Are We a Step Closer to Nuclear Fusion?

Material science and superconductivity have come a long way, and they benefit from the feedback loop with fusion research.

All of which reminds me of what a friend told me quite a few years back. At the time, she was doing her PhD in superconductivity at Cern, and while there, her instructor had a very nice project result. The instructor and team discovered an alloy composition that happened to keep superconductivity at temperatures nearly 20 Kelvin higher than other state-of-the-art compounds. At the time most promising superconductors required temperatures in the range of -210°C.

The discovery sounded neat, and a temperature bump like that certainly was cool but it didn't sink in until a bit further just what they had achieved. Superconductivity at temperatures in "low -190's" Celcius meant that suddenly it was possible to use liquid nitrogen (boiling point ~-196°C).

The availability and cost of coolant improved quite a bit.

There have been huge improvements since - the state-of-the art high temperature superconductors now keep up at temperatures around -135°C.[0] Cheaper and more abundant coolant, along with lower delta-T, means that research into applying superconductivity is much more accessible.

Small-scale fusion is likely going to be just a start; I expect to see major improvements in energy transfer, particularly on power loss, over the next 20-30 years.

0: https://en.wikipedia.org/wiki/High-temperature_superconducti...

But on a more practical note: the containment for the plasma is a vacuum. All the matter inside the magnetic container is held within the plasma, and in simplified terms, between the "surface" of the plasma and the wall of the container there is _nothing_. Vacuum is a very good insulator, and the magnetic fields that control the plasma serve a dual purpose. Always, to prevent plasma from getting into contact with the walls of the container - but both to keep the energies within the ring, and to make sure any contact with the vessel can't cool the plasma down.

The reason why vacuum is such a great insulator is easy to explain. Heat is transferred by conduction (contact), convection (heat exchangers), and radiation (ejected particles). When surrounded by vacuum, matter isn't in contact with anything and heat transfer by conduction is 0. Because there is nothing for heat to flow to, also convection is effectively 0. Heat loss by radiation is far, far less than by conduction - and since plasma is a cloud of charged particles, even that is subject to the strong magnetic fields pushing the matter back.

0: https://en.wikipedia.org/wiki/ITER#Vacuum_vessel