Raman scattering

1986 ◽  
Vol 64 (8) ◽  
pp. 956-960 ◽  
Author(s):  
Albert Simon
Keyword(s):  
Raman Scattering ◽  
Alternative Explanation ◽  
Stimulated Raman Scattering ◽  
Scattered Light ◽  
Hot Electrons ◽  
Critical Surface ◽  
Laser Produced Plasma ◽  
Stimulated Raman

Observations of Raman scattered light from inhomogeneous laser-produced plasma have shown characteristics quite different from the simple predictions for the stimulated Raman scattering instability. An alternative explanation in terms of enhanced scattering, produced by bursts of hot electrons arising at the quarter-critical or critical surface, is described. Comparison is made between the predictions of this theory and four experiments.

scholarly journals Stimulated Raman scattering in a non-eigenmode regime

2020 ◽  
Vol 8 ◽  
Author(s):  
Yao Zhao ◽  
Suming Weng ◽  
Zhengming Sheng ◽  
Jianqiang Zhu
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Laser Energy ◽  
Scattered Light ◽  
Incident Light ◽  
Loss Mechanism ◽  
Constant Frequency ◽  
Electrostatic Wave ◽  
Particle In Cell ◽  
Stimulated Raman

Stimulated Raman scattering (SRS) in plasma in a non-eigenmode regime is studied theoretically and numerically. Different from normal SRS with the eigen electrostatic mode excited, the non-eigenmode SRS is developed at plasma density $n_{e}>0.25n_{c}$ when the laser amplitude is larger than a certain threshold. To satisfy the phase-matching conditions of frequency and wavenumber, the excited electrostatic mode has a constant frequency around half of the incident light frequency $\unicode[STIX]{x1D714}_{0}/2$ , which is no longer the eigenmode of electron plasma wave $\unicode[STIX]{x1D714}_{pe}$ . Both the scattered light and the electrostatic wave are trapped in plasma with their group velocities being zero. Super-hot electrons are produced by the non-eigen electrostatic wave. Our theoretical model is validated by particle-in-cell simulations. The SRS driven in this non-eigenmode regime is an important laser energy loss mechanism in the laser plasma interactions as long as the laser intensity is higher than $10^{15}~\text{W}/\text{cm}^{2}$ .

scholarly journals Stimulated Raman scattering in plasmas produced by short intense laser pulses

1995 ◽  
Vol 13 (4) ◽  
pp. 525-537 ◽  
Author(s):  
H.C. Barr ◽  
T.J.M. Boyd ◽  
F.I. Gordon ◽  
S.J. Berwick
Keyword(s):  
Raman Scattering ◽  
Growth Rates ◽  
Stimulated Raman Scattering ◽  
Mode Conversion ◽  
Scattered Light ◽  
Laser Pulses ◽  
Laboratory Frame ◽  
Intense Laser ◽  
Strongly Coupled ◽  
Stimulated Raman

Stimulated Raman scattering driven by intense subpicosecond laser drivers is analyzed, in particular, the effects of the pulse shape and relativity on the instability and its characteristic spectra. The analysis is carried out in the pulse group velocity frame (Lorentz transformed) where growth rates for backscattering are decreased relative to their values when analyzed in the laboratory frame, while forward-scattered growth rates have greatly enhanced values. A range of intensities and densities is considered, appropriate to recent experiments, which ranges from strongly coupled scattering at high densities (even for forwardscattering) to stimulated Compton scattering regimes for backscattering and relativistically trapped forwardscattering at low densities. The inhomogeneities in intensity and density cause mode conversion between waves inside and outside the pulse. This can be at a modest level, as for backscattering, or extreme as in the case of forwardscattering when the Raman scattered light can be trapped within the laser pulse. The consequent feedback between modes within the pulse allows solutions, absolutely growing in the pulse frame, to be found.

Measurement of time-resolved spectra of scattered light by stimulated Raman scattering from laser plasma

2010 ◽  
Vol 22 (9) ◽  
pp. 2051-2054
Author(s):  
王传珂 Wang Chuanke ◽  
焦春晔 Jiao Chunye ◽  
王峰 Wang Feng ◽  
蒋小华 Jiang Xiaohua ◽  
刘永刚 Liu Yonggang ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Laser Plasma ◽  
Stimulated Raman Scattering ◽  
Scattered Light ◽  
Time Resolved ◽  
Stimulated Raman

Stimulated Brillouin scattering enhanced by stimulated Raman process near the quarter-critical density

2021 ◽  
Author(s):  
Zhanjun Liu ◽  
Qiang Wang ◽  
Bin Li ◽  
Jiwei Li ◽  
Li-hua Cao ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Stimulated Raman Scattering ◽  
Brillouin Scattering ◽  
Second Harmonic ◽  
Scattered Light ◽  
Incident Light ◽  
Critical Density ◽  
Stimulated Brillouin Scattering ◽  
Stimulated Brillouin ◽  
Stimulated Raman

Abstract Stimulated Raman scattering can occur near the quarter critical density in direct-drive fusions, and the frequency of Raman scattered light is about half of the incident light frequency. The second harmonic of the Raman scattered light can be produced due to the inhomogeneity density profile. It can serve as the seed of stimulated Brillouin scattering (SBS). When the second harmonic of stimulated Raman scattering light propagates against the incident light, some components will match to the frequency of backward SBS and SBS is induced. Thus SBS could be enhanced greatly.

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