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Superconductivity Michael Spreitzer. Overview „Superconductivity“ ? Who discovered it ? Meissner & Ochsenknecht effect? BCS – Theory Different types of.

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Presentation on theme: "Superconductivity Michael Spreitzer. Overview „Superconductivity“ ? Who discovered it ? Meissner & Ochsenknecht effect? BCS – Theory Different types of."— Presentation transcript:

1 Superconductivity Michael Spreitzer

2 Overview „Superconductivity“ ? Who discovered it ? Meissner & Ochsenknecht effect? BCS – Theory Different types of superconductivity Applications

3 Superconductivity Zero resistance Expulsion of magnetic field lines

4 Critical temperature MaterialTcTc Gallium1.1K Aluminum1.2 K Indium3.4 K Tin3.7 K Mercury4.2 K Lead7.2 K Niobium9.3 K La-Ba-Cu-oxide17.9 K Y-Ba-Cu-oxide92 K Tl-Ba-Cu-oxide125 K Electrical resistance drops to zero Materals with a ct arround 120 K can be cooled down with liquid nitrogen (77K )

5 Heike Kamerlingh Onnes Dutch physicist Liquified He 1908 (4K) 1911

6 Meissner- Ochsenknecht Effect pushes out magentic field lines -and keep them out This „diamagnetic“ property is more fundermental than zero resistance

7 BCS - Theory John Bardeen Leon Cooper John Schrieffer Nobel Prize 1972 for theory from 1957 which explained conventional superconductors

8 Different types Type 1: ◦only below critical temperature & critical magnetic field strength ◦changing between states abruptly Type 2: ◦much higher critical fields & could carry higher current densities while remaining superconductivity

9 Applications Strong magnets: ◦MRI, Maglev, LHC, Coilguns,... SQID magnetometer RF and microwave filter Low-loss power cables Electric powered: ◦Motors, generators, transformers

10 Summary Zero resistance Expulsion of magnetic field lines Two different types Cool but very expensive applications Questions ?


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