Observation of Energy Transfer between Frequency-Mismatched Laser Beams in a Large-Scale Plasma

Kirkwood, R. K.; Afeyan, Bedros; Kruer, W. L.; MacGowan, B. J.; Moody, J. D.; Montgomery, David; Pennington, D. M.; Weiland, Timothy L.; Wilks, S. C.

doi:10.1103/physrevlett.76.2065

Cited by 103 publications

(73 citation statements)

References 13 publications

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“…Energy transfer between the two laser beams as well as plasma-wave and electronbeam enhancement are observed. The mechanism responsible for the energy transfer in this case differs from that studied in previous long-pulse and low-power crossedbeam experiments [9][10][11][12]. In our study, the mechanism was scattering from a stationary electron-density grating that was driven directly by optical interference, while in these previous experiments it was scattering from ion waves.…”

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confidence: 52%

“…It has been suggested theoretically [5] that this stochastic heating of electrons is ultimately responsible for the acceleration of multi-MeV energy beams of ions from laser-irradiated thin foils [6 -8]. In inertial fusion research, the electron heating and modification of the laser reflectivity that results from crossed laser beams [9][10][11][12] must be controlled in order to efficiently couple energy to the fusion target. High-intensity crossed beams are relevant to fastignition fusion research [13].…”

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confidence: 99%

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Laser-Energy Transfer and Enhancement of Plasma Waves and Electron Beams by Interfering High-Intensity Laser Pulses

et al. 2003

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confidence: 52%

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Laser-Energy Transfer and Enhancement of Plasma Waves and Electron Beams by Interfering High-Intensity Laser Pulses

et al. 2003

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“…This problem is further exacerbated by crossed-beam energy transfer (CBET) [9]. Here, pairs of beams, propagating at different angles into the can, typically overlap near the target entrance, where their intensities are high.…”

Section: Creation Of Hot Radiation Environments In Laser-driven Targetsmentioning

confidence: 99%

Creation of Hot Radiation Environments in Laser-Driven Targets

et al. 2006

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“…These demonstrations included the seeding of forward stimulated Brillouin scattering (SBS) of one beam by additional beams with resonant wavelengths, 10,11 and the amplification and subsequent saturation of long wavelength light 12 can occur when single beam Raman scatter encounters additional intersecting beams. The first of these multi-beam processes was identified as being important for controlling radiation symmetry in hohlraum targets both because the high amplitude seed consisting of one or more co-propagating beams could cause significant power and energy transfer from other beams even when the overall gain exponents were <1, and because the plasma conditions in the beam crossing volume in ignition targets have the sonic flows needed to match the SBS amplification resonance when the beams have the same wavelength.…”

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Multi-beam effects on backscatter and its saturation in experiments with conditions relevant to ignition

et al. 2011

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To optimize the coupling to indirect drive targets in the National Ignition Campaign (NIC) at the National Ignition Facility [E. Moses et al., Phys. Plasmas 16, 041006 (2009)], a model of stimulated scattering produced by multiple laser beams is used. The model has shown that scatter of the 351 nm beams can be significantly enhanced over single beam predictions in ignition relevant targets by the interaction of the multiple crossing beams with a millimeter scale length, 2.5 keV, 0.02−0.05 × critical density, plasma. The model uses a suite of simulation capabilities and its key aspects are benchmarked with experiments at smaller laser facilities. The model has also influenced the design of the initial targets used for NIC by showing that both the stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS) can be reduced by the reduction of the plasma density in the beam intersection volume that is caused by an increase in the diameter of the laser entrance hole (LEH). In this model, a linear wave response leads to a small gain exponent produced by each crossing quad of beams (<∼1 per quad) which amplifies the scattering that originates in the target interior where the individual beams are separated and crosses many or all other beams near the LEH as it exits the target. As a result all 23 crossing quads of beams produce a total gain exponent of several or greater for seeds of light with wavelengths in the range that is expected for scattering from the interior (480 to 580 nm for SRS). This means that in the absence of wave saturation, the overall multi-beam scatter will be significantly larger than the expectations for single beams. The potential for non-linear saturation of the Langmuir waves amplifying SRS light is also analyzed with a two dimensional, vectorized, particle in cell code (2D VPIC) that is benchmarked by amplification experiments in a plasma with normalized parameters similar to ignition targets. The physics of cumulative scattering by multiple crossing beams that simultaneously amplify the same SBS light wave is further demonstrated in experiments that benchmark the linear models for the ion waves amplifying SBS. The expectation from this model and its experimental benchmarks is shown to be consistent with observations of stimulated Raman scatter in the first series of energetic experiments with ignition targets, confirming the importance of the multi-beam scattering model for optimizing coupling.

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Observation of Energy Transfer between Frequency-Mismatched Laser Beams in a Large-Scale Plasma

Cited by 103 publications

References 13 publications

Laser-Energy Transfer and Enhancement of Plasma Waves and Electron Beams by Interfering High-Intensity Laser Pulses

Laser-Energy Transfer and Enhancement of Plasma Waves and Electron Beams by Interfering High-Intensity Laser Pulses

Creation of Hot Radiation Environments in Laser-Driven Targets

Multi-beam effects on backscatter and its saturation in experiments with conditions relevant to ignition

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