A Unified Approach to Two-Region Ionization-Excitation Density Calculations

A method is developed to evaluate the spatial dependence of the energy spectrum of charged particle currents entering a process fluid from a bordering solid fuel region. This enables calculation of spatially dependent ionization-excitation rates including the general case where the formation rate varies with particle energy. Nondimensional plots permit application of the results to various fluid-fuel combinations and, with adjustment of two parameters, they may also be used for various particles including fission fragments, betas, alphas, and protons. The example of excitation of helium by alpha irradiation is examined in some detail.