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3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
3.magnetic levitation over a superconductor
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3.magnetic levitation over a superconductor

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Magnetic levitation over a superconductor

Magnetic levitation over a superconductor

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  • 1911 Onnes got Nobel prize for it Bednots and miller Bell labs Nobel prizes
  • Transcript

    • 1. Magnetic Levitation Over a Superconductor
    • 2.  
    • 3.  
    • 4. Evolution of superconducting materials with time Element / Compound T c Al 1 K Pb 7 K Nb 9 K Nb-Ti 9 K Nb 3 Sn 18 K Nb 3 Ge 23 K La-Sr-Cu-O 38 K Y-Ba-Cu-O 92 K Bi-Sr-Ca-Cu-O 110 K Tl-Ba-Ca-Cu-O 125 K Hg-Ba-Ca-Cu-O 165 K
    • 5.
      • Superconductivity history
      • Three Waves of Discovery of Superconducting Materials
        • Normal superconductors - 1911
        • Metals: Mercury, tin, lead, etc.
          • Low Tc
          • Low Hc
        • High-field superconductors - 1961
        • Alloys: Niobium titanium, niobium tin, magnesium diboride (2001), etc.
          • Low Tc
        • High temperature superconductors - 1986
        • Ceramics: bismuth strontium calcium & yttrium barium
        • copper oxides, etc.
          • Low Jc (not inherent)
    • 6.  
    • 7.  
    • 8.  
    • 9.
      • High Tc
      • Granularity
      • Large Anisotropy
      • Small coherence length
    • 10. Melt Processed Nd-123 Excess Nd-422 precipitates - cause interfacial defects and aid flux pinning V. Seshu Bai et al. Eur. Phys. J. B 4 , 55 (1998)
    • 11.
      • Superconducting Magnets cooled by 77 K :
      • a) Trapped field magnets aimed at use in MRI
      • Being investigated at Cambridge, UK
      • b) Superconducting wires.
      • Superconducting Foam for use as Fault current limiters
      • being developed at Germany
      • Microwave cavities with High Q for finely tuned
      • communication devices
      • Magnetic bearings based on the large levitation force
        • due to high Jc
      Bulk Applications of RE-123
    • 12. Nb 3 Sn Wire Fabrication Cu Ta-40wt%Nb Nb-1wt%Ti Sn-2wt%Mg
    • 13. Shape Forming with high Jc IG processed Y- 123 cylinder Microwave Cavities Magnetic shields
    • 14.
      • Summary of classes of materials
        • “ workhorse” LTS : NbTi
        • A15 class : Nb 3 Sn, Nb 3 Al, V 3 Ge, etc…
        • Medium T c HTS : BSCCO, MgB 2 , Chevrel phases
        • High T c HTS : YBCO
      Vacuumschmelze 64000 filaments NbTi wire IGC 19 elements Nb 3 Sn wire
    • 15.
      • Example of Nb 3 Sn : NMR magnets
      NbTi Outer coils Nb 3 Sn Inner coils Potential upgrade to 1 GHz with BSCCO coils Systems used for chemistry, materials research, etc… NHMFL 900 MHz facility (21.1 T)
    • 16. Magnetically Levitated Trains December 24,1997 Achieved world speed record for unmanned train 550km/h December 12,1997 Achieved world speed record for manned train 531km/h
    • 17. Levitation Force on a magnet : Present experiment 1.Superconductor used : YBa 2 Cu 3 O 7-  … .. called (Y-123 compound) Melt-processed with extra Y 2 BaCuO 5 called (Y- 211 compound) T c = 92 K 2. Magnet used A permanent magnet SmCo 5 weighing ~ 8 gram
    • 18.
      • Measurements done
      • Zero field cooled : Levitation effect
      • a) Place the magnet on the pan of a balance
      • b) Keep the magnet far away so that H =0 and cool the superconductor from RT to 77 K
      • c) Note the change in weight of the magnet as the superconductor approaches it.
      • 2. Field Cooled : Suspension effect
      • Repeat the above steps but ensure that the magnet is kept near the superconductor while it is getting cooled so that finite H exists.
      F d
    • 19.
      • Determination of T c :
      • Fix a thermocouple to the superconductor in order to measure the temperature of it
      • Cool the superconductor using liquid nitrogen (whose boiling point is 77 K)
      • Now levitate a magnet which signifies its superconducting nature
      • Record the temperature of the superconductor when the levitating magnet levitates no more
      • This recorded temperature will be the T c of the given superconductor.

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