Stimulated Raman backscattering with and without optical fiber smoothing technique in 0.53 {mu}m laser-created plasmas

Journal Article · Thu Jun 01 04:00:00 EDT 1995 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.871294· OSTI ID:165287

Rousseaux, C; Meyer, B; Thiell, G ^[1]

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1. Commissariat a l`Energie Atomique, Centre d`Etudes de Limeil---Valenton, 94195 Villeneuve Saint-Georges Cedex (France)

Backward stimulated Raman scattering (SRS) experiments have been performed using the optical fiber smoothing implemented on the high-power Phebus laser facility [Laser Part. Beams {bold 4}, 93 (1988)]. The interaction took place in low-{ital Z} plasmas presenting either exponential density profiles (solid targets) or Gaussian-type profiles. Raman instability was driven with 1.4 ns duration---0.53 {mu}m laser pulses, containing an energy up to 1.8 kJ. Comparative and absolute measurements of SRS reflectivity are reported as a function of the incident laser intensity, both with and without beam smoothing. Near-backward time-resolved SRS spectra are also presented. Random phase plates are not used in these experiments. With or without smoothing, SRS reflectivities of the order of 10% have been measured. However, smoothing becomes effective in exponential profiles below 10{sup 15} W/cm{sup 2}. Although the optical fiber efficiently reduces the contrast of the energy modulations in the focal spot, the spectral bandwidth may be insufficient to quench SRS development in these conditions. This last assumption is in agreement with theoretical predictions. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

• OSTI ID: 165287
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 6 Vol. 2; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BACKSCATTERING
LASER RADIATION
LASER-PRODUCED PLASMA
OPTICAL FIBERS
PARAMETRIC INSTABILITIES
PHEBUS REACTOR
RAMAN EFFECT