Stimulated Brillouin backscattering (B-SBS) from delayed interaction with a preformed, long scale-length expanding plasma was experimentally investigated in a regime favorable to strong self-focusing (SF) and filamentation. An extremely low backscattering reflectivity (of the order of 10(-4)) was measured and anomalous time-resolved spectra were observed. Spectral and temporal features of the reflectivity suggest a strong effect of SF on B-SBS: In the early phase of the interaction SF lowers the B-SBS threshold and possibly leads to rapid saturation, while in the late phase there is a substantial decoupling of the SBS active regions from the plasma bulk due to their motion towards the laser beam. This motion is attributed to a moving focus effect driven by ponderomotive SF. [S1063-651X(99)00601-7].
|Autori:||Giulietti A; Macchi A; Schifano E; Biancalana V; Danson C; Giulietti D; Gizzi LA; Willi O|
|Titolo:||Stimulated Brillouin backscattering from underdense expanding plasmas in a regime of strong filamentation|
|Anno del prodotto:||1999|
|Digital Object Identifier (DOI):||10.1103/PhysRevE.59.1038|
|Appare nelle tipologie:||1.1 Articolo in rivista|