top four panels refer to the L=4 case and the bottom three panels refer to the L=3 case. Each panel shows the plasma flow velocity (ordinate in logarithmic scale) as function of time at particular locations on the field line. For the L=4 case, the locations are: at the equator, at 1/3 and 2/3 of the way down the field line and at the ionosphere. The solid lines denote plasma flow in the +x direction. Thus, at the equator at time t=0, the plasma flow is 130 km/sec (outside of the scale of Fig. 10) and the flow decays with a time constant of ~ 6 sec as the Alfven wave, carrying the beam momentum, propagates away from the equator towards the ionosphere. At ~ 50 sec after beam release, a reflected wave from the ionosphere, indicated by the negative plasma flow, arrives at the equator. Because of ionospheric dissipation, the reflected wave amplitude is much smaller than the original beam speed (note that the ordinate scale is logarithmic). The next panels, as well as the L=3 case, illustrate the time history of plasma flow as observed at the indicated fixed locations along the field line. The characteristics are much the same as described above. Detailed study of the momentum transfer properties as functions of beam and plasmasphere parameters have been implemented. The results indicate that uniform increases and decreases of the plasmaspheric density by factors of 2 or 1/2 have only moderate effects upon the key time constants discussed above; thus, our results are typical even if we have a substantially heated plasmasphere. The dependence of the critical momentum transfer time constant (~ [[spi:math]]) upon the location of injection, via B0(O) [cf (34) and (37)], must be noted. As is expected, [[spi:math]]; therefore, we expect beammagnetosphere interaction to be most important in the region L <= 4 where most of the argon fuel is expended. Argon ions released outside of the plasmasphere, approximately between 4 RE and GEO probably interact with the magnetosphere via mechanisms involving beam-plasma turbulence, which must also be 29
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