Ion-acoustic compressive and rarefactive double layers in a warm multicomponent plasma with negative ions

Propagation of ion-acoustic double layers has been studied in plasma consisting of warm positive- and negative-ion species with different masses, concentrations, and charge states along with electrons with two-electron temperature distributions. It is found that there exist two critical concentrations of negative ions, alpha(R) and alpha(Q). One of them (alpha(R)) generally decides the existence of the double layer, whereas the other one (alpha(Q)) decides the nature of the double layer. It is found that the system supports ion-acoustic double layers only when the negative-ion concentration (alpha) is greater than the critical concentration alpha(R). It is also found that below the critical concentration alpha(Q), compressive double layers exist and above it rarefactive double layers exist. For some values of cold-electron concentrations (mu) it is found that if the temperature of the negative-ion species is higher than the positive-ion species, then the system supports compressive double layers for all values of alpha lying in the range 0