On the role of double layers in astrophysical plasmas

Limitations of current knowledge of plasma double layers create difficulties in extrapolating double-layer concepts for application to astrophysical models. Some problems of this sort are described, and some central issues in structure and dynamics of double layers are identified, which must be addressed in astrophysical contexts. These include the determination of kinetic boundary conditions, and the relations of time and length scales of local dynamics and structure to those of the global circuit in which the double layer is contained.