Imma Perfetto
Cosmos science journalist
Chinese scientists have designed a resistive magnet which achieved a steady magnetic field of 42.02 tesla – a new world record for magnets of its kind.
Resistive magnets are powered by electricity and can be switched on and off. These are different to the magnets that decorate people’s refrigerators, which are called permanent magnets.
The Chinese beat out the previous record of 41.4 tesla, which was set by the US National High Magnetic Laboratory in 2017.
The strength of the magnetic field is roughly equivalent to 40,000 times that of a strong fridge magnet!
The recording-breaking steady magnetic field of 42.02 tesla was generated by a resistive magnet hooked up to a DC power supply of 32.3 megawatts, which is equivalent to roughly 43,300 horsepower.
Powerful magnets are important tools for scientific research, providing scientists with the ability to study what happens when materials are subjected to high magnetic fields.
The researchers – from the High Magnetic Field Laboratory of Hefei Institutes of Physical Science, Chinese Academy of Sciences – achieved the breakthrough after almost 4 years of research.
Magnets are materials or devices that generate a magnetic field. They come in 2 main types: permanent magnets and electromagnets.
Permanent magnets are made of ferromagnetic materials – like iron, cobalt, nickel, and their alloys – that have been magnetised to produce their own permanent magnetic field. A common example is a fridge magnet.
In electromagnets the magnetic field is generated by an electric current (moving electrons) travelling through a coiled wire. The magnetic field can be turned on and off or changed by controlling the amount of electric current passing through the coils.
Electromagnets come in 3 different forms: superconducting magnets, resistive magnets, and hybrid magnets that combine the other 2.
Superconducting magnets are made of superconductors. These are materials which, when cooled below a critical temperature (usually close to absolute zero, –273°C), carry an electric current with no electrical resistance. This means that electrons move around without losing any energy to heat.
Resistive magnets are made of normal metals, like copper or aluminium, which means they do produce heat along with the magnetic field. The key to building a powerful resistive magnet is maximising the amount of electricity it can carry while minimising the likelihood that it will overheat and melt.
