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The idea for the polar wind originated with the desire to solve the paradox of the terrestrial helium budget. This paradox consists of the fact that helium in the Earth's atmosphere seems to be produced (via radioactive decay of uranium and thorium) faster than it is lost by escaping from the upper atmosphere. The realization that some helium ...
Helium is a commonly used carrier gas for gas chromatography. The age of rocks and minerals that contain uranium and thorium can be estimated by measuring the level of helium with a process known as helium dating. [28] [30] Helium at low temperatures is used in cryogenics and in certain cryogenic applications.
The abundance of the chemical elements is a measure of the occurrences of the chemical elements relative to all other elements in a given environment. Abundance is measured in one of three ways: by mass fraction (in commercial contexts often called weight fraction), by mole fraction (fraction of atoms by numerical count, or sometimes fraction of molecules in gases), or by volume fraction.
Scientists have detected a surprising amount of a rare version of helium, called helium-3, in volcanic rocks on Canada’s Baffin Island, lending support to the theory that the noble gas is ...
Terrestrial helium consists almost exclusively (all but ~2ppm) [16] of 4 He. 4 He's boiling point of 4.2 K is the lowest of all known substances except 3 He. When cooled further to 2.17 K, it becomes a unique superfluid with zero viscosity. It solidifies only at pressures above 25 atmospheres, where it melts at 0.95 K.
Helium 3 is rare on Earth, primarily produced by the radioactive decay of tritium, but it does reside in abundance in the lunar regolith, deposited by billions of years of solar wind. The isotope ...
From this source with some modifications and additions of later data: W.S. Fyfe, Geochemistry, Oxford University Press, (1974). Further referring to: C.K. Jorgensen, Comments Astrophys. 17, 49–101 (1993). Values are subject to various geological assumptions but assumed acceptable as an indication of elemental abundance in crustal rocks (C3).
Helium is also present as up to 7% of some natural gas sources, [20] and large sources have over 0.5% (above 0.2% makes it viable to extract). [21] The fraction of 3 He in helium separated from natural gas in the U.S. was found to range from 70 to 242 parts per billion.