Accession Number : ADP006498

Title :   On the validity of the Weak Turbulence Approximation,

Corporate Author : TROMSOE UNIV (NORWAY)

Personal Author(s) : Hanssen, A. ; Mjoelhus, E.

Report Date : OCT 1990

Pagination or Media Count : 12

Abstract : The weak Langmuir turbulence approach to explain the artificial plasma line in ionospheric radio modification experiments, is examined. The mathematical model is a version of the one dimensional Zakharov equations, including damping and a nonlinear a.c. driving. Numerical full wave solutions to this set of equations are compared with the saturation spectrum determined by a wave kinetic equation derived from the same set of equations. We found that a distance below the 0-mode reflection level, w - wp > (-IM)wp (w applied frequency; wp plasma frequency; m, M electron and ion masses), the full wave solution is in good qualitative agreement with the cascade theory. The number of cascades seen in the full wave solution is generally smaller than that of the saturation spectrum of the wave kinetic equation. On the other hand, in the reflection region w - wp < (m/M)wp, a qualitatively different process takes place, describable as many localized cycles of nucleation, (one dimensional driven) collapse, and burnout, similar to the results of Doolen et al.8. These findings are discussed with respect to the experiments performed in Arecibo and Tromso.

Descriptors :   *IONOSPHERIC MODIFICATION, APPROACH, BURNOUT, COLLAPSE, CYCLES, DAMPING, ELECTRONS, EQUATIONS, FREQUENCY, IONS, KINETICS, MATHEMATICAL MODELS, ONE DIMENSIONAL, REFLECTION, REGIONS, SATURATION, THEORY, TURBULENCE, NORWAY.

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE