Radiation Induced F-Region Plasma Phenomena
PRINCETON UNIV NJ
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Collective plasma phenomena induced in the ionospheric F-region by intense high-frequency radiation are examined on several time and length scales. The short wavelength, high-frequency turbulence associated with the observed high-frequency enhanced electron density fluctuations at the electron plasma frequency is shown to result from parametric excitation of plasma and acoustic waves by the high-frequency radiation. The wave kinetic equation describing the non-linear evaluation of the turbulence is presented. The time asymptotic spectral intensity is calculated and a formula for the total energy absorption from the incident radiation via nonlinear collective effects is obtained. A radiation induced self-focussing instability is found on a length scale somewhat larger than an ion Larmor radius. and is offered as a possible explanation for the occurrence of magnetic field aligned density filaments, which are associated with the phenomenon of artificial Spread-F. The calculated growth rates are in agreement with the time delay for appearance of spread-F after modifier turn on.
- Atmospheric Physics