Magnetic field cloak could help submarines evade detection

Researchers in Spain believe they have found a way of cloaking materials that have a magnetic signature.

They have managed this by designing a so-called anti-magnet that conceals the magnetic response of an object without altering external magnetic fields. Furthermore, the researchers say the cloak can be made with superconductors and isotropic magnetic materials.

‘We knew how to make magnetic fields but we didn’t know how to cancel them in a given space region,’ Prof Alvaro Sanchez from the Autonomous University of Barcelona told The Engineer.

‘By surrounding a magnetic object with a superconductor, such as a tube, it becomes impassive to any external magnetic field; the object would not feel any magnetic force.

‘However, the superconductor distorts the applied field — actually, it expels it from its interior — so the superconducting tube would be magnetically detectable. With our design, we’ve added some fine-tuned layers of magnetic materials so that they cancel the field distortion caused by the superconductor.’

In this way, the object inside the superconducting tube, the superconductor itself and the magnetic shells that surround it can become invisible to magnetic fields, he explained.

The team is now aiming to produce a working model of such an anti-magnet, which Prof Sanchez said may eventually find application in allowing users of pacemakers and other medical devices such as cochlear implants to undergo MRI scans without damaging the implant or MRI machine.

The idea could also disguise the magnetic signatures of naval vessels to evade detection from mines that are designed to explode when a magnetic field is detected.