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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.
1

THE PROPAGATION OF ENERGETIC PARTICLES IN FINITE TEMPERATURE ASTROPHYSICAL PLASMAS.

DAVILA, JOSEPH MICHAEL. January 1982 (has links)
Solutions to the dispersion relation for waves propagating parallel to the static magnetic field in a plasma of arbitrary β are obtained. (β is the ratio of thermal to magnetic pressure.) Resonant scattering by these waves is evaluated. It is found that the magnetostatic approximation, used extensively in the past, breaks down for particles with pitch angles near 90°, and one must consider the more complicated process of particle scattering in electromagnetic turbulence. Many aspects of particle propagation in a finite temperature plasma can be discussed without assuming magnetostatic turbulence. This is accomplished by using a graphical method to obtain the solutions of the resonance condition. Results show that in a high β plasma, wave damping causes a gap, or hole, in μ-space where the resonant particle scattering rate is severely depressed. It is found that only high energy (γ ≥10⁵) electrons can be trapped within a typical supernova remnant. When the notion of electromagnetic resonance is applied to particle propagation in the interplanetary β ≤ 1) plasma, it is found that significant modifications to the conventional scattering picture must be made. It is found that a resonance gap exists which is similar to the one in a high β plasma. For electrons, this gap provides a natural explanation for scatter-free events. Theory predicts that these events should occur for kinetic energies T ≤ 300 keV while observations indicate that the majority have T ≤ 500 keV. For protons and energetic electrons, the scattering mean free path is critically dependent on the non-resonant scattering rate for particles within the gap. This fact provides a way to resolve the well known discrepancy between the theoretical and observational values for the mean free path, λ.
2

The dynamics of the low energy plasma in the Jovian magnetosphere

McNutt, Ralph L. (Ralph Leroy) January 1980 (has links)
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1980. / Vita. / Bibliography: leaves 140-156. / by Ralph L. McNutt, Jr. / Ph.D.
3

Bernstein-Greene-Kruskal electron solitary waves in collisionless plasmas /

Chen, Li-Jen, January 2002 (has links)
Thesis (Ph. D.)--University of Washington, 2002. / Vita. Includes bibliographical references (leaves 66-71).
4

Beam generated instabilities in space plasma.

Misthry, Surversperi Suryakumari. January 1999 (has links)
Electrostatic instabilities associated with a model applicable to the auroral acceleration region consisting of an ion beam, precipitating electrons and stationary background electrons are theoretically investigated. The kinetic dispersion relation is solved numerically without approximations. It is shown that two low-frequency plasma instabilities are present and these may generate the low-frequency electric field fluctuations (LEFs) that have been observed in the acceleration region. A parameter variation study is carried out in order to reveal the features of the instabilities. The model is adapted to suit two possible regions of study: (1) drifting cool ions and (2) drifting cool ions and counter-streaming hot electrons. The slow ion-acoustic instability which dominates at low ion beam drift velocities is studied by varying plasma parameters such as the propagation angle, ky/k, the wavenumber, k, the cold background electron density, nco, the hot electron temperature and the cool ion beam temperature. The second mode, the modified two-stream instability, which dominates at larger ion beam drift velocities and at oblique angles of propagation is investigated in a similar manner. To complete the study of these two instabilities, the effect of drifting hot electrons is examined briefly through a similar parameter variation study. / Thesis (M.Sc.)-University of Durban-Westville, 1999.
5

Experimental investigation of ion temperature anisotropy driven instabilities in a high beta plasma

Keiter, Paul A. January 1999 (has links)
Thesis (Ph. D.)--West Virginia University, 1999. / Title from document title page. Document formatted into pages; contains iv, 131 p. : ill. (some col.) Includes abstract. Includes bibliographical references (p. 127-131).
6

Low frequency waves in the solar system

Lachin, Anoosh January 1998 (has links)
No description available.
7

Simulations of high-latitude ionosphere-magnetosphere region plasma density structures and the Alfven waves effects

Jaafari, Fajer Bitar. January 2009 (has links)
Thesis (Ph.D.) -- University of Texas at Arlington, 2009.
8

Gas and plasma structures.

January 2004 (has links)
No abstract available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2004.
9

Low-dimensional dynamics of the earth's magnetosphere /

Smith, James Paul, January 1999 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 1999. / Vita. Includes bibliographical references (leaves 157-163). Available also in a digital version from Dissertation Abstracts.
10

Quantitative studies of terrestrial plasmaspheric dynamics enabled by the IMAGE spacecraft

Larsen, Brian Arthur. January 2007 (has links) (PDF)
Thesis (Ph. D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: David M. Klumpar. Includes bibliographical references (leaves 102-108).

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