Energetic particle studies can provide essential insights into many processes of importance to solar-terrestrial physics. For example, the elemental composition of solar energetic particles in large flares yields the composition of the solar corona, and is systematically different from the photospheric composition in a manner depending on the first ionization potential of the element. This dependence is of key importance in understanding the transport of heavy ions from the photosphere to the corona. As another example, particle energization by shock waves occurs at many sites in the solar system including the corona and the interplanetary medium, offering the opportunity to study particle acceleration in regions with different sizes and time scales. As a final example, the transport of energetic particles from the sun to the earth through the turbulent interplanetary medium, and the transport of shock accelerated particles give insights into the plasma properties of the solar wind plasma under widely differing levels of turbulence. This NSF grant will take advantage of the existing computers and program libraries, and large data sets at the University of Maryland to investigate a number of solar and interplanetary physics problems which in many cases can be best attacked using statistical surveys and/or multi-spacecraft observations. The Maryland instrument on IMP, ISEE, and Voyager used for this study is able to distinguish different ionic species in low energy particle populations, making it possible to investigate unique aspects of energetic particle phenomena. Specific studies to be undertaken include: 1) Solar particle acceleration and transport in small, impulsive solar flares will be investigated using a detailed particle transport. 2) Interplanetary shock acceleration processes will be studied using particle composition information to compare the shock accelerated particle population with candidate seed populations such as solar flare particles. 3) Upstream diffusion coefficients in interplanetary shocks will be derived from particle data using gradient techniques. 4) The radial evolution of shock accelerated particle populations between 1 and 4-5 AU will be characterized. 5) Acceleration processes in the interplanetary medium produce the Anomalous Cosmic Ray component and accelerate ions in the turbulent regions near comets will be probed.
