Demonstration of the Meissner

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

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Demonstration of the Meissner
Effect Using Superconducting

Y
2
BaCuO
5
(YBCO)


Michael Moore

College of the Redwoods

Superconducting Magnet Program

Lawrence Berkeley National Lab

Y
2
BaCuO
5
is a High Temperature
Superconductor

0
20
40
60
80
100
120
140
160
1
Superconductors
Tc(k)
Hg0.8TI0.2Ba2Ca2Cu2O8.33
Bi1.6Pb0.6Sr2Ca2Sb0.1Cu3Oy
Bi2Sr2CaCu2O9
YBa2CuO5
(La,Sr,Ca)3Cu2O6
Nb3Si
Nb3Sn
Hg
LN
-
80 K

LHe
-
4.2 K

The critical temperature(Tc) is the temperature at which a material
becomes superconductive

YBCO is a Type II
Superconductor


Type I has a much sharper
transition to
superconductivity and
exhibits perfect
diamagnetism


Type II allows flux
pinning and has a higher
Tc


The Meissner Effect only
occurs in Type II

Resistance

T
c

0 K

Non
-
superconductive metals

Type II

Type I

0 Ω


Superconductivity Creates
Diamagnetism

The surface of the YBCO assumes the same Flux value as the external flux
from the magnets and allows none of it to enter the YBCO’s interior.


Because Like poles repel each other, the YBCO is levitated


Impurities in the YBCO Causes
Flux Pinning


Diamagnetism in
superconducting material

Impurities(non
-
superconducting
materials) pin flux lines in flux
lattice votices

The Meissner Effect is a Combination
of Diamagnetism and Flux Pinning

The classic Meissner Effect demonstration

Permanent
Magnet

Type II
superconductor

Flux Density and Magnetic Flux
Lines of Track Configuration

Flux Lines

High
Density

Low
Density

Permanent Magnets

The YBCO will only move along
the track


Flux Pinning will only allow

flux lines of the same

value to enter the

vortexes


Since the values only stay the

same in a line parallel

to the track, the YBCO

only moves in that

direction

YBCO

Liquid Nitrogen Cools the YBCO
Below its Tc

Liquid Nitrogen

YBCO

When the LN boils away, the YBCO stays
superconducting for ≈ 3 minutes

Acknowledgements

I would like to thank my mentor, Stephen Gourlay for his guidance and support
on this project, Zach Radding for Design works’ involvement, Kathleen Weber
for helping me get used to lab culture, Ron Scanlen, Dan Dietderich, GianLuca
Sabbi and Shlomo Caspi for their help with the properties of superconductors,
Jim Swithwick for computer assistance, Alan Lietzke for putting up with my
love for gauss meters, Jim Swanson, Hugh Higley, Scott Bartlett, Ray Hafalia,
Roy Hannaford, and Nate Liggens who all helped immensly with tools and
inspiration. A big thanks to Goli Modeste who took the time to machine parts
for me. Jon Zbasnik was a great inspiration, and Dawn Faessler and Tom
Martin were great friends that made work more enjoyable. Thanks to Sara
Mattafirri for sharing her space with me. I would also like to thank Laurel
Egenberger, Susan Aberg and everyone at CSEE who made this summer a
fulfilling one. Last but not least, thanks to the U.S. Department of Energy,
Office of Science. The research described here was performed at the Lawrence
Berkeley National Laboratory and funded by the Department of Energy Office
of Science under Contract No. DE
-
AC03
-
76SF00098.