Research in S/T relations has two major thrusts. The first involves the study of the interactive, nonlinear processes that govern the behavior of plasma within the magnetospheres and ionospheres of the earth, other planets, and in the interplanetary medium. Special emphasis today is on the development of quantitative models with the aim of understanding and eventually predicting the influence of solar variations - both short and long term - on the earth's magnetosphere, ionosphere, and atmosphere. This includes detailed studies of microscopic processes which affect the transport of energy, momentum, and mass through the solar wind-magnetosphere-ionosphere (SMI) system as well as the global modeling of this system. The second thrust uses the geo-plasma environment as a laboratory for furthering our knowledge of fundamental plasma processes which may duplicate natural processes under controlled conditions (e.g. artificial aurora) or which occur under plasma conditions difficult to achieve in ground laboratories (e.g., collisionless shocks). This will help to better understand the complex interactions of the plasma environment with man-made objects (shuttle, space station, satellites) such as wake effects, differential charging, and perturbations due to gas releases and particle-beam injections, for example. This grant supports the study of plasma waves, small-scale structures and their dynamics, and turbulence which have considerable impact on the global dynamics of the large-scale SMI system. Regions in which processes of this kind occur are to be found throughout the earth's magnetosphere and ionosphere. Because of the lack of multi-point observations, the true temporal and three-dimensional spatial structures on spatial scales of several 100 to several 1000km are not well known. Such measurements will, however, become available in the future. Small-scale structures, turbulent motions, and microscopic wave-particle interactions can also be studied without detailed knowledge of the overall state of the system, whereas the reverse is not true. Global studies require knowledge of boundary conditions and transport coefficients which only local studies can provide. Thus the microscopic plasma phenomena developed under this grant are needed prior to the task of developing global models.