Simulating time-dependent energy transfer between crossed laser beams in an expanding plasma
- Center for Applied Scientific Computing, L-561, Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551-0808 (United States)
- AX Division, L-038, Lawrence Livermore National Laboratory, PO Box 808, Livermore, CA 94551-0808 (United States)
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 Newton's 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.
- OSTI ID:
- 20687263
- Journal Information:
- Journal of Computational Physics, Vol. 209, Issue 2; Other Information: DOI: 10.1016/j.jcp.2005.03.024; PII: S0021-9991(05)00194-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-9991
- Country of Publication:
- United States
- Language:
- English
Similar Records
The Center for Momentum Transport and Flow Organization in Plasmas - Final Scientific Report
Effects of a descending lithospheric slab on yield estimates of underground nuclear tests. Final technical report, 8 Mar 88-31 Aug 90