It was suspected that the horizon glow observed over the lunar terminator was caused by electrostatically‐levitated dust particles, but do high concentrations of dust particles really exist over the lunar terminator? This is an important question that cannot be answered even today. In fact, no in‐situ investigations about the lunar dust have been conducted on lunar surface since Apollo. Here we first report in‐situ investigations of lunar dust at Chang’E‐3 (CE‐3) landing site using solar cell probe (SCP). The results show that, different from Apollo’s observation, the short‐circuit current of SCP did not decrease sharply during the first several lunations except the first lunation, indicating the recently developed minimalist qualitative model of sunrise‐driven dust transport might not be applicable at the geologically young CE‐3 landing site. In addition, within detector’s detection limit, no abrupt changes in dust concentration were observed above the sharp sunlight/shadow boundaries on lunar surface.

Carbon nanotubes (CNTs) as ideal electron emitters have been widely used in a variety of electronic devices, including the x-ray tube, vacuum microwave tubes, flat panel displays, electron microscopes, ionization gauges, etc. In this paper, we summarize the current status of research on a variety of ionization gauges with CNT cathodes and discuss the advantages as well as the existing problems of the novel ionization gauge. The CNT emitter-based ionization gauges have proved highly effective at ultra high and extra high vacuum measurements. This review also provides some suggestions to improve gauge performance in future work.

Titanium (Ti)-coated multiwall carbon nanotubes (CNTs) emitters based on the magnetron sputtering process are demonstrated, and the influences of modification to CNTs on the residual gas adsorption, gas desorption, and their field emission characteristic are discussed. Experimental results show that Ti nanoparticles are easily adsorbed on the surface of CNTs due to the “defects” produced by Ar⁺ irradiation pretreatment. X-ray photoelectron spectroscopy (XPS) characterization showed that Ti nanoparticles contribute to the adsorption of ambient molecules by changing the chemical bonding between C, Ti, and O. Field emission of CNTs coated with Ti nanoparticles agree well with the Fowler–Nordheim theory. The deviation of emission current under constant voltage is 6.3% and 8.6% for Ti-CNTs and pristine CNTs, respectively. The mass spectrometry analysis illustrated that Ti-coated CNTs have a better adsorption capacity at room temperature, as well as a lower outgassing effect than pristine CNTs after degassing in the process of field emission.

In this study, a cylindrical triode ultrahigh vacuum ionization gauge with a screen-printed carbon nanotube (CNT) electron source was developed, and its metrological performance in different gases was systematically investigated using an ultrahigh vacuum system. The resulting ionization gauge with a CNT cathode responded linearly to nitrogen, argon, and air pressures in the range from ~4.0 ± 1.0 × 10⁻⁷ to 6 × 10⁻⁴ Pa, which is the first reported CNT emitter-based ionization gauge whose lower limit of pressure measurement is lower than its hot cathode counterpart. In addition, the sensitivities of this novel gauge were ~0.05 Pa⁻¹ for nitrogen, ~0.06 Pa⁻¹ for argon, and ~0.04 Pa⁻¹ for air, respectively. The trend of sensitivity with anode voltage, obtained by the experimental method, was roughly consistent with that gained through theoretical simulation. The advantages of the present sensor (including low power consumption for electron emissions, invisible to infrared light radiation and thermal radiation, high stability, etc.) mean that it has potential applications in space exploration.