Ion-acoustic solitons and double layers in a two-electron temperature plasma with hot isothermal electrons and cold ions

It is found that a two-electron temperature plasma with isothermal electron s and cold ions admits both compressive and rarefactive solitons, as well a s compressive and rarefactive double layers (depending on the concentration of low-temperature electrons). In this paper, a Korteweg-de Vries (K-dV) e quation and a K-dV-type equation with cubic and fourth-order nonlinearity a t the critical density of the low-temperature isothermal electrons are deri ved to discuss the properties of ion-acoustic solitons in a two-electron te mperature plasma. In the vicinity of the critical electron density of low-t emperature isothermal electrons, we have derived a K-dV-type equation with mixed nonlinearity, and the solution of this equation will have both compre ssive and rarefactive double layers for those values of critical electron d ensity of low-temperature electrons for which ion-acoustic solitons do not exist. By using quasipotential analysis, critical Mach numbers M-1c and M-2 c are obtained such that compressive ion-acoustic solitons exist when 1 < M < M-1c and rarefactive ion-acoustic solitons exist when 1 < M < M-2c. (C) 2000 American Institute of Physics. [S1070-664X(00)01003-X].