Observation De l'HARMONIQUE 2 Dans Un Plasma Cree Par Laser

Decroisette, M.; Meyer, Bernard De; Piar, G.

doi:10.1051/jphyscol:1971596

Cited by 4 publications

(2 citation statements)

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“…3 On the other hand, harmonic generation in a plasma has been evidenced either with microwaves in the presence of a magnetic field 4 " 5 or with laser light. 6 The former effect was due to the vicinity of a hybrid resonance whereas the latter was attributed to nonlinear electron conduction. 7 Observation of the coupling between the two mechanisms will be reported here, the driving frequency being in the optical range.…”

Section: Francementioning

confidence: 99%

Harmonic Generation and Parametric Excitation of Waves in a Laser-Created Plasma

et al. 1973

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ond, the short-time dynamics of all the simple fluids over remarkably large ranges of density and temperature are quantitatively described by Eq. (1) which should serve as an important benchmark for theories of the dynamics of dense fluids. Third, the phenomenon of melting has a negligible effect on the short-time dynamics-in marked contrast to the large discontinuities it causes in static properties. Fourth, the measured scattering efficiencies have confirmed recent theoretical estimates for the solid and provide insight into the mechanisms of nonlinear optical effects in simple condensed media.

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Section: Francementioning

confidence: 99%

Harmonic Generation and Parametric Excitation of Waves in a Laser-Created Plasma

et al. 1973

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“…4-8(a)], where x 0 is the incident laser frequency, they were able to plot the critical and quartercritical surfaces as functions of time [ Fig. 4-8 130 in 1971, is understood to result from nonlinear processes at the critical surface, and the 3x 0 =2 emission, a signature of the two-plasmon-decay instability (Sec. X A), comes from quarter critical.]…”

Section: Plasma Diagnosticsmentioning

confidence: 99%

Direct-drive inertial confinement fusion: A review

et al. 2015

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The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

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