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You searched for subject:(Anomalous electron transport). Showing records 1 – 3 of 3 total matches.

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1. McDonald, Michael Sean. Electron Transport in Hall Thrusters.

Degree: PhD, Applied Physics, 2012, University of Michigan

Despite high technological maturity and a long flight heritage, computer models of Hall thrusters remain dependent on empirical inputs and a large part of thruster development to date has been heavily experimental in nature. This empirical approach will become increasingly unsustainable as new high-power thrusters tax existing ground test facilities and more exotic thruster designs stretch and strain the boundaries of existing design experience. The fundamental obstacle preventing predictive modeling of Hall thruster plasma properties and channel erosion is the lack of a first-principles description of electron transport across the strong magnetic fields between the cathode and anode. In spite of an abundance of proposed transport mechanisms, accurate assessments of the magnitude of electron current due to any one mechanism are scarce, and comparative studies of their relative influence on a single thruster platform simply do not exist. Lacking a clear idea of what mechanism(s) are primarily responsible for transport, it is understandably difficult for the electric propulsion scientist to focus his or her theoretical and computational tools on the right targets. This work presents a primarily experimental investigation of collisional and turbulent Hall thruster electron transport mechanisms. High-speed imaging of the thruster discharge channel at tens of thousands of frames per second reveals omnipresent rotating regions of elevated light emission, identified with a rotating spoke instability. This turbulent instability has been shown through construction of an azimuthally segmented anode to drive significant cross-field electron current in the discharge channel, and suggestive evidence points to its spatial extent into the thruster near-field plume as well. Electron trajectory simulations in experimentally measured thruster electromagnetic fields indicate that binary collisional transport mechanisms are not significant in the thruster plume, and experiments altering the bias potential of thruster surfaces show minimal effects from electron collisions with thruster surfaces. Taken together these results motivate further investigation of the rotating spoke instability and development of an analytic description to permit its inclusion in next generation Hall thruster models. Advisors/Committee Members: Gallimore, Alec D. (committee member), Foster, John Edison (committee member), Hofer, Richard R. (committee member), Lau, Yue Ying (committee member).

Subjects/Keywords: Hall Thrusters; Electron Transport; Anomalous Transport; Cross-field Transport; Rotating Spoke Instability; High-speed Camera; Aerospace Engineering; Physics; Engineering; Science

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APA (6th Edition):

McDonald, M. S. (2012). Electron Transport in Hall Thrusters. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/91553

Chicago Manual of Style (16th Edition):

McDonald, Michael Sean. “Electron Transport in Hall Thrusters.” 2012. Doctoral Dissertation, University of Michigan. Accessed March 07, 2021. http://hdl.handle.net/2027.42/91553.

MLA Handbook (7th Edition):

McDonald, Michael Sean. “Electron Transport in Hall Thrusters.” 2012. Web. 07 Mar 2021.

Vancouver:

McDonald MS. Electron Transport in Hall Thrusters. [Internet] [Doctoral dissertation]. University of Michigan; 2012. [cited 2021 Mar 07]. Available from: http://hdl.handle.net/2027.42/91553.

Council of Science Editors:

McDonald MS. Electron Transport in Hall Thrusters. [Doctoral Dissertation]. University of Michigan; 2012. Available from: http://hdl.handle.net/2027.42/91553


Université de Lorraine

2. Cavalier, Jordan. Modèles cinétiques et caractérisation expérimentale des fluctuations électrostatiques dans un propulseur à effet Hall : Kinetic modeling and experimental characterization of electrostatic fluctuations in a Hall thruster.

Degree: Docteur es, Physique, 2013, Université de Lorraine

L'étude des phénomènes turbulents se développant en sortie du propulseur de Hall est nécessaire pour pouvoir modéliser le transport anormal (par opposition au transport diffusif) des électrons à travers les lignes de champ magnétique. Les relations de dispersion de deux instabilités pouvant être responsables de ce transport ont été mesurées à des échelles millimétriques à l'aide du diagnostic de diffusion collective de la lumière. Ce travail de thèse s'attache à en donner une description aussi bien théorique qu'expérimentale, pierre à l'édifice de la compréhension du transport dans le propulseur. Une instabilité se propageant majoritairement dans la direction azimutale du propulseur y est caractérisée comme étant l'instabilité de dérive électronique ExB et un modèle analytique décrivant la fréquence expérimentale y est dérivé et validé. De plus, le manuscrit présente une méthode de déconvolution du signal de la diffusion collective de la fonction d'appareil pour ce mode. Une fois déconvoluées, les relations de dispersion expérimentales peuvent être ajustées par la fréquence du modèle analytique, ce qui permet de mesurer expérimentalement et de manière originale la température et la densité électronique dans le jet d'ions énergétiques du plasma du propulseur. Enfin, la seconde instabilité, se développant autour de la direction axiale du propulseur, est caractérisée comme l'instabilité double faisceau entre les ions simplement et doublement chargés du plasma

The study of turbulent phenomena that grow at the exit plane of the Hall thruster is required to modelize the anomalous transport (in contrast to the diffusion transport) of electrons across the magnetic field lines. The dispersion relations of two instabilities that can be responsible for this transport have been mesured at millimetric scales by mean of the collective light scattering diagnostic. The aim of the thesis is to describe them theoretically as well as experimentally, improving the understanding of the Hall thruster transport. In the thesis, an instability that propagates principally azimuthally is caracterized as the ExB electron drift instability and an analytical model that describes the experimental frequency is derived and validated. In addition, the manuscript presents an original method to unfold the signal of the collective scattering diagnostic from the instrumental function of this mode. Once corrected, the experimental dispersion relations can be adjusted by the frequency given by the analytical model, allowing to measure experimentally and in an original way the electron temperature and density in the energetic ion jet of the Hall thruster plasma. The second instability that is mainly propagating in the axial direction is caracterized as the two-stream instability between the simply and doubly charged ions of the plasma

Advisors/Committee Members: Bonhomme, Gérard (thesis director), Lemoine, Nicolas (thesis director).

Subjects/Keywords: Plasma magnétisé; Propulseur de Hall; Turbulence; Transport électronique anormal; Diffusion collective; Modélisation cinétique; Instabilité de dérive électronique; Instabilité de faisceau; Magnetised plasma; Hall thruster; Turbulence; Anomalous electron transport; Collective scattering; Kinetic model; Electron drift instability; Beam instability; 530.41; 629.475

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Cavalier, J. (2013). Modèles cinétiques et caractérisation expérimentale des fluctuations électrostatiques dans un propulseur à effet Hall : Kinetic modeling and experimental characterization of electrostatic fluctuations in a Hall thruster. (Doctoral Dissertation). Université de Lorraine. Retrieved from http://www.theses.fr/2013LORR0130

Chicago Manual of Style (16th Edition):

Cavalier, Jordan. “Modèles cinétiques et caractérisation expérimentale des fluctuations électrostatiques dans un propulseur à effet Hall : Kinetic modeling and experimental characterization of electrostatic fluctuations in a Hall thruster.” 2013. Doctoral Dissertation, Université de Lorraine. Accessed March 07, 2021. http://www.theses.fr/2013LORR0130.

MLA Handbook (7th Edition):

Cavalier, Jordan. “Modèles cinétiques et caractérisation expérimentale des fluctuations électrostatiques dans un propulseur à effet Hall : Kinetic modeling and experimental characterization of electrostatic fluctuations in a Hall thruster.” 2013. Web. 07 Mar 2021.

Vancouver:

Cavalier J. Modèles cinétiques et caractérisation expérimentale des fluctuations électrostatiques dans un propulseur à effet Hall : Kinetic modeling and experimental characterization of electrostatic fluctuations in a Hall thruster. [Internet] [Doctoral dissertation]. Université de Lorraine; 2013. [cited 2021 Mar 07]. Available from: http://www.theses.fr/2013LORR0130.

Council of Science Editors:

Cavalier J. Modèles cinétiques et caractérisation expérimentale des fluctuations électrostatiques dans un propulseur à effet Hall : Kinetic modeling and experimental characterization of electrostatic fluctuations in a Hall thruster. [Doctoral Dissertation]. Université de Lorraine; 2013. Available from: http://www.theses.fr/2013LORR0130

3. Tran, Jonathan. Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters.

Degree: Aerospace Engineering, 2017, UCLA

Plasma turbulence and the resulting anomalous electron transport due to azimuthal current driven instabilities in Hall-effect thrusters is a promising candidate for developing predictive models for the observed anomalous transport. A theory for anomalous electron transport and current driven instabilities has been recently studied by [Lafluer et al., 2016a]. Due to the extreme cost of fully resolving the Debye length and plasma frequency, hybrid plasma simulations utilizing kinetic ions and quasi-steady state fluid electrons have long been the principle workhorse methodology for Hall-effect thruster modeling. Using a reduced dimension particle in cell simulation implemented in the Thermophysics Universal Research Framework developed by the Air Force Research Lab, we show collective electron-wave scattering due to large amplitude azimuthal fluctuations of the electric field and the plasma density. These high-frequency and short wavelength fluctuations can lead to an effective cross-field mobility many orders of magnitude larger than what is expected from classical electron-neutral momentum collisions in the low neutral density regime. We further adapt the previous study by [Lampe et al., 1971] and [Stringer, 1964] for related current driven instabilities to electric propulsion relevant mass ratios and conditions. Finally, we conduct a preliminary study of resolving this instability with a modified hybrid simulation with the hope of integration with established hybrid Hall-effect thruster simulations.

Subjects/Keywords: Plasma physics; Aerospace engineering; Anomalous Electron Transport; Computer Simulation; Current Driven Instabilities; Hall-effect Thrusters

…3.2 Anomalous Electron Transport Simulation In order to study the effects of current… …instabilities and resulting anomalous transport is poor and is lagging behind the progress… …understanding the anomalous component of the cross-field electron mobility and developing predictive… …continue to struggle with an accurate electron transport model. The shortcomings of these… …electron transport within the channel and near-plume of a Hall-effect thruster. This work is of… 

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Tran, J. (2017). Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters. (Thesis). UCLA. Retrieved from http://www.escholarship.org/uc/item/64h68744

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Tran, Jonathan. “Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters.” 2017. Thesis, UCLA. Accessed March 07, 2021. http://www.escholarship.org/uc/item/64h68744.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Tran, Jonathan. “Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters.” 2017. Web. 07 Mar 2021.

Vancouver:

Tran J. Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters. [Internet] [Thesis]. UCLA; 2017. [cited 2021 Mar 07]. Available from: http://www.escholarship.org/uc/item/64h68744.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Tran J. Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters. [Thesis]. UCLA; 2017. Available from: http://www.escholarship.org/uc/item/64h68744

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.