Parametric excitation of plasma waves by gravitational radiation

We consider the parametric excitation of a Langmuir wave and an electromagn etic wave by gravitational radiation, in a thin plasma on a Minkowski backg round. We calculate the coupling coefficients starting from a kinetic descr iption. The growth rate of the instability is thus found. The Manley-Rowe r elations are fulfilled only in the limit of a cold plasma. As a consequence , it is generally difficult to view the process quantum mechanically, i.e., as the decay of a graviton into a photon and a plasmon. Finally we discuss the relevance of our investigation to realistic physical situations and pr esent an example. [S0031-9007(99)08933-4].