MODULATED ION-ACOUSTIC WAVES IN INHOMOGENEOUS PLASMAS

A modified nonlinear Schrodinger equation, governing the behaviour of nonlinear ion acoustic waves in a plasma with density and temperature gradients is derived. For small amplitudes, the wave gets damped when it propagates towards increasing density. The finite amplitude waves, after an initial damping, grow asymmetrically into different shapes. An envelope soliton is found to split into two envelope solitons, one of which damps afterwards. In the case of an envelope hole two soliton-like humps developed on either side of the central depression whereas a periodic modulation excites other wave numbers and develops a spectrum. An increase in inhomogeneity scale lengths slows down the evolution of these processes.