Numerical Study of Optical Ray Retracing in Laser-Plasma Backscatter.
Abstract
Optical ray retracing in stimulated Brillouin backscatter from laser-produced plasmas is studied numerically, using a 2-D propagation code (BOUNCE). This code treats steady state behavior in the strong damping limit, and includes self focusing effects. Ray retracing phenomena are grouped into two limiting cases. In the 'whole beam' limit, the pump field at the lens has a broad spatial profile that can be focused to a long narrow waist within the plasma. This geometry selectively amplifies only those initial noise components that are propagating back along the axis, where the net gain is highest. The simulations show that such effects exhibit a pronounced threshold due to self focusing, and disappear when the focal width becomes comparable to the length of the gain medium. In the opposite limit, where the pump radiation at the lens is dominated by small scale transverse structure, the backscatter can reproduce this structure in detail (i.e., exhibit wavefront reversal) when the far field of the pump produces an interference pattern in the plasma.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1980
- Accession Number
- ADA084987
Entities
People
- K. A. Holder
- R. H. Lehmberg
Organizations
- United States Naval Research Laboratory