According to current understanding, the major part of the Earth's radiation belt region is populated primarily (1) by external sources where particles from the outside of this region convectively and diffusively transport to the deep interior of the geomagnetic trapping region, and (2) by in-situ acceleration of pre-existing lower energy particles. But there are also secondary processes that contribute to the characteristics and composition of the trapped particle population, particularly in the inner radiation zone. These include not only the well-known Cosmic Ray Albedo Neutron Decay (CRAND) source of multi-MeV inner zone protons, but also sources of deuterium, tritium, Helium-3 and Helium-4 ions from tertiary nuclear reactions of the secondary CRAND-produced protons interacting further with the residual atmosphere. Indeed, unusually high 3He/4He flux ratios at MeV energies have been observed in the radiation belts near L=1.2 and may have their origin in such processes. In this report we present quantitative calculations of the source strength of deuterium, tritium and Helium-3 ions resulting from these interactions. And we extend diffusion theory for inner magnetosphere MeV ions by combining radial diffusive transport with local generation of deuterium and tritium and helium isotope ions due to nuclear reactions. Magnetospheric transport computations have been made in the range of L=1.0 to 1.6. The resulting MeV D, T and 3He ion flux distributions show a strong influence of the local nuclear source mechanism on the inner zone energetic ion content.


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