1. Topics Unidentified Flying Objects Alien Abductions Flying Saucers End of the World April 1, 2014

2. Capacitance and Dielectrics Capacitance Capacitance examples Energy stored in capacitor Dielectrics Nat’s research (just fun stuff)

3. Capacitance

4. Capacitance of Parallel Plate

5. Capacitance Typical capacitors

6. Capacitance examples

9. Materials can do 2 things: Polarize – Initial alignment of charge with applied voltage – Charge proportional to voltage – Temporary short-range alignment Conduct – Continuous flow of charge with applied voltage – Current proportional to voltage – Continuous long-range movement Electrical Properties of Materials

10. Dielectrics

11. Dielectric constants

12. Dielectric Spectroscopy (Nat’s Research) Most insulators contain polar molecules and free ions These can align as a function of frequency (up to a point) Where they fail to align is called “relaxation frequency” Characteristic spectrum 2010-12-03www.msi-sensing.com

13. TDR Dielectric Spectroscopy Sensor admittance from incident and reflected Laplace Transforms. Sample complex permittivity from sensor admittance. Differential methods Bilinear calibration methods. 1 Non-uniform sampling. 2 13

14. www.msi-sensing.com Dielectric Permittivity in Epoxy Resin 1 MHz -1 GHz Aerospace resin Hexcel 8552. High frequency range 1 MHz – 1 GHz. Temperature constant 125°C, transition decreases with cure. TDR measurement method.

15. www.msi-sensing.com Permittivity in Epoxy Resin during Complete Cure Cycle

16. www.msi-sensing.com Application to cement hydration Cement Conductivity - Variation with Cure Imaginary counterpart of real permittivity (  ’’). Multiply by  to remove power law (  o  ’’). Decrease in ion conductivity, growth of intermediate feature with cure Frequency of intermediate feature does not match permittivity

17. Basic signal evolution in cement paste 3 Permittivity (ε’ ) and conductivity (ε o ωε’’) from 10 kHz to 3 GHz. Initial behavior at zero cure time. Evolution with cure time. Low, medium, and high (free) relaxations. 17

18. Dielectric modeling in cement paste 2010-12-03www.msi-sensing.com

19. Model evolution with cement cure Free-relaxation decreases as water consumed in reaction. Bound-water 8, grain polarization 9 forms with developing microstructure. Variations in frequency and distribution factor. Conductivity decrease does not match free-water decrease. 2010-12-03www.msi-sensing.com

20. Energy stored in capacitor V 0 +