THEORETICAL INVESTIGATIONS OF IONOSPHERIC MODIFICATIONS PRODUCED BY ROCKET EXHAUST Paul A. Bernhardt Radioscience Laboratory - Stanford University Stanford, California 94305 Placing a Solar Power Satellite in orbit will probably require the firing of rocket engines in the ionospheric F-layer. These engine burns will cause a temporary reduction in the ionospheric plasma concentration. The plasma reduction process involves chemical reactions between the exhaust and the monoatomic ions in the atmosphere above 100 km altitude. Polyatomic neutral species, such as H20, C02, H2 and N2s are common constituents of rocket exhaust. By reaction with the 0* ion in the F-layer, these neutrals are converted into polyatomic ions such as H20+, 02+, 0H+ and N0+. These ions rapidly recombine with the free electrons in the ionosphere. The net effect of the chemical reaction is to convert as much as 95% of the local plasma into neutral species. The rates for reaction between the 0+ ion and the exhaust molecules can be 1000 times larger than the rates for reaction with the normal constituents of the atmosphere. In order to realistically model the ionospheric modification process, one must not only consider the chemical coupling between the injected neutrals and the ambient plasma, but one must also consider: 1) Neutral gas expansion including the effects of condensation, collisional heating, diffusion in a reactive environment and transport via winds, 2) Plasma dynamics including interhemispherical flow along magnetic field lines and transport due to electric fields and neutral winds, 3) Thermal processes describing the changes on the ion and electron temperatures, 4) Infrared, visible and ultraviolet radiation from excited neutral species and 5) Instabilities generated by internal electric fields. Models have been constructed which incorporates one or more of each of these mechanisms listed above. However, no one numerical model of the modified ionosphere contains all of these items. Simulation of expansion from rocket nozzles predicts a variety of changes in the exhaust vapors. Immediately after release, the pressure and temperature of the plume rapidly drops. At some point, condensation sets in, causing as much as 30% of the exhaust to form into sub-micron ice clusters. The exhaust which remains as vapor undergoes molecular collisions with the ambient
RkJQdWJsaXNoZXIy MTU5NjU0Mg==