With the development of vacuum technology, vacuum applications are increasingly expanding to various aspects of industry and scientific research. Vacuum application refers to the use of the physical environment of rarefied gases to accomplish specific tasks. Some use this environment to manufacture products or equipment, such as light bulbs, electronic tubes, and accelerators. These products maintain a vacuum throughout their use; Others only consider vacuum as a step in production, and the final product is used in the atmospheric environment, such as vacuum coating, vacuum drying, and vacuum impregnation.

The application range of vacuum is extremely wide, mainly divided into low vacuum, medium vacuum, high vacuum, and ultra-high vacuum applications. Low vacuum is the use of the pressure difference obtained from low (coarse) vacuum to clamp, lift, and transport materials, as well as to vacuum and filter, such as vacuum cleaners and vacuum suction cups.

Medium vacuum is generally used to remove gases or moisture trapped or dissolved in materials, manufacture light bulbs, vacuum metallurgy, and serve as thermal insulation. If vacuum concentration is used to produce condensed milk, the water in the dairy product can be evaporated without heating.

Vacuum metallurgy can protect active metals from oxidation during melting, casting, and sintering processes, such as vacuum melting of refractory metals such as tungsten, molybdenum, tantalum, niobium, titanium, and zirconium; Vacuum steelmaking can avoid the burning of some small elements added at high temperatures and the infiltration of harmful gas impurities, which can improve the quality of steel.

High vacuum can be used for thermal insulation, electrical insulation, and to avoid collisions between molecular electrons and ions. The free path of molecules in high vacuum is greater than the linear size of the container, so high vacuum can be used in devices such as electron tubes, phototubes, cathode ray tubes, X-ray tubes, accelerators, mass spectrometers, and electron microscopes to avoid collisions between molecules, electrons, and ions. This feature can also be applied to vacuum coating for optical, electrical, or decorative purposes.

The energy transfer in outer space is similar to that in ultra-high vacuum, so ultra-high vacuum can be used for space simulation. Under ultra-high vacuum conditions, the formation time of monolayers is long (measured in hours), which allows for the study of surface properties such as friction, adhesion, and emission before a surface is contaminated by gas.