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Title: Beyond nonlinear saturation of backward Raman amplifiers

Abstract

Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. We employed pump detuning in order to mitigate the relativistic phase mismatch and to overcome the associated saturation. In an amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. Finally, this detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small.

Authors:
ORCiD logo [1];  [2];  [3]; ORCiD logo [4]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Technion Israel Inst. of Technology, Haifa (Israel)
  3. Inst. of Applied Physics RAS, Nizhnii Novgorod (Russia)
  4. Princeton Univ., NJ (United States). Dept. of Astrophysical Sciences
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1305352
Grant/Contract Number:
NA0002948; FA9550-15-1-0391; AC02-09CH11466; HDTRA1-11-1-0037; 15-32-20641
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review E
Additional Journal Information:
Journal Volume: 93; Journal Issue: 6; Journal ID: ISSN 2470-0045
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; short laser-pulses; amplification; plasma; compression; regime

Citation Formats

Barth, Ido, Toroker, Zeev, Balakin, Alexey A., and Fisch, Nathaniel J. Beyond nonlinear saturation of backward Raman amplifiers. United States: N. p., 2016. Web. doi:10.1103/PhysRevE.93.063210.
Barth, Ido, Toroker, Zeev, Balakin, Alexey A., & Fisch, Nathaniel J. Beyond nonlinear saturation of backward Raman amplifiers. United States. doi:10.1103/PhysRevE.93.063210.
Barth, Ido, Toroker, Zeev, Balakin, Alexey A., and Fisch, Nathaniel J. 2016. "Beyond nonlinear saturation of backward Raman amplifiers". United States. doi:10.1103/PhysRevE.93.063210. https://www.osti.gov/servlets/purl/1305352.
@article{osti_1305352,
title = {Beyond nonlinear saturation of backward Raman amplifiers},
author = {Barth, Ido and Toroker, Zeev and Balakin, Alexey A. and Fisch, Nathaniel J.},
abstractNote = {Backward Raman amplification is limited by relativistic nonlinear dephasing resulting in saturation of the leading spike of the amplified pulse. We employed pump detuning in order to mitigate the relativistic phase mismatch and to overcome the associated saturation. In an amplified pulse can then be reshaped into a monospike pulse with little precursory power ahead of it, with the maximum intensity increasing by a factor of two. Finally, this detuning can be employed advantageously both in regimes where the group velocity dispersion is unimportant and where the dispersion is important but small.},
doi = {10.1103/PhysRevE.93.063210},
journal = {Physical Review E},
number = 6,
volume = 93,
place = {United States},
year = 2016,
month = 6
}

Journal Article:
Free Publicly Available Full Text
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  • Cited by 1
  • Backward Raman amplification of laser pulses in plasmas can produce nearly relativistic unfocused output intensities and multi-exawatt powers in compact devices. The largest achievable intensity depends on which of major competitive processes set this limit. It is shown here that the relativistic electron nonlinearity can cause saturation of the leading amplified spike intensity before filamentation instabilities develop. A simple analytical model for the saturation, which supports numerical simulations, is suggested. The upper limit for the leading output spike unfocused intensity is calculated.
  • In a Raman plasma amplifier, the aim is to create plasma conditions in which Raman backscattering is the fastest growing instability, outrunning all competing effects so that it is possible to amplify and compress a laser beam to unprecedented unfocused intensities by utilizing that instability. However, achieving high efficiencies via this scheme has proven very difficult experimentally. Recent data show the simultaneous occurrence of stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), and stimulated electron-acoustic scattering (SEAS). The appearance of SEAS is indicative of strong particle trapping, the existence of which is hard to justify without highlighting the interplay betweenmore » SRS and SBS.« less
  • Cited by 5
  • Theoretical and numerical calculations are performed using the system of Zakharov and electromagnetic wave equations, to describe the nonlinear behavior of stimulated Raman scattering (SRS) in a finite homogeneous plasma slab. The enhancement of secondary scattering processes due to the nonlinear SRS saturation is investigated. The parametric decay of the resonantly driven Langmuir wave provides a mechanism which saturates SRS and greatly broadens the Langmuir and ion acoustic wave spectra. These enhanced electrostatic fluctuations scatter the incident electromagnetic radiation. Scaling laws for enhanced Brillouin, forward Raman, and anti-Stokes forward and backward Raman scattering as well as criteria for their strongmore » enhancement are given. The frequency spectra of enhanced Brillouin scattering shows red- and blue-shifted components, with different amplitudes depending on the plasma density and laser intensity. The numerical results have been compared with experimental data providing new or alternative explanations for the observations. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.« less