Sb. Lee et al., Coaxial probe and apparatus for measuring the dielectric spectra of high pressure liquids and supercritical fluid mixtures, REV SCI INS, 71(11), 2000, pp. 4226-4230
A probe and apparatus were developed for measuring the dielectric spectra (
complex permittivity) of high pressure liquids and supercritical fluid mixt
ures. The probe consisted a 2.2 mm semirigid coaxial cable that was cut off
flat and mounted into a high pressure tube. The apparatus for measuring co
mplex permittivity consisted of the dielectric probe, cell, densimeter, pis
ton for varying the system density at constant composition, and magnetic pu
mp for agitation and recirculation, all of which were housed in a constant
temperature air bath. The probe is simple, robust, inexpensive, and further
, its design allows for quick connection to high pressure systems. Probe ac
curacy is estimated to be +/-0.5 in epsilon' and +/-0.5 in epsilon' from 20
0 MHz to 18 GHz based on replicate measurements of calibration and 2 sigma
deviations over the interval. Dielectric spectra were measured over the 200
MHz-20 GHz range for methanol+carbon dioxide mixture at 323.2 K and a pres
sures up to 18 MPa. (C) 2000 American Institute of Physics. [S0034-6748(00)
02112-2].