AbstractThe generation of an electromagnetic field in a region with a perfectly conducting boundary by a long duration pulse of ionizing radiation is considered. The problem of calculating the field by numerically solving the complete system of Maxwell equations is posed. The approximations of the large and small radiation conductivity of the medium in the region are formulated. Analytical estimates of the solution of Maxwell’s equations are constructed for approximations in simplified formulations. By analyzing them, methods for calculating the electromagnetic field in a model based on the Maxwell equations in the full formulation are substantiated. An approach to modeling the field in the formulations that require an unacceptable number of computation for the stable solution of the Maxwell difference equations is proposed. The approach makes it possible to simulate the generation of an electromagnetic field by radiation from outer space in apparatus blocks using programs that solve Maxwell’s equations in a complete formulation.