Scattering of an electromagnetic wave by an inhomogeneous turbulent plasma
A Born--eikonal formalism describing the scattering of an electromagnetic wave by an inhomogeneous turbulent plasma with a spacially varying electron collision frequency is described. The ensemble averaged properties of the plasma are taken irto account in an eikonal approximation, while the fluctuating properties are treated by use of a perturbation series in which eikonal Green's functions describe the propagation between successive scatterings. A partial summation method which sums a larger class of perturbation terms than does the usual ladder (bilocal) approximation is suggested. This method is referred to as the uncrossed correlation line approximation in that all diagrams with correlation lines which do not cross are summed. The conditions under which the Bethe-Salpeter equation for the two- point correlation of the electric field reduces to the transport equation are discussed. In order to illustrate numerically some of the formal considerations discussed in this report, the backscattering of microwaves by a random plasma slab was computed for a variety of values of the parameters characterizing the plasma and the microwaves. For almost all of the values of the parameters for which the calculations were performed, the predictions of the Born -eikonal formulation to lowest order in the perturbation Bxpansion were closer to the exact results than were the predictions of the Born approximation. The predictions of the Born-eikonal series to fourth onder in the electron density fluctuations were usually closer to the exact results than were the lowest order Born--eikonal predictions. Transport equation results were in close agreement with the exact results when the plasma was underdense and not strongly absorbing. For an overdense or a strongly absorbing plasma, the transport equation yielded meaningless results such as negative scattering cross sections. (auth)
- Research Organization:
- Sandia Labs., Albuquerque, N.Mex. (USA)
- DOE Contract Number:
- AT(29-1)-789
- NSA Number:
- NSA-29-025824
- OSTI ID:
- 4351799
- Report Number(s):
- SLA-73-1116
- Resource Relation:
- Other Information: Orig. Receipt Date: 30-JUN-74
- Country of Publication:
- United States
- Language:
- English
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