Recently, a joint team of Ningbo Institute of Materials Technology and Engineering of China Academy of Sciences, Qian Xuesen Laboratory of the Fifth Academy of Astronautics, Institute of Physics of Chinese Academy of Sciences and Nanjing University has explored and studied helium atoms in the lunar soil particles of Chang ‘e-5. It is found that there is a layer of amorphous glass on the surface of ilmenite particles in lunar soil. Researchers have observed a large number of helium bubbles in the glass layer, with a diameter of about 5 ~ 25 nm, and most of them are located near the interface between the glass layer and the crystal. However, there are basically no helium bubbles in the intra-granular crystals. In view of the high solubility of helium in ilmenite, researchers believe that helium atoms are first injected into ilmenite lattice by solar wind, and then helium will be gradually released under the channel diffusion effect of lattice. However, the surface glass has a disordered stacking structure of atoms, which limits the release of helium atoms, is captured and gradually stored, and forms bubbles.
Helium -3, as an isotope of helium, has important application value in the fields of energy and scientific research. The energy generated by 100 tons of helium -3 nuclear fusion can be supplied to the whole world for one year, and the process of helium -3 nuclear fusion has no danger of neutron secondary radiation, which is more clean and controllable. In addition, helium -3 is a key refrigerant to obtain extremely low temperature environment, and it is an essential substance in the frontier research fields such as superconductivity, quantum computing and topological insulators. However, the helium element on the earth is mainly helium -4, and the reserve of helium -3 is only about 0.5 tons, which is far from meeting the existing demand.
Helium -3 is an important component of the solar wind, and the moon is irradiated by the solar wind all the year round, which stores a lot of helium -3. But why is the moon rich in strategic resources helium -3? In what form is helium -3 stored on the moon? There are no clear answers to these questions. Exploring the content, distribution and exploitation of lunar resources, especially helium -3, has become the inevitable trend and main task of international deep space exploration. Previous studies believe that helium -3 is dissolved in lunar soil particles, and the extraction of helium -3 is limited by diffusion rate, which requires high temperature above 700℃, which not only consumes high energy, but also is slow, which is not conducive to in-situ mining on the moon.
The latest research by the research team shows that it is expected to extract helium -3 stored in the form of bubbles at room temperature by mechanical crushing method without heating to high temperature. Moreover, ilmenite has weak magnetism and can be separated from other lunar soil particles by magnetic screening, which is convenient for in-situ mining on the moon. According to the total amount of ilmenite on the moon, the total amount of helium -3 stored in the form of bubbles may be as high as 260,000 tons. If all of it is used for nuclear fusion, it can meet the global energy demand in 2600. These results not only provide a new insight into the enrichment mechanism of helium -3 on the moon, but also lay a theoretical foundation for the in-situ exploitation and utilization of helium -3 on the moon in the future, which is of great significance for exploring the effective utilization path of lunar resources.
(Source: Ningbo Science and Technology Bureau)