CAMBRIDGE, UK At the 10th Cambridge Enterprise Conference, at the end of September, a number of startups showed up to exhibit what could be the next wave of technology to penetrate our everyday lives. Magnifye Ltd was one of them, grabbing the visitors' attention with a levitating magnet on display and a poster making the bold statement: a one-inch magnet could lift a lorry.
This mind-boggling assertion refers to the actual magnetic lift that the company's superconducting magnets are capable of sustaining, as these could find use in a maglev train for example. Superconducting magnets are not new and company founder Dr Tim Coombs certainly doesn't claim to be reinventing the wheel, nor has he come up with a new high-temperature superconducting material.
Indeed, his work at the engineering department of Cambridge university was carried out using standard bulk magnets made from yttrium barium copper oxide (YBCO), a superconducting ceramic material that is readily available from many manufacturers worldwide. The superconducting properties only come into effect as the magnets are chilled to 93K (minus 180 degrees Celsius) using liquid nitrogen, unleashing the magnets' capability to maintain very high current loops and hence very strong magnetic fields.
Magnetization is key
Currently, all commercial magnetization processes require the presence of a magnetic field of equal or greater magnitude than the one to be induced into the superconducting material. This problem in itself translates into huge and expensively crafted electromagnetic coil assemblies that limit very much the use of superconducting permanent magnets in industrial applications.
The external magnetic field applied also turns out to be a limiting factor, when depending on geometries, the actual superconducting material would have the potential to trap a stronger magnetic field. The method that Dr Coombs has developed to magnetize the YBCO bulk eliminates these limitations and yields magnetic fields about ten times stronger than what alternative processes are capable of. The resulting magnets range in strength from 2 Tesla up to around 17 Tesla and are only limited by their intrinsic superconducting properties.