This document summarizes a presentation about superconductivity. It discusses how superconductivity was discovered in 1911 by Heike Kammerlingh Onnes when he found that mercury's resistance disappeared at 4.2K. Type I superconductors can only tolerate small magnetic fields, while Type II can carry large currents and make powerful electromagnets. High-temperature superconductors were later discovered in ceramic materials. Applications of superconductors include maglev trains, MRI machines, and particle accelerators.

1. TOPIC : SUPERCONDUCTIVITY
 ROLL NOS. : 21 TO 26
PRESENTED BY
1. VARUN
2. YASH G.
3. SARVESH
4. MADHURA
5. NIKITA
6. SIDDHANT

2. Superconductivity
Exploring the world of Low Temperatures and Quantum effects

3. Introduction
What are superconductors?
• Superconductors are the material having almost zero
resistivity and behave as diamagnetic below the
superconducting transiting temperature
• Superconductivity is the flow of electric current
without resistance in certain metals, alloys, and
ceramics at temperatures near absolute zero, and in
some cases at temperatures hundreds of degrees
above absolute zero = -273ºK.

4. Discoverer of Superconductivity
 Superconductivity was first discovered in
1911 by the Dutch physicist,Heike
Kammerlingh Onnes.

5. The Discovery
 Onnes, felt that a cold wire's resistance would
dissipate. This suggested that there would be a steady
decrease in electrical resistance, allowing for better
conduction of electricity.
 At some very low temperature point, scientists felt that
there would be a leveling off as the resistance reached
some ill-defined minimum value allowing the current to
flow with little or no resistance.
 Onnes passed a current through a very pure mercury
wire and measured its resistance as he steadily
lowered the temperature. Much to his surprise there
was no resistance at 4.2K.

6. Superconducting magnets
An electrical current in a wire creates a magnetic field around a wire. The
strength of the magnetic field increases as the current in a wire increases.
Because SCs are able to carry large currents without loss of energy, they are
well suited for making strong magnets. When a SC is cooled below its Tc and a
magnetic field is increased around it, the magnetic field remains around the SC.
If the magnetic field is increased to a critical value Hc the SC will turn normal.
• Support a very high current density with
a very small resistance
• A magnet can be operated for days or
even months at nearly constant field
A typical Nb3Sn SC magnet.
It produces 10.8T with a current
of 146A. Bore diameter is 3.8 cm.
Cross-section of multifilament
Nb-Ti of 1mm overall diameter,
consisting from 13255 5-µm
filaments

7. Other Uses of Superconductivity
Fault current limiters
• Electric motors
• Electric generators
• Petaflop computers (thousand trillion
floating point operations per second)

9. A superconductor like this, called a Type I superconductor, is limited in its
current-carrying capability because it can tolerate only very small
magnetic fields.
The Meissner effect is the litmus test for superconductivity.

10. A Type II superconductor acts like a Type I superconductor in small
magnetic fields. In large magnetic fields, it “sacrifices” part of itself so
that the rest can remain superconducting.
Type II superconductors can carry enormous currents and make incredibly
powerful superconducting electromagnets.

11. Picture below is the levitation of a magnet above a cooled
superconductor, the Meissner Effect

12. High-Tc Superconductivity
Alex Müller and Georg Bednorz
Paul Chu

13. K.A. Muller J. G. Bednorz
The Discovery of
superconductivity
in ceramic materials
The Nobel Prize in Physics
1987

14. Super
conductor
lattice

15. Super conductor lattice

16. Due to attract of electron by positive
charge, ions in conductor is disturbed

17. Ions attracted by positive charges

18. Due to deformation positive
charge increased

19. Electrons get attracted due to
increased positive charges

20. Cooper pairs formed

21. advantages
 Can carry large quantities of energy without heat
loss.
 Able to generate strong magnetic fields.
 Superconductors beneficial applications in medical
imaging techniques.
 New superconductive films may result in
miniaturization .
 Superconductors increased speed in computer chips.

22. disadvantage
 Superconducting materials conduct current
at only given temperature known as
transition temperature.
 Superconductors still do not show up in
most everyday electronics.

23. MAGNETIC LEVITATION
 Magnetic levitation, maglev,
or magnetic suspension is a
method by which an object is
suspended with no support other
than magnetic fields. Magnetic
force is used to counteract the
effects of the gravitational and any
other accelerations.
 The two primary issues involved
in magnetic levitation are lifting
force: providing an upward force
sufficient to counteract gravity,
and stability: insuring that the
system does not spontaneously
slide or flip into a configuration
where the lift is neutralized.

25. APPLICATIONS
Magnetically levitated vehicles are called Maglev vehicles
 Maglev trains:
 Based on two techniques:
1)Electromagnetic suspension
2)Electrodynamic suspension
 In EMS,the electromagnets
installed on the train bogies attract
the iron rails. The magnets wrap
around the iron & the attractive
upward force is lift the train.
 In EDS levitation is achieved by
creating a repulsive force between
the train and guide ways.
 The basic idea of this is to levitate
it with magnetic fields so that there
is no physical contact between the
trains and guideways.
Consequently the maglev train can
travel at hihg speed of 500 km/h.

26. Maglev Train

28. 2. The production of
sensitive magnetometers based
on SQUIDs
.

29. Powerful superconducting electromagnets used in maglev
trains, Magnetic Resonance Imaging (MRI) and Nuclear magnetic
resonance (NMR) machines, magnetic confinement fusion reactors
(e.g. tokomaks), and the beam-steering and focusing magnets used in
particle accelerators.
• Superconducting generators has the benefit of small size and low
energy consumption than the conventional generators.
• Very fast and accurate computers can be constructed using
superconductors and the power consumption is also very low.
Superconductors can be used to transmit electrical power over very long
distances without any power or any voltage drop

31. THANKING YOU!!!!!!!!!