A finite material temperature model for ion energy deposition in ion-driven inertial confinement fusion targets

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Abstract
We have developed a model for use in ion-driven inertial confinement fusion (ICF) target design to describe the deposition of energy by an arbitrary ion traversing a material of arbitrary composition, density, and temperature. This model particularly emphasizes the deposition physics of light ions having specific energies of 3 MeV/amu or less. However, the model is also applicable to heavy ion fusion problems where there are specific energies in excess of 10 MeV/amu. We have found that an accurate description of the cold material stopping power must include both shell corrections to the Bethe theory as well as the alternative LSS (Linhard-Scharff-Schio/tt) model at low energies. We have incorporated finite temperature effects by scaling the relevant bound electron parameters with the degree of material ionization as well as by including the free-electron stopping power. We discuss both the phenomenon of range shortening and range relengthening in heated material. Our preliminary calculations indicate that the minimum ion range in heated material is approximately one-half that in cold dense targets, independent of the identities of the projectile ion and the host material.