We have designed a specialized lightweight, low-power and highly
sensitive marine induction coil magnetometer and amplifier system. The picture
below shows several coils during construction. The long highly permeable magnetic
bar collects the nearby magnetic field into the bar, increasing the flux passing
through the several thousand turns of wire contained in the yellow bobbins.
The voltage induced in the wire turns is then amplified using a low noise
chopper amplifier similar to that used for seafloor electric field measurement.
The assembly is housed in a 6 foot long 7075-T6 aluminum pressure case that
is anodized and painted to resist corrosion by seawater and terminated by two
end caps sealed with O-rings, enabling deployments to about 7000 meters deep.
