Uses

Uses
vaccum is useful in a variety of processes and devices. Its first common use was in incandescent light bulbs to protect the tungsten filament from chemical degradation. Its chemical inertness is also useful for electron beam welding, for chemical vapor deposition and dry etching in semiconductor fabrication and optical coating fabrication, for cold welding, for vaccum packing and for vaccum frying. The reduction of convection improves the thermal insulation of thermos bottles and double-paned windows. Deep vaccum promotes outgassing which is used in freeze drying, adhesive preparation, distillation, metallurgy, and process purging. The electrical properties of vaccum make electron microscopes and vaccum tubes possible, including cathode ray tubes. The removal of air friction is useful for flywheel energy storage and ultracentrifuges.
High to ultra-high vaccum is used in thin film deposition and surface science. The high vaccum allows for contamination-free deposition of materials. Ultra-high vaccum is used when atomically clean substrates are studied, as only a very good vaccum preserves atomic-scale clean surfaces for a reasonably long time of the order of minutes to days.
Suction is used for a very wide variety of applications. The Newcomen steam engine used vaccum instead of pressure to drive a piston. In the 19th century, vaccum was used for traction on Isambard Kingdom Brunel's experimental atmospheric railway.