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Numerical Study Of Current Driven Instabilities And Anomalous Electron Transport In Hall Effect Thrusters
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Book Synopsis Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters by : Jonathan Tran
Download or read book Numerical Study of Current Driven Instabilities and Anomalous Electron Transport in Hall-effect Thrusters written by Jonathan Tran and published by . This book was released on 2017 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Two-dimensional Axial-azimuthal (Z-Ø) Simulation of Cross-field Electron Transport in a Hall Thruster Plasma Discharge by : Cheryl Meilin Lam
Download or read book Two-dimensional Axial-azimuthal (Z-Ø) Simulation of Cross-field Electron Transport in a Hall Thruster Plasma Discharge written by Cheryl Meilin Lam and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hall thruster (or Hall effect thruster) is an electric propulsion device used for space flight applications. Despite its use as a deployed production technology, much of the underlying plasma physics which governs thruster behavior and performance is not well understood. Specifically, laboratory experiments indicate an anomalously high electron mobility in the direction perpendicular to the magnetic field, which exceeds that predicted by classical theory. Predicting this so-called anomalous electron transport remains a key research challenge. One possible mechanism for the generation of super-classical electron transport is the interaction of correlated quasi-coherent fluctuations in the plasma properties. Instabilities in the plasma can lead to quasi-coherent wave fluctuations in the electric potential, electron number density, and electron velocities; if these fluctuations are appropriately correlated, they can serve to either enhance or reduce electron transport across the magnetic field. In this work, we use numerical simulations as a tool to characterize axial and azimuthal fluctuations in the plasma discharge properties and study their impact on cross-field electron transport. We employ a two-dimensional axial-azimuthal (z-theta) model to simulate an annular Hall thruster discharge. We use a hybrid fluid-Particle-In-Cell approach in which the positive ion (Xe+) and neutral (Xe) species are modeled using a Particle-In-Cell (PIC) treatment and the electrons are modeled as a fluid continuum. The ion and neutral species are modeled as discrete collisionless superparticles; due to their large mass and consequently large Larmor radius, we neglect the magnetic field effect on the ions. For the electron fluid, we include the first three moments of the Boltzmann equation to obtain 2D continuity and momentum equations, using the drift-diffusion approximation, and a quasi-1D energy equation. The PIC and fluid treatments are coupled by assuming space charge neutrality, or quasineutrality, between the ions and electrons. We chose a simulated thruster model geometry and operating conditions to enable comparisons to experimental measurements of the Stanford Hall Thruster (SHT) laboratory discharge. The simulated thruster channel is 8 cm long, with an outer diameter of 9.4 cm; we include the full azimuth throughout the simulated domain, which includes the entire channel length and the near-plume. Using a non-uniform spatial resolution of 3 mm - 10 mm and maximum time step of 10 ns, we can achieve a simulated time of extent on the order of milliseconds, using a single PC processor core for a wall clock time of several days. We present results for a representative simulated low voltage operating condition. Simulated plasma properties are compared to experimental measurements of the plasma properties and the effective electron mobility. We further analyze the simulated data to characterize predicted axial and azimuthal fluctuations in the electric potential, electron number density, and electron velocities. We consider the simulated wave fluctuations in the context of linearized fluid theory models for specific dispersive propagation modes, as we attempt to characterize their impact on the effective axial electron transport for various axial regions within the thruster discharge. For the simulated time and spatial scales presented here, correlated fluctuations appear to enhance electron transport in some regions of the discharge and inhibit electron transport in others. In the mid-channel region, where we believe gradients and in the electron density and magnetic field may contribute to gradient-driven waves, we observe enhancement of the electron mobility beyond classical mobility values. Near the channel exit plane, however, we observe a distinct electron transport barrier, similar to that observed in experimental measurements. Just upstream of the channel exit plane, correlated fluctuations in the electron number density and the axial electron velocity appear to generate negative current which opposes the positive bulk discharge current; in this region, we believe the axial shear in the electron velocity may play a role in disrupting fluctuations and reducing electron transport. In both cases, it is clear that simulated wave fluctuations impact axial electron transport. Even in regions of observed transport enhancement, however, the simulated fluctuation-driven transport does not fully account for the experimentally-observed super-classical mobility. We believe that an additional transport mechanism -- perhaps electron wall scattering or higher frequency, shorter wavelength fluctuations -- is necessary to account for the experimentally-observed electron mobility. Towards this end, we present results for additional simulations which include an artificially enhanced electron collision frequency; these simulations show improved agreement with experimental results and confirm the need to include additional physical mechanisms for anomalous electron transport. Finally, suggestions for future work are included.
Book Synopsis Fundamentals of Electric Propulsion by : Dan M. Goebel
Download or read book Fundamentals of Electric Propulsion written by Dan M. Goebel and published by John Wiley & Sons. This book was released on 2008-12-22 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: Throughout most of the twentieth century, electric propulsion was considered the technology of the future. Now, the future has arrived. This important new book explains the fundamentals of electric propulsion for spacecraft and describes in detail the physics and characteristics of the two major electric thrusters in use today, ion and Hall thrusters. The authors provide an introduction to plasma physics in order to allow readers to understand the models and derivations used in determining electric thruster performance. They then go on to present detailed explanations of: Thruster principles Ion thruster plasma generators and accelerator grids Hollow cathodes Hall thrusters Ion and Hall thruster plumes Flight ion and Hall thrusters Based largely on research and development performed at the Jet Propulsion Laboratory (JPL) and complemented with scores of tables, figures, homework problems, and references, Fundamentals of Electric Propulsion: Ion and Hall Thrusters is an indispensable textbook for advanced undergraduate and graduate students who are preparing to enter the aerospace industry. It also serves as an equally valuable resource for professional engineers already at work in the field.
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 818 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Theory of Plasma Waves by : Thomas Howard Stix
Download or read book The Theory of Plasma Waves written by Thomas Howard Stix and published by . This book was released on 2012-03-01 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analytical and Numerical Study of a Hall Effect Thruster with a Particle-in-cell Model by : Alejandro Benítez Martín
Download or read book Analytical and Numerical Study of a Hall Effect Thruster with a Particle-in-cell Model written by Alejandro Benítez Martín and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Space propulsion, and more specifically electric propulsion, has been growing widely strong for the last 20 years thanks to the increasingly frequent technological advances in this field. That's why there are plenty of studies arising seeking for new ways of computing simulations of propulsion systems. This is the case of the Particle-in-Cell method. This method is nowhere near new, for it started being used in the 1950s, but the computational advances in the recent years have opened new doors for this numerical method that makes it one of the best options. So, this thesis has the main purpose of proving that Particle-in-Cell simulations of a onedimensional Hall-effect thruster channel give similar results to experimental data obtained via analytical models. For it, first an introduction to different electric propulsion systems and plasma physics will be done in order to have the basis of Hall thrusters functioning so the analysis can be performed. Once the basis are settled, the analytical model will be performed comparing the results with those obtained by professor E. Ahedo and then, using the results obtained in the analytical model as reference, the numerical model using the PIC method will be computed. Finally, by discussing and comparing the two models, we will see that the results obtained in both models resemble a lot those obtained by professor E. Ahedo and the experimental data from real life thrusters, with the only difference that some discrepancies appear. In the case of the analytical model, values in electrons temperature will tend to have a sudden decrease due to not taking into account wall losses and plume divergence, while in the PIC numerical model a little oscillation appears at the beginning due to the finite difference solver used. Although the appearance of such discrepancies, the results obtained are exactly the ones that were expected, hence proving the viability of the PIC model for plasma computation.
Book Synopsis Dynamic Models of Electron Transport in Hall Thruster Simulations by : Eunsun Cha
Download or read book Dynamic Models of Electron Transport in Hall Thruster Simulations written by Eunsun Cha and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Hall-effect thruster (HET) is an electrostatic propulsion device that relies on the Hall effect to generate a dense ExB electron current to ionize the propellant gas. In simulating Hall thrusters, describing electron cross- eld transport has been one of the greatest challenges because the electron transport in a Hall thruster is anomalously higher than that predicted by classical collision theory. Researchers have suggested some explanations of the anomalous transport, but they have failed to establish a reliable physical model for general applications. Establishing a physical model that is applicable to various types of Hall thrusters in various operating conditions is an objective of this work. In this thesis, a 2-D hybrid particle-in-cell (PIC) simulation for the Stanford Hall thruster (SHT) is used to implement the transport (electron mobility) models. Among various attempts, an entropy closure model, as well as a turbulent transport model were successfully implemented and demonstrated results that show reasonable agreement to measured data. The entropy closure model uses a 1-D entropy transport equation in the plasma of a Hall thruster discharge to derive a relation for electron mobility as a function of other plasma properties. The simulated results show a reasonable agreement with experiments. The turbulent transport model seeks for a more straightforward way to incorporate the entropy production mechanism into the simulation. By assuming that the Joule heating is the main source of entropy production, we adopted the turbulent kinetic theory to relate the energy dissipated from the largest eddies with the energy production rate. Through a scaling analysis, electron mobility is expressed as an explicit function of other plasma properties of the simulation. The simulated electron mobility captures the electron transport phenomenon measured experimentally. To test the transportability of the turbulent model, the simulation was modi ed for an SPT-type thruster with a different geometry than the SHT. Also, an alternative propellant, molecular nitrogen, was simulated on the geometry of the SHT using the turbulent model. The dynamic mobility models make it possible to observe the dynamic characteristics of the Hall thruster. The mobility models in this study magnify the capability of Hall thruster simulations to explore design space cost effectively.
Book Synopsis Numerical Study of Cathode Emission Constraints on Cylindrical Self-field MPD Thruster Performance by :
Download or read book Numerical Study of Cathode Emission Constraints on Cylindrical Self-field MPD Thruster Performance written by and published by . This book was released on 1993 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Genetic Programming Theory and Practice IX by : Rick Riolo
Download or read book Genetic Programming Theory and Practice IX written by Rick Riolo and published by Springer Science & Business Media. This book was released on 2011-11-02 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt: These contributions, written by the foremost international researchers and practitioners of Genetic Programming (GP), explore the synergy between theoretical and empirical results on real-world problems, producing a comprehensive view of the state of the art in GP. Topics include: modularity and scalability; evolvability; human-competitive results; the need for important high-impact GP-solvable problems;; the risks of search stagnation and of cutting off paths to solutions; the need for novelty; empowering GP search with expert knowledge; In addition, GP symbolic regression is thoroughly discussed, addressing such topics as guaranteed reproducibility of SR; validating SR results, measuring and controlling genotypic complexity; controlling phenotypic complexity; identifying, monitoring, and avoiding over-fitting; finding a comprehensive collection of SR benchmarks, comparing SR to machine learning. This text is for all GP explorers. Readers will discover large-scale, real-world applications of GP to a variety of problem domains via in-depth presentations of the latest and most significant results.
Book Synopsis Fundamentals of Plasma Physics by : J. A. Bittencourt
Download or read book Fundamentals of Plasma Physics written by J. A. Bittencourt and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Plasma Physics is a general introduction designed to present a comprehensive, logical and unified treatment of the fundamentals of plasma physics based on statistical kinetic theory, with applications to a variety of important plasma phenomena. Its clarity and completeness makes the text suitable for self-learning and for self-paced courses. Throughout the text the emphasis is on clarity, rather than formality, the various derivations are explained in detail and, wherever possible, the physical interpretations are emphasized. The mathematical treatment is set out in great detail, carrying out the steps which are usually left to the reader. The problems form an integral part of the text and most of them were designed in such a way as to provide a guideline, stating intermediate steps with answers.
Book Synopsis Selected Topics in Plasma Physics by : Sukhmander Singh
Download or read book Selected Topics in Plasma Physics written by Sukhmander Singh and published by BoD – Books on Demand. This book was released on 2020-11-19 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is planned to introduce the advances topics of plasma physics for research scholars and postgraduate students. This book deals with basic concepts in plasma physics, non-equilibrium plasma modeling, space plasma applications, and plasma diagnostics. It also provides an overview of the linear and nonlinear aspects of plasma physics. Chapters cover such topics as plasma application in space propulsion, microwave–plasma interaction, plasma antennas, solitary waves, and plasma diagnostic techniques.
Book Synopsis Plasma Physics via Computer Simulation by : C.K. Birdsall
Download or read book Plasma Physics via Computer Simulation written by C.K. Birdsall and published by CRC Press. This book was released on 2018-10-08 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: Divided into three main parts, the book guides the reader to an understanding of the basic concepts in this fascinating field of research. Part 1 introduces you to the fundamental concepts of simulation. It examines one-dimensional electrostatic codes and electromagnetic codes, and describes the numerical methods and analysis. Part 2 explores the mathematics and physics behind the algorithms used in Part 1. In Part 3, the authors address some of the more complicated simulations in two and three dimensions. The book introduces projects to encourage practical work Readers can download plasma modeling and simulation software — the ES1 program — with implementations for PCs and Unix systems along with the original FORTRAN source code. Now available in paperback, Plasma Physics via Computer Simulation is an ideal complement to plasma physics courses and for self-study.
Book Synopsis Introduction to Plasma Dynamics by : A. I. Morozov
Download or read book Introduction to Plasma Dynamics written by A. I. Morozov and published by CRC Press. This book was released on 2012-12-06 with total page 828 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the twenty-first century progresses, plasma technology will play an increasing role in our lives, providing new sources of energy, ion-plasma processing of materials, wave electromagnetic radiation sources, space plasma thrusters, and more. Studies of the plasma state of matter not only accelerate technological developments but also improve the
Book Synopsis 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit July 20-23, 2003, Huntsville, Alabama: 03-4850 - 03-4899 by :
Download or read book 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit July 20-23, 2003, Huntsville, Alabama: 03-4850 - 03-4899 written by and published by . This book was released on 2003 with total page 470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Partially Ionized Gases by : Morton Mitchner
Download or read book Partially Ionized Gases written by Morton Mitchner and published by Wiley-Interscience. This book was released on 1973 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Propulsion written by Kazuo Matsuuchi and published by BoD – Books on Demand. This book was released on 2021-12-15 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Almost all animals move around frequently in space. Their aim is to walk and fly in search of food or to propagate their species. Thus, changing positions is important for creatures’ survival and maintaining the environment. As such, this book examines movement with a focus on force and propulsion. Chapters cover topics including rocket engines, electric propulsion, mechanisms of force, and more.
Book Synopsis Transport Phenomena in Partially Ionized Plasma by : V.A. Rozhansky
Download or read book Transport Phenomena in Partially Ionized Plasma written by V.A. Rozhansky and published by CRC Press. This book was released on 2001-11-22 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transport phenomena in plasmas are the relatively slow processes of particle momentum and energy transport systems in a state of mechanical equilibrium. In contrast to neutral gases, these phenomena in plasmas are greatly influenced by self-consistent fields, in particular electric fields. These can produce particle and energy fluxes, in addition to those generated by the inhomogeneity of the plasma composition and temperature. As a result, the physical effects accompanying transport phenomena in plasmas are far more numerous and complicated than those in neutral gases, and the solution of corresponding problems is more difficult. The effects, however, are usually far more interesting and sometimes surprising. This book presents a systematic survey and analysis of the main mechanisms of transport phenomena in plasma and gives examples of gradually increasing complexity to illustrate these mechanisms and the relationships between them. The author pays special attention to the analysis of experimental measurements and considers the relevant processes analytically as well as qualitatively. The majority of problems dealt with in this book are of considerable practical interest, and the phenomena described often determine the main characteristics of processes and devices. Transport Phenomena in Partially Ionized Plasma will be of interest to researchers who need to know the properties of real, specific systems, as well as to engineers and advanced students in the physics of plasmas, semiconductors, various types of gas discharges and the ionosphere.
