A Fluxgate Magnetometer is a tool for precisely measuring the ambient magnetic forces of a given point. Far more exact than premodern machines like compasses and magnetized balls, it detects magnetism precisely enough to allow for underground mapping of magnetic anomalies. These anomalies can represent mineral concentrations or rock faults, both of which can indicate undiscovered mineral wealth. Consequently, fluxgate magnetometers are often used in conjunction with gravity surveys in order to locate new mining opportunities.
Magnetism and Electricity
Fluxgate magnetometers work because of a special property of electrical current: the production of a magnetic field. Electric current produces a magnetic field around wires that can be intensified by coiling the wires. On the other hand, a magnetic field can produce current in coil of wires. This principle underlies both the electric engine and the electric generator.
The Principles Behind the Fluxgate
The “fluxgate” is a ring-shaped coil that is designed to be oriented in a particular direction, called Hext by engineers. Half the coil produces a magnetic force pulling towards Hext, while the other half creates an exactly equal force pulling away from it. A “sensor coil” wrapped around the fluxgate will produce a current in one or two directions, depending on whether the total force in the direction of Hext is positive or negative. In completely magnetically inert conditions, like in deep space, the force pulling towards and pulling away should be exactly even, and thus the sensor coil will produce no current in either direction. On Earth or near another planet, on the other hand, the additional magnetism creates a flux in Hext, resulting in a small amount of current. This allows calculation of the ambient force towards or away from Hext.
Using a Fluxgate Magnetometer
Geologists can orient the fluxgate towards any direction that they wish to measure. By taking several measurements over a large area, they can triangulate exactly where any variations in the Earth’s magnetic field originate. These areas most likely have crystalline iron formations, a common feature of mineral seams and underground cavities.
Triaxial Fluxgate magnetometers can also be used from the air. In the air, specialized magnetometers use three fluxgates at once to measure all possible vectors of magnetism. They also use gimbals (pivoted supports) to keep the magnetometers oriented to the ground, regardless of the tilt of the plane. Flying over a large area creates tens of thousands of data points that a computer can crunch into a map of the underlying rock structure.
The Fluxgate Magnetometer Advantage
A fluxgate magnetometer cannot be replaced by any other tool known to the scientists. It can detect rock formations that are invisible to both gravitational and seismic methods easily. Particularly in comparison to seismic methods, a fluxgate magnetometer is incredibly cheap per square mile. For surveying a wide area for mineral wealth, a magnetometer is the correct tool suiting for the job. Even though there are various proton precision controlled magnetometers, no other instrument can work essentially like a Triaxial fluxgate magnetometer.
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