How does the magnetic field intensity of an eddy current test coil behave in air?

The behavior of the magnetic field intensity generated by an eddy current test coil in air is characterized by its decrease with distance from the coil. As the distance from the coil increases, the strength of the magnetic field diminishes due to the natural dispersion of the magnetic field lines in space. This is a common phenomenon associated with electromagnetic fields, where the intensity weakens as you move farther away from the source.

Within the diameter inside the coil, the magnetic field intensity tends to vary. This variability can be attributed to the coil's design and the distribution of current within it, which creates a non-uniform magnetic field distribution across its cross-sectional area. As a result, while the magnetic field decreases with distance outside the coil, the variation in intensity across the coil's diameter reflects the complexity of how the magnetic field is generated and structured.

This understanding is crucial in eddy current testing, as accurate knowledge of the magnetic field behavior directly impacts the test's sensitivity and effectiveness in detecting flaws or changes in material properties.