Free expansion of a plasma with two electron temperatures

A theory for the free expansion of a plasma with two electron temperatures is presented. It is shown that in the case of a laser-produced plasma expansion the ions separate into a fast and a slow component, and that the number of fast ions is particularly sensitive to the hot to cold electron temperature ratio. If the electron temperature ratio is > approximately 10 then the quasi-neutral self-similar solution breaks down. The regions in the rarefaction expansion where the quasi-neutrality assumption fails are discussed. (author)