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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Pressure balance in the Martian ionosphere - Solar Wind interaction

Xystouris, George January 2015 (has links)
Mars is the fourth planet from the Sun and its interaction with the solar wind is a quite interesting subject tostudy. While it is a rocky planet it doesn't have an intrinsic magnetic eld, but an ionosphere, created by thephotoionization of a relatively thin atmosphere. In addition there are magnetic "patches" on its surface, remnantsof an ancient fossilized magnetic eld. All these factors make the study of its interaction with the solar wind quiteintriguing. In this work we tried to extract information about the electron population and the magnetic eld intensity aroundthe planet, but also about the corresponding pressures to those magnitudes: electron -thermal- and magneticpressure respectively. Also, we tried to determine the position of the magnetic pileup boundary (MPB) andcompare it to the theoretical one, and lastly, we search for any possible structures along the MPB -both aboveand below it- by analyzing the ratio of the above mentioned pressures.We used data collected by Mars AdvancedRadar for Subsurface andIonosphereSounding (MARSIS), in a period of almost 9 years - December 2005 to May2014.
12

MHD analysis of the solar-terrestrial interaction : development of tools for studying magnetopause reconnection and the plasma depletion layer

Lawrence, Gareth Rhys January 1998 (has links)
No description available.
13

Magnetohydrodynamic discontinuities and the structure of coronal mass ejections

Kilmurray, Richard Ian January 1999 (has links)
No description available.
14

PITCH-ANGLE SCATTERING OF ENERGETIC CHARGED PARTICLES IN NEARLY CONSTANT MAGNITUDE MAGNETIC TURBULENCE

Sun, P., Jokipii, J. R., Giacalone, J. 03 August 2016 (has links)
We use a method developed by Roberts. that optimizes the phase angles of an ensemble of plane waves with amplitudes determined from a Kolmogorov-like power spectrum, to construct magnetic field vector fluctuations having nearly constant magnitude and large variances in its components. This is a representation of the turbulent magnetic field consistent with that observed in the solar wind. Charged-particle pitch-angle diffusion coefficients are determined by integrating the equations of motion for a large number of charged particles moving under the influence of forces from our predefined magnetic field. We tested different cases by varying the kinetic energy of the particles (E-p) and the turbulent magnetic field variance (sigma(2)(B)). For each combination of E-p and sigma(2)(B), we tested three different models: (1) the so-called "slab" model, where the turbulent magnetic field depends on only one spatial coordinate and has significant fluctuations in its magnitude (b=root delta B-x(2)(z)+ delta B-y(2)(z) + B-0(2)); (2) the slab model optimized with nearly constant magnitude b; and. (3) the slab model turbulent magnetic field with nearly constant magnitude plus a "variance-conserving" adjustment. In the last case, this model attempts to conserve the variance of the turbulent components (sigma(2)(Bx) + sigma(2)(By)), which is found to decrease during the optimization with nearly constant magnitude. We found that there is little or no effect on the pitch-angle diffusion coefficient D mu mu between. models 1 and 2. However, the result from model 3. is significantly different. We also introduce a new method to accurately determine the pitch-angle diffusion coefficients as a function of mu.
15

Study of the electron component of the solar wind and magnetospheric plasma

Sittler, Edward Charles January 1978 (has links)
Thesis. 1978. Ph.D.--Massachusetts Institute of Technology. Dept. of Physics. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Vita. / Includes bibliographical references. / by Edward Charles Sittler, Jr. / Ph.D.
16

Analysis of geomagnetic storms and substorms with the WINDMI model

Spencer, Edmund Augustus. January 1900 (has links) (PDF)
Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.
17

A study of nitrogen isotopic systematics in lunar soils and breccias.

Brilliant, Debra. January 1997 (has links)
Thesis (Ph. D.)--Open University. BLDSC no. DXN024724.
18

Analysis of geomagnetic storms and substorms with the WINDMI model

Spencer, Edmund Augustus 28 August 2008 (has links)
Not available / text
19

Experimental investigation of plasma sail propulsion concepts using cascaded arcs and rotating magnetic field current drive /

Giersch, Louis Roy Miller. January 2005 (has links)
Thesis (Ph. D.)--University of Washington, 2005. / Vita. Includes bibliographical references (leaves 111-113).
20

The relationship between galactic cosmic rays and solar wind

Ihongo, Grace Dominic January 2016 (has links)
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.

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