Research On The Magnetic Shielding Properties Of Superconducting And Other Magnetic Shield Containing Slits

Base on the electromagnetic radiation,which is harmful to human health,economic construction and national defense construction,electromagnetic compatibility problem has become a hot point of the research.Electromagnetic shielding can not be separated from the shield,the effectiveness of the shield is often affected by its own integrity.However,it often needs to make slits on the shield surface for the electrical equipment to ventilate air,dissipate hot and lead wire.At the same time,it is difficult to make large volume shield because the new type of shielding material represented by high-temperature superconductors and ceramics are always brittle,shield needs to be spliced in blocks which will cause silts at the interface.These will all resulting in electromagnetic leakage to affect the shielding effectiveness.First,this paper reviews several typical shielding materials and their development status,analyzes the basic principles of electromagnetic shielding and the basic idea of Maxwell finite element method.A three-dimensional finite element simulation model with splitting slits was established.The excitation coils generated current along the axial direction of the shield,shield type is passive.First,the three different materials properties of YBCO,Fe and Cu shields,with one slit were studied.The simulation studies the influence of the excitation source frequency on shielding effectiveness and finds that the magnetic field intensity at the reference point decreases with increasing frequency.Secondly,the paper builds a shield model of three different materials with two sub-slits on the upper floor,and changes the angle between the splits,comparative analysis of its shielding performance,finds that the shielding effect of symmetrical splitting is better than that of asymmetric splitting.Once again,a shield model of three different materials with two splits on the bottom and the bottom is established,and changes the angle between the splits,comparative analysis of its shielding performance,finds that the shielding effect of non-perforating splitting is better than that of through splitting.Then the paper builds a shield model with three different materials on the side with two axial splits and a cross section with a circumferential split,comparative analysis and reveals that the shielding effect of YBCO and Cu materials deteriorated when the side splits were high frequency,the shielding effect of Fe materials deteriorated when the circumferential split were low frequency.It is concluded that the position of the splits has differenteffects on the shielding effect of the shielding of different materials.Then,the paper studies the use of different materials to repair split at different excitation source frequencies.The simulation finds that the type of shielding material used for repair and the frequency of the excitation source all affect the effect of magnetic shielding repair,and finds the best results when repairing with Fe at low frequencies and repairing with Cu at high frequencies.Finally,a preliminary verification of the simulation was carried out through an electromagnetic shielding experiment of the energy meter,and found that the shielding effect of Fe material is better than that of Cu material when the power frequency,which is consistent with the theoretical results.By studying the magnetic shielding effectiveness of the slit on the magnetic shield,we can get the optimization method of slits and the best solution for slits and reduce the influence of magnetic effectiveness of slits,and inhibit the leakage of electromagnetic.It provides theoretical and experimental basis for electromagnetic shielding design,which has important theoretical value and application significance for solving the electromagnetic compatibility problem.