Applications

Superconductor Power Transmission Lines

Superconductors are useful for applications needing high current densities, large magnetic fields, and energy efficiency. Superconductor power transmission lines would minimize energy loss, and the high current densities of superconductors would allow the conductor and cable to have smaller dimensions than a conductor. One difficulty in implementing superconductor power transmission lines is that multiple cooling stations would be required to keep the material below its critical temperature.

CERN's LHC utilizes superconducting magnets

Superconductor Magnets

Superconductor magnets are made using type 2 superconductors used as coil windings and are usually cooled with liquid helium. They have important uses in high-energy accelerators and MRI apparatuses. CERN's large hadron collider and Fermilab's proton antiproton collider both use superconducting magnets. The strong magnetic fields produced by superconducting magnets are used to focus proton beams on interaction regions.

Maglev Trains

One well-known example of the applications of superconductors is their use in transportation. Maglev trains involve a superconducting system on the train that can repel the train rail. Once in motion, a maglev train experiences repulsion and is supported with no friction. The Central Japan Railway Company's SCMaglev can travel over 600 km/h.

The SCMaglev applies magnetic levitation

A Joseph junction (top) and a SQUID magnetometer (bottom)

Josephson Junctions

When a thin insulator is placed between two superconductors to form a junction, the quantum wave representing the condensate of Cooper pairs can tunnel through the insulating layer and end up in the other superconducting section creating a current, even without an applied voltage; however, when a constant voltage is applied to the barrier, the phase variation causes an alternating current to be produced. The alternating current’s frequency is proportional to voltage through the junction. Since the frequency can be precisely measured, Josephson junctions have been used to designate a universal voltage reference value, and they are also used in measuring devices such as the SQUID magnetometer.

SQUID Magnetometer

A superconducting quantum interference device (SQUID) superconducting a loop made up of two Josephson junctions. The junction is highly responsive to changes in magnetic flux, so when a magnetic field flows through the loop, the measured frequency can be used to determine the value of the magnetic field with great precision. The SQUID magnetometer has biological applications and can measure magnetic fields from neurological currents in the brain or heart. It can be used for military purposes; SQUID can detect magnetic fields from submarines in the ocean. There are also SQUID microscopes which generate an image based on magnetic variation in the surface of a material.

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