This project involves an investigation of plasma wave phenomena which play an important role in the nergization of ions and electrons in the topside ionosphere. A new mechanism that enables the transfer of wave energy from large-scale waves to small-scale waves is of particular interest. The small-scale waves have been observed to be associated with elevated ion temperatures and intense field-aligned electron fluxes. The recent Freja satellite observations together with preliminary theoretical results indicate a causal relationship between the transfer of Alfven wave energy to ion acoustic waves and the heating of ions together with parallel electron acceleration. The primary goal of this project will be to identify and characterize the underlying mechanisms of energy transfer from waves to particles. The study involves a combination of analysis, numerical simulation and comparison to spacecraft data to ascertain physical characteristics of the phenomena as well as their geophysical relevance.