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LINEAR DIFFUSION INTO A FARADAY CAGE

By K. C.-Y. Chen, Y. T. Lin, L. K. Warne, and K. O. Merewether

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Abstract:
In this paper, linear lightning diffusion into a Faraday cage is studied. The high-altitude Electromagnetic Pulse (HEMP) and nearby lightning are used as examples for a uniform field drive and the direct-strike lightning adjacent to the enclosure is used as a worst-case configuration of a line source excitation. The time-derivative of the magnetic field (HDOT) inside the enclosure for a uniform field drive with a decaying exponential waveform is analyzed and numerically determined. The physically relevant time-derivative of the magnetic field and voltage characterizations of an optimum coupling loop inside the enclosure for a decaying exponential waveform in a worst-case line source coupling configuration are numerically determined. First, the impulse and the unit step response peaks are shown to bound the decaying exponential peaks. Next, a simple fit function for a decaying exponential peak HDOT or a voltage bound for a single-turn loop inside the Faraday cage is constructed from peak responses of the unit step and impulse limiting cases. Excitations used are from (1) a uniform field drive of HEMP or nearby lightning and (2) a line source of direct-strike lightning. Comparisons of HDOT and voltage bounds of the fit function and actual numerical evaluations are given in Table 3.

Citation:
K. C.-Y. Chen, Y. T. Lin, L. K. Warne, and K. O. Merewether, "Linear Diffusion into a Faraday Cage," Progress In Electromagnetics Research M, Vol. 23, 299-311, 2012.
doi:10.2528/PIERM12010410

References:
1. Lee, K. S. H. (ed.), EMP Interaction: Principle, Techniques, and Reference Data, 559-573, Revised Printing, Hemisphere Publishing Corporation and Taylor & Francis, 1986 and 1995..

2. Warne, L. K., W. A. Johnson, and K. C. Chen, "Maximum interior voltage and magnetic field penetration through a linear conducting layer," Journal of Electromagnetic Waves and Applications, Vol. 9, No. 4, 569-598, 1995.

3. Chen, K. C., Y. T. Lin, L. K.Warne, and K. O. Merewether, "Linear diffusion into a Faraday cage,", Sandia National Laboratories, Albuquerque, NM, SAND2011-8012, November 2011.

4. Widder, D. V., Advanced Calculus, 2nd edition, 44, Dover Publication, Inc., 1989.

5., "EMP engineering and design principles,", Chapter 2, Bell Laboratories Report, Whippany, NJ, 1975.

6. Bedrosian, G. and K. H. S. Lee, "EMP penetration through metal skin panels and into aircraft cavities,", Air Force Weapons Laboratory, AFWL Interaction, Note 314, Albuquerque, NM, August 1976.


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