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An experimental study of the stimulated Brillouin scattering (SBS) instability has investigated the effects of velocity gradients and kinetic effects on the saturation of ion-acoustic waves in a plasma. For intensities less than I < 1.5 x 10{sup 15} W cm{sup -2}, the SBS instability is moderated primarily by velocity gradients, and for intensities above this threshold, nonlinear trapping is invoked to saturate the instability. We report direct evidence of detuning of SBS by a velocity gradient which was achieved by directly measuring the frequency shift of the SBS driven acoustic wave relative to the local resonant acoustic frequency. Furthermore, a novel use of Thomson scattering has allowed us to gather direct evidence of kinetic effects associated with the SBS process. Specifically, a measured two-fold increase of the ion temperature has been linked with laser beam excitation of ion-acoustic waves to large amplitudes by the SBS instability. Ion-acoustic waves were excited to large amplitude with a 2{omega} 1.2-ns long interaction beam with intensities up to 5 x 10{sup 15} W cm{sup -2}. The local frequency, amplitude, and spatial range of these waves were measured with a 3{omega} 200ps Thomson-scattering probe beam. These detailed and accurate measurements in well-characterized plasma conditions …