Superconductor

A **superconductor** is a material that has no electrical resistance and magnetic flux fields are expelled from it. Such a material exhibits *superconductivity*. It can store electrical energy indefinitely and is capable of lossless energy transmission.

Superconductivity was discovered in 1911 by Heike Onnes, who observed that when he cooled a sample of mercury to 4.2 degrees above absolute zero, its electrical resistance plunged to zero.

An ordinary metallic conductor's resistance decreases as its temperature is lowered towards absolute zero, but a superconductor has a critical temperature below which the resistance is zero. The current in these superconductors can flow for billions of years without losing any energy. As electrons become coupled and all move together, avoiding the collisions that cause electrical resistance, they approach a state of perpetual motion.

Superconductor materials include mercury, lead, niobium alloys, ceramics, pnictides, fullerenes and carbon nanotubes.

Initially wires and cables allowed electric power in the form of supercurrents to flow without losing energy to resistance or heating the wires. In time they were replaced by superconductive ribbons for use in inductors, transformers, motors and generators.

The world's first superconductor at room temperature was achieved in 2021 with carbonaceous sulphur hydride, at 270 gigapascals, and 15 degrees celsius.

Uses of room-temperature superconductors:

* Lossless power transmission, which enables perfect transmission over huge distances.
* Superconducting wires can capture and store electricity indefinitely, which means battery degradation is no longer a problem.
* Computers, tablets, and other electronics can be made to run cooler, more efficiently, and with far less energy consumption.
* Compact nuclear fusion is especially useful in space travel.
* High-end, portable medical imaging is more efficient and in smaller form factors
* Large-scale science facilities such as particle accelerators will need less energy and capital costs

### Energy storage

If a superconductive path forms a complete loop, a supercurrent can flow around the loop forever. A device that produces a strong magnetic field will store large amounts of energy. A superconductive ribbon wound tightly around a tube creates an electromagnet, creating a superconductive *solenoid* can discharge all of its energy instantly if needed. This effect can be harnessed in the manufacture of explosives.

Solenoids are competitive with other forms of consumer energy storage such as torsion batteries and flywheels and have the highest specific electrical power of any energy storage device. Vehicles make use of solenoidal tubes and tension cable/sheet construction for their chassis. This leads to cars that can be deflated and easily stored in a compact volume, useful in Type I where there could be a premium of parking space.

### Magnetic Levitation

When superconductors expels all magnetic fields from their interior, it will be repelled from all sources of a magnetic field, and the field sources will likewise be repelled from the superconductor. This levitates magnets over a superconductive surface, or a superconductor over a magnet. This effect has many uses, including maglev trains, vactrains and frictionless bearings.

### Electromagnetism

Superconductors reflect electromagnetic waves. This allows powerful sources of radio waves, microwaves, and far infrared to be produced. These have applications ranging from radar beams to mass drivers to free electron lasers.

### Sensors and computing

If two superconducting regions are placed closely adjacent to each other, a current flows between them. This produces sensitive magnetic field detectors called Superconducting Quantum Interference Devices (SQUIDs) which enable a wide range of sensor and detector technologies such as medical and MRI scanners. Their high switching rate, low energy per switch, and low energy dissipation makes them ideal for quantum computers.

### Other uses:

* force fields and where magnetic confinement is needed
* high-performance smart electric grid
* enhancing spintronic devices
* magnetic refrigeration
* Superconducting magnetic energy storage (SMES) systems store energy in the magnetic field created by the flow of direct current in a superconducting coil. This is used for improving the quality and stability of power grids.