Plane fronted parallel waves in a warm two-component plasma

A general system of equations is derived, using the 1+3 orthonormal tetrad formalism, describing the influence of a plane-fronted-parallel gravitational wave on a warm relativistic two-component plasma. We focus our attention on phenomena that are induced by terms that are higher order in the gravitational wave amplitude. In particular, it is shown that parametric excitations of ion-acoustic waves takes place, due to these higher order gravitational non-linearities. The implications of the results are discussed.