Electromagnetic Induction E-Sensor for Underwater UXO Detection
QUASAR FEDERAL SYSTEMS INC SAN DIEGO CA
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QUASAR Federal Systems QFS endeavored to adapt its innovative underwater capacitive electrode electric field E sensors for use in detection of Unexploded Ordnance UXO objects in seawater. The system was based around an existing Time Domain Electromagnetic TDEM sensor, in which a pulsed magnetic B field induces eddy currents in the target. The eddy currents produce a secondary B-field, which in a conducting medium can be detected with either E-sensors or B-sensors. The E-sensor was used to measure decaying eddy currents in a standard UXO-like target. The results were compared to both previously measured B-fields and calculated values for the same target. The E-sensor showed similar response to the B-sensor, with roughly 13 the signal-to-noise ratio SNR but a broader detection range. The E-sensor data from a steel rod were in excellent agreement, in both shape and amplitude, to the calculated value for a vertical magnetic dipole of moment 0.03 Am2. The UXO detection capability of the QFS underwater E-sensor has been clearly demonstrated. The vector nature of the fields also suggests the sensor could be use for discrimination, using inversion algorithms such as the Time Domain 3-Dipole Model. In future work the detection capability of this sensor will be enhanced and the discrimination potential will be explored.
- Ammunition and Explosives