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A Basic Study of Superconductivity

A Basic Study of Superconductivity. By: Mohsen Fatemi Info@superconductors.ir FALL 2012. Contents:. Introduction History Types of superconductivity Uses for superconductivity Contribution in market References. Introduction.

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A Basic Study of Superconductivity

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  1. A Basic Study of Superconductivity By: Mohsen Fatemi Info@superconductors.ir FALL 2012

  2. Contents: • Introduction • History • Types of superconductivity • Uses for superconductivity • Contribution in market • References

  3. Introduction • Superconductivity is a property of certain material to conduct an electrical current with no voltage drop or power dissipation when their temperature is below a critical temperature (Tc). • This is a thermodynamic phase. • Superconductivity is a macroscopic quantum phenomenon.

  4. History • In 1908 first time KamrlinghOnnes succeeded in liquefying Helium ( 4.2 Kelvin-normal state and 1.7 Kelvin-vacuum state) • He cooled Mercury to the temperature of liquid Helium. The resistance disappeared suddenly at 4 K!

  5. Onnes measured a sharp drop in the resistance of Mercury At 4.25 K. source: Reference 2

  6. Meissner and Ochsenfeld discovered that a superconducting material will repel a magnetic field (Meissner effect-1933) • Meissnereffect. Source: Reference 2

  7. In 1957 Abrikosov predicted the existence of different type of superconductor in which magnetic field could penetrate the superconductor without causing it to go normal (Type II superconductors). • Microscopic theories such as Ginzburg-Landau (Ψ) stipulated that superconducting electrons condense into a macroscopic quantum state. • Final microscopic explanation of superconductivity developed by John Bardeen, Leon Cooper and Robert Schriffer (BCS Theory-1957)

  8. John Bardeen Leon Cooper Robert Schriffer Nobel Prize ceremony in 1972.Source: Reference 1

  9. Brian Josephson worked out the situation of the current flowing a thin insulator separating two superconductors. He predicted that current would flow with no voltage across the insulator and if a small DC voltage was impressed current would not just flow, it would oscillate at a frequency equal to (2eV/h!). This prediction confirmed in 1963 (Josephson effect)

  10. Types of superconductivity • Superconductors are classified into various types based on (H,T,J) characteristics of the material.

  11. Superconducting is maintained only when three parameters T,J and H do not exceed the respective critical values. Source: Reference 2

  12. Critical temperature classification • Low Temperature SuperConductors (LTSC): material which need to be cooled to extremely low temperatures below 20 K to obtain superconductivity. This require a helium based cryogenic system. • High Temperature SuperConductors (HTSC): materials which show superconductivity at higher temperatures in range of 77 K. Hydrogen, Neon or Nitrogen are used as the cryogen.

  13. Type I and Type II superconductors • Type I superconductors: accept no magnetic field and for H>Hc change to normal state. • Type II superconductors: for H<Hc1 behave like Type I but for Hc1<H<Hc2 still remain a superconductor but accept magnetic field. At H=Hc2the material is fully penetrated by magnetic field and any increase in field would drive the material completely normal.

  14. Uses for superconductivity • Magnets for particle accelerators. Tevatron, the first superconducting accelerator. This incorporates 800 superconducting magnets. Source: Reference 1

  15. Magnet Resonance Imaging (MRI) A 1.5 Tesla MRI scanner at Stanford University for a functional neuroimaging. An MRI machine contains 10 Km of superconducting wire. Source: Reference 1

  16. Superconducting cables for power transmission Superconducting power cable

  17. Superconducting Magnet Energy Storage (SMES) • Power generators and electric motors

  18. Magnetically levitated trains The Yamanashi MLX01 MagLev train . Source: Reference 6 (Left), Resource 7 (Right)

  19. Superconducting Quantum Interface Device (SQUID) A DC SQUID configuration showing two Josephson junctions connected in parallel. Source: Reference 1

  20. Contribution in market Source: Reference 3

  21. Notes • A copy of these slides are available at our website, www.superconductors.ir

  22. References • 1- Superconductivity a macroscopic quantum phenomenon, John Clarke, summer/fall 2000 • 2- Design concepts for a superconducting cable, EPRI TR-103631 Final report, September 1994 • 3- www.superconductors.org • 4-http://en.wikipedia.org/wiki/Superconductivity • 5- http://www.ted.com/talks/boaz_almog_levitates_a_superconductor.html • 6-http://www.skyscrapercity.com/showthread.php?t=246063 • 7- http://namti.org/?page_id=433

  23. Thanks for your attention! Question?

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