Helium is a rare gas with the chemical formula of He. It is a colorless, odorless, inert gas with inert chemical properties. It is difficult to react with other substances under normal conditions.
1. Helium can be used as a pressurizing agent and pressurizing agent for rocket liquid fuel, and is widely used in missiles, spacecraft and supersonic aircraft.
2. Helium is used as a protective gas in smelting and welding, which is very important in shipbuilding and the manufacture of aircraft, spacecraft, rockets and weapons.
3. Helium has excellent permeability and is used for cooling of nuclear reactors, leak detection of some pipes and electronic and electrical devices of rockets and nuclear reactors.
4. Helium is a gas with ideal gas properties and is an ideal gas for vapor pressure thermometers at extremely low temperatures.
5. Helium has low mass density and weight density, and is not flammable. It can be used to fill light bulbs and neon light tubes, and it is also an ideal gas for balloons and airships.
6. Liquid helium can be obtained at a low temperature close to the absolute temperature (-273°C) for the manufacture of superconducting equipment.
7. Helium is a kind of inert gas. Its solubility in blood is lower than that of nitrogen, so its anesthesia is lower than that of nitrogen. Therefore, helium is often mixed with oxygen as a breathing gas for divers.