Fluxgate Magnetometer

What does Fluxgate Magnetometer mean?

A fluxgate magnetometer is a type of magnetometer that employs a ferromagnetic core to sense changes in the magnetic field. It operates on the principle of magnetic Flux modulation, where the nonlinear relationship between the applied magnetic field and the core’s magnetic permeability is utilized to measure the field strength.

The magnetometer comprises a toroidal or rod-shaped ferromagnetic core wrapped with two coils, a primary coil that carries a high-frequency alternating current and a secondary coil that measures the output Signal. When no external magnetic field is present, the alternating current in the primary coil induces a Mirror-image magnetic field in the core, which increases the core’s magnetic permeability. This, in turn, decreases the magnetic reluctance and lowers the impedance of the primary coil.

When an external magnetic field is applied, it perturbs the symmetric distribution of the magnetic domains within the core, reducing its permeability. Consequently, the impedance of the primary coil increases. By monitoring the change in primary coil impedance, the strength and direction of the external magnetic field can be determined.

Applications

Fluxgate magnetometers find widespread applications in various fields due to their compact size, ruggedness, low cost, and high reliability. They are employed in:

• Navigation and Heading Reference: Inertial navigation systems, compasses, and other orientation devices utilize fluxgate magnetometers to provide accurate magnetic field measurements, enabling precise determination of direction and position.

• Geophysical Surveys: Fluxgate magnetometers are used in archaeological surveys to locate buried objects or geological anomalies by detecting disturbances in the Earth’s magnetic field caused by underground ferrous materials or other geological formations.

• Metal Detection: Metal detectors commonly employ fluxgate magnetometers to identify metallic objects, ranging from small coins to large buried pipelines.

• Magnetic Interference Detection: Fluxgate magnetometers can detect electromagnetic interference from electronic devices or power lines, aiding in the diagnosis and mitigation of sources of magnetic noise.

• Military and Security Applications: Fluxgate magnetometers play a crucial role in mine detection, magnetic field mapping, and counter-terrorism efforts.

History

The concept of fluxgate magnetometers was first proposed by Frederic Callendar in 1922. However, the first working Device was developed by Victor Vacquier in 1948 while searching for submarines during World War II. Early fluxgate magnetometers were primarily used in military applications.

In the 1950s, fluxgate magnetometers became important in geophysical exploration, particularly in the search for iron ore and oil. The development of solid-State electronics in the 1960s led to improved designs with enhanced accuracy and stability.

Since then, fluxgate magnetometers have seen continuous advancements, such as the use of non-metallic cores for enhanced sensitivity and the development of high-resolution three-axis magnetometers for precise magnetic field measurements. Today, fluxgate magnetometers remain an indispensable tool in various fields, from navigation to geophysical surveying.