On the surface tension of plasmas

The electric field energy in the inhomogeneous surface of a plasma (due to the presence of a double layer at the surface) divided by the surface area defines a surface tension. Two cases of interest are studied. First, the magnitude of the surface tension for a thermally produced double plasma layer is evaluated. Secondly, the surface tension for a double layer at the surface of a degenerate electron gas in a metallic ion lattice is evaluated. The results are in fair agreement with the measured surface tensions. A numerical hydrodynamic evaluation of the surface tension for the particular case of laser-plasma interaction is given, as well as discussions on the stabilization of the Rayleigh-Taylor instability and the charging of spherical plasmas. The theory may find application to laboratory and cosmic plasmas when regions of different plasma densities and temperatures are sufficiently delineated by thin surfaces of charge separation