Calculations of DT fill times and time-temperature behavior during injection for some representative ICF pellets

Commercial ICF pellets are likely to consist of concentric spherical shells, the innermost one containing a solid layer of DT. We obtain estimates of the time required to fill the inner shell with DT by means of gaseous diffusion by numerically solving the diffusion equation. In addition, the mathematically similar thermal diffusion equation is solved to determine whether the DT remains solid during the time the pellet spends in the reaction chamber before ignition. The boundary condition for the thermal problem contains both convective and radiative heat transfer contributions. We present the mathematical procedure in general terms, obtaining numerical results for some special choices of pellet configurations and dimensions