Speaker
Stefan Hüller
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.2003.pdf
Cross-beam energy transfer (CBET) in ICF :
the effect of laser speckles in presence of ponderomotive self-focusing
Stefan Hüller1, Gaurav Raj1, Wojciech Romus2, and Denis Pesme1
1
Centre de Physique Théorique, CNRS, Ecole Polytechnique, Palaiseau, France
2
Faculty of Science, University of Alberta Edmonton, Canada T6G 2E9
Both in the direct- and the indirect drive scheme for Intertial Confinement Fusions (ICF)
Crossed beam Energy Transfer (CBET) between laser beams is still a major issue. Part of this
problem is the complexity of the process involving both the plasma hydrodynamics and its
interaction with the numerous incident laser beams.
We model CBET by taking into account the speckle (hot spot) substructure of “smoothed”
laser beams that has been disregarded in most of the previous studies. By means of numerical
simulations with a wave coupling model [1], it can be shown that transfer from laser hot spots
of one beam to the another beam, via self-focusing in presence of plasma flow [2,3] and
“beam bending”[4,5], proves to affect considerably the angular spread of the light behind the
region of beam overlap for laser intensities I λ2 > 1014 W cm-2 μm2 . For this reason the angular
distribution of transmitted light from smoothed laser beams (with speckles) is very different
from the angular distribution of beam when the beam speckle structure is disregarded. We
also show the importance of non-linear, shock-like structures of ion waves and of the so-
called plasma-induced smoothing to CBET.
[1] G. Raj and S. Hüller, Phys. Rev. Lett. 118, 055002 (2017).
[2] R. W. Short, R. Bingham, and E. A. Williams, Phys. Fluids 25, 2302 (1982).
[3] A. J. Schmitt, Physics of Fluids 1, 1287 (1989).
[4] B. Bezzerides, Physics of Plasmas 5, 2712 (1998).
[5] D. E. Hinkel, E. A. Williams, and C. H. Still, Phys. Rev. Lett.77, 1298 (1996).
