Frequency dependence of magnetic permeability of hollow cylindrical ferromagnetic pieces

The frequency dependence of the magnetic permeability of hollow cylindrical samples has been studied. Experiments were conducted in an inhomogeneous a c magnetic field generated by a narrow cylindrical coil. The pickup coil ax is was aligned with the driving coil and the sample, and the distance betwe en the coils varied during the experiment. The experimental data were compa red to calculations of the real and imaginary components of the complex mag netic permeability of samples. Experimentally determined hodographs are giv en, alongside frequency dependences of the magnetic permeability components obtained at different diameters, wall thicknesses, separations between the coils, and sample lengths.