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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.
By mid-1948, Aerojet had selected centrifugal pumps for both liquid hydrogen and liquid oxygen. They obtained some German radial-vane pumps from the Navy and tested them during the second half of the year. [6] By the end of 1948, Aerojet had designed, built, and tested a liquid hydrogen pump (15 cm diameter).
Pfeiffer Vacuum Technology AG is a German manufacturer of vacuum pumps. [1] It is headquartered in Aßlar in Germany with 70% of the total production catering to the export market. In July 1996 the company was listed on the NYSE and in April 1998 on the TecDAX. Due to low trading volumes, it was de-listed from the NYSE in October 2007. [2]
In the first stage, a roughing pump clears most of the gas from the chamber. This is followed by one or more vacuum pumps that operate at low pressures. Pumps commonly used in this second stage to achieve UHV include: Turbomolecular pumps (especially compound pumps which incorporate a molecular drag section and/or magnetic bearing types) Ion pumps
In general, molecular drag pumps are more efficient for heavy gasses, so the lighter gasses (hydrogen, deuterium, helium) will make up the majority of the residual gasses left after running a molecular drag pump. [4] The turbomolecular pump invented in the 1950s, is a more advanced version based on similar operation, and a Holweck pump is often ...
A cutaway view of a turbomolecular high vacuum pump. In a momentum transfer pump (or kinetic pump [16]), gas molecules are accelerated from the vacuum side to the exhaust side (which is usually maintained at a reduced pressure by a positive displacement pump). Momentum transfer pumping is only possible below pressures of about 0.1 kPa.
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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.