Short-pulse-laser-heated plasma experiments

Soures, J. M.; Goldman, L. M.; Lubin, M. J.

doi:10.1088/0029-5515/13/6/007

Cited by 24 publications

(4 citation statements)

References 16 publications

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“…Recently, an effort has been made to explain the low level of backscattered radiation due to the effect of turbulence [3]. Another significant result which has emerged from the laser plasma experiments is the absence of sidescatter [2]. In this letter we suggest a physical mechanism which could be relevant to this interesting observation.…”

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confidence: 76%

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Non-resonant pump field modification of the sidescatter threshold

Guzdar

Sen

1978

Nucl. Fusion

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confidence: 76%

“…The problem of radiation backscatter from laser plasmas has received significant attention because of its relevance to laser fusion [1]. The extensive theoretical work, however, does not agree very well with the experimental findings [2]. Recently, an effort has been made to explain the low level of backscattered radiation due to the effect of turbulence [3].…”

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confidence: 99%

Non-resonant pump field modification of the sidescatter threshold

Guzdar

Sen

1978

Nucl. Fusion

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“…In Ref. 79, Soures et al reported over 10 4 neutrons from a one-beam laser tightly focused onto solid spherical LiD targets; based on time-of-flight measurements, these neutrons originated from the target. This same conclusion was drawn by Basov et al 80 from time-of-flight measurements in their multibeam system.…”

Section: A the Quest For Neutronsmentioning

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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“…As an example, definite values of the intensity of radiation in the interaction domain are difficult to settle and figures given can as a rule only be taken as estimates. Diagnostics of the laser-plasma interaction region for the pellet problem is for obvious reasons very intricate, and new diagnostic techniques are searched for, [15]. The experimental results on the reflectivity of laser produced plasmas also differ widely, Concerning the present and future laser-plasma experiments let us here only furthermore mention that the laser technology progresses along several lines including the carbon dioxide, neodynium, iodine and other types of lasers and that by 1976 lasers producing 10 kJ within 100 ps are expected to be available, [19].…”

Section: Introductionmentioning

confidence: 99%

Coherent Nonlinear Backscattering by Laser-Plasma Interactions

Anderson

Wilhelmsson

1975

Phys. Scr.

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A theoretical analysis is carried out for the problem of coherent nonlinear backscattering of laser radiation by a high density plasma. A number of effects of direct interest to the DT-pellet fusion research are investigated. A simple physical description is introduced, which relies on a nonlinear potential formulation of the scattering equations. The simplicity and the unified nature of the approach enables us to evaluate and compare the influence on the radiation reflectivity of different effects, such as e.g. inhomogeneities, blow-off velocities, temperature gradients, laser band width and relativistic oscillatory velocities. Our understanding of the role played by the various phenomena has consequently improved and we think that our approach should be useful for the interpretation of laser-plasma data obtained by computer simulation or laboratory experiments. The results may also be utilized to estimate how and to what extent one may avoid undesired anomalous reflection when planning new laser-plasma devices.

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Short-pulse-laser-heated plasma experiments

Cited by 24 publications

References 16 publications

Non-resonant pump field modification of the sidescatter threshold

Non-resonant pump field modification of the sidescatter threshold

Direct-drive inertial confinement fusion: A review

Coherent Nonlinear Backscattering by Laser-Plasma Interactions

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