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.

Giulietti, A., Macchi, A., Schifano, E., Biancalana, V., Danson, C., Giulietti, D., et al. (1999). Stimulated Brillouin backscattering from underdense expanding plasmas in a regime of strong filamentation. PHYSICAL REVIEW E, 59(1), 1038-1046 [10.1103/PhysRevE.59.1038].

Stimulated Brillouin backscattering from underdense expanding plasmas in a regime of strong filamentation

Biancalana, V.;
1999-01-01

Abstract

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.
1999
Giulietti, A., Macchi, A., Schifano, E., Biancalana, V., Danson, C., Giulietti, D., et al. (1999). Stimulated Brillouin backscattering from underdense expanding plasmas in a regime of strong filamentation. PHYSICAL REVIEW E, 59(1), 1038-1046 [10.1103/PhysRevE.59.1038].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11365/45375
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