Method and apparatus for measurement of magnetic permeability of a material

A system for determining magnetic permeability of a material, comprising:

• a) a first electrical inductor;
• b) a second electrical inductor;
• c) an AC voltage source connected to said first electrical inductor to induce a magnetic field surrounding said first and second electrical inductors and a sample of said material;
• and
• d) means for measuring an induced AC voltage in said second electrical inductor, wherein the amplitude of said induced AC voltage is proportional to said magnetic permeability of said material,
• wherein said first electrical inductor is a first coil, said second electrical conductor is a second coil coaxial with said first coil, said magnetic field is axially-directed within said first and second coils, and said sample of said material is disposed within said axially-directed magnetic field, and
• wherein said first and second coils define a sample cell having a first sample coil and a second sample coil for receiving a test sample of said material, said system further comprising
• a reference cell having a first reference coil and a second reference coil for receiving a sample of a reference material having known magnetic permeability;
• means connecting said first sample coil and said first reference coil in parallel to said AC voltage source;
• means connecting said second sample coil and said second reference coil in series wherein a sample current induced in said second sample coil is opposed by a reference current induced in said second reference coil;
• and
• means for determining a difference in amplitude between said sample current and said reference current, said difference being proportional to said magnetic permeability of said test sample relative to said magnetic permeability of said reference material.