THE FREQUENCY AND DAMPING OF ION-ACOUSTIC-WAVES IN HYDROCARBON (CH) AND 2-ION-SPECIES PLASMAS

The kinetic theory of ion-acoustic waves in multi-ion-species plasmas is discussed. Particular application is made to hydrocarbon (CH) plasmas, which are widely used in laser-plasma experiments. The mode frequencies and Landau damping of the two, dominant, ion-acoustic modes in CH plasmas are calculated by numerical solution of the kinetic dispersion relation. In addition, some useful results are obtained analytically from expansions of the kinetic dispersion relation and from fluid models. However, these results disagree with the numerical results in domains of particular practical interest. When ion temperatures exceed two-tenths of the electron temperature, the least damped mode is the one with the smaller phase velocity, and this mode is then found to dominate the ponderomotive response of the CH plasma. © 1995 American Institute of Physics.