，缩减仪器主体结构、电子控制以及其它单元的尺寸和质量。本项目将研制出具有自主知识产权的基于动量加速和场发射电子源的TOF-MS仪器，其关键技术指标达到或超过国际先进水平，在空间技术研究单位推广应用，也在环保监测等领域开拓新的应用前景。

深空探测的一项重要任务是分析地外天体的物质成分。基于空间质谱仪的原位物质分析已经被美国等发达国家证明有独特优势。本项目就是针对我国深空探测对于微型低功耗质谱仪的急需而提出的。通过探索性研究，本项目取得了一些新认识，在一些关键的新技术方面有突破。首先，通过理论研究，认识到基于等动量加速的飞行时间质谱仪（CAM-TOF-MS）确实可以在小空间里实现较高分辨，但是只能针对一个较窄的质量数范围来实现；第二，通过大量实验研究，实现了场发射电离源的长寿命和高稳定，这是实现CAM-TOF-MS小型化和低功耗的关键；第三，通过理论分析和实验研究相结合的途径，实现了高压窄脉冲电路的可靠运行并解决了电磁匹配问题，实现了质谱分析功能；第四，通过研制外围配套组件和优化关键技术，实现了小型质谱仪的整机化，为航天机构提供了测试样机，测试结果优良。本项目为我国深空探测提供了技术积累，所研制的小型质谱仪在军工和民用领域也有很大发展前景。