  The plasma analog of an adiabatic lapse rate (or temperature variation with
height) in atmospheric physics is obtained. A new source of plasma temperature
gradient in a binary ion species mixture is found that is proportional to the
concentration gradient and difference in average ionization states .
Application to inertial-confinement-fusion implosions indicates a potentially
strong effect in plastic (CH) ablators that is not modeled with mainline
(single-fluid) simulations. An associated plasma thermodiffusion coefficient is
derived, and charge-state diffusion in a single-species plasma is also
predicted.
