Diffusion in the Io plasma torus and its relation to the torus spatial structure.

Persistent Link:
http://hdl.handle.net/10150/185421
Title:
Diffusion in the Io plasma torus and its relation to the torus spatial structure.
Author:
Davis, Eric Wesley.
Issue Date:
1991
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
This is a study of the plasma diffusion processes relevant to the physical nature of the Io plasma torus at Jupiter. A knowledge of the diffusion processes involved in the Io plasma torus is essential to an understanding of the spatial structure and energetics of the torus. The only published theory of Io torus plasma diffusion, centrifugally driven flux tube interchange instability, is based on turbulent plasma interchange instability. We have examined physical properties that lead us to conclude that flux tube interchange diffusion is not a valid mechanism in the plasma torus. The collisional nature of the hot torus plasma is seen through its observed EUV emissions which dominate the energy loss from the system. Further, the torus plasma parameters fall in the range of values satisfying the criteria for the use of collisional transport theory to derive a collisional diffusion coefficient. The collisional nature of the torus plasma is characterized in the long mean free path regime where classical transport theory breaks down. We study the Chapman-Enskog method of calculating the plasma diffusion coefficient from a solution of the Boltzmann equation. Simplifying approximations of a fully ionized plasma dominated by Coulomb elastic charged particle collisions are made to derive an ad hoc non-classical diffusion coefficient which results in slow differential diffusion rates for the various sulfur and oxygen ions in the plasma torus. The radial spatial structure and energetics of the plasma torus is modeled by employing the collisional diffusion coefficient in a computer model calculation of collisional ionization-diffusive equilibrium and energy branching. The computer model employs the known significant plasma reactions involving the torus sulfur and oxygen species, utilizing the most recently available atomic parameters. In view of the failure of Neutral Cloud Theory to adequately power the copious amounts of UV radiation emitted by the Io plasma torus, we employed the radial plasma model to investigate this "energy crisis." Toward this end, we investigate the application to our plasma model of a proposed heterogeneous source of energetic electrons and a proposal of inward diffusing energetic outer-magnetospheric OII and SII ions as ad hoc heat inputs to the plasma torus electrons, in order to maintain a steady state energy balance.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Dissertations, Academic; Plasma turbulence; Astrophysics
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Physics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Shemansky, Donald E.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleDiffusion in the Io plasma torus and its relation to the torus spatial structure.en_US
dc.creatorDavis, Eric Wesley.en_US
dc.contributor.authorDavis, Eric Wesley.en_US
dc.date.issued1991en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThis is a study of the plasma diffusion processes relevant to the physical nature of the Io plasma torus at Jupiter. A knowledge of the diffusion processes involved in the Io plasma torus is essential to an understanding of the spatial structure and energetics of the torus. The only published theory of Io torus plasma diffusion, centrifugally driven flux tube interchange instability, is based on turbulent plasma interchange instability. We have examined physical properties that lead us to conclude that flux tube interchange diffusion is not a valid mechanism in the plasma torus. The collisional nature of the hot torus plasma is seen through its observed EUV emissions which dominate the energy loss from the system. Further, the torus plasma parameters fall in the range of values satisfying the criteria for the use of collisional transport theory to derive a collisional diffusion coefficient. The collisional nature of the torus plasma is characterized in the long mean free path regime where classical transport theory breaks down. We study the Chapman-Enskog method of calculating the plasma diffusion coefficient from a solution of the Boltzmann equation. Simplifying approximations of a fully ionized plasma dominated by Coulomb elastic charged particle collisions are made to derive an ad hoc non-classical diffusion coefficient which results in slow differential diffusion rates for the various sulfur and oxygen ions in the plasma torus. The radial spatial structure and energetics of the plasma torus is modeled by employing the collisional diffusion coefficient in a computer model calculation of collisional ionization-diffusive equilibrium and energy branching. The computer model employs the known significant plasma reactions involving the torus sulfur and oxygen species, utilizing the most recently available atomic parameters. In view of the failure of Neutral Cloud Theory to adequately power the copious amounts of UV radiation emitted by the Io plasma torus, we employed the radial plasma model to investigate this "energy crisis." Toward this end, we investigate the application to our plasma model of a proposed heterogeneous source of energetic electrons and a proposal of inward diffusing energetic outer-magnetospheric OII and SII ions as ad hoc heat inputs to the plasma torus electrons, in order to maintain a steady state energy balance.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectDissertations, Academicen_US
dc.subjectPlasma turbulenceen_US
dc.subjectAstrophysicsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePhysicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorShemansky, Donald E.en_US
dc.contributor.committeememberKohler, Sigurden_US
dc.contributor.committeememberSmyth, William H.en_US
dc.contributor.committeememberJenkins, Edgar W.en_US
dc.contributor.committeememberBowen, Theodoreen_US
dc.identifier.proquest9123473en_US
dc.identifier.oclc709777428en_US
All Items in UA Campus Repository are protected by copyright, with all rights reserved, unless otherwise indicated.