Non-linear stimulated Raman back-scattering burst driven by a broadband laser

A new evolution pattern for broadband laser excited stimulated Raman back-scattering (BSRS) in the kinetic regime is proposed by numerical simulations. It is found that the change of coherence of different frequency beamlets will cause the fluctuation of laser intensity, generating an ensemble of ra...

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Bibliographic Details
Published in:Physics of plasmas 2022-10, Vol.29 (10)
Main Authors: Liu, Q. K., Zhang, E. H., Zhang, W. S., Cai, H. B., Gao, Y. Q., Wang, Q., Zhu, S. P.
Format: Article
Language:English
Subjects:
Bandwidths
Broadband
Deactivation
Hot electrons
Mathematical models
Plasma physics
Scattering
Synergistic effect
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Summary:A new evolution pattern for broadband laser excited stimulated Raman back-scattering (BSRS) in the kinetic regime is proposed by numerical simulations. It is found that the change of coherence of different frequency beamlets will cause the fluctuation of laser intensity, generating an ensemble of random intensity pulses and leading to an intermittent excitation of BSRS. The kinetic inflation and intense amplification of scattered light are observed due to the synergism between these pulses, which cause a burst of instantaneous reflectivity. The synergistic effect is highly bandwidth-dependent. Under the bandwidth similar to the existing broadband laser facilities, these bursts will generate over-expected scattered light and hot electrons. Fortunately, a large bandwidth laser can still inactivate the synergy mechanism and mitigate the scattering effectively. We formulated a theoretical model to predict the inactivate point, and the calculation Δ ω / ω 0 = 2.57 % is in good agreement with the numerical results.
ISSN:1070-664X
1089-7674
DOI:10.1063/5.0105089