Japan's National Institute for Fusion Science (NIFS) has achieved an electrical current of 100,000 amperes, the highest to be generated so far in the world. This has major implications for its use in fusion reactors.
They used state-of-the-art yttrium-based high-temperature superconducting tapes to fabricate a large-scale magnet conductor by a relatively simple technique of stacking the tapes to obtain a conductor of exceptional mechanical strength. For the conductor joints, NIFS developed low-resistance joint technology through collaborative research with Tohoku University.
At the absolute temperature of 20 degrees Kelvin (minus 253 degrees Celsius) the electrical current exceeds 100,000 amperes.
The current is induced by magnetic induction.
Superconductors conduct electricity with no resistance. This means that, unlike the more familiar conductors such as copper or steel, a superconductor can carry a current indefinitely without losing any energy in the form of heat. The current carried by a superconductor also generates a magnetic field, and the more field strength that can be contained within the superconductor, the more current it can carry.
In fusion reactors, a superconductor acts as a giant magnet which has the ability to confine the hot plasma by repulsing the magnetic field of the plasma, and ensuring that it does not touch the reactor walls.
Practical superconductors can carry currents that are typically 100 times greater than copper, which gives them considerable performance advantages over conventional conductors and permanent magnets.
Earlier, researchers managed to 'trap' a magnetic field with a strength of 17.6 Tesla -- roughly 100 times stronger than the field generated by a typical fridge magnet -- in a high temperature gadolinium barium copper oxide (GdBaCuO) superconductor, beating the previous record by 0.4 Tesla.
The research demonstrates the potential of high-temperature superconductors for applications in a range of fields, including flywheels for energy storage, 'magnetic separators', which can be used in mineral refinement and pollution control, and in high-speed levitating monorail trains.
Superconductors are currently used in scientific and medical applications, such as MRI scanners, and in the future could be used to protect the national grid and increase energy efficiency, due to the amount of electrical current they can carry without losing energy.