According to the character of Magneto-rheological fluid (MRF), a type of MRF damper was designed. The direction of magnetic field is vertical to the flowing direction of MRF.

According to the influence of the perpendicular direction magnetic field upon the optical magnetic resonance signal, the perpendicular terrestrial magnetic field are measured.

Based on the spatial distribution of magnetic dipole, the equation of the normal component of leakage magnetic field on the tube surface under low-intensity field was derived.