Physicists from the University of Tokyo have generated the strongest controllable magnetic field ever produced at 1200 Tesla. The field was sustained for longer than any previous field of a similar strength.
At 1,200 teslas, the generated field dwarfs almost any artificial magnetic field ever recorded; however, it’s not the strongest overall. In 2001, physicists in Russia produced a field of 2,800 teslas, but their explosive method literally blew up their equipment and the uncontrollable field could not be tamed. Lasers can also create powerful magnetic fields, but in experiments they only last a matter of nanoseconds.
The magnetic field created by Takeyama’s team lasts thousands of times longer, around 100 microseconds, about one-thousandth of the time it takes to blink. It’s possible to create longer-lasting fields, but these are only in the region of hundreds of teslas.
A peak field of 1200 T was generated by the electromagnetic flux-compression (EMFC) technique with a newly developed megagauss generator system. Magnetic fields closely up to the turn-around peak were recorded by a reflection-type Faraday rotation magnetic-field optical-fiber probe. The performance was analyzed and compared with data obtained by the preceding EMFC experiments to show a significant increase in the liner imploding speed of up to 5 km/s.
Magnetic fields are one of the fundamental properties of a physical environment. They can be controlled with high precision and interact directly with electronic orbitals and spins; this makes them indispensable for research in areas of solid state physics such as magnetic materials, superconductors, semiconductors, strongly correlated electron materials, and other nanomaterials. When a material is placed in a magnetic field of 1000 T, the Zeeman energy induced in the electrons becomes enormously high (as high as 1300 K), which corresponds to an energy far above room temperature, resulting in substantial effects on the electronic properties of the material.
A magnetic field of 1000 T corresponds to 0.8 nm cyclotron-orbit radius (magnetic length) of an electron; this is of the same order as a typical lattice constant. Therefore, in these extreme conditions the Broch electron model, which is based on the atomic periodic potential, does not hold anymore. Such ultra-high magnetic fields provide new opportunities for insights into material science and may allow us to develop a deeper understanding of novel physical concepts.
The generation of magnetic field is always accompanied by strong Maxwell stress; at 1000 T, this amounts to 4 × 1011 N/m2 (4 million times atmospheric pressure). All aspects of the megagauss generator, including the coil and surrounding instruments, are designed to protect against the violent self-destruction of the magnetic coil, disregarding all of the reinforcement techniques accumulated so far for nondestructive pulsed magnets.