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Module A-3 Carbon Nanotubes

Module A-3 Carbon Nanotubes. Space Elevators. First elevator: 20 ton capacity (13 ton payload) Constructed with existing or near-term technology. Space Elevators. Space Elevators. Challenges. Induced Currents: milliwatts and not a problem

josephroberson
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Module A-3 Carbon Nanotubes

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  1. Module A-3 Carbon Nanotubes

  2. Space Elevators • First elevator: 20 ton capacity (13 ton payload) • Constructed with existing or near-term technology

  3. Space Elevators

  4. Space Elevators

  5. Challenges • Induced Currents: milliwatts and not a problem • Induced oscillations: 7 hour natural frequency couples poorly with moon and sun, active damp- ing with anchor • Radiation: carbon fiber composites good for 1000(?) years in Earth orbit (LDEF) • Malfunctioning climbers: up to 3000 km reel in the cable, above 2600 km send up an empty climber to retrieve the first • Lightning, wind, clouds: avoid through proper anchor location selection • Meteors: ribbon design allows for 200 year probability-based life • Damaged or severed ribbons: collatoral damage is minimal due to mass and distribution

  6. Anchor • Anchor station is a mobile, ocean-going platform identical to ones used in oil drilling • Anchor is located in eastern equatorial pacific, weather and mobility are primary factors

  7. Processing Techniques

  8. Discharges • Cheap • Yield ~30% • Short (<50 microns) • Random deposits

  9. CVD Growth Mechanisms

  10. MWNTs by CVD Methods

  11. Single Walled NTs

  12. Heterostructure Carbon nanotubes

  13. Catalytic CVD Growth Hongjie Dai, Stanford

  14. Catalytic Methods • High potential for scale-up production • Long lengths • Multiwall CNTs • Many defects in the materials

  15. CNT for Electronics • Carrier transport is 1-D. • All chemical bonds are satisfied  CNT Electronics not bound to use SiO2 as an insulator. • High mechanical and thermal stability and resistance to electromigration  Current densities up to 109 A/cm2 can be sustained. • Diameter controlled by chemistry, not fabrication. • Both active devices and interconnects can be made from semiconducting and metallic nanotubes.

  16. Transport on a single CNT

  17. Transport on a single CNT

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