9313801 Pesnell Collisions strongly affect the dynamics of the thermosphere and ionosphere. The solar wind induces electric fields in the ionosphere, accelerating the ions, which then accelerate the neutral gas through collisions. The reverse is also true. If the neutral species are accelerated by a pressure gradient or other force, the ions are also accelerated. One example is the diurnal tide, which propagates up through the thermosphere. The periodic neutral winds act as a dynamo, generating global electrical currents. One important quantity for each of those interactions is the collision frequency. When the collision frequency is large for a certain scattering process, those two gases are dynamically coupled. Unfortunately, the relevant collision cross sections are extremely difficult to measure. Laboratory measurements have been done only at energies substantially greater than those found in the thermosphere (Stebbings, 1964). It is necessary to use quantum mechanical calculation to extend theoretically the measurements to the low energies of the thermosphere. The transport coefficients are calculated as part of the proposed research. The theoretical values of these transport coefficients will be compared to published coefficients and with empirically derived coefficients. The discrepancy between published empirical and theoretical collision frequencies is on the order of a factor of three. An estimate of the error in the other transport coefficients will be made based on this discrepancy and the empirical coefficients. Data from the Dynamics Explorer 2 satellite will be used to give empirical values of the collision frequency and thermal diffusion coefficient. Simplified momentum and energy equations will be used in that analysis. ***
