Observation of resonant energy transfer between identical-frequency laser beams

Wharton, K. B.; Kirkwood, R. K.; Glenzer, S. H.; Estabrook, K. G.; Afeyan, Bedros; Cohen, B. I.; Moody, J. D.; MacGowan, B. J.; Joshi, C.

doi:10.1063/1.873500

Cited by 17 publications

(13 citation statements)

References 35 publications

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“…The power transfer in flowing plasma of equal frequency laser beams was shown in a series of experiments [5,6]. These experiments stimulated multidimensional simulations and theory that considered a variety of physical effects that influence the power transfer such as self-focusing and geometry [7], beam intensity non-uniformity and beam deflection of overlapping beams [8], nonlinear power transfer between different frequency beams in a homogeneous plasma in two and three dimensions [9,10], and power transfer between beams that each have multiple frequencies [11] such as occurs with some beam smoothing techniques [12].…”

Section: Introductionmentioning

confidence: 99%

Simulating time-dependent energy transfer between crossed laser beams in an expanding plasma

Hittinger

Dorr

Berger

et al. 2005

Journal of Computational Physics

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A coupled mode system is derived to investigate a three-wave parametric instability leading to energy transfer between co-propagating laser beams crossing in a plasma flow. The model includes beams of finite width refracting in a prescribed transverse plasma flow with spatial and temporal gradients in velocity and density. The resulting paraxial light equations are discretized spatially with a Crank-Nicholson-type scheme, and these algebraic constraints are nonlinearly coupled with ordinary differential equations in time that describe the ion acoustic response. The entire nonlinear differential-algebraic system is solved using an adaptive, backward-differencing method coupled with NewtonÕs method. A numerical study is conducted in two dimensions that compares the intensity gain of the fully time-dependent coupled mode system with the gain computed under the further assumption of a strongly damped ion acoustic response. The results demonstrate a time-dependent gain suppression when the beam diameter is commensurate with the velocity gradient scale length. The gain suppression is shown to depend on time-dependent beam refraction and is interpreted as a time-dependent frequency shift.

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Section: Introductionmentioning

confidence: 99%

Simulating time-dependent energy transfer between crossed laser beams in an expanding plasma

Hittinger

Dorr

Berger

et al. 2005

Journal of Computational Physics

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“…[5][6][7][8][9][10][11][12][13][14][15][16] In this process, described as induced Brillouin scattering in Ref. 5, the beat wave generated by the interference pattern of two laser beams crossing at a half-angle s resonantly excites an ion acoustic wave ͑IAW͒ that can in turn transfer energy from one beam to another.…”

Section: Introductionmentioning

confidence: 99%

Energy transfer between laser beams crossing in ignition hohlraums

et al. 2009

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The full scale modeling of power transfer between laser beams crossing in plasmas is presented. A new model was developed, allowing calculations of the propagation and coupling of pairs of laser beams with their associated plasma wave in three dimensions. The complete set of laser beam smoothing techniques used in ignition experiments is modeled and their effects on crossed-beam energy transfer are investigated. A shift in wavelength between the beams can move the instability in or out of resonance and hence allows tuning of the energy transfer. The effects of energy transfer on the effective beam pointing and on symmetry have been investigated. Several ignition designs have been analyzed and compared, indicating that a wavelength shift of up to 2 Å between cones of beams should be sufficient to control energy transfer in ignition experiments.

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“…Viewed in the moving frame of the plasma flow, the two crossing laser beams have unequal Doppler-shifted frequencies; and if the ponderomotive beat wave frequency and wavenumber of the two lasers resonate with the local ion acoustic wave dispersion relation, the stimulated Brillouin scattering interaction will transfer energy from the higher frequency to the lower frequency laser beam. [1][2][3][4][5][6][7] Current designs for inertial confinement fusion experiments on the National Ignition Facility ͑NIF͒ 8 have multiple laser beams crossing as they enter a cylindrical radiation enclosure ͑''hohlraum''͒. A finite transfer of energy between the crossing beams can spoil the high degree of illumination symmetry required for the fusion experiments in NIF.…”

Section: Introductionmentioning

confidence: 99%

Effects of ion trapping on crossed-laser-beam stimulated Brillouin scattering

et al. 2004

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Articles you may be interested inEffects of ion-ion collisions and inhomogeneity in two-dimensional kinetic ion simulations of stimulated Brillouin backscattering Phys. Plasmas 13, 022705 (2006); An analysis of the effects of ion trapping on ion acoustic waves excited by the stimulated Brillouin scattering of crossing intense laser beams is presented. Ion trapping alters the dispersion of ion acoustic waves by nonlinearly shifting the normal mode frequency and by reducing the ion Landau damping. This in turn can influence the energy transfer between two crossing laser beams in the presence of plasma flows such that stimulated Brillouin scattering ͑SBS͒ occurs. The same ion trapping physics can influence the saturation of SBS in other circumstances. A one-dimensional analytical model is presented along with reasonably successful comparisons of the theory to results from particle simulations and laboratory experiments. An analysis of the vulnerability of the National Ignition Facility Inertial Confinement Fusion point design ͓S. W. Haan et al., Fusion Sci. Technol. 41, 164 ͑2002͔͒ is also presented.

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Observation of resonant energy transfer between identical-frequency laser beams

Cited by 17 publications

References 35 publications

Simulating time-dependent energy transfer between crossed laser beams in an expanding plasma

Simulating time-dependent energy transfer between crossed laser beams in an expanding plasma

Energy transfer between laser beams crossing in ignition hohlraums

Effects of ion trapping on crossed-laser-beam stimulated Brillouin scattering

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