Electric field measurement in cable in conductive medium e.g. seawater - channelling current in medium using electrodes on opposite walls of chamber, measuring induced local magnetic field in coil using NMR, EPR or SQUID detector and determining electric field within medium.

摘要

The appts. comprises two conducting electrodes (12,14) allowing the channelling of current and passage of current through one or more coils (16a,16b). The induced magnetic field of the coils is measured by magnetic sensors (28a,28b) eg nuclear magnetic or electron paramagnetic resonance, or SQUID. The electromagnetic parameters of the coils and the conductivity of the medium concerned, together with the ambient magnetic field allow calculation of the additional electromagnetic field. USE/ADVANTAGE - E.g. for corrosion measurement of cable caused by seawater, or other surrounding media. E.g. also for measuring EM fields in drilling using hollow conductor filled with mud. Improved measurement of magnetic fields with sensitivity independent of inter-electrode distance and measures signals of bandwidth from dc to several kilohertz.