Study On Atomic Oxygen Effect And Detection

Atomic oxygen(AO) is the most abundant element of the neutral atmosphere in the LEO orbit. It is one of the most serious factors affecting the spacecraft in LEO. Atomic oxygen is produced by the shortwave radiation of solar ultraviolet. The minimal collision probability of atomic oxygen leads to low probability of recombination. The number density is eighty pecent of the neutral atmosphere. Atomic oxygen is active in chemistry. It has fast speed relative to the spacecraft and high energy. A series of flight experiments show that atomic oxygen has obvious erosion effect on the surface materials of spacecraft exposed to the space environment. The efficiency of the subsystems exposed to the space decreases significantly under the atomic oxygen environment. Therefore, it makes sense to study the atomic oxygen flux and erosion effect on the materials used by spacecraft.In this paper, the physical background of atomic oxygen in LEO is analysised; then the atomic oxygen spacecraft encountered is simulated, as well as erosion rate of the typical materials used on spacecraft surface. The atomic oxygen erosion under different attitudes, different positions and different solar activity levels are given. The intergated detector of atomic oxygen effect based on piezoelectric effect of Quartz Crystal Microbalance(QCM) is designed. It can monitor the atomic oxygen flux in-situ and erosion effect on the materials. Spin-coating technology, namely coating on the wafer surface under different processing conditions is studied. And the processing condition is preliminarily confirmed. Performance of coating film on wafer surface is tested precisely in the nano field, including thickness, surface morphology, mechanical properties, and binding force between film and substrate. Performance and stability of coating film under thermal cycling and vacuum environment are also examinated. The results show that the surface coating of wafer film is fine and stable, and can withstand the space environment. The calibration of mass deposition is performed in the micro-quality acquisition and calibration system in NSSC(Nation Space Science Center). The results show that the scientific parameter can indicate change of deposition mass on the wafer in real time. Calibration for sensing capability of atomic oxygen flux and material erosion will be performed in the ground atomic oxygen simulation system later.The detector will be used as an important part of the passive material exposure device in the experiment module of space station after successful development. It can be used to monitor the atomic oxygen erosion effect in-situ by telemetry. Miniaturization of the detector can be designed further, so that it can be applied by the platform of the LEO spacecraft conveniently. At the same time, research of atomic oxygen protective material will be performed. More study and on orbit test on protective material used now and in future, such as self-healing material, will be carried out. This work will be a solid foundation for the study of the atomic oxygen effect in LEO in our country.