4 MAGNETOSPHERIC EFFECTS 4.1 INTRODUCTION As one goes to outer regions of the earth's atmosphere where plasma effects become important, the character of the problem changes. In this very low density regime the relative injections of both mass and energy are large, and on account of the infrequency of collisions and of the predominance of long-range interactions associated with the geomagnetic field, the possible distance scale of phenomena becomes very large, and so do the unknowns and major uncertainties. Chemical rockets produce large injections of hydrogen atoms both from the personnel vehicle, POTV, which is chemically propelled and makes some 12- 17 flights per year between LEO and GEO, each with a duration of a few hours, and also from the cargo vehicle, COTV. The COTV uses electrical propulsion as its primary mode, and thus one round trip from LEO to GEO takes 160-180 days because of the very low thrust of its argon ion engines. Nevertheless, while it uses chemical (H2~O2) engines only for attitude control and other auxiliary power, yet the total number of hydrogen versus argon atoms emitted is comparable (see Table 3). The main propulsion for COTV is provided by a series of 1-5 keV Ar ion engines, which also put out a neutralizing beam of electrons. The energy distribution of the argon ions is approximately thermal, so that the ion beam is less efficient at exciting plasma instabilities than is a monoenergetic ion beam. The quantities of injectants per flight and per year are listed in Tables 1 and 3, respectively. The reason why so many hydrogen atoms are emitted is that each argon ion provides perhaps 5000 times as much energy and 400 times as much thrust (i.e., momentum) as does a hydrogen atom. The phonomenology of H2O/H2 injections is sketched in Section 4.2, while that of Ar ion injections is outlined in Section 4.3. Some possible effects are mentioned in Section 4.4. The need for a synthesis of H and Ar injections, and some possibly important phenomena, are discussed in Section 4.5, and some possibly relevant atmospheric experiments are reviewed in Section 4.6. 4.2 PHONOMENOLOGY OF H20/H2 INJECTION IN THE PLASMASPHERE AND MAGNETOSPHERE (Zinn) The fate of H20 and H2 molecules injected in the F-region and the changes that they produce in electron and ion concentrations have been discussed in great detail (see Mendillo (1978, 1979), Zinn et al. (1978, 1979), and Section 3 of this report). For injections at higher altitudes, the same phenomena will occur, provided that the molecules are not injected with velocity vectors such that they become trapped in stable orbits or escape from the earth. That is, if they can fall, they will fall to 270 km, or so, where they produce the now familiar F-layer effects. There are several situations among the proposed SPS rocket scenarios where the exhaust molecules can escape or become trapped. Some of those
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