Suppression of Instabilities in a Long-Scalelength Preformed Plasma

We report on measurements made of the levels of stimulated Raman and Brillouin scattering in a long-scalelength preformed plasma. The effectiveness of a random phase plate and an induced spatial incoherence system to suppress these instabilities by reducing the coherence of the laser beam have been studied. It has been found that both these methods give rise to a significant reduction in the levels of the Raman and Brillouin instabilities under these experimental conditions.