First Optical Observation of Intensity Dependent Laser Beam Deflection in a Flowing Plasma

Jd, Moody; Bj, MacGowan; De, Hinkel; Wl, Kruer; Ea, Williams; Estabrook, K. G.; Rl, Berger; Rk, Kirkwood; Montgomery, D. S.; Td, Shepard

doi:10.1103/physrevlett.77.1294

Cited by 52 publications

(13 citation statements)

References 6 publications

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“…͑22͒ comes from the edge of a speckle, where the derivative of the ponderomotive potential is large. For qϽ 3 2 , Fϭ1ϩ1/2qϩ1/4q 2 ϩ1/6q 3 ϩ¯. The effect of F in Eq.…”

Section: Two-dimensional Casementioning

confidence: 99%

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Intrinsic bending of a laser beam in a flowing plasma

Bezzerides¹

1998

Physics of Plasmas

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In this paper a simple analytic model for deflection of a laser beam in the presence of flowing plasma is presented. The model utilizes a nonlinear solution of the paraxial wave equation in the random phase approximation. This approximation excludes any contribution from hot-spot induced self-focusing, but allows for the effects of intensity fluctuations of the beam. For a speckled beam the solution for the beam intensity in wave number space depends sensitively on the properties of the incident beam. It is shown that for an incident beam whose initial spectrum in wave number space is Gaussian, the final spectrum is also Gaussian with the overall spectrum rotated in wave number space by a radius of curvature function that is an explicit expression of the Mach number of the flow, the local acoustic damping, and the local average intensity. This result is applicable to the case in which the speckle develops upon transmission of the beam through a random phase plate (RPP). The bending rate thus calculated for a RPP-smoothed beam is compared to the bending rate in the absence of the RPP. This comparison provides some insight into the efficacy of the RPP in reducing the bending of the laser beam.

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“…͑22͒ comes from the edge of a speckle, where the derivative of the ponderomotive potential is large. For qϽ 3 2 , Fϭ1ϩ1/2qϩ1/4q 2 ϩ1/6q 3 ϩ¯. The effect of F in Eq.…”

Section: Two-dimensional Casementioning

confidence: 99%

“…[1][2][3] These experimental observations may impact the conditions to achieve symmetric capsule implosions, since the proper beam pointing may need to take this effect into account.…”

Section: Introductionmentioning

confidence: 99%

Intrinsic bending of a laser beam in a flowing plasma

Bezzerides¹

1998

Physics of Plasmas

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“…However, in recent years, several experiments have been performed of relevance or at least related to LPI aspects of SI [10] . Experiments have been performed that concern beam propagation [25][26][27] , SBS [25,[28][29][30][31][32][33][34][35] , SRS [36][37][38][39] and TPD (Refs. [40,41] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of parametric instabilities in the context of the shock-ignition approach to inertial confinement fusion

Weber

Riconda

2015

High Pow Laser Sci Eng

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The role of the coronal electron plasma temperature for shock-ignition conditions is analysed with respect to the dominant parametric processes: stimulated Brillouin scattering, stimulated Raman scattering, two-plasmon decay (TPD), Langmuir decay instability (LDI) and cavitation. TPD instability and cavitation are sensitive to the electron temperature. At the same time the reflectivity and high-energy electron production are strongly affected. For low plasma temperatures the LDI plays a dominant role in the TPD saturation. An understanding of laser-plasma interaction in the context of shock ignition is an important issue due to the localization of energy deposition by collective effects and hot electron production. This in turn can have consequences for the compression phase and the resulting gain factor of the implosion phase.

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“…This is due to the density gradient of the wall plasmas which enter into the laser path. Although the laser deflection is predicted theoretically [20,21] and observed in flowing plasmas [22,23], this result is the first direct experimental observation of the laser beam deflection inside a hohlraum. Nevertheless, the plasmas entering the laser path are very thin and the deflection is small, and the laser energy is mainly absorbed at the initial pointing position in the experiment.…”

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confidence: 68%

First demonstration of improving laser propagation inside the spherical hohlraums by using the cylindrical laser entrance hole

Huo

Yang

et al. 2016

Matter and Radiation at Extremes

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The octahedral spherical hohlraums have natural superiority in maintaining high radiation symmetry during the entire capsule implosion process in indirect drive inertial confinement fusion. While, in contrast to the cylindrical hohlraums, the narrow space between the laser beams and the spherical hohlraum wall is usually commented. In this Letter, we address this crucial issue and report our experimental work conducted on the SGIII-prototype laser facility which unambiguously demonstrates that a simple design of cylindrical laser entrance hole (LEH) can dramatically improve the laser propagation inside the spherical hohlraums. In addition, the laser beam deflection in the hohlraum is observed for the first time in the experiments. Our 2-dimensional simulation results also verify qualitatively the advantages of the spherical hohlraums with cylindrical LEHs. Our results imply the prospect of adopting the cylindrical LEHs in future spherical ignition hohlraum design.

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First Optical Observation of Intensity Dependent Laser Beam Deflection in a Flowing Plasma

Cited by 52 publications

References 6 publications

Intrinsic bending of a laser beam in a flowing plasma

Intrinsic bending of a laser beam in a flowing plasma

Temperature dependence of parametric instabilities in the context of the shock-ignition approach to inertial confinement fusion

First demonstration of improving laser propagation inside the spherical hohlraums by using the cylindrical laser entrance hole

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