Introduction
Helium: Sources and Uses
Helium is thought to be the most abundant element in the universe [3], as it the product of the fusion reaction that happens in the heart of stars. On Earth, however helium is exceedingly rare and comprises only 5.2 ppm of Earth’s atmosphere. Most of the helium on Earth comes from radiological sources. As elements like uranium and thorium decay deep underground into thorium and radium, respectively, α-particles consisting of two protons and two neutrons are released and trapped. As these α-particles pick up electrons from their environment they become stable helium atoms.
U238→Th234+α; U235→Th231+α; Th232→Ra228+α
Figure 2: Common Sources of Helium through Radiological Decay. [4]
The major sources for terrestrial helium are natural gas deposits that can contain up to 2.7% helium. [5] Because helium is a noble gas with a full electron shell, it is extremely unlikely to react with other chemicals, and once it reaches the surface, rapidly rises to the highest levels of the atmosphere. Over most of the planet, the Earth’s magnetic field lines are able to retain the vast majority of our atmosphere; however over the poles, these field lines trail off due to the solar wind allowing lighter atoms like hydrogen and helium to escape. [6] 
Figure 3: Helium Loss From the Polar Wind [6]
This polar wind is the cause of almost all of Earth’s lost helium at a rate of 1600 metric tons per year. [6] [7] For many years and, in many cases still today, radiogenic helium was wasted as a byproduct of the natural gas extraction process. It was only during World War I that the federal government began to recognize the usefulness of the noble gas for potential military applications including dirigible flight. [5] In 1917, Congress authorized the Federal Helium Program and started processing helium in its facility in Texas. The Bureau of Land Management (BLM) under the Department of the Interior extracts and refines helium from the Hugoton shale field in Oklahoma and pipes it into the natural caves of the Bush Dome Reservoir in Amarillo, TX, that are used as the storage facility. As of 2013, 35% and 70% of the world’s helium supply came from the Federal Helium Reserve in specific and the United States in general. [3] [8]
While helium has moved far beyond its original military dirigible use, today it is still used for flight in certain rockets and weather balloons, and for the welding of advanced materials like titanium needed for such crafts using helium arc welding. [9] It is used extensively by deep sea divers to avoid the bends. [9] Most importantly for our purposes it is used in its liquid state at 4K (-452F) to perform cutting edge scientific experiments probing the structure of matter across physics, chemistry, materials science, biology, and medicine.