OBSERVATION OF 2 ION-ACOUSTIC-WAVES IN A 2-SPECIES LASER-PRODUCED PLASMA WITH THOMSON SCATTERING

We report the first observations of two separate ion-acoustic waves in a two-ion-species plasma with Thomson scattering. A flat disk coated with thin multilayers of gold and beryllium was irradiated with one la ser beam, and the resulting two-ion-species plasma was probed with a s econd laser at a distance of 500 mu m. The phase velocities of the ion -acoustic waves are shown to be a sensitive function of the relative c oncentrations of the two-ion species. Moreover, an accurate measuremen t of the ion temperature can be derived from the relative damping of t he two-ion-acoustic waves.