Cryogenics (Liquefied Air & Helium)
In 1895 Linde and Hampson made air so cold that it turns liquid, and in 1908 Onnes did the same to helium; cheap oxygen and nitrogen, rocket fuel and the cold for superconductors followed.
Open in the interactive tree →In May and June 1895 William Hampson and Carl von Linde independently patented the same method: compress air, cool it in a counter-current heat exchanger and let it expand through a valve, so that each round gets colder until the air turns liquid at about -190 °C. Adding a distillation column let Linde split liquid air into nearly pure oxygen and nitrogen, and the first large air-separation plant ran in 1903; on 10 July 1908 Heike Kamerlingh Onnes used the same cycle with pre-cooling to liquefy helium at 4.2 K, and in 1911 he found superconductivity. Oxygen steelmaking only became practical once liquid-air plants delivered oxygen cheaply (it needs almost two tonnes per tonne of steel), liquid oxygen drove Goddard's first liquid-fuel rocket in 1926, and liquid helium still cools MRI magnets and the 1.9 K magnets of the LHC.
Prerequisites
- Thermodynamics1824A gas expanding through a valve cools down (Joule-Thomson effect)
- Mechanical Refrigeration1834Linde's refrigeration machines taught compression and heat exchange
Unlocks
- Superconductivity1911Onnes found superconductivity in mercury cooled with the liquid helium he first made in 1908
- Goddard's Liquid-Fuel Rocket1926Goddard's 1926 rocket burned gasoline and liquid oxygen
- Basic Oxygen Steelmaking (LD)1952Oxygen steelmaking needs large amounts of cheap oxygen from liquid-air plants
- Superconducting Qubit (Transmon)1999-2007Qubits only work in refrigerators cooled to a few thousandths of a degree above zero.
- Large Hadron Collider (LHC)2008Its magnets are held at 1.9 K by superfluid helium.