Zhang Huzhong, Li Detian, Wurz Peter, Etter Adrian, Cheng Yongjun, Dong Changkun, Huang Weijun
Science and Technology on Vacuum Technology and Physics Laboratory, Lanzhou Institute of Physics, Lanzhou 73000, China.
Physics Institute, University of Bern, 3012 Bern, Switzerland.
Nanomaterials (Basel). 2020 Feb 18;10(2):354. doi: 10.3390/nano10020354.
Low energy ion measurements in the vicinity of a comet have provided us with important information about the planet's evolution. The calibration of instruments for thermal ions in the laboratory plays a crucial role when analysing data from in-situ measurements in space. A new low energy ion source based on carbon nanotube electron emitters was developed for calibrating the ion-mode of mass spectrometers or other ion detectors. The electron field emission (FE) properties of carbon nanotubes (CNTs) for H, He, Ar, O, and CO gases were tested in the experiments. H, He, Ar, and CO adsorbates could change the FE temporarily at pressures from10 Pa to10 Pa. The FE of CNT remains stable in Ar and increases in H, but degrades in He, O, and CO. All gas adsorbates lead to temporary degradation after working for prolonged periods. The ion current of the ion source is measured by using a Faraday cup and the sensitivity is derived from this measurement. The ion currents for the different gases were around 10 pA (corresponding to 200 ions/cm s) and an energy of ~28 eV could be observed.
对彗星附近的低能离子进行测量，为我们提供了有关该行星演化的重要信息。在分析来自太空原位测量的数据时，实验室中热离子仪器的校准起着至关重要的作用。为校准质谱仪或其他离子探测器的离子模式，开发了一种基于碳纳米管电子发射器的新型低能离子源。在实验中测试了碳纳米管（CNT）对H、He、Ar、O和CO气体的电子场发射（FE）特性。H、He、Ar和CO吸附物在10 Pa至10 Pa的压力下可暂时改变FE。CNT的FE在Ar中保持稳定，在H中增加，但在He、O和CO中降低。所有气体吸附物在长时间工作后都会导致暂时退化。使用法拉第杯测量离子源的离子电流，并从该测量中得出灵敏度。不同气体的离子电流约为10 pA（对应于200个离子/cm·s），并且可以观察到约28 eV的能量。
