Impact of atmospheric ionization by delayed radiation from high-altitude nuclear explosions on radio communication

Abstract

In this study, we investigated the motion, shape, and delayed radiation intensity of a radioactive cloud by establishing a volume-source model of delayed radiation after high-altitude nuclear explosions. Then, the spatial distribution of electron number density at different moments on the north side of the explosion point generated by delayed γ-rays and delayed β-rays from the radioactive cloud under the influence of the geomagnetic field was calculated by solving chemical reaction kinetics equations. The impact of radio communication in the different frequency bands on the process of atmospheric ionization was also studied. The numerical results of the high-altitude nuclear explosion (120 km high and with a 1 megaton equivalent at 40° N latitude) indicated that the peak of electron number density ionized delayed γ-rays is located at a height of approximately 100 km and that of electron number density ionized delayed β-rays is about 90 km high. After 1 min of explosion, the radio communication in the medium frequency (MF) and high-frequency (HF) bands was completely interrupted, and the energy attenuation of the radio wave in the very high-frequency (VHF) band was extremely high. Five minutes later, the VHF radio communication was basically restored, but the energy attenuation in the HF band was still high. After 30 min, the VHF radio communication returned to normal, but its influence on the HF and MF radio communication continued.