Crossed beam energy transfer in the presence of laser speckle ponderomotive self-focusing and nonlinear sound waves - Archive ouverte HAL
Article Dans Une Revue Physics of Plasmas Année : 2020

Crossed beam energy transfer in the presence of laser speckle ponderomotive self-focusing and nonlinear sound waves

Résumé

Crossed beam energy transfer, CBET, is investigated by taking into account the speckle structure of smoothed laser beams that overlap in a plasma with an inhomogeneous flow profile. Using the two-dimensional simulation code HARMONY, it is shown how ponderomotive self-focusing of laser speckles in crossing beams can significantly affect the transfer of energy from one beam to the other. The role of plasma flow on speckle self-focusing is investigated and revisited, in particular its consequences in terms of redirection and increasing angular spread of the laser beams due to beam bending and plasma-induced smoothing, respectively. At close-to-sonic flow the onset of self-focusing in the beam speckle structure occurs at considerably lower beam intensities than expected for the case without flow. CBET and speckle self-focusing can hence occur together when two crossed beams with equal frequency will resonantly exchange energy via their ponderomotively driven density perturbations flowing with sound speed. From the simulations it is found that consequences of ponderomotive self-focusing can be expected above an average intensity threshold scaling as I L ∼ 2 × 10 14 W cm −2 (λ 0 /1µm) −2 (T e /keV) with impact on the spatial and temporal coherence of the transmitted light. The density perturbations due to the ponderomotive force of the crossing beams can locally be enhanced in self-focusing speckles, partly leading to shock-like structures. These structures eventually increase the effect of plasma-induced smoothing and are at the origin of the stronger angular spread.
Fichier principal
Vignette du fichier
POP19-AR-58588.pdf (2.95 Mo) Télécharger le fichier
Origine Fichiers produits par l'(les) auteur(s)
Loading...

Dates et versions

hal-02443680 , version 1 (17-01-2020)
hal-02443680 , version 2 (13-02-2020)

Identifiants

Citer

Stefan Hüller, Gaurav Raj, Wojciech Rozmus, Denis Pesme. Crossed beam energy transfer in the presence of laser speckle ponderomotive self-focusing and nonlinear sound waves. Physics of Plasmas, 2020, 27 (022703), ⟨10.1063/1.5125759⟩. ⟨hal-02443680v2⟩
152 Consultations
131 Téléchargements

Altmetric

Partager

More