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Sa-Lin Cheng Bernstein's third PowerPoint presentation Sa-Lin Cheng Bernstein's third PowerPoint presentation Presentation Transcript

  • Where Does the Real World Meet Superconductors? Saturday Morning Physics December 13, 2003 Dr. Sa-Lin Cheng Bernstein
  • Type I Superconductors T H H c T c Normal State Meissner State Phase Diagram Image courtesy: Joseph Bernstein Theory: BCS & Ginzburg-Landau © Akira Tonomura (Hitachi, Japan)
  • Type II Superconductor T H H c1 T c Normal State Meissner State Phase Diagram Mixed or Vortex State H c2 Image courtesy: Joseph Bernstein Theory: Abrikosove & Ginzburg-Landau © Akira Tonomura (Hitachi, Japan)
  • When applying current Lorentz force pushes vortices (Flux motion) Dissipation of energy Resistance Increase of temperature Quench!!!
    • Superconducting state:
      • T < T c
      • H < H c2
      • J < J c
    Critical Surface Phase Diagram
  • Vortex Pinning
    • To increase Jc
    • Artificial pinning centers:
    • How do vortices move?
      • Avalanche vortex movies
      • See first time (1993): Akira Tonomura using transmission electron microscope
    • Bezryadin et al.
    • © Phys. Rev. B 53 , 8553 (1996)
  • Power Transmission
    • 2001: Copenhagen, Denmark
      • high-temperature superconducting (HTS)
      • only 30 meters long
    • High cost!!
    http://www.howstuffworks.com/power.htm
  • Power Transmission in USA
    • 2001: Detroit, USA
      • Detroit Edison at the Frisbie Substation
      • three 400-foot HTS cables
      • 100 million watts of power
    http://www.ornl.gov/sci/fed/applied/htspa/cable.htm
  • Superconducting Magnet
    • Normal electromagnet: 1 Tesla (= 10000 G)
    • Argonne bubble chamber:
      • Magnetic field = 1.8 T
      • Alloy of niobium and titanium (Nb 3 Ti wire)
      • Tc = 10 K
      • Hc2 = 15 T
    © Argonne National Laboratory
  • Maglev Trains
    • “Maglev”: Mag netic Lev itation
    MLX01 http://www.rtri.or.jp/rd/maglev/html/english/maglev_frame_E.html
  • Working Model National Institute of Technology and Standards
  • How does it work? http://www.acmaglev.com/technology.htm http://www.acmaglev.com/technology.htm © John Wiley & Sons, Inc. © John Wiley & Sons, Inc.
  • The Real Deal http://www.visionengineer.com 430 km/h = 267.2 mph
  • American Maglev
    • Atlanta Project
    • Florida Project
    • Old Dominion University Project
    • Virginia Project
    • Edgewater Project
    • Charlotte Project
  • MHD Propulsion
    • MHD = m agneto h ydro d ynamic
    • First MHD ship: Yamato 1
    http://voyager55.cool.ne.jp/norimono/ship/public.html © John Wiley & Sons, Inc.
  • Tevatron
    • 1983
    • Radius = 6.3 km
    • 1000 superconducting magnets (Nb 3 Ti wires)
    • Protons + Antiprotons
    • Energy = 1000 GeV (=1 TeV)
    • v ~ 200 mph slower than speed of light
  • The Circular Trajectory
    • F is directed toward the center of the circular path
    © John Wiley & Sons, Inc.
  • MRI
    • M agnetic R esonance I maging
    http://www.upstate.edu/mrilab/equipment/equipment.htm http://www.etch.com/mri.cfm
  • An Example
    • Human body: fat and water
    • Approximately 63% hydrogen atoms
    • NMR signal from the hydrogen nuclei
    Image courtesy: Seth Blumberg
  • Spin of A Proton
    • Can be thought of as a small magnetic field
    • Spin of a proton = ½
    • Spin of a hydrogen nucleus = ½
    http://www.cis.rit.edu/htbooks/mri/inside.htm P
  • Energy Levels Low energy state High energy state http://www.cis.rit.edu/htbooks/mri/inside.htm
  • Transitions
    • The energy of the photon must exactly match the energy difference between the two states
    Frequency=f http://www.cis.rit.edu/htbooks/mri/inside.htm
  • Resonance Frequency
    • f = resonance frequency
    Energy of photon Plank’s constant Frequency http://www.cis.rit.edu/htbooks/mri/inside.htm
  • Probe Energy
    • B = magnetic field
    •  = gyromagnetic ratio (H: 42.58 MHz/T)
    http://www.cis.rit.edu/htbooks/mri/inside.htm
  • Detect Tumors
    • The signal in NMR spectroscopy: energy difference (absorption & emission)
    • Raymond Damadian:
    • Nuclear magnetic relaxation times of tissues and tumors differed (1971)
    • Paul Lauterbur and Peter Mansfield:
    • 2003 Nobel Prize in Medicine
  • SMES
    • S uperconducting M agnetic E nergy S torage
    http://www.epri.com/journal/details.asp?id=349
  • Neutron Stars (NS)
    • Stellar corpses
      • result from collapse of massive star
      • big ball of neutrons ( n ) with some protons ( p+ ) and electrons (e-)
    • What opposes gravity?
      • density so high, n , p+ , e- packed as tightly as possible
      • degenerate matter supported by degeneracy pressure
  • Crab Nebula (M1) Here!
  • Cassiopeia-A: Image courtesy B. T. Koralesky, U. Minnesota Mono-frequency Radio Here!
  • NS Physical Properties Factor Different 1.5 1/70,000 500 Trillion 200 Billion Sun NS Property 1.4  10 03 7.2  10 17 Density [kg/m 3 ] 7.0  10 08 1.0  10 04 Radius [m] 2.0  10 30 3.0  10 30 Mass [kg] 9.8 2.0  10 12 g [m/s 2 ]  world pop. in 1-cm 3 box  Object dropped from 1m has v  4.5  10 6 mph at surface
  • Orbit Near the Surface by Robert Nemiroff, Michigan Tech. Univ.
  • What’s Inside a NS?
    • Average density of NS is about 3 times
    • the density of an atomic nucleus
    •  nuclei dissolve into free n and p +
    • get n Cooper pairs and p + Cooper pairs
    SUPERFLUID! SUPERCONDUCTOR!
  • Inside A Neutron Star http://www.stormpages.com/swadhwa/stellarevolution/lecture20.htm
  • Room-Temp. Superconductivity
    • Carbon nanotubes ? ? ?
    Image: Dr Chris Ewels
  • Acknowledgement
    • The audience
    • Demo lab (Warren, Mark, and Harminder)
    • Prof. Franco Nori
    • Seth Blumberg
    • Joseph Bernstein