Precise dielectric profiling of ice cores: A new device with improved guarding and its theory

Dielectric profiling (DEP), a capacitive method for measuring an ice core's electrical conductivity and permittivity, has been in use for several years. We have built an improved DEP instrument with a modified guarded-electrode geometry whose capacitance can be determined from potential theory. The new instrument can measure an ice core's conductivity and permittivity to within a few per cent error, a high enough accuracy to infer its density using well-known models.