Treatment of late time instabilities in finitedifference EMP scattering codes
Abstract
Constraints applicable to a finite difference mesh for solution of Maxwell's equations are defined. The equations are applied in the time domain for computing electromagnetic coupling to complex structures, e.g., rectangular, cylindrical, or spherical. In a spatially varying grid, the amplitude growth of high frequency waves becomes exponential through multiple reflections from the outer boundary in cases of latetime solution. The exponential growth of the numerical noise exceeds the value of the real signal. The correction technique employs an absorbing surface and a radiating boundary, along with tailored selection of the grid mesh size. High frequency noise is removed through use of a lowpass digital filter, a linear least squares fit is made to thy low frequency filtered response, and the original, filtered, and fitted data are merged to preserve the high frequency earlytime response.
 Publication:

IEEE Transactions on Nuclear Science
 Pub Date:
 December 1982
 DOI:
 10.1109/TNS.1982.4336475
 Bibcode:
 1982ITNS...29.1943S
 Keywords:

 Computer Programs;
 Electromagnetic Pulses;
 Electromagnetic Scattering;
 Finite Difference Theory;
 Numerical Stability;
 Time Functions;
 B52 Aircraft;
 Curve Fitting;
 Data Recording;
 Digital Filters;
 Electromagnetic Coupling;
 F111 Aircraft;
 InFlight Monitoring;
 Maxwell Equation;
 Electronics and Electrical Engineering