Helium source

A standard Pyrex vacuum apparatus is employed in this preparation. The system includes a fractionation train consisting of four U-tube traps, attached with ball joints, a mercury manometer, and several ball-joint connections on the manifold. The mercury in the manometer is covered with outgassed Kel-F-10 oil, and the stopcocks and ball joints are lubricated with Kel-F-90 grease. The fluorine metering system consists of a fluorine tank properly shielded and vented, a sodium fluoride scrubber (45 X 13 cm.), two calibrated rotameters for measuring flow rate and fluorine concentration, and a helium source, and is constructed of -J-in. copper tubing. 

He/ He ratio. The measurement of the He/ He ratio (R) in groundwaters is particularly important, because it reflects the relative importance of crustal (radiogenic/nucleogenic) and mantle helium sources. Typical crustal rock He/ He production ratios have been estimated... 

The detection of mantle-derived helium in sedimentary fluids (water and hydrocarbon) suggests the occurrence of large-scale upward fluid migration and helium sources external to the aquifers. Moreover, the presence of mantle-derived He often implies the occurrence of still active tectonics under the concerned basins, since it requires mantle melting and the generation of magma to transport efficiently He and other volatiles to the Earth s surface. 

Figure 5 Map of <5( He)% contoured on a surface at 2500 m depth in the Pacific. Contour intervai is 4%. The major helium sources iie aiong the East Pacific Rise (EPR) and the Juan de Fuca Ridge (JdFR) systems. The dashed arrows indicate areas where the heiium piumes define regionai circuiation patterns. Data aiong WOCE iines P4 and P6 are from Jenkins (unpublished data). All other data are from Lupfon (1998).

UHV is required for this technique. The helium source should be free of impurities to ensure UHV and a high pumping speed is needed in order to pump away the helium after it has interacted with the surface. The helium ions are created by collision with an electron beam and focused onto the sample surface. The incident ion energy is usually in the range of 5 to 10 eV. The energy distribution of electrons... 

Note from Fig. 9.49 that the energies of the bound electrons are negative and that zero corresponds to electrons that are free of the influence of the two N nuclei—they are free electrons. Also note that no transition is represented for the <72s electrons. These electrons have such low energy that they require more than the 21.2 eV that can be furnished by the helium source. 

The industry s demand for neon is exclusively covered from air separation plants, where neon is a by-product. The neon content of the atmospheric air is 18 ppm (see Table 2.1). In contrast the recovery of helium from atmospheric air is of minor importance. The most important helium source is natural gas (cf. Chapters 4 and 7). 

Helium source and reserves, http //members.truepalh.com/gr/helium.html... 

Apparatus. The apparatus used was very straight forward and simple. A typical fluorine handling apparatus was used as shown in Figures 1 and 2. Items one and two are fluorine and helium sources respeceively. Item three is a Hastings-Raydist model LF50... 

Figure 8.2.10 Schematics of a He atom scattering apparatus that consists of a helium source where an atomic beam is formed by the nozzle and the skimmer. The scattered beam is detected by a (in some...

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