Spatio-temporal development of the filaments due to the thermal self-focusing instability near the critical surface in ionospheric plasmas |
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Authors: | N A Gondarenko P N Guzdar G M Milikh A S Sharma K Papadopoulos S L Ossakow |
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Institution: | (1) Institute for Plasma Research, University of Maryland, 20742 College Park, MD, USA;(2) Department of Astronomy, University of Maryland, 20742 College Park, MD, USA;(3) Naval Research Laboratory, Plasma Physics Division, 20375 Washington, DC, USA |
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Abstract: | We study fully nonlinear spatio-temporal development of the thermal self-focusing instability of high-power radio waves near
the critical surface of the ionosphere. These simulations improve on our earlier work by including an evolution equation for
the density instead of using the assumption of constant pressure to determine the perturbed density connected with the known
temperature perturbation. Using our two-dimensional nonlinear code we analyze the time scale and associated velocity for the
development of the field-aligned irregularities as they spread from the critical surface both in the underdense as well as
the overdense regions. The scaling of this velocity as a function of the radiated power of the heater electromagnetic wave
(ERP) is determined. We also study the characteristic size of the self-focused filament as a function of ERP. Finally, the
spectrum of the density and temperature fluctuations as well as modifications in the equilibrium values of these parameters
for different values of ERP are presented.
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 42, No. 7, pp. 670–681, July 1999. |
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