Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 111-113).

Modeling the highly energetic particles known as galactic cosmic rays is a highly nontrivial task. This process may require numerical simulations of the complex processes occurring continuously in the heliosphere due to changes in solar wind reflecting the solar activity. However, if reasonable assumptions are employed, considering only the diffusion and convection processes, the above phenomenon can be reduced to a simplified scenario that can be modeled analytically. The variable solar wind may be responsible for solar modulation of galactic cosmic rays. The aforementioned, in addition to the postulated role of cosmic rays in climate change, has led to the following questions: what is the relationship between galactic cosmic rays and solar wind? What are the possible effects of solar wind on galactic cosmic ray flux? In an attempt to address these questions, we have modeled the transport of galactic cosmic rays in the heliosphere theoretically. Our model describes solar modulation and transport of galactic cosmic rays in the heliosphere mainly in terms of the size of the heliosphere, timedependent solar wind, and a uniform diffusion coefficient. Our results suggest that solar wind causes significant decrease in galactic cosmic ray flux at r ≈ 1AU. In further investigation, we examine a short-time variation of the calculated flux, and the result is reflected by exposing a negative correlation of −0.988 ± 0.001 between galactic cosmic ray flux variation and the solar wind variation at r ≈ 1AU. This outcome may suggest that the higher the solar wind, the lower the galactic cosmic ray flux and vice-versa. For completeness, we compared our results with available observational data that shows a good fit to the model. Thus, based on our model results, it may be possible to predict that galactic cosmic ray flux variation and solar wind variation at Earth are negatively correlated.

Thesis. 1976. M.S.--Massachusetts Institute of Technology. Dept. of Earth and Planetary Sciences. / Microfiche copy available in Archives and Science. / Bibliography: leaves 60-63. / M.S.

The polar electric potential imposed on the ionosphere by coupling between the earth's magnetosphere and the solar wind has been shown to have a non-linear response to the interplanetary electric field (IEF). This dissertation presents an empirical study of this polar cap potential saturation phenomenon. First, the saturation of the reverse convection potential under northward is demonstrated using bin-averaged SuperDARN data. Then, the saturation reverse convection potential is shown to saturate at a higher value at higher solar wind plasma beta. The reverse convection flow velocity is then compared with cross-polar cap flows under southward IMF under summer, winter and equinox conditions. It is demonstrated that the reverse convection flow exhibits the opposite seasonal behavior to cross polar cap flow under southward IMF. Then, an interhemispheric case study is performed to provide an explanation for the seasonal behavior of the reverse convection potential. It is found using DMSP particle precipitation data that the reverse convection cells in the winter circulate at least partially on closed field lines. Finally, SuperDARN and DMSP data are merged to provide polar cap potential measurements for a statistical study of polar cap potential saturation under southward IMF. It is found that the extent of polar cap potential saturation increases with increasing Alfvenic Mach number, and has no significant relation to Alfven wing transmission coefficient or solar wind dynamic pressure. / Ph. D.

The solar wind has an important impact on the Earth and its magnetic field. Among the solar wind perturbations, there can be jumps in the solar wind dynamic pressure as well as strong magnetic excursions in the z-component of the Interplanetary Magnetic Field (IMF B_(Z )). When coronal mass ejections and other solar disturbances take place in the solar wind, there can be clear changes in the global geomagnetic field, as measured by a magnetic index called Sym-H. In this thesis some unusual events were found for which there were large fluctuations either in the solar wind dynamic pressure or in the IMF B_Z but not simultaneously in both. These events suggest that the response of the geomagnetic field to the dynamic pressure fluctuations of the solar wind is variable. In particular, it was found that the earthward component (x-component) of the IMF appeared to influence the magnitude of the Sym-H response. By contrast, there was no visible impact of the y-component of the IMF. In a second exceptional event it was found that the IMF was changing substantially while the solar wind dynamic pressure remained very constant. From this study a time delay between the IMF B_Z component and the resulting Sym-H was found to be of the order of 60 to 90 minutes.

Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Physics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 90-91. / Ph.D.

As means of investigating the various mechanisms which contribute to the persistence of magnetized turbulence in the solar wind, this dissertation details the development of tools through which turbulence theories can be directly compared to in situ observations. This comparison is achieved though the construction of synthetic spacecraft time series from spectra of randomly phased linear eigenmodes. A broad overview of the current understanding of plasma turbulence through analytic theory, spacecraft observation, and numerical simulation is presented with particular emphasis on previous uses of linear eigenmode characteristics in the literature. An analytic treatment of relevant fluid and kinetic linear waves follows, providing motivation for the choice of three eigenmode characteristics for studying solar wind turbulence in this dissertation. The novel synthetic spacecraft time series method is next detailed and its use in describing magnetized turbulence justified. The three metrics are then individually employed as a means of comparing the turbulence models used to generate synthetic time series with in situ observations. These comparisons provide useful constraints on various proposed mechanisms for sustaining the turbulence cascade and heating the solar wind plasma.

Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (p. 108-119).

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / Includes bibliographical references (leaves 95-99). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

abstract: The present work covers two distinct microanalytical studies that address issues in planetary materials: (1) Genesis Na and K solar wind (SW) measurements, and (2) the effect of water on high-pressure olivine phase transformations. NASA’s Genesis mission collected SW samples for terrestrial analysis to create a baseline of solar chemical abundances based on direct measurement of solar material. Traditionally, solar abundances are estimated using spectroscopic or meteoritic data. This study measured bulk SW Na and K in two different Genesis SW collector materials (diamond-like carbon (DlC) and silicon) for comparison with these other solar references. Novel techniques were developed for Genesis DlC analysis. Solar wind Na fluence measurements derived from backside depth profiling are generally lower in DlC than Si, despite the use of internal standards. Nevertheless, relative to Mg, the average SW Na and K abundances measured in Genesis wafers are in agreement with solar photospheric and CI chondrite abundances, and with other SW elements with low first ionization potential (within error). The average Genesis SW Na and K fluences are 1.01e11 (+9e09, -2e10) atoms/cm2 and 5.1e09 (+8e08, -8e08) atoms/cm2, respectively. The errors reflect average systematic errors. Results have implications for (1) SW formation models, (2) cosmochemistry based on solar material rather than photospheric measurements or meteorites, and (3) the accurate measurement of solar wind ion abundances in Genesis collectors, particularly DlC and Si. Deep focus earthquakes have been attributed to rapid transformation of metastable olivine within the mantle transition zone (MTZ). However, the presence of H2O acts to overcome metastability, promoting phase transformation in olivine, so olivine must be relatively anhydrous (<75 ppmw) to remain metastable to depth. A microtextural analysis of olivine phase transformation products was conducted to test the feasibility for subducting olivine to persist metastably to the MTZ. Transformation (as intracrystalline or rim nucleation) shifts from ringwoodite to ringwoodite-wadsleyite nucleation with decreasing H2O content within olivine grains. To provide accurate predictions for olivine metastability at depth, olivine transformation models must reflect how changing H2O distributions lead to complex changes in strain and reaction rates within different parts of a transforming olivine grain. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2015