Superconducting Applications

The unique properties of superconductivity facilitated many great discoveries of the 20th century such as the magnetic resonance imaging (MRI) technique. Established commercial applications of superconductivity are dominated by the use of LTS materials and include:

• Magnets for Magnetic Resonance Imaging (MRI)
• Low and high field magnets for Nuclear Magnetic
Resonance (NMR)
• Low and high field magnets for physical sciences
and research
• Accelerators for high-energy physics
• Large scale magnet demonstrators for plasma
fusion reactors
• Industrial magnets for materials magnetic separation

All these applications are only possible because of the significant improvement in production of LTS wires in long lengths with uniform performance.

Other small-scale commercial applications of superconductivity that use LT S materials include research magnets, Magneto Encephalography (MEG) based on Superconducting Quantum Interference Device (SQUID) technology used for measuring weak magnetic fields generated by the brain. These superconducting magnets saw their first uses in laboratories as an enabling device for experimentation and developed into a market of 4B€ dominated by the bioimaging Magnetic Resonance Imaging (MRI) scanning machines and the Nuclear Magnet Resonance (NMR) scientific instruments used widely by researchers and pharmaceutical companies for drug research and development.

What are superconductors used for?

If you set up a current in a loop of superconductor there is nothing to stop it and it will continue flowing forever, forming a very powerful electromagnet, that needs no maintenance other than keeping them cold. The strongest man made permanent magnetic fields are produced using superconductors.

Superconducting magnets are used in MRI (Magentic Resonance Imaging) which is a way of looking at the soft parts of the body.

They are also going to be used in the new ‘Large Hadron Collider’ experiment at the CERN Particle Physics Lab. The idea is to accelerate protons and antiprotons to almost the speed of light in a circle and then smash them together. To keep the particles in a circle requires huge magnetic fields which can only be provided by superconductors.

 

It is also possible to use superconducting magnets to produce a levitating train. The idea is to put very powerful light superconducting magnets on the train, then use copper coils in the track which use repulsion to lift the train up to make it levitate. It is also possible to use the track magnets to push the train along. Because this force is not limited by friction between wheels and a track it is theoretically possible for a maglev train to go much faster and more importantly accelerate and brake faster than a conventional train. Various test maglev trains have been built, in Birmingham, Japan and Germany, although the only one used commercially is a german design built in Shanghi, which uses very strong permanent magnets instead of superconductors.

Superconducting Sensors

Due to a subtlety of the quantum mechanics of how superconductors interact with magnetic fields, it is possible to make the most sensitive magnetometers possible called SQUIDs (Superconducting Quantum Interference Devices). These can be used to detect submarines, measure the magnetic field produced by your brain, find ore deposits deep underground, sense minute signals from stars etc.

Power Cables

An obvious use of superconductors would be to move power around, huge amounts of electrical energy are wasted just heating up power cables, and superconductors would help. However if you put alternating current through them they are no longer lossless, and it reqiures a lot of energy to cool them, so although it is possible they could be used to save energy in the long run in the short term it is more likely they will be used to save space, superconducting cables have been installed in Chicago and Copenhagen, in old cable ducts with restricted space, allowing you to get more power through the same duct, hence saving lots of money digging up the road. Similarly the US Navy is very interested in them for making small powerful electric motors to power ships with, because it is efficient to put the propellers on pods under the ship however the bigger the motor the more drag it produces, so a much smaller superconducting motor would be advantageous.

So superconductors may not be about to revolutionise the world like it looked in 1986, but they are becoming more and more useful in the modern world.