[en] A one dimensional simulation code for interpenetrating multi-component plasmas is presented. Separate fluid equations for multiple species and the Poisson equation for the electric field are solved implicitly to allow stable accurate solutions over a wide range of the time scale parameters ω_pΔt and ν_cΔt (ω^p is the plasma frequency, ν_c a typical collision frequency and Δt the time step). In regions where ω_pΔt<<1 and ν_cΔt<<1, electron dynamics and space-charge effects are resolved, while in regions where ω_pΔt >>1 and/or ν_cΔt>>1, the ambipolar and/or diffusion models are recovered. In regions of low collisionality, particles may be created and deleted which are followed using particle and cell techniques combined with scatter and drag due to collisions with the fluids. Applications of this code to interpenetrating laser generated plasmas are presented