Superconductivity and Classroom Applications

8/3/2019 Superconductivity and Classroom Applications

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Superconductivity and its Applications

By:

ANUBHAV AGARWAL


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Peering into the body without cutting

it open

Traveling hundreds of miles per hour

in a levitated train

Steering antimatter moving at the

speed of light


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Why Is All ThisImportant?

Superconductivity generates over200,000 hits on any given websearch

Addresses major societal

issues such as energy.

Attracts thousands of scientistsfrom all over the world to

conferences.

Government and PrivateInvestments are in Billions ofDollars


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What Defines aSuperconductor?

There are TWO distinct properties. They have ZERO resistance

They exhibit DIAMAGNETISM

Diamagnetism: repelled by a magnet

Condition: The superconductor must be cooled by liquid nitrogen.


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How This AllBegan?

H.K. Onnes first discovered the idea

of zero resistance in 1911 whiledoing experiments on mercury

cooled with liquid helium.

Three different hypotheses

existed on how resistancewould respond astemperature approaches 0 K:

1. Resistance would increase(Kelvin)

2. Resistance would plateau(Matthiessen)

3. Resistance would continue todrop gradually to 0 and 0K (Dewar).

di d


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UnpredictedResults

The idea that a superconductor can

pin a magnet in free space was

first characterized by Meissner

and Ochsenfeld in 1933. This

phenomenom is now known as

the Meissner effect.

None of the three hypothesespredicted the real data

the resistance of mercurySUDDENLY drops to ZERO

near 4.2 K. Superconductivity isdiscovered.


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Applications usingSuperconductors

MRI Body scannersLHC

ITER

Transport

Power transmissionPublic outreach


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Superconductors Powering thefuture, probing the past


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Uses ofSuperconductors: MRI

MRI is a technique that allows doctors to seewhat is happening inside the body withoutdirectly performing surgery.

The development of superconductors hasimproved the field of MRI as the superconducting

magnet can be smaller and more efficient than anequivalent conventional magnet.

Radiofrequency receivers that are currentlymade of copper coils can be replaced bysuperconducting receiver coils, increasing signal-

to-noise ratio by a factor of two in some cases. This change is especially important in low-

strength MRI fields (based on lower costmagnets), where weak fields mean weak signals.Superconducting coils could boost theperformance of these machines by improvingimage quality and reducing measurement time.


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ses oSuperconductors:Magnetic field sensing

Compared with the rest of the bodys lowcurrent operations, the heart is a highlyelectric organ. Its faint magnetic field(about 100 picoteslas) can be measuredwith superconducting quantuminterference devices (SQUIDs), the mostsensitive magnetic sensors known.

When arranged in arrays, SQUIDs canprovide an image of the heart s magneticfield and yield clues to abnormal

conduction patterns that are the basis ofsome heart arrhythmias (abnormalrhythms). About 3 million persons aretreated for arrhythmias each year in theUnited States.


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Uses ofSuperconductors:

Levitation 'MagLev' trains have been under

development in Japan for the past twodecades

Superconducting magnets are used create astrong magnetic force to propel the vehicle.But they offer more than just propulsionthey also levitate the vehicles and guidethem within the bounds of the guideway.The system takes advantage of the naturally

stabilizing effect provided by electromagnetinduction. No controlling deviceswhatsoever are needed to keep the train onits guideway, and there is no risk of the trainderailing. The magnetic levitation force isideal for supporting a train at very high

speeds.


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Applied Uses ofSuperconductors

Electric generators made with superconducting wire are

far more efficient than conventional generators woundwith copper wire. Their efficiency is above 99% and their size about half

that of conventional generators. They make lucrative ventures for power utilities.

Recently, power utilities have begun to usesuperconductor-based transformers and "fault limiters". Superconducting fault limiters can respond within a few

milli-seconds to limit thousands of amperes of current such as after a lightning strike.

An idealized application for superconductors is toemploy them in the transmission of commercial power tocities.

BUT, due to the high cost and impracticality of coolingmiles of superconducting wire to cryogenic temperatures,this has only happened with short "test runs".

Superconducting material takes up less space. In one instance 250 pounds of superconducting wire

replaced 18,000 pounds of vintage copper cable, makingit over 7000% more space-efficient.


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Applications usingSuperconductors

Superconducting power transmission- currently we waste ~ 20 % of our

energy just transporting it around

- potentially the next industrialrevolution


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superconductorsFaster (petaflop) computers.

A petaflop is a measure of acomputer's processing

speed and can be expressedas: A thousand trillionfloating point operations persecond (FLOPS)

Today's fastest computingoperations have only

reached "teraflop" speeds -trillions of operations persecond.

Currently the fastest areNEC's Earth Simulator,which operates at a top-endof40 teraflops

Cellular(wireless) technology

Since super-conducting wire has near zero resistance, even at highfrequencies, many more filter stages can be employed to achieve a desiredfrequency response.This translates into an ability to pass desired frequencies and blockundesirable frequencies in applications such as cellular telephone systems.


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Conclusions

Superconductivity offers excellent science,

excellent technology, excellent training and

the possibility of saving the planet !!

Using world-class science to produce technology istough. It requires first class scientists, time,perserverance, creativity, luck and funding.

The many uses for superconductivity means that many ofthe technological tools required to exploit new materialsare in place.

The new materials discovered in the last 20 years werefound by relatively small determined groups.


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Documents

Superconductivity and Classroom Applications