Research on Magnetic Field Uniformity of Compensated Helmholtz Coil

Electromagnetic field has an important effect on the proliferation and differentiation of osteoblasts. The necessary condition for the study of the electromagnetic field effect on the proliferation and differentiation of osteoblasts is the uniform magnetic field with controllable magnetic induction intensity. At present, the main device to produce controllable uniform magnetic field is Helmholtz coil, but the uniform magnetic field produced by standard Helmholtz coil cannot meet the requirements of medical experimental space. In this paper, a model of compensated Helmholtz coil is proposed. A compensation coil with the same parameters as the main coil is added to the middle of the standard Helmholtz coil, and the axial distance of the three coils is equal to the radius of the coil. The mathematical model of the spatial magnetic field of the compensated Helmholtz coil is given, under the condition that the current ratio of the main coil to the compensation coil is fixed, the magnetic induction intensity of any point in the space is proportional to the current of the main coil. The magnetic field distribution of the compensated Helmholtz coil is simulated by COMSOL software, and the current proportional coefficient between the main coil and the compensation coil is optimized, and the maximum effective uniform magnetic field cross section area is obtained. For the compensated Helmholtz coil whose diameter is 300mm, the effective uniform magnetic field cross-sectional area is the largest when the current ratio coefficient between the main coil and the compensation coil is 1.57. On the premise that the magnetic induction intensity of the central point and magnetic field uniformity are the same, compared with the standard Helmholtz coil, the effective uniform magnetic field cross-sectional area of the compensated Helmholtz coil is increased by 80%. The compensated Helmholtz coil has the advantages of good magnetic field uniformity, large effective uniform magnetic field cross-sectional area and increasing the ratio of magnetic induction intensity to the current of the main coil. It can meet the requirements of uniform magnetic field space in medical experiments, and has important theoretical significance and practical value.