Inside a future fusion reactor, a magnet weighing as much as a small car will float. It holds the superheated plasma like an invisible hand holding a cloud. Previously, such a magnet was considered unsuitable for deuterium-tritium fuel: neutron fluxes would quickly destroy it. Now engineers have figured out how to shield the magnet and replace the damaged part.
The magnet is made of superconducting tape that operates at very low temperatures. Around it are layers of tungsten and boron carbide, like armor. This armor absorbs neutrons and conducts heat away, preventing the magnet from overheating. The part of the magnet that takes the brunt of the impact is designed for one year of operation. Then it is replaced, like a printer cartridge.
The main benefit is simplicity of maintenance. The magnet is not attached to the walls; it can be quickly removed and replaced. This reduces downtime and the cost of energy. Fusion promises clean energy without carbon dioxide and with radioactive waste lasting only thousands of years.
The magnet in the reactor will create a field of 23 tesla—500,000 times stronger than Earth's magnetic field.
In the TV series 'The Expanse', fusion reactors on ships use magnetic plasma confinement, similar to this principle.