碳纳米管阴极电离真空计计量学特性研究

The extremely high vacuum measurement is an important research frontier in vacuum metrology field. The existing ionization vacuum gauges have some technologic bottlenecks in measuring the extremely high vacuum pressure, and the achievement of extremely high vacuum measurement is expected to adopt new principles and techniques. Therefore, in this project, the novel carbon nanotube electron source will be applied in an ionization vacuum gauge, and the influence of electrode structural parameters and electrical parameters on gauge sensitivity will be investigated by the method combined theoretical simulation with experimental validation, and the experimental model for high sensitivity ionization vacuum gauge, which can meet the demands for extremely high vacuum measurement, will be built. The vacuum pressure in calibration chamber will be accurately calibrated by using a vacuum calibration apparatus with dynamic flow conductance principle, and the influence of pumping effect and outgassing effect of ionization vacuum gauge on vacuum metrology properties will be investigated systematically, and new theoretical approaches, being used to descript the relationship between gauge performances and relative physical effects, be will be developed. On this foundation, it is expected that the accurate measurement of vacuum pressure as low as 10-10 Pa is achieved for the first time by using ionization vacuum gauge with carbon nanotube cathode. The relative results have the meaning for accelerating the development of vacuum metrology in China.

极高真空精确测量是真空计量学科的前沿研究领域。目前，已有的电离真空计在极高真空测量中具有难以逾越的技术瓶颈，极高真空的精确测量还有待于新原理的提出和新技术的应用。因此，本项目拟将新型碳纳米管场致发射电子源应用到电离真空计上，通过理论模拟和实验验证相结合的方法，系统研究电离真空计电极结构参数和电学参数对其灵敏度的影响规律，建立满足极高真空测量的高灵敏度碳纳米管阴极电离真空计的实验模型；利用动态流导法真空校准装置精确标定实验气体的真空度，并通过系统研究碳纳米管阴极电离真空计抽、放气效应对其计量学特性的影响，初步建立能够定量描述真空计性能和相关物理效应之间关系的新理论和方法，在此基础上，以期首次利用碳纳米管阴极电离真空计实现10-10 Pa的极高真空的精确测量。研究成果对促进我国极高真空计量技术的发展具有重要意义。

超高/极高真空测量技术在以深空探测为代表的高新尖端技术领域具有迫切需求，电离规是目前唯一可用于超高/极高真空测量的电子真空传感器件。传统的热阴极电离规和冷阴极电离规存在影响测量下限进一步延伸的技术瓶颈。因此，超高/极高真空测量还有待于新型阴极的真空传感技术研究和应用。本项目针对传统极高真空测量器件的存在的技术瓶颈，创新性地提出了基于碳纳米管场发射阴极电离规的思想，并做出了如下贡献：. 1.开发了一种在金属合金衬底上通过氧化-还原处理后直接生长碳纳米管场发射阴极的新方法，生长的碳纳米管阴极具有优异的场发射性能，包括较低的开启电场（~2.2 V/μm）和较低的开启电场（~4.2V/μm），极好的场发射稳定性（在大电流发射条件下（~10.0mA/cm2）连续工作50小时，发射电流波动仅有~3.4%）。. 2.通过采用研制的场发射电子源，成功减小了长期限制圆筒状三极式热阴极电离规测量下限延伸的x射线效应，在国际上首次研制了一种比原圆筒状热阴极电离规测量下限更低的碳纳米管阴极电离规，且测量下限整整延伸了2个数量级。. 3.针对传感器输出离子电流的特点，设计了一种定制的检测电路，通过一系列的测试和标定，确定了传感器的线性度、噪声、带宽和增益等性能。. 在本项目的执行过程中，项目组获2020年甘肃省自然科学三等奖1项《基于碳纳米管阴极的超高真空测量技术》，项目负责人获中国航天五院杰出青年人才计划——第一类基金资助，共发表2篇中文期刊论文，13篇英文SCI期刊论文，授权3件国家发明专利，参加了6次国内外学术会议，并在2019年瑞典举报的第21届国际真空大会上作了题为《Metrological behaviors of ionization gauges with carbon nanotube cathodes》的分会场交流报告。