Energy transfer between crossing laser beams

Kruer, W. L.; Wilks, S. C.; Afeyan, Bedros; Kirkwood, R. K.

doi:10.1063/1.871863

Cited by 181 publications

(109 citation statements)

References 5 publications

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“…1a). This diagnostic captures time-integrated images of the interior of the hohlraum wall x-ray emission at [3][4][5] keV through the LEH. As the backscatter losses on the outer beams were negligible (<1%), SXI provides a direct measurement of the decrease of the laser energy deposited on the hohlraum wall by the outer beams.…”

Section: Inferring Srs On the 235 • Conementioning

confidence: 99%

“…Laser plasma instabilities (LPI) determine the laser energy deposition into the hohlraum wall. In particular, forward-or side-scatter between laser beams crossing at the laser entrance holes (LEH) of the hohlraum can lead to transfer of energy between cones of beams and affect the hohlraum radiation symmetry [2][3][4][5][6], while backscatter instabilities can cause an energy loss as well as an imbalance of the energy deposited onto the wall [7].…”

Section: Introductionmentioning

confidence: 99%

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Three-wavelength scheme to optimize hohlraum coupling on the National Ignition Facility

Michel¹,

Divol²,

Town³

et al. 2011

Phys. Rev. E

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By using three tunable wavelengths on different cones of laser beams on the National Ignition Facility, numerical simulations show that the energy transfer between beams can be tuned to redistribute the energy within the cones of beams most prone to backscatter instabilities. These radiative hydrodynamics and laser-plasma interaction simulations have been tested against large scale hohlraum experiments with two tunable wavelengths, and reproduce the hohlraum energetics and symmetry. Using a third wavelength provides a greater level of control of the laser energy distribution and coupling in the hohlraum, and could significantly reduce stimulated Raman scattering losses and increase the hohlraum radiation drive while maintaining a good implosion symmetry.

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Section: Inferring Srs On the 235 • Conementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Three-wavelength scheme to optimize hohlraum coupling on the National Ignition Facility

Michel¹,

Divol²,

Town³

et al. 2011

Phys. Rev. E

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show abstract

“…Crossed-beam energy transfer from the outer cones of laser beams (angles to hohlraum axis θ = 44.5 • and 50 • ) to inner cones (θ = 23.5 • and 30 • ) is needed to control implosion symmetry [6]. CBET is a form of stimulated Brillouin scatter where two light waves beat to drive an ion acoustic wave (IAW) which transfers energy to the light wave with lower frequency in the plasma frame [7]. Shots with high fill density have high inner-beam backward stimulated Raman scatter, or decay of a laser into a scattered light wave and LW.…”

mentioning

confidence: 99%

Interplay of Laser-Plasma Interactions and Inertial Fusion Hydrodynamics

et al. 2017

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The effects of laser-plasma interactions (LPI) on the dynamics of inertial confinement fusion hohlraums is investigated via a new approach that self-consistently couples reduced LPI models into radiation-hydrodynamics numerical codes. The interplay between hydrodynamics and LPIspecifically stimulated Raman scatter (SRS) and crossed-beam energy transfer (CBET) -mostly occurs via momentum and energy deposition into Langmuir and ion acoustic waves. This spatially redistributes energy coupling to the target, which affects the background plasma conditions and thus modifies laser propagation. This model shows reduced CBET, and significant laser energy depletion by Langmuir waves, which reduce the discrepancy between modeling and data from hohlraum experiments on wall x-ray emission and capsule implosion shape.

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“…This ability to vary the inner cone fraction was successfully used to tune the implosion symmetry of the capsule [24]. It was predicted by Kruer et al [25] A. In our post-shot simulations of these experiments we now take account of the predicted power transfer in the following manner.…”

Section: Symmetrymentioning

confidence: 99%