Helium is a noble gas, possessing unique properties that make it indispensable for numerous high-technology and industrial applications. It is colorless, odorless, non-toxic, and chemically inert, meaning it does not readily react with other elements. It has the lowest boiling point of any known substance, making it the coldest liquid on Earth, and is the second-lightest element after hydrogen. Terrestrial helium is a finite and non-renewable resource, primarily extracted as a byproduct from natural gas deposits. Once released, its lightness allows it to escape Earth’s gravity, making its preservation a growing concern for scientific and industrial sectors.
The Role of Extreme Cooling
The most significant consumption of commercial helium is in its liquid form as a cryogen. Liquid helium has a boiling point of only 4.2 Kelvin, or approximately -269 degrees Celsius. This extreme cold is necessary to achieve and maintain the superconducting state in specialized magnets, where electrical resistance completely disappears.
The primary medical application leveraging this property is in Magnetic Resonance Imaging (MRI) machines. MRI scanners rely on powerful superconducting magnets to generate the strong, stable magnetic fields required for detailed internal images. These magnets must be continually bathed in liquid helium to remain at temperatures near absolute zero, allowing the magnet to operate without energy loss.
A similar principle applies to Nuclear Magnetic Resonance (NMR) spectroscopy, a technique used extensively in chemistry and pharmaceuticals for analyzing molecular structure. Liquid helium cools the NMR’s superconducting magnets, ensuring the stability and strength of the magnetic field needed for precise spectral analysis. Liquid helium is also employed in fundamental scientific research, such as cooling sensors in space telescopes, maintaining superconducting coils in particle accelerators, and facilitating the operation of quantum computing systems.
Creating Protective Environments
Helium’s non-reactive nature is leveraged in industrial processes that require an atmosphere free of contaminants like oxygen or nitrogen. As a noble gas, it acts as an effective shield, preventing unwanted chemical reactions with sensitive materials during the manufacturing of high-purity components.
In arc welding, especially Gas Tungsten Arc Welding (GTAW or TIG), helium is used as a shielding gas to protect the molten weld pool and the tungsten electrode from oxidation. Its higher thermal conductivity compared to argon allows for faster heat transfer, resulting in deeper penetration and quicker welding speeds, particularly when working with materials that rapidly dissipate heat, such as aluminum and copper.
The semiconductor and fiber optic industries also rely heavily on helium to maintain high-purity environments. In the creation of silicon wafers and integrated microchips, helium is used as an inert atmosphere to prevent contamination that could compromise the microscopic circuitry. This protective function is also essential in manufacturing optical fibers, ensuring the glass preform is free of impurities that could scatter light and reduce data transmission efficiency.
Detection and Pressurization
Helium’s physical attributes, specifically its small atomic size and low density, make it ideal for two distinct industrial applications: leak detection and pressurization. Helium atoms are so tiny that they can pass through microscopic leaks that other, larger gas molecules cannot. This makes it the preferred tracer gas for identifying minute leaks in vacuum systems, high-pressure containers, and complex industrial piping.
Mass spectrometer leak detectors are calibrated to specifically detect the presence of helium, allowing manufacturers to ensure the integrity of sealed components like automotive fuel tanks, air conditioning systems, and medical devices. This high-sensitivity testing is essential in aerospace and military applications where containment failure could be catastrophic.
In rocketry, helium serves as a non-reactive pressurant and purge gas. It is used to push liquid propellants, such as liquid hydrogen and liquid oxygen, from their storage tanks into the rocket engines. Helium is uniquely suited for this role because it remains gaseous even at the extremely cold, cryogenic temperatures of the propellants and does not react with the fuel or oxidizer. Furthermore, it is used to purge fuel lines and tanks of residual propellants after engine cutoff, ensuring safety.
Everyday and Atmospheric Uses
While the majority of industrial helium is consumed by high-tech sectors, its buoyancy and non-flammability are recognized in public-facing applications. The most common use is as a lifting gas for balloons and airships, providing lift due to its lower density than air. Helium replaced flammable hydrogen after the Hindenburg disaster, offering a safe alternative for meteorological balloons and surveillance blimps.
In deep-sea diving, helium is a component in specialized breathing gas mixtures, often combined with oxygen in a blend called Heliox or with oxygen and nitrogen in Trimix. Nitrogen in compressed air can cause nitrogen narcosis at significant depths, impairing judgment and motor skills. Helium replaces nitrogen because it is less soluble in the bloodstream and has no narcotic effect, allowing divers to safely descend to greater depths for extended periods. The lower density of helium also reduces the effort required to breathe the compressed gas at high pressure.