Effect of magnetic relaxation times on electromagnetic pulse shielding

The penetration of an electromagnetic pulse (EMP) through a ferromagnetic conducting thin film is investigated for the case in which the magnetization of the material has a characteristic time delay tau . Both saturation and hysteresis effects of he magnetization are considered and the susceptibility is defined in the nonlinear region as dM/dh. It is found that the response time tau has a significant effect on the shielding factor with optimum shielding when tau is on the order of twice the rise time of the pulse.<
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