Vacuum turbomolecular pump

Such vessels can also be baked at a temperature of several hundred degrees, to drive off any gas adsorbed on metal surfaces. The pumping function of an ion gauge was developed into efficient ionic pumps and turbomolecular pumps , supplemented by low-temperature traps and cryopumps. Finally, sputter-ion pumps, which rely on sorption processes initiated by ionised gas, were introduced. A vacuum of 10 "-10 Torr, true UHV, became routinely accessible in the late 1950s, and surface science could be launched. 

Resistance to physical shocks and vibration required careful attention to selection of rugged components and to securing electrical and vacuum systems, wiring, connectors, components, and boards. Chemical ionization (Cl) was used for the first time in a fieldable military detector because of the advent of rugged turbomolecular pumps capable of handling the gas load from the Cl reagent. 

A further development of the turbomolecular pump is the hybrid or compound turbomolecular pump. This is actually two pumps on a common shaft in a single casing. The high vacuum stage for the molecular flow region is a classic turbomolecular pump, the second pump for the viscous flow range is a molecular drag or friction pump. 

For the production of pressures in the ultrahigh vacuum region, sputter-ion, and sublimation pumps, as well as turbomolecular pumps and cryopumps, are used in combination with suitable forepumps. The pump best suited to a particular UHV process depends on various conditions (for further details, see Section 2.5). 

If the container is evacuated with a TURBOVAC 50 turbomolecular pump, for example (S = 50 I/s), which is attached to the vacuum vessel by way of... 

Vacuum pumps acceptance specifications Part III (Turbomolecular pumps) 28428 1973... 

The exhaust from a rotary pump, especially if it is being run in the ballast mode, i.e. pumping a fair quantity of air or other gas, is an aerosol of oil in the gases from the line. A variety of filters is now available commercially for cleaning exhaust gas, but a good additional safety precaution is a wide tube fitted to the outlet so that the gas stream can be vented to the nearest fume-cupboard or window. The pumping efficiency of a rotary pump drops off rapidly below ca. 10 Torr even under optimum conditions, and such pumps are therefore usually installed as a back-up to a more efficient high vacuum pump, such as a diffusion or a turbomolecular pump. 

A vacuum chamber is pumped by a turbomolecular pump (mass spectrometer for gas analysis. The MS is maintained at 2 x 10 5mbar with a turbo-... 

In a vacuum chamber at 20 °C, the rate of water vapour desorption is 5 x 10-2 mbarL s 1. The chamber has an overall leakage rate of 1 x 10"2 mbar Ls l. An attached turbomolecular pump (TMP) has an effective, gas-independent speed of 1500 L s-1. 

In this chapter, those pumps that are frequently encountered throughout the range of vacuum pressures are dealt with (see Table 3.1). Where necessary, to support the calculations, the operating principles and pump characteristics are reviewed. With gas-transfer pumps operating in the HV/UHV range (typically diffusion or turbomolecular pumps), continuous operation of backing (forevacuum) pumps is required for efficient performance. In such cases, the combination is considered. 

---