PHENOMENOLOGICAL MODELING OF TURBULENCE IN Z-PINCH IMPLOSIONS

A phenomenological investigation into the effects of magnetohydrodynam ic (MHD) turbulence on the initial stagnation dynamics of aluminum wir e array and argon gas puff Z-pinch implosions is performed. The increa ses that turbulence produces in the plasma viscosity, heat conductivit y, and electrical resistivity are modeled by using multipliers for the se quantities in one-dimensional (1-D) MHD calculations. The major eff ect of these increases is to soften the 1-D implosions by decreasing t he densities that are achieved on axis at stagnation. As a consequence , a set of multipliers can be found that reasonably duplicates the ave rage electron temperatures, ion densities, and mass of the K-shell emi ssion region that were measured at stagnation for a variety of Physics International aluminum wire array and argon gas puff experiments. It is determined that the dependence of these measured;quantities on the multipliers is weak once a level of enhancement is reached, where agre ement between calculations and experiments is attained. The scaling of K-shell yield with load mass for a fixed implosion velocity is then r eexamined, and the minimum load mass needed to efficiently produce K-s hell emission by thermalization of kinetic energy is calculated for al uminum and argon using this phenomenological soft implosion modeling. The results show an upward shift in the minimum mass by a factor of 6 when compared to the original nonturbulent hard implosion calculations .