High Temperature Superconductivity Allen Moussa http://www.rise ...

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15 Νοε 2013 (πριν από 3 χρόνια και 10 μήνες)

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High Temperature
Superconductivity



Allen Moussa

http://www.rise.org.au/info/Tech/scon/image001.jpg

single crystal x
-
ray diffraction


http://www.teachnet.ie/dkeenahan/images/xrayCrystalDiffraction.jpg



Single crystal X
-
ray diffraction technique can be used to determine
crystal structure, a collimator is used to narrow the X
-
ray beam as show in
the image




When X
-
rays reflect off layers in a crystal they produce patterns of
destructive and constructive interference on photographic film (see image)




X
-
rays have a small enough wavelength to allow the atomic spacing
between planes in crystals to act as a diffraction grating



X
-
rays produce an interference
pattern after reflecting off several
layers of atoms in a pure crystal.
The superposition of many
reflected waves results in a
pattern of bright spots on the
photographic film, this pattern is
analyzed.

SEM
-

Scanning electron microscope




High powered electron beams are fired at the surface of the sample in a
raster like fashion providing a 3D image of the surface




Electrons are reflected from the surface of the crystal when hit by the
beam, this causes the emission of X
-
rays which are then detected




The electron beam causes the sample to displace inner
-
shell
electrons,a higher energy electron fills the shell and energy is released

http://media
-
2.web.britannica.com/eb
-
media/88/113688
-
004
-
B14FDB14.gif

powder x
-
ray diffraction




This technique requires the sample to be grounded into a finely
powdered material and placed onto a diffractometer




Involves diffraction of a monochromatic X
-
ray beam from a sample
containing an enormous number of tiny crystals having random
orientation




A detector moves around the crystal to measure the intensity of X
-
rays
at different angles, and plots a relative intensity pattern at these different
positions

http://folk.ntnu.no/krill/mineralogee/7
-
filer/xrd.gif

advances leading to HTS
-

ceramics




Heike Onnes the ‘farther of superconductivity’ began experimentation
with pure metals such as mercury




Ceramic materials are normally insulators, although in 1986 a layered
ceramic compound (
Ba
-
La
-
Cu oxide)

was created that superconducted at
the highest temperature then known, 30 K




The problem with ceramics is that they are hard and brittle making it a
challenge to make long, flexible wires out of them








Improvements in transmission electron microscopy have led to
increased understanding of the crystalline structure of high temperature
superconductors

The Meissner effect can
be used to identify
properties of different
types of HTS, by analyzing
the HTS critical magnetic
field strength

http://www.magnet.fsu.edu/education/tutorials/magnetacademy/su
perconductivity101/images/superconductivity
-
meissner.jpg

advances leading to HTS
-

BCS theory




High temperature superconductors are made from ceramic materials
largely containing copper oxide




The discovery of HTS meant that liquid nitrogen could now be used as
opposed to liquid helium which is expensive to produce




BSC provided a firm understanding of the mechanism underlying low
temperature superconductivity which eventually led to HTS

http://www.cartage.org.lb/en/themes/sciences/physics/SolidStatePhysics/Superconductivity/Fundamentals/fig5.gif

At critical temperatures
electrons attract the positive
ions and create a region of
excess positive charge, which
than attracts another nearby
electron, these two electrons
are now cooper pairs

Superconductor applications
-

maglev train




Maglev (magnetic levitation) trains use the Meissner effect, they use
superconducting magnets in the train and levitation coils attached to the
side track




High temperature superconductors are now being used and this means
that liquid nitrogen can be utilized, which lowers the operating cost
significantly




Since there is no friction with the track air resistance is the only force
slowing the train, the front has a streamlined design to reduce drag

http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html

http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html

In
image 1
the levitation coils
attached to the track have north and
south polarities due to Lenz’s law
that they must oppose the change in
flux caused by the moving
superconducting magnets


In

image 2
a substation constantly
reverses the polarity of the levitation
coils so that each superconducting
magnet is either being repelled of
pulled along the track

Image 1

Image 2

Superconductor applications
-

SQUID




SQUID magnetometers are so sensitive that they can detect magnetic
fields caused by electrical currents produced by the brain




SQUIDs use a superconducting ring to resists changes in flux from the
external environment and give recordings of magnetic field strength




SQUIDs provide a safer method to analyze electrical currents in the
brain, this has allowed researchers to further understand the brain
differences between individuals with a disorders and those without

http://superconductors.org/uses.htm#squid1

future applications
-

computers


Component

Advantages

Disadvantages

Society





Significantly

smaller

computers

and

increased

speed

of

computer

chips




The

superconductive

approach

has

advantages

in

power

consumption




Faster

calculations

will

help

engineers

to

analyze

problems

faster

and

more

accurately



Powerful

computers

can

be

used

by

the

military

or

terrorist

groups

to

develop

weapons




Cyber

criminals

e
.
g
.

hackers

will

now

be

able

to

take

advantage

of

faster

computing


Environment



Computers

will

have

a

low

energy

consumption



Increased

mining

for

rare

Earth

elements





Many

HTS

are

made

of

toxic

metals

and

disposal

of

them

can

affect

the

environment

http://www.superconductors.org/Uses.htm

future applications
-

transmission of
electricity


Component

Advantages

Disadvantages

Society






HTS wires can carry 150
times as much as a standard
copper wire of the same
dimensions



Transformers will no longer be
required



Reduced electricity costs



The

manufacturing

cost

will

be

100

times

that

of

todays

conventional

wires




Keeping

the

wires

at

the

required

critical

temperature

Environment



HTS

wires

conduct

with

100
%

efficiency

when

cooled

with

environmentally

friendly

liquid

nitrogen



Replacement

of

existing

overhead

transmission

lines

with

underground

cable



Increased

mining

for

rare

Earth

elements




http://www.azom.com/Details.asp?ArticleID=942#
_What_are_the

future applications
-

motors and generators


Component

Advantages

Disadvantages

Society





HTS

generators

and

motors

are

substantially

smaller

and

lighter

than

copper

based

machines




Heat

is

eliminated

and

life

expectancy

of

motors

and

generators

increases




Environment



HTS

generators

reduced

pollution

per

unit

of

energy

produced




Reduction

in

fossil

fuel

usage

since

HTS

generators

are

very

efficient



Smaller

size

means

that

less

materials

is

needed

for

construction




http://www.superconductors.org/Uses.htm

future applications
-

superconducting magnetic
energy storage

Component

Advantages

Disadvantages

Society





SMES

recharges

within

minutes

and

can

be

charged

thousands

of

times

without

any

degradation

of

the

magnet
.




Power

is

available

almost

instantaneously,

no

loss

of

power







SMES

requires

a

large

space

to

provide

useful

storage

of

energy


Possible

adverse

health

effects



Environment




Future

power

storage

that

would

have

no

hydrocarbon

emission



Large

magnetic

fields

in

SMES

could

possibly

disrupt

the

Earth’s

magnetic

field


http://www.accel.de/pages/2_mj_superconducting_magnetic_energy_storage_smes.html

Bibliography




http://folk.ntnu.no/krill/mineralogee/7.htm


Physics Contexts 2
-

Textbook


http://serc.carleton.edu/research_education/geochemsheets/techniques/SXD.html


http://www.trifieldmeter.com/magdone.htm


http://www.azom.com/Details.asp?ArticleID=1123#_What_is_SMES


http://www.eere.energy.gov/de/supercon_magnetic.html


http://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage#Technical_challenges



Mac os x dictionary application


http://en.wikipedia.org/wiki/High_temperature_superconductor


http://en.wikipedia.org/wiki/X_ray_diffraction


http://superconductors.org/History.htm


http://science.uniserve.edu.au/school/curric/stage6/phys/ideas/


http://www.hsc.csu.edu.au/physics/core/implementation/9_4_4/944net.html


http://www.ornl.gov/info/reports/m/ornlm3063r1/contents.html


http://www.cartage.org.lb/en/themes/Sciences/Physics/SolidStatePhysics/Superconductivity/Funda
mentals/fundamentals.htm


http://www.tlchm.bris.ac.uk/webprojects2000/igrant/hightctheory.html


http://www.hscphysics.edu.au/home


http://hyperphysics.phy
-
astr.gsu.edu/HBASE/Solids/hitc.html


http://www.howstuffworks.com/framed.htm?parent=superconductivity.htm&url=http://www.ornl.gov/r
eports/m/ornlm3063r1/contents.html


http://www.walter
-
fendt.de/ph14e/singleslit.htm


http://www.amsc.com/aboutus/super_fact.cfm


http://www.wmi.badw
-
muenchen.de/FG538/projects/P4_crystal_growth/index.htm


http://inventors.about.com/od/sstartinventions/a/superconductors_4.htm


Get smart Physics
-

written by Winston Grossley


Alasdair Hey
-

the physics guy