by David Shane

Created on: March 21, 2010

While helium is the second most common element in the universe, on Earth it isn't as easy to come by.  Because it is a noble gas, it is unreactive and will generally not form compounds with other elements.  When released into the atmosphere, most of it eventually diffuses into space.  Therefore the helium we have is almost all extracted from underground traps, often with natural gas.  The United States is currently the largest supplier of helium to the world, drawing it from a (mostly) federally owned reserve near Amarillo, Texas.  Because the helium is believed to be produced very slowly over time by radioactive decay, when it's gone, it's gone for good.  This is unfortunate, because helium has many uses, detailed below.

The greatest single use of helium is in cryogenics.  This is because helium, when liquified, is one of the coldest substances known to man, boiling at 4 Kelvin (-452 degrees Fahrenheit.)  It is commonly used in magnets used for MRIs and nuclear magnetic resonance spectroscopy.  (These magnets are made with superconducting wires that allow electric current to circulate forever without any resistive losses as long as they are kept cold enough.)  The Tevatron, a particle accelerator at Fermilab in Batavia, Illinois, uses 400,000 liters of each year for its magnets.  Liquid helium finds other uses any time someone needs extremely cold temperatures - whether as part of scientific research or material creation.

A second category of usage is in rockets and balloons - and not just the ones you buy for Valentine's day.  NASA uses large helium filled balloons to take objects almost into space to study atmospheric composition and to make observations of space that the atmosphere makes difficult - see their Ballooning Program website for details.  In rockets, it is used for pressurizing liquid fuels - the Space Shuttle has a helium tank in its aft-section, as shown here.

A third use is in welding.  In arc welding an electric arc is created to heat the materials being worked on up to very high temperatures, so that they melt.  At these temperatures an inert gas is needed to protect the material from damage from the atmosphere, and unreactive helium is a good choice.  Helium also has a high thermal conductivity (it conducts heat well), which can help with heat penetration when welding.

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For more information, see:

"Government handling of helium gets report card: Think again", by Toni Feder

"Selling the Nation's Helium Reserve", by the National Research Council

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