TRANSVERSELY ACCELERATED IONS IN THE TOPSIDE IONOSPHERE

Data from the rocket campaigns MARIE and TOPAZ III, within regions of low-altitude transversely accelerated ions, are interpreted to explain the acceleration of the ions. Using the Monte Carlo kinetic technique to evaluate the ion heating produced by the simultaneously observed l ower hybrid waves, we fin; that their observed electric field amplitud es are sufficient to explain the observed ion energies in the MARIE ev ent. Much of the uncertainty in evaluating the efficiency of a plasma wave induced particle heating process which is dependent on a velocity resonance comes from the lack of information on the phase velocities of the waves. In the case of the MARIE observations, our modeling effo rts show that features in the ion velocity distribution are consistent with the wave phase velocities inferred from interferometer measureme nts of wavelengths. The lower hybrid waves with which low-altitude tra nsversely accelerated ions are associated are frequently observed to b e concentrated in small-scale wave packets called ''spikelets''. We de monstrate through the scaling of the sizes of these wave packets that they are consistent with the theory of lower hybrid collapse. Using th e Monte Carlo technique, we find that if the lower hybrid field energy is concentrated in these wave packets, it is still adequate to accele rate the ionospheric ions to the observed energies.