scholarly journals Collective absorption of laser radiation in plasma at sub-relativistic intensities

2019 ◽  
Vol 7 ◽  
Author(s):  
Y. J. Gu ◽  
O. Klimo ◽  
Ph. Nicolaï ◽  
S. Shekhanov ◽  
S. Weber ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Laser Energy ◽  
Brillouin Scattering ◽  
Critical Density ◽  
Plasma Waves ◽  
High Amplitude ◽  
Inertial Confinement ◽  
Hot Electron ◽  
Plasma Parameters

Processes of laser energy absorption and electron heating in an expanding plasma in the range of irradiances $I\unicode[STIX]{x1D706}^{2}=10^{15}{-}10^{16}~\text{W}\,\cdot \,\unicode[STIX]{x03BC}\text{m}^{2}/\text{cm}^{2}$ are studied with the aid of kinetic simulations. The results show a strong reflection due to stimulated Brillouin scattering and a significant collisionless absorption related to stimulated Raman scattering near and below the quarter critical density. Also presented are parametric decay instability and resonant excitation of plasma waves near the critical density. All these processes result in the excitation of high-amplitude electron plasma waves and electron acceleration. The spectrum of scattered radiation is significantly modified by secondary parametric processes, which provide information on the spatial localization of nonlinear absorption and hot electron characteristics. The considered domain of laser and plasma parameters is relevant for the shock ignition scheme of inertial confinement fusion.

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 Imposed magnetic field and hot electron propagation in inertial fusion hohlraums

2015 ◽  
Vol 81 (6) ◽  
Author(s):  
David J. Strozzi ◽  
L. J. Perkins ◽  
M. M. Marinak ◽  
D. J. Larson ◽  
J. M. Koning ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Inertial Confinement Fusion ◽  
Stimulated Raman Scattering ◽  
Axial Magnetic Field ◽  
Early Time ◽  
Hot Electrons ◽  
Hydrodynamic Effect ◽  
Test Case ◽  
Inertial Confinement ◽  
Hot Electron

The effects of an imposed, axial magnetic field $B_{z0}$ on hydrodynamics and energetic electrons in inertial confinement fusion indirect-drive hohlraums are studied. We present simulations from the radiation-hydrodynamics code HYDRA of a low-adiabat ignition design for the National Ignition Facility, with and without $B_{z0}=70~\text{T}$. The field’s main hydrodynamic effect is to significantly reduce electron thermal conduction perpendicular to the field. This results in hotter and less dense plasma on the equator between the capsule and hohlraum wall. The inner laser beams experience less inverse bremsstrahlung absorption before reaching the wall. The X-ray drive is thus stronger from the equator with the imposed field. We study superthermal, or ‘hot’, electron dynamics with the particle-in-cell code ZUMA, using plasma conditions from HYDRA. During the early-time laser picket, hot electrons based on two-plasmon decay in the laser entrance hole (Regan et al., Phys. Plasmas, vol. 17(2), 2010, 020703) are guided to the capsule by a 70 T field. Twelve times more energy deposits in the deuterium–tritium fuel. For plasma conditions early in peak laser power, we present mono-energetic test-case studies with ZUMA  as well as sources based on inner-beam stimulated Raman scattering. The effect of the field on deuterium–tritium deposition depends strongly on the source location, namely whether hot electrons are generated on field lines that connect to the capsule.

Spatio-temporal evolution of two-plasmon decay in homogeneous plasma

2009 ◽  
Vol 76 (5) ◽  
pp. 749-761
Author(s):  
D. R. DIMITRIJEVIĆ ◽  
A. A. MALUCKOV
Keyword(s):  
Temporal Evolution ◽  
Critical Density ◽  
Plasma Waves ◽  
Electron Plasma ◽  
Hot Electron ◽  
Plasma Parameters ◽  
Principal Mechanism ◽  
Homogeneous Plasma ◽  
Spatio Temporal ◽  
The Impact

AbstractA hydrodynamic model of two-plasmon decay in a homogeneous plasma slab near the quarter-critical density is utilized to study the spatio-temporal evolution of the daughter electron plasma waves in plasma in the course of the instability. The influence of laser and plasma parameters on the evolution of the amplitudes of the participating waves is discussed, assuming that the secondary coupling of two daughter electron plasma waves with an ion-acoustic wave is the principal mechanism of saturation of the instability. The impact of inherently non-resonant nature of this secondary coupling on the development of TPD is investigated for the first time and it is shown to significantly influence the electron plasma wave dynamics. Its inclusion leads to non-uniformity of the spatial profile of the instability and causes the burst-like pattern of the instability development, which should result in the burst-like hot-electron production in homogeneous plasma.

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 Laser driven implosion

1990 ◽  
Vol 8 (1-2) ◽  
pp. 3-17 ◽  
Author(s):  
C. Yamanaka
Keyword(s):  
Inertial Confinement Fusion ◽  
Laser Energy ◽  
Laser Fusion ◽  
Plastic Shell ◽  
Inertial Confinement ◽  
Liquid Density ◽  
Direct Drive ◽  
Uniform Compression ◽  
Confinement Fusion ◽  
Key Issues

Inertial confinement fusion (ICF) has made great progress. In fact several significant scientific firsts have been achieved in the last year. These developments have presented the ICF community with an opportunity to embark on a new phase in ICF research. The key issues of laser fusion are to attain a high absorption of laser light in a plasma, to prevent preheating of fuel during the compression, and to achieve highly efficient implosion by uniform compression of fuel due to the homogeneous deposition of laser energy on the pellet surface. Direct drive and indirect drive have been investigated. The progress in both schemes is remarkable. The neutron yield by the stagnation free compression of the LHART target has attained 1013 which corresponds to a pellet gain of 1/500. The plastic shell target has reached a fuel density as large as 600 times the liquid density which is measured by the Si activation method as well as the D knockon method. A cryogenic foam target is now under investigation.

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

scholarly journals Progress in inertial confinement fusion physics at Centre d'Etudes de Limeil-Valenton

1994 ◽  
Vol 12 (3) ◽  
pp. 329-342 ◽  
Author(s):  
M. André ◽  
D. Babonneau ◽  
C. Bayer ◽  
M. Bernard ◽  
J-L. Bocher ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Scaling Laws ◽  
Laser Energy ◽  
Hot Spot ◽  
Beam Quality ◽  
Systematic Investigation ◽  
Analytical Models ◽  
Inertial Confinement ◽  
Direct Drive ◽  
X Ray

The laser program developed at the Centre d'Etudes de Limeil-Valenton, Saint-Georges, France (CEL-V) is concentrated on a systematic investigation of indirect drive fusion; by comparison with direct drive, this process is expected to provide the required irradiation uniformity with relaxed constraints on laser beam quality. The main concerns are radiative transfer and preheat, hydrodynamic instabilities, and high-density X-ray driven implosions. Ablative implosion experiments have been conducted with the two beams at the Phebus facility (5 kJ, 1.3 ns, 0.35 μm). Symmetry was proved to be controlled by the casing structure, following scaling laws describing hohlraum physics. A compressed DT density ∼100 ρ0 (ρ0 liquid DT density) has been deduced from activation measurements. Different aspects of the soft X-ray transfer processes, and particularly of the ablation of a low-Z material, which drives the capsule implosion, are dealt with in detailed investigations. Reported here are results on X-ray reemission and penetration in several materials, and on induced hydrodynamics of accelerated foils. The laser energy required to reach fuel ignition conditions has been evaluated from numerical simulations as well as from analytical models, taking into account hohlraum physics, capsule implosion, hot spot formation, and burn propagation. Several crucial parameters have been drawn, the most important being the radiation temperature. A target gain in the order of 10 appears achievable with a 2-MJ laser.

Sign in / Sign up

Export Citation Format

Share Document