Ionospheric heating with oblique HF waves
Abstract
Calculations of ionospheric electron density perturbations and ground-level signal changes produce by intense oblique high frequency (HF) transmitters are presented. This analysis considers radio field focusing at caustics, the consequent joule-heating of the surrounding plasma, heat conduction, diffusion, and recombination processes: these being the effects of a powerful oblique 'modifying' wave. It neglects whatever plasma instabilities might occur. Then effects on a secondary 'test' wave that is propagated along the same path as the first are investigated. Calculations predict ground-level field-strength reductions of several dB in the test wave for modifying waves having ERP in the 85 to 90 dBW range. These field-strength changes are similar in sign, magnitude, and location to ones measured in Soviet experiments. The results are sensitive to the model ionosphere assumed, so future experiments should employ the widest possible range of frequencies and propagation conditions. An effective power of 90 dBW seems to be a sort of threshold that, if exceeded, results in substantial rather than small signal changes. The conclusions are based solely on joule-heating and subsequent defocusing of waves passing through caustic regions.
- Publication:
-
In AGARD
- Pub Date:
- October 1990
- Bibcode:
- 1990imip.agar.....F
- Keywords:
-
- High Frequencies;
- Ionospheric Disturbances;
- Ionospheric Electron Density;
- Ionospheric Heating;
- Ionospheric Propagation;
- Radio Frequency Heating;
- Conductive Heat Transfer;
- Defocusing;
- Field Strength;
- Military Technology;
- Ohmic Dissipation;
- Plasma Diffusion;
- Radio Transmitters;
- Recombination Reactions;
- Resistance Heating;
- Geophysics