1 / 7

Superconductivity - 100 years

Superconductivity - 100 years. Heike Kamerlingh Onnes (Leiden) 1908 liquefaction of helium 1911 electrical resistance measurements of mercury at low temperatures (< 4.2 K) 1913 Nobel Prize. http://de.wikipedia.org/wiki/Heike_Kamerlingh_Onnes.

mary
Download Presentation

Superconductivity - 100 years

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Superconductivity - 100 years • Heike KamerlinghOnnes (Leiden) • 1908 liquefaction of helium • 1911 electrical resistance measurements of mercury at low temperatures (< 4.2 K) • 1913 Nobel Prize http://de.wikipedia.org/wiki/Heike_Kamerlingh_Onnes http://www.tikalon.net/blog/blog.php?article=2011/superconductivity

  2. Theory behind – BCS theory http://eng.super-kics.or.kr/infos/history • Bardeen –Cooper –Schrieffer (1957) • e- are fermions, Pauli exclusion principle • Energy reduction for FA Superconductivity

  3. Theory behind – BCS theory Presentation of P.Hedegard: “Theory_Behind” • Cooper pairs • Between e- (different spin) • Attractive force (i+ and e-) • Positive charge attracts the following e- • Time delayed due to heavy i+ • Large distance between the e- • FC→ 0 • Energy drop for the e- of a Cooper pair Superconductivity

  4. Energy gap, TC Normal conducting Superconducting • TC of pure metals: • Al @ 1.2 K • Hg @ 4.15 K • Nb @ 9.2 K • Not superconducting: • Good normal electrical conductor (Cu, Ag, Au) • Ferromagnetic materials (Fe, Co, Ni) Superconductivity

  5. MeissnerOchsenfeld effect http://www.google.de/ Superconductivity • Superconductor is diamagnetic • Shielding of external magnetic flux by electrical currents at its surface • Transition to normal conducting state • For B ≥ BC→ Ekin,shield_e-≥ D • For both: shield current or transport current (jC)

  6. Types of Superconductors Normal conducting Shubnikov Meissner http://news.sciencemag.org/sciencenow/ 2003/10/07-01.html Superconductivity • Type 1 Superconductor • Meissner phase • Type 2 Superconductor • Shubnikov phase (alloys) • Magnetic flux is entering the superconductor in quantum (normal conducting islands)

  7. Applications http://cdsweb.cern.ch/record/43859 Superconductivity • @ CERN: • electrical conductors (cables) at the LHC for magnets (di-, quadro- sextupol), cavities • NbTi (TC=9.2 K, BC2=15 T; workhorse among superconductors) • Else: • MRI (Magnetic Resonance Imaging) Tim Havens – GE Healthcare • 1977 first clinical imaging, • 30.000 scanners worldwide in 2011, • > 50% of superconductor worldwide,Script of TU Dresden • SQUID (Superconducting Quantum Interference Devices), • Transport (ship motor, train, centrifuge, clean room) • SMES (Superconducting Magnetic Energy storage) • FCL (Fault Current Limiter) is promising

More Related