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Helium-3 (3He[1][2] see also helion) is a light, stable isotope of helium with two protons and one neutron. (In contrast, the most common isotope, helium-4, has two protons and two neutrons.) Helium-3 and protium (ordinary hydrogen) are the only stable nuclides with more protons than neutrons. It was discovered in 1939.
Nuclear fusion is a reaction in which two or more atomic nuclei, usually deuterium and tritium (hydrogen isotopes), combine to form one or more different atomic nuclei and subatomic particles (neutrons or protons). The difference in mass between the reactants and products is manifested as either the release or absorption of energy.
In Earth's atmosphere, the ratio of 3 He to 4 He is 1.343(13) × 10 −6. [5] However, the isotopic abundance of helium varies greatly depending on its origin. In the Local Interstellar Cloud, the proportion of 3 He to 4 He is 1.62(29) × 10 −4, [6] which is ~121 times higher than in Earth's atmosphere.
Helium. hexagonal close-packed (hcp) Helium (from Greek: ἥλιος, romanized: helios, lit. 'sun') is a chemical element; it has symbol He and atomic number 2. It is a colorless, odorless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table.
An observation balloon is a type of balloon that is employed as an aerial platform for gathering intelligence and spotting artillery. The use of observation balloons began during the French Revolutionary Wars, reaching their zenith during World War I, and they continue in limited use today. Synonyms include espionage balloon, reconnaissance ...
Homer Hadley Hickam Jr. (born February 19, 1943) is an American author, Vietnam War veteran, and a former NASA engineer who trained the first Japanese astronauts. His 1998 memoir Rocket Boys (also published as October Sky) was a New York Times Best Seller and was the basis for the 1999 film October Sky. Hickam's body of written work also ...
The helium trimer (or trihelium) is a weakly bound molecule consisting of three helium atoms. Van der Waals forces link the atoms together. The combination of three atoms is much more stable than the two-atom helium dimer. The three-atom combination of helium-4 atoms is an Efimov state. [ 1][ 2] Helium-3 is predicted to form a trimer, although ...
A helium-3 refrigerator is a simple device used in experimental physics for obtaining temperatures down to about 0.2 kelvins. By evaporative cooling of helium-4 (the more common isotope of helium ), a 1-K pot liquefies a small amount of helium-3 in a small vessel called a helium-3 pot. Evaporative cooling at low pressure of the liquid helium-3 ...