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PIV Techniques in Helium II

Stephanie Law REU Final Presentation July 27, 2005. PIV Techniques in Helium II. Overview. Project Goal: to visualize second sound flow in Helium II using PIV This talk: Review superfluidity and second sound Discuss PIV Describe experimental apparatus Explain setup Discuss results

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PIV Techniques in Helium II

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  1. Stephanie Law REU Final Presentation July 27, 2005 PIV Techniques in Helium II

  2. Overview • Project Goal: to visualize second sound flow in Helium II using PIV • This talk: • Review superfluidity and second sound • Discuss PIV • Describe experimental apparatus • Explain setup • Discuss results • Conclusion

  3. Helium II • Lambda point=2.17K • Properties • zero viscosity • zero entropy • high thermal conductivity • Two-fluid model Fig. 1 1. Cramer, M.S. (n.d.) Superfluid helium – what is it? Retrieved 22 June, 2005 from http://www.fluidmech.net/msc/super/super-f.htm

  4. Second Sound • Thermal disturbances propagate like waves • Total density remains constant • Temperature function analogous to pressure function • Can set up standing waves in a cavity Fig. 3 3. Atkins, K.R. (1959). Liquid Helium. Cambridge, Massachusetts: Cambridge University Press

  5. Particle Image Velocimetry (PIV) • Seed neutrally buoyant and non-reactive particles • Illuminate particles using a laser • Take two pictures • Determine velocity field from displacement of particles

  6. My Channel • Heater • nichrome thin film on silica substrate • heat dissipated quickly • constant resistance • Thermometer • graphite on G10 • temperature sensitive • responds quickly 5. van Sciver, S. (April 2005) Presentation given at NHMFL-CMT seminar Fig. 5

  7. Second Sound Pulse Results

  8. Resonance Results n=1 n=250Hz n=2 n=500Hz n=3 n=750Hz n=frequency, n= normal mode number, c2=speed of second sound=21m/s, L=length of channel=2cm

  9. PIV • Attempted twice • able to get small particles • good separation • particles left window too quickly to get data • Solution • lengthen channel so particles stay longer

  10. Conclusion • Completed tasks • channel construction • wiring • second sound detected • resonance peaks plotted • Remaining tasks • modify channel for PIV measurements

  11. Acknowledgements • Steve van Sciver for providing this opportunity • Sylvie Fuzier for her guidance and help • Scott Maier, David Hilton, Matthieu Dalban-Canassy, and Ali Hemmatti for technical assistance • The CIRL staff

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