D. Enhanced generation of geomagnetic storms. This is a somewhat more speculative possibility, based on the assumption that the ion beam will not be contained in the inner magnetosphere but will instead penetrate great distances. If the beam is directed into the earth's magnetotail, it may alter the local resistivity in the merging region and thus change the merging rate. 4.3.2 Phenomenology Issues to be Resolved A. Beam stopping distance. There is a certain question about how rapidly the ion beam is stopped in the magnetosphere. Chiu et al. (1979), using the observations of Haerendel and Lust (1970) on a barium cloud in the magnetosphere, suggest that the ions are stopped even in the very tenuous outer magnetosphere; Curtis and Grebowski (1979) have questioned this. In view of our limited understanding of ion motions in the magnetosphere, this issue calls for further work. B. Argon lifetime in the magnetosphere. This is a critical question. The loading of argon in the magnetosphere will be determined by balancing injection rates with the loss rates associated with diffusion and pitch angle scattering processes. If the loss rates are high, the argon loading will be relatively small (short argon lifetime). In the opposite case, argon accumulates for a long time and the loading is large. The lifetime of Ar+ in the magnetosphere is a parameter that must be determined or estimated in order to make quantitative assessments of the possible consequences of argon injection. C. Energy lifetime in the magnetosphere. This is similar to B above. The argon energy may be shared with ambient ions, and we must estimate an energy lifetime in order to assess the magnetospheric energy loading. D. Relativistic Electron Precipitation (REP) events. The proton cyclotron instability discussed in Item A of Section 4.3.1 above may not be the only mechanism for precipitating energetic electrons; indeed, some REP events cannot be explained on this basis. If another process does exist and can be identified, the likelihood of occurrence of the proton cyclotron instability and/or the severity of its effect may be reduced. 4.4 SOME POSSIBLE EFFECTS 4.4.1 Enhancement of Trapped Radiation (Chiu) Modification of the plasmaspheric composition, from a natural H+ plasmasphere to one consisting mainly of the heavier 0-r and Ar ions, may lead to the suppression of ion cyclotron wave generation. This activity in turn means a possible enhancement of trapped relativistic electron dosage level to about 2-3 times the present level, although it must be noted that pitch angle scattering by ion cyclotron waves is not the only mechanism by which relativistic electrons are precipitated into the atmosphere. Argon ions may possibly be recycled and energized by radial diffusion, ion cyclotron turbulence, electronic fields, and magnetospheric circulation to
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