Computational modeling of the spatial distribution and temporal decay of geomagnetically trapped debris of a high altitude nuclear detonation

Abstract

With the absence of nuclear weapons testing there has been an increase in the reliance on simulation and modeling for the analysis of nuclear weapons effects. The principal objective of this dissertation was to develop a particle code for modeling the spatial distribution and temporal decay of ionized fission fragments and beta-decay electrons injected into the magnetic field of the earth. No known code existed for this explicit purpose. The code provides a robust, realistic computational capability to predict the persistent radiation environment produced for such an injection (most likely due to a nuclear detonation at high altitudes) into L-shells less than 1.5. The code can also be used to produce a source term for the weapons debris from a nuclear detonation at any high altitude location. Using the model, several of the free parameters are examined and reported to highlight the sensitivity of the persistent environment to the initial conditions fission fragment release. The parameters examined and reported here include the effects of ion release location (longitude, latitude, and altitude), the charge state of the fission fragments, the beta decay half-life, the initial pitch angle of the fission fragments, and the significance of neutral fission fragments. Additionally, the effects of the magnetic bubble on the dispersion and trapping efficiency of the particles is studied and reported.