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Probe

Team 16. Probe. Amy Eckerle Andrew Whittington Philip Witherspoon. Sponsors. NHMFL Applied Superconductivity Center. The Project. Modify existing cryostat probe to conserve the amount of liquid helium used during a critical current measurement test. Objectives. Conserve Helium

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Probe

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  1. Team 16 Probe Amy Eckerle Andrew Whittington Philip Witherspoon

  2. Sponsors • NHMFL • Applied Superconductivity Center

  3. The Project • Modify existing cryostat probe to conserve the amount of liquid helium used during a critical current measurement test.

  4. Objectives • Conserve Helium • Test 6-8 straight samples • 1 Spiral sample • Capability to deliver 1000 Amps to samples • Durable

  5. Existing Probes Current leads

  6. Concept 1 – Heat Exchanger • Exposed Copper leads source of major heat leak • Cooling these exposed leads will decrease temperature difference

  7. Concept 1 – Design • Covers current leads • Cools leads using excess gaseous helium • Vent valve at top

  8. Concept 1 - Pros & Cons Pros Cons Self design and manufacture May not decrease temperature enough to implement • Simple concept • Reduces temperature difference • Uses excess helium as cooling gas

  9. Concept 2- HTS Leads • Replacing Copper with HTS leads • Path of least resistance

  10. Concept 2 Pros Cons Possible quenching expensive • Reduces amount of helium used • Provides current a path with less resistance • Reduces heat leak from current leads

  11. Concept 3 – Structural Support • Concept 2 • HTS leads – tape • Shell • Casing • Currently a stainless steel casing, 16 W/m*K • Replace • Spacers

  12. Concept 3 – Pros & Cons Pros Cons Material must withstand cryogenic temperatures Sacrifice structural support for thermal conductivity? • Lower thermal conductivity • If correct materials, should reduce heat leak and provide structural support

  13. Concept 4 – Reduce Leads • Reduce the amount of leads • Leads are major heat leak • Temperature gradient • Possible double PCL • Possible Parallel • Maintain 6-8 samples with least amount of leads possible • Optimization

  14. Concept 4 – Pros & Cons Pros Cons None because it is an optimization • Optimizes system • Less leads = less heat generation = less helium consumption

  15. Concept 5 - Fins • Increase heat transfer • Reduce the temperature gradient • Ideally use circular fins • Easy to manufacture

  16. Concept 5 – Pros & Cons Pros Cons Effectiveness of fins may be hard to determine due to space Hard to implement • Increases the surface area • Decreases the heat transfer taking place in the liquid helium

  17. Concept 6 – Gas Insulation • Using the helium burn off gas to insulate the material. • Layer of gas between the leads and fluid • Non-boiling, Nucleate boiling, film boiling • Changing the orientation of leads • Vertical Vs. inclined • Trapping of gas, wells

  18. Orientation • Wells

  19. Concept 6 – Pros & Cons Pros Cons Space Design constraints • Create an insulating layer • Can theoretically decrease heat transfer by an order of magnitude

  20. Concept 7–Spoke Thermal Cap • G-10, a fibrous material, is used as a current lead spacer • Modification to this part can interrupt thermal conduction of the stainless steel tube.

  21. Concept 7- Design • Thermal cap protrudes through stainless steel

  22. Concept 7 – Pros & Cons Pros Cons Difficult assembly Increase in resistance may be small • Increases thermal resistance through the stainless steel tube

  23. Next Step • Evaluating each concept by modeling and experimentation • Assign value to ease of use, effectiveness, cost and other criterion • Decision matrix or other methods of concept selection

  24. Questions

  25. References • Ekin, J. W. Experimental Techniques for Low-temperature Measurements: Cryostat Design, Material Properties, and Superconductor Critical-current Testing. Oxford: Oxford UP, 2006. Print. • Cengel, Yunus A., Robert H. Turner, and John M. Cimbala. Fundamentals of Thermal-fluid Sciences. Boston, MA: Mcgraw Hill Higher Education, 2008. Print. • "October 2010." Gaming News and Reviews. Web. 24 Oct. 2011. <http://gamingnewsreviews247.blogspot.com/2010_10_01_archive.html>.

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