Vacuum pump getter

Rubidium forms numerous compounds, but only a few are useful. One of the main uses for rubidium is as a getter in vacuum tubes used in early radios, TVs, and cathode-ray tubes. These kinds of tubes work best if all the air is removed, so a getter absorbs the remaining few atoms of air that cannot be removed mechanicahy by vacuum pumps, thus extending the hfe of the vacuum tube. 

Vacuum pumps acceptance specifications Part IV (Getter-ion pumps) 28429 1976... 

The pumping system is the most important part of the vacuum line, it is certainly the most expensive, and it should therefore be chosen with care. Because the pumping system on a chemist s vacuum line must be robust and capable of removing large quantities of gases, often in repeated cycles, sorption pumps, getter ion pumps, and sublimation pumps are generally unsuitable and are therefore not discussed in this book. 

The remaining vacuum pumps to be discussed in this chapter fall into a group which remove gas particles from systems by sorption effects such as adsorption, chemisorption/gettering and implantation. They tend to be used on systems where any contamination of the vacuum by pump fluids, lubricants, etc. must be avoided. However, those pumps that remove gas particles exclusively by temperature-dependent gas adsorption on molecular sieves or A1203 (adsorption pumps) will not be discussed. 

Fig. 5.6. Reactive sputter process for depositing the compound film AB. (a) Balance of reactive gas flow Qtot, which is partially gettered at the target (Qt) and at the substrate (Qc) and partially pumped by the vacuum pump (Qp). The fraction of the target surface At that is covered by the compound AB is 6>t. The fraction of the collecting area Ac covered is Gc. j is the sputter current density, (b) Definition of particle fluxes that alter the target and collecting area coverage fractions 6>t and 6>c (see text), (modified from [70])...

The charcoal getter normally contained within these devices is retained in modified form as part of the cryostat (B). In practice, the vacuum space is evacuated by attaching any suitable vacuum pumping system to the valve (C) [13], after which the cryostat is disconnected from the pumping system. The charcoal getter is capable of maintaining a satisfactorily low pres sure for several months without re-evacuation. 

Sputter-ion pump A capture (getter) pump in which the gettering material is continuously being renewed by sputter deposition. See also Vacuum pump. 

Vacuum pump, ion pump A capture-type vacuum pump where a getter material is deposited by sputtering and gaseous ions are accelerated to the reactive surface to react with the surface or be physically buried in the depositing material. Also called a Getter ion pump. 

Vacuum pump, sublimation pump A getter pump where the getter material, such as titanium, is deposited by sublimation from a solid surface. 

Fig. 4.22. Reaction cell 1 - ZnO sensor 2 - evaporator of silver atoms 3 shutter used to terminate the beam of Ag atoms 4 - collimating apertures 5 an aperture used for pumping the cell out 6 - magnet 7 - magnetic drive for a shutter 8 - getter 9 — vacuum-measuring tube iO, 11 - electrodes 12 - thermocouple.

Table IV shows X-ray data (55) on the homogeneity of Pd-Ag films prepared by simultaneous evaporation from separate sources, either in conventional vacuum or in UHV, with the substrate maintained at 0°C. The second group of films was prepared using a stainless steel system incorporating a large (100 1/sec) getter-ion pump, sorption trap, etc., but deposited inside a glass vessel. By the tests of homogeneity adopted, alloy films evaporated in conventional vacuum were not satisfactory, i.e., the lattice constants were generally outside the limits of the experimental error, 0.004 A, and the X-ray line profiles were not always symmetrical. In contrast, alloy films evaporated in UHV were satisfactorily homogeneous. Further, electron micrographs showed that these latter films were reasonably unsintered and thus, this method provides clean Pd-Ag alloy films with the required characteristics for surface studies.

Vacuum technology acceptance specifications for getter-ion pumps 8/85... 

Wagener (31) reported that the sticking probability of CO on titanium at room temperature was very close to unity. In consequence, since CO is one of the primary residual components in most ultrahigh vacuum systems, titanium has received extensive use in recent years in ion and getter pumps for attaining this type of vacuum condition. It... 

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