ABSTRACT
This chapter presents an analysis that refers to the “standard” problem, where the authors assume an initial condition imposed on the plasma in the form of a plane wave. In a laboratory experiment, a boundary value problem is much more easily realized, for instance by assuming some oscillating charges imposed on the plasma in a fixed point. In the analysis of ion acoustic waves, without restrictions on the plasma parameters, the electron/ion temperature rations in particular, the branch with the temporally least damped wave (the initial value problem) need not be the branch with the least spatial damping (the boundary value problem). One should bear in mind that in case we have an inhomogeneous, possibly double humped ion velocity distribution, there is still a freedom in choosing the direction of the wave-vector, and a complete analysis should consider all directions, just as in the case of Langmuir waves.
