scholarly journals Multibeam Stimulated Raman Scattering in Inertial Confinement Fusion Conditions

2015 ◽  
Vol 115 (5) ◽  
Author(s):  
P. Michel ◽  
L. Divol ◽  
E. L. Dewald ◽  
J. L. Milovich ◽  
M. Hohenberger ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Stimulated Raman

Controlling stimulated Raman scattering by two-color light in inertial confinement fusion

2017 ◽  
Vol 24 (8) ◽  
pp. 082704 ◽  
Author(s):  
Z. J. Liu ◽  
Y. H. Chen ◽  
C. Y. Zheng ◽  
L. H. Cao ◽  
B. Li ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Stimulated Raman

Reducing reflectivity of stimulated Raman scattering by discretely changing phase of incident light in inertial fusion plasmas

2021 ◽  
Author(s):  
Tian Yang ◽  
Shutong Zhang ◽  
yuanzhi Zhou ◽  
Deji Liu ◽  
Xueming Li ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Brillouin Scattering ◽  
Incident Light ◽  
Inertial Confinement ◽  
Fusion Plasmas ◽  
Confinement Fusion ◽  
Coupling Equations ◽  
Stimulated Raman

Abstract A new method to reduce the stimulated Raman scattering (SRS) in inertial confinement fusion conditions is proposed by changing the incident light phase discretely. The proposal is first examined by three-wave coupling equations and then verified by Vlasov simulations. A remarkable decreasing in SRS reflectivity is observed when the period of phase changing is less than 2π/γ, where γ is the growth rate of SRS. By contrast, some simulations with continuously changing phase of incident light are carried out to compare their influence on SRS. In addition, the proposal may suppress the stimulated Brillouin scattering.

scholarly journals Using polarization control plate to suppress transverse stimulated Raman scattering in large-aperture KDP crystal

2018 ◽  
Vol 36 (4) ◽  
pp. 454-457 ◽  
Author(s):  
Xinmin Fan ◽  
Sensen Li ◽  
Xiaodong Huang ◽  
Jianxin Zhang ◽  
Chunyan Wang ◽  
...  
Keyword(s):  
Raman Scattering ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Dihydrogen Phosphate ◽  
Inertial Confinement ◽  
Kdp Crystal ◽  
Polarization Control ◽  
Large Aperture ◽  
Control Plate ◽  
Stimulated Raman

AbstractTransverse stimulated Raman scattering (TSRS) is strongly generated in the third-harmonic-generation crystal potassium dihydrogen phosphate (KDP) and can even damage the KDP crystal in inertial confinement fusion drivers. In this work, a method to suppress TSRS is proposed in which the polarization control plate (PCP) is moved to a new position in the existing optical path. The proposed method can suppress TSRS significantly and doubles the laser threshold intensity in KDP crystal when the order of the PCP is 16. This result is attributed to the reduction of the gain length for the Stokes radiation. The proposed method may also be used to suppress other nonlinear effects, including transverse stimulated Brillouin scattering in large-aperture optical components.

scholarly journals Absolute instability modes due to rescattering of stimulated Raman scattering in a large nonuniform plasma

2019 ◽  
Vol 7 ◽  
Author(s):  
Yao Zhao ◽  
Zhengming Sheng ◽  
Suming Weng ◽  
Shengzhe Ji ◽  
Jianqiang Zhu
Keyword(s):  
Raman Scattering ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Langmuir Wave ◽  
Pump Light ◽  
Absolute Instability ◽  
Nonuniform Plasma ◽  
Instability Modes ◽  
The Absolute ◽  
Stimulated Raman

Absolute instability modes due to secondary scattering of stimulated Raman scattering (SRS) in a large nonuniform plasma are studied theoretically and numerically. The backscattered light of convective SRS can be considered as a pump light with a finite bandwidth. The different frequency components of the backscattered light can be coupled to develop absolute SRS instability near their quarter-critical densities via rescattering process. The absolute SRS mode develops a Langmuir wave with a high phase velocity of about $c/\sqrt{3}$ with $c$ the light speed in vacuum. Given that most electrons are at low velocities in the linear stage, the absolute SRS mode grows with very weak Landau damping. When the interaction evolves into the nonlinear regime, the Langmuir wave can heat abundant electrons up to a few hundred keV via the SRS rescattering. Our theoretical model is validated by particle-in-cell simulations. The absolute instabilities may play a considerable role in the experiments of inertial confinement fusion.

scholarly journals Time evolution of stimulated Raman scattering and two-plasmon decay at laser intensities relevant for shock ignition in a hot plasma

2019 ◽  
Vol 7 ◽  
Author(s):  
G. Cristoforetti ◽  
L. Antonelli ◽  
D. Mancelli ◽  
S. Atzeni ◽  
F. Baffigi ◽  
...  
Keyword(s):  
Laser Pulse ◽  
Raman Scattering ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Critical Density ◽  
Time History ◽  
High Energy ◽  
Experimental Results ◽  
Stimulated Raman ◽  
Shock Ignition

Laser–plasma interaction (LPI) at intensities $10^{15}{-}10^{16}~\text{W}\cdot \text{cm}^{-2}$ is dominated by parametric instabilities which can be responsible for a significant amount of non-collisional absorption and generate large fluxes of high-energy nonthermal electrons. Such a regime is of paramount importance for inertial confinement fusion (ICF) and in particular for the shock ignition scheme. In this paper we report on an experiment carried out at the Prague Asterix Laser System (PALS) facility to investigate the extent and time history of stimulated Raman scattering (SRS) and two-plasmon decay (TPD) instabilities, driven by the interaction of an infrared laser pulse at an intensity ${\sim}1.2\times 10^{16}~\text{W}\cdot \text{cm}^{-2}$ with a ${\sim}100~\unicode[STIX]{x03BC}\text{m}$ scalelength plasma produced from irradiation of a flat plastic target. The laser pulse duration (300 ps) and the high value of plasma temperature ( ${\sim}4~\text{keV}$ ) expected from hydrodynamic simulations make these results interesting for a deeper understanding of LPI in shock ignition conditions. Experimental results show that absolute TPD/SRS, driven at a quarter of the critical density, and convective SRS, driven at lower plasma densities, are well separated in time, with absolute instabilities driven at early times of interaction and convective backward SRS emerging at the laser peak and persisting all over the tail of the pulse. Side-scattering SRS, driven at low plasma densities, is also clearly observed. Experimental results are compared to fully kinetic large-scale, two-dimensional simulations. Particle-in-cell results, beyond reproducing the framework delineated by the experimental measurements, reveal the importance of filamentation instability in ruling the onset of SRS and stimulated Brillouin scattering instabilities and confirm the crucial role of collisionless absorption in the LPI energy balance.

scholarly journals Raman–Brillouin interplay for inertial confinement fusion relevant laser–plasma interaction

2016 ◽  
Vol 4 ◽  
Author(s):  
C. Riconda ◽  
S. Weber
Keyword(s):  
Raman Scattering ◽  
Acoustic Waves ◽  
Inertial Confinement Fusion ◽  
Clear Correlation ◽  
Inertial Confinement ◽  
Decay Instability ◽  
Wide Range ◽  
Confinement Fusion ◽  
Parameter Ranges ◽  
Langmuir Decay

The co-existence of the Raman and Brillouin backscattering instability is an important issue for inertial confinement fusion. The present paper presents extensive one-dimensional (1D) particle-in-cell (PIC) simulations for a wide range of parameters extending and complementing previous findings. PIC simulations show that the scenario of reflectivity evolution and saturation is very sensitive to the temperatures, intensities, size of plasma and boundary conditions employed. The Langmuir decay instability is observed for rather small $k_{epw}{\it\lambda}_{D}$ but has no influence on the saturation of Brillouin backscattering, although there is a clear correlation of Langmuir decay instability modes and ion-fractional decay for certain parameter ranges. Raman backscattering appears at any intensity and temperature but is only a transient phenomenon. In several configurations forward as well as backward Raman scattering is observed. For the intensities considered, $I{\it\lambda}_{o}^{2}$ above $10^{15}~\text{W}~{\rm\mu}\text{m}^{2}/\text{cm}^{2}$ , Raman is always of bursty nature. A particular setup allows the simulation of multi-speckle aspects in which case it is found that Raman is self-limiting due to strong modifications of the distribution function. Kinetic effects are of prime importance for Raman backscattering at high temperatures. No unique scenario for the saturation of Raman scattering or Raman–Brillouin competition does exist. The main effect in the considered parameter range is pump depletion because of large Brillouin backscattering. However, in the low $k_{epw}{\it\lambda}_{D}$ regime the presence of ion-acoustic waves due to the Langmuir decay instability from the Raman created electron plasma waves can seed the ion-fractional decay and affect the Brillouin saturation.

Analysis of electroless nickel thin films

1991 ◽  
Vol 49 ◽  
pp. 510-511 ◽  
Author(s):  
C. W. Price ◽  
E. F. Lindsey
Keyword(s):  
Thin Films ◽  
Inertial Confinement Fusion ◽  
Electroless Nickel ◽  
Inertial Confinement ◽  
Plating Bath ◽  
X Ray ◽  
Nickel Thin Films ◽  
Nickel Deposits ◽  
Confinement Fusion ◽  
Thickness Measurements

Thickness measurements of thin films are performed by both energy-dispersive x-ray spectroscopy (EDS) and x-ray fluorescence (XRF). XRF can measure thicker films than EDS, and XRF measurements also have somewhat greater precision than EDS measurements. However, small components with curved or irregular shapes that are used for various applications in the the Inertial Confinement Fusion program at LLNL present geometrical problems that are not conducive to XRF analyses but may have only a minimal effect on EDS analyses. This work describes the development of an EDS technique to measure the thickness of electroless nickel deposits on gold substrates. Although elaborate correction techniques have been developed for thin-film measurements by x-ray analysis, the thickness of electroless nickel films can be dependent on the plating bath used. Therefore, standard calibration curves were established by correlating EDS data with thickness measurements that were obtained by contact profilometry.

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