limitation of superconductivity
Answers
Answer:
- Low critical temperatures are difficult, expensive and energy intensive to maintain.
- The materials are usually brittle, not ductile and hard to shape.
- They are also chemically unstable in some environments.
Answer:
Uses and limitations of Superconductors
Introduction
It is no surprise that all major uses for superconductors rely on two major properties:
Zero resistance below its critical temperature
The Meissner effect
Yet their limitations are also very straightforward:
Low critical temperatures are difficult, expensive and energy intensive to maintain.
The materials are usually brittle, not ductile and hard to shape.
They are also chemically unstable in some environments.
It cannot function with AC electricity, as the switching in AC destroys Cooper pairs.
There is a "limit" to the current passing through the material before it loses its superconducting properties.
Power Transmission
The lack of resistance means it can transmit electricity without losing power in heat.
This allows for large current densities (up to about 5 times more) to be conducted in thin wires with no power loss.
This would also reduce the demand for new power stations & reduce the cost of power.
However the brittleness of the material in the high temperature superconductors (G2) makes superconducting wires impossible.
Also since only DC can be used, the voltages cannot be transformed easily.
Power Generation
Using the Meissner effect, a very powerful magnetic field could be generated with the use of superconductors.
This means a smaller magnet can be used as a rotor/stator in a motor/generator, meaning less mass has to be moved to generate the same amount of power.
This then leads to an increase in efficiency and thus a decrease in the amount of fossil fuels required to make electricity.
Power Storage
Currently, electricity cannot be stored for long periods of time.
However with superconductors, this becomes possible with the use of Superconducting Magnetic Energy Storage.
This is a system that "traps" electricity within it by forcing it to flow inside the SMES until it is necessary to be used.
Since it's using superconductors, no energy loss occurs during the storage.
Of course this is used with DC instead of AC.
This also opens the way to renewable energy sources such as solar power and wind energy as the energy can be stored rather than used immediately.
Electronics
Research is still being done in this field, but there's an almost unlimited scope here.
In integrated circuits, further miniaturisation is prevented by generation of heat due to resistance (less area, more resistance)
The speed that signals can be transmitted are also limited by current standards due to resistance.
The Josephson Effect
It was found that if two superconducting layers are separated by an insulator, it is possible for Cooper pairs to pass the barrier without any resistance.
This is because of a quantum tunnelling effect, and its consequences are that:
a current will flow through this Josephson function without any Voltage applied
when a Voltage IS applied, the current oscillates at a constant frequency
This superconducting film has achieved extremely fast switching speeds (9×10−12s), which means that superfast computers can be created.
It also allows very precise measurements of magnetic flux, allowing for better magnetometers used in geological surveys.
Medical Diagnoses
To diagnose patients, doctors sometime perform Magnetic Resonance Imaging (MRI).
The process requires extremely strong magnetic fields.
To generate such fields without superconductors, massive solenoids and large amounts of energy are needed.
With the use of superconductors and the Meissner effect, the device could be smaller and much more efficient.
It should be noted that when the desired current level is reached in the SC, it runs in a ''persistent current mode'
This means it DOES NOT NEED FURTHER INPUT as electricity becomes trapped inside it, flowing with no energy loss.
Also the ability for it to detect magnetic flux precisely allows the electrical signals sent out by nerves to be analysed
This is done using a Superconducting Quantum Interference Device (SQUID) which can detect fields as small as 1×10−13T.