Friday is here, and the 'Weekend Science Bite' corner is back — number 95.
This time: the fascinating connection between helium and MRI machines, transistor lithography, and the blockade of the Strait of Hormuz.
-
Helium is a gas made of exceptionally light atoms, which is why it's a popular filling gas for birthday balloons.
But helium has properties that make it a truly extraordinary and essential gas.
Helium is a noble gas. It doesn't react with other atoms, and as a result it remains a gas and doesn't solidify even at temperatures close to absolute zero. For this reason it makes an excellent coolant and is used to cool systems that require extremely low temperatures.
The helium most common in the atmosphere is helium-4, whose nucleus contains 2 neutrons and 2 protons. Helium-3 contains only one neutron in its nucleus — it's a rare, expensive, and fascinating material that we'll cover next week.
-
Helium-4 is produced in Earth's core as a byproduct of the decay of radioactive elements. Today it is extracted as a byproduct of the natural gas industry, with Qatar being one of the world's largest helium exporters.
Ballistic missiles fill their fuel tanks with helium to pressurize and push the fuel out into the engines. Rocket fuel is typically liquid hydrogen or liquid oxygen, both of which require extremely low temperatures, and any other gas introduced into the tank could freeze.
MRI systems rely on liquid helium to cool the powerful magnetic coils that drive them. To achieve the required magnetic field strength, the coils must be cooled until they become superconductors — a temperature so low that only helium can reach it.
More recently, helium has also been used to fill HDD hard drives, reducing the friction of their internal components during operation.
-
One of the more interesting developments in the helium field comes from the Norwegian startup Lace Lithography, which uses a beam of helium atoms to etch transistors onto chips — in place of light beams.
Today, etching is performed using ultraviolet light, whose drawbacks include the high energy that damages the lower layers of the chip, as well as the inability to focus the beam below a certain wavelength.
In the past, electron beams were tried for this purpose, but electrons repel each other electrically and damage the chip in an uncontrolled manner.
The neutrality of helium atoms allows them to be focused into an exceptionally dense beam at lower energy than a light beam, achieving an etching resolution 135 times finer while protecting the chip's underlying layers.
In the classical chip industry, helium is used to cool chips during the manufacturing process, to detect leaks in the vacuum systems of fabrication equipment, and to purge foreign materials from production systems.
-
Iran has attacked one of the world's largest helium plants, located in Qatar, shutting down production entirely. The blockade of the Strait of Hormuz is preventing tankers already loaded with helium from reaching their destinations, and the helium is slowly evaporating and dissipating into the atmosphere.
All industries that depend on helium — led by the semiconductor industry — now find themselves at a dead end, with emergency reserves rapidly dwindling.
In the video you can see the U.S. national helium reserve that the United States maintained until a few years ago, when it decided, on cost grounds, to empty most of it and sell all remaining helium to the private market. It is now becoming clear that this was one of the most unfortunate decisions the American government has ever made, as the costs of the shortage are expected to far exceed the cost of maintaining the facility.
Shabbat Shalom 😊
--
If you enjoy this corner, you're welcome to follow along and catch it again next week.
Video credit: Tom Scott
#Weekend_Science_Bite