Small amplitude ion-acoustic double layers in electron-positron-ion plasmas with finite ion temperature

The nonlinear small amplitude ion-acoustic double-layers in a collision less warm plasma consisting of isothermal positrons, warm ions and two-temperature distribution of electrons are investigated. Using standard hydrodynamic equations for the ions and the two species of electrons separately in thermal equilibrium following Maxwellian distributions have been considered. Using reductive perturbation method we have derived modified Korteweg-de Vries (m-KdV) equation for the system. On numerical investigations the double layer solution of the system, we have found a new range of parameters for which system supports compressive double layers and rarefactive double layers depending on the concentration of cold electron (μ). Numerical analysis reveals that the system supports compressive double layer for lower values of cold electron concentration (μ), and rarefactive double layers for higher values of (μ). For these cases, the amplitude depends on positron concentration α), finite ion temperature (σ) and the temperature ratio of the two electron species (β). The effect of various plasma parameters on the characteristics of the double layers have been investigated in detail. The results may be useful in space as well as in laboratory plasmas. (author)