Magnetic field intensity is modeled using Laplacian equations to study the spatial distribution of magnetic field under spherical shell plasma. The influences of different internal and external radii are also considered. In addition, the magnetic field calculation of plasma space is analyzed. The main conclusions are as follows. The external uniform magnetic field H0 is the scalar magnetic bit, and the magnetic charge of the shell of the plasma is equivalent to that of a magnetic dipole. The magnetic field in the spherical shell is a super position of a uniform field and a magnetic dipole field. The uniform field is composed of an externally applied uniform field H0 and a uniform field generated by the magnetic charge on the outer surface of the ball. The magnetic dipole field is generated by the magnetic charge on the inner surface of the shell, and the inside of the shell is a uniform magnetic field. When μ2/μ1 is high and a/b is low, the ratio of the magnetic field strength H3 (the regionis r<a) to the magnetic field strength H0 (the region is r>b) is low. By contrast, when μ2/μ1 and a/b are high, the ratio of the magnetic field strength H3 to the magnetic field strength H0 is high. When the magnetic permeability of the inner object is small and the spherical shell is thick, the produced plasma sheath is thick, and the external magnetic field in the spherical shell is weak. Therefore, when the shielding effect is good, the possibility that the ``black barrier'' phenomenon will occur is high, and ground radar detection will be difficult.
2. Vidmar, R. J., "On the use of atmospheric pressure plasmas as electromagnetic reflectors and absorbers," IEEE Transactions on Plasma Science, Vol. 18, No. 4, 733-741, 1990.
3. Laroussi, M. and J. R. Roth, "Numerical calculation of the reflection, absorption, and transmission of microwaves by a nonuniform plasma slab," IEEE Transactions on Plasma Science, Vol. 21, No. 4, 366-372, 1993.
4. Mitchell, F. H., "Communication-system blackout during reentry of large vehicles," Proceedings of the IEEE, Vol. 55, No. 5, 619-626, 1967.
5. Rybak, J. P. and R. J. Churchill, "Progress in reentry communications," IEEE Transactions on Aerospace & Electronic Systems, Vol. 7, No. 5, 879-894, 1971.
6. Liu, J. F., X. L. Xi, and Y. Liu, "A solution to the propagation of electromagnetic wave in plasma sheath using FDTD method," International Symposium on Antennas, 442-445, 2008.
7. Kim, M., M. Keidar, and I. D. Boyd, "Electrostatic manipulation of a hypersonic plasma layer: Images of the two-dimensional sheath," IEEE Transactions on Plasma Science, Vol. 36, No. 4, 1198-1199, 2008.
8. Liu, J. F., X. L. Xi, G. B. Wan, and L. L. Wang, "Simulation of electromagnetic wave propagation through plasma sheath using the moving-window finite-difference time-domain method," IEEE Transactions on Plasma Science, Vol. 39, No. 3, 852-855, 2011.
9. Hodara, H., "The use of magnetic fields in the elimination of the re-entry radio blackout," Proceedings of the IRE, Vol. 49, No. 12, 1825-1830, 1961.
10. Russo, F. P. and J. K. Hughs, "Measurments of the effects of static magnetic fields on vhf transmission in ionized flow fields," NASA: Langley Research Center, 1964.
11. Russo, F. P., "Electromagnetic wave/magnetoactive plasma sheath interaction for hypersonic vehicle telemetry black out analysis," 34th AIAA Plasmadynamics and Lasers Conference, Orlando, USA, Jun. 23–26, 2003.
12. Keidar, M., M. Kim, and I. D. Boyd, "Electromagnetic reduction of plasma density during atmospheric reentry and hypersonic flights," Journal of Spacecraft and Rockets, Vol. 45, No. 3, 445-453, 2008.
13. Kim, M., M. Keidar, and I. D. Boyd, "Two-dimensional modal of an electromagnetic layer for the mitigation of communication blackout," 47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition, 092407, Orlando, Florida, 2009.
14. Tai, Y.-C. and S.-J. Fang, Electromagnetic Field and Electromagnetic Wave, 184, Dalian Maritime University Press, 2003 (in Chinese).
15. Zhang, X.-H., Manufacturing Technology and Practice, Vol. 22, Beihang University Press, 2011 (in Chinese).
16. Yang, J., L.-M. Zhu, W.-Y. Su, and G.-W. Mao, "Study on calculation of power reflection coefficient of electromagnetic wave on magnetized plasma surface," Acta Physica Sinica, Vol. 54, No. 7, 3236-3240, 2005.
17. Guan, J. and H. Zheng, Electrodynamics, China University of Petroleum Press, 2015 (in Chinese).