The layered-capacitor method for bridge measurements of conductive dielectrics

Conductive dielectrics (ice, rocks) exhibit both dielectric relaxation and DC conductance. To suppress electrode polarization effects in bridge measurements, ice samples are sandwiched between layers of polytetrafluorethylene (Teflon). A previous approach fitted up to four discrete relaxation ranges to the effective response functions of the layered dielectric and in a final step computed relaxation parameters corresponding to ice. New algorithms, based on a generalized equivalent circuit, first invert the data to extract ice response from that of the layered capacitor. Polarization strengths and relaxation times are then fitted to the ice response by a least-square procedure. DC conductivity is obtained separately at each measurement frequency. Experimental and computational methods have been carefully verified and documented. Methodology developed by the authors provide a basis for systematic investigation of contaminant effects on the electrical properties of ice. Intrinsic processes can be measured free from carrier injection effects. Future directions for computational strategies are suggested.>