Posted by: Glow-worm PJ6 NOV 2008
It has been reported recently that a worldwide shortage of helium is pushing up wholesale prices. A recent story in the Wall Street Journal pointed out that scientific research has dramatically increased worldwide use of the element, especially in magnetic resonance imaging machines, and the production of semiconductors.
Pierre Janssen obtained the first evidence of helium during the solar eclipse of 1868, when he discovered a new line in the solar spectrum, and the new element was named from the Greek “helios”, or sun.
A few years later it was discovered in the uranium mineral cleveite. It is present in various radioactive minerals as a decay product; alpha particles are helium nuclei, and the gas remains trapped within the rock.
Apart from hydrogen, it is the most abundant element in the universe, and has been detected spectroscopically in abundance. It is an important component in both the proton-proton reaction and the carbon cycle, which account for the energy of the sun and stars. It is extracted from natural gas, mainly in wells in the US, Russia, and Poland.
One-third of the world’s supply comes from the US Federal Helium Reserve outside Amarillo, Texas, but some estimates state that it could run out of the gas within a decade.
Its principal uses are as an inert gas for arc welding, as a protective gas in growing silicon and germanium crystals, and in the production of zirconium. It is also needed in the electronics industry, providing the controlled environments required in the production of semiconductors, as well as enhancing thermal conductivity.
Its small molecules are ideal for testing for leaks in pressure and vacuum systems used in these fields.
Helium has the lowest melting point of any element and is widely used in cryogenic research because its boiling point is close to absolute zero. Its cooling properties are used in nuclear reactors, as well as to ensure that the magnets in magnetic resonance imaging machines remain cold.
Helium is also used in respiratory medicine. It has a low coefficient of solubility and high rate of diffusion compared with nitrogen, and is inert and non-toxic. When helium replaces nitrogen in air, the specific gravity of the resultant helium/oxygen mixture is 341 (compared with air at 1,000).
This mixture flows through the bronchi three times as easily than air, and so, in patients with respiratory obstruction, more oxygen can be presented to the alveoli for the same ventilatory effort. Absorption of helium from the alveoli is very slow, and inhalation of helium may be used to prevent atelectasis (collapsing of the lung).
As the price of this precious gas continues to rise, it may mean the demise of its most familiar use of inflating party balloons.