257 research outputs found
Vlasov Simulations of Trapping and Inhomogeneity in Raman Scattering
We study stimulated Raman scattering (SRS) in laser-fusion conditions with
the Eulerian Vlasov code ELVIS. Back SRS from homogeneous plasmas occurs in
sub-picosecond bursts and far exceeds linear theory. Forward SRS and re-scatter
of back SRS are also observed. The plasma wave frequency downshifts from the
linear dispersion curve, and the electron distribution shows flattening. This
is consistent with trapping and reduces the Landau damping. There is some
acoustic () activity and possibly electron acoustic scatter.
Kinetic ions do not affect SRS for early times but suppress it later on. SRS
from inhomogeneous plasmas exhibits a kinetic enhancement for long density
scale lengths. More scattering results when the pump propagates to higher as
opposed to lower density.Comment: 4 pages, 6 figures. Submitted to "Journal of Plasmas Physics" for the
conference proceedings of the 19th International Conference on Numerical
Simulation of Plasma
A Forward semi-Lagrangian Method for the Numerical Solution of the Vlasov Equation
This work deals with the numerical solution of the Vlasov equation. This
equation gives a kinetic description of the evolution of a plasma, and is
coupled with Poisson's equation for the computation of the self-consistent
electric field. The coupled model is non linear. A new semi-Lagrangian method,
based on forward integration of the characteristics, is developed. The
distribution function is updated on an eulerian grid, and the pseudo-particles
located on the mesh's nodes follow the characteristics of the equation forward
for one time step, and are deposited on the 16 nearest nodes. This is an
explicit way of solving the Vlasov equation on a grid of the phase space, which
makes it easier to develop high order time schemes than the backward method
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