Helium

The fusion point of helium is the lowest of any element, which makes it useful for cryogenics (extremely low temperature studies) research and superconductivity (electrical conductivity at very low temperatures).   Helium also is used as an inert gas shield for arc welding and as a protective gas in growing silicon and germanium crystals for semiconductors.   It is used also in titanium and zirconium production, as a nuclear reactor coolant, and as a gas for supersonic wind tunnels.   A mixture of helium and oxygen provides an artificial atmosphere for people working under pressure, such as divers and excavators   Balloons and blimps are filled with it since it is light in weight, inert and safe, unlike hydrogen, which is flammable.   Helium is used for pressuring liquid fuel rockets, and in magnetic resonance imaging (MRI) to detect blood cancer.   The fusion of hydrogen into helium provided the energy for the hydrogen bomb and potentially is another energy source for generating electrical power. ^{Lide 4-14}

Helium was discovered in 1868 by Pierre Janssen, a French astronomer, by detecting a new line in the solar spectrum during an eclipse.   Helium is extracted from natural gas.   Most of the world's supply of helium is obtained from natural gas wells in Texas, Oklahoma and Kansas. ^{Lide 4-14}