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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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