The Research On Ionization Processes And Ionization Effects Of Atmosphere By High-altitude Nuclear Explosions

The ionization processes by high-altitude nuclear explosions are very complex. Most energy of high-altitude nuclear burst is released by X rays, γ rays, β rays, and neutrons. And these are all ionization sources, which ionize air by different ionization processes. The rays from high-altitude nuclear explosions have effects on the ionosphere for long time, and then affect the propagation characteristic of electromagnetic wave.X rays are the most important ionization sources from high-altitude nuclear explosions. Most of the energy of X rays from high-altitude nuclear explosion is deposited from the burst point to 80 km. And the X rays have less effect on the atmosphere below 70 km. The X rays from high-altitude nuclear explosion have seriously effect on atmosphere, and with the increase of burst altitude, the ionization range increases. The lifetime of electrons is less than 1ms at 80 km, and the lifetime decrease with the reduction of altitude.The peak altitude of energy deposition of γ rays and neutrons is about 30 km below the burst point, and the cut-off altitude is about 20 km. The prompt γ rays and neutrons have serious ionization effects on the atmosphere several kilometers far away from the burst point. The temporal evolution of the low-energy electrons, which is produced by Compton electrons, can be divided into three periods: the generation period, the retention period, and the consumption period. The life of low-energy electrons is much longer than the duration of γ rays and Compton electrons. The low-energy electrons are gradually removed predominantly by the attachment processes at low altitude.The delayed rays are radiated from the fragments of the burst. A model was build based the diffusion processes of fragment, which agrees well with the high-altitude nuclear test of U.S.. The peak value altitude of density of electrons, which are generated by delayed γ rays, is about 90km-100 km, and that is about 90 km generated by delayed β rays. The affected wave band of electrons generated by delayed rays from high-altitude nuclear explosions is MF band and HF band after several tens minutes from the burst time, and it has little effect on VHF band and microwave.