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An oil diffusion pump is used to achieve higher vacuum (lower pressure) than is possible by use of positive displacement pumps alone. Although its use has been mainly associated within the high-vacuum range, down to 1 × 10 −9 mbar (1 × 10 −7 Pa), diffusion pumps today can produce pressures approaching 1 × 10 −10 mbar (1 × 10 −8 Pa) when properly used with modern fluids and accessories.
Diffusion pumps blow out gas molecules with jets of an oil or mercury vapor, while turbomolecular pumps use high speed fans to push the gas. Both of these pumps will stall and fail to pump if exhausted directly to atmospheric pressure, so they must be exhausted to a lower grade vacuum created by a mechanical pump, in this case called a backing ...
Ion pumps; Titanium sublimation pumps; Non-evaporable getter (NEG) pumps; Cryopumps; Diffusion pumps, especially when used with a cryogenic trap designed to minimize backstreaming of pump oil into the systems. Turbo pumps and diffusion pumps rely on supersonic attack upon system molecules by the blades and high speed vapor stream, respectively.
A noble diode pump is a type of ion pump used in high-vacuum applications that employs both a chemically reactive cathode, such as titanium, and an additional cathode composed of tantalum. The tantalum cathode serves as a high-inertia crystal lattice structure for the reflection and burial of neutrals, increasing pumping effectiveness of inert ...
Pumps that use oil either as their working fluid (diffusion pumps), or as their lubricant (mechanical rotary pumps), are often the sources of contamination in vacuum systems. Placing a cold trap at the mouth of such a pump greatly lowers the risk that oil vapours will backstream into the cavity.
Most turbomolecular pumps employ multiple stages, each consisting of a quickly rotating rotor blade and stationary stator blade pair. The system is an axial compressor that puts energy into the gas, rather than a turbine, which takes energy out of a moving fluid to create rotary power, thus "turbomolecular pump" is a misnomer.
A vacuum ejector, or simply ejector, or aspirator, is a type of vacuum pump, which produces vacuum by means of the Venturi effect.. In an ejector, a working fluid (liquid or gaseous) flows through a jet nozzle into a tube that first narrows and then expands in cross-sectional area.
The vacuum system for evacuating a TEM to an operating pressure level consists of several stages. Initially, a low or roughing vacuum is achieved with either a rotary vane pump or diaphragm pumps setting a sufficiently low pressure to allow the operation of a turbo-molecular or diffusion pump establishing high vacuum level necessary for operations.