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Hello Tim, As you are probably already aware, water's permittivity and dispersion loss vary with frequency, E-field strength, temperature, pressure, and even with externally applied magnetic fields. And of course, everything changes again when water freezes. Water is really a very interesting polar liquid - how interesting can be gleaned from the following site that discusses (and explains) 41 different anomalies of water: There are a couple of books that may help you in your quest. Although they are both out of print, they should still be available through university library loan programs. The titles are: Coelho, Roland J.,”Physics of Dielectrics for the Engineer”, Elsevier, 1978, 175p, ISBN 0444417559 Hasted, J. B., “Aqueous Dielectrics”, Chapman & Hall, 1973, 302pp, HC, ISBN 0412098008. The identical book was also published in the USA by John Wiley and Sons as ISBN 0470358882 If you have access to published scientific literature, here's an excellent 18 page article which covers the the real and imaginary portions (e' and e") of the dielectric constant for pure deionized water in the range of 20 Hz - 1 MHz using regular brass and blocking electrodes (to eliminate space charge double-layer effects at the electrodes). It also compares the results for various purities of water as well as various concentrations of Cu2SO4. Frood and Gallagher used brass electrodes and a precision LCR meter to measure de-ionized water. They found that the real portion of the dielectric constant (due mainly to space charge double layer effects) was as high as 10e5 - 10e6 at low frequencies, dropping down to the normally quoted range of ~80 at higher (~10 kHz) frequencies. A similar effect was found for the dielectric loss, which was as high as 10e6 - 10e7 at low frequencies due to conduction effects, decreasing inversely with frequency (through the entire frequency range studied) to about 20 at 1 MHz. They then compare the results using insulated ("blocking") electrodes to remove double layer effects.The latter results show a slowly rising peak in dissipation factor of 0.8 at about 500 kHz. The measured capacitance stayed approximately level until 10e4 Hz, then declined through the range of 10e4 - 0.5x10e7 Hz, leveling off to a much lower value (about 20% of the initial value seen below 10e4 Hz). If you have difficulty obtaining the article, please contact me directly at my email address. Good luck and best regards, -- Bert --
: Hi Bert,
: It's me again, :D
: I'm looking for the curve of permittivity (epsilon' )and loss
: index(epsilon")of water in function of frequency (in particular in
: lower frequency: MHz until mHz).
: But i only found this spectrum in high frequency region (MHz to GHz).
: I hope that you know that somewhere and give me some advises
: Thanks alot
: Tim
:
http://www.lsbu.ac.uk/water/explan.html
"Space-charge dielectric properties of water and aqueous electrolytes", Journal of Molecular Liquids, Volume 69, July 1996, Pages 183-200, by D. G. Frood and T. J. Gallagher.
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