Download or read book Comparison of Numerical and Experimental Near Field Ion Velocity Distributions of the BHT 200 X3 Hall Thruster written by and published by . This book was released on 2006 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Near-field ion velocity distributions of a BusekBHT-200-X3 xenon Hall thruster obtained through numerical simulation are compared with laser-induced fluorescence measurements taken for one nominal operating condition. The numerical code Hybrid-PIC Hall, a 2D hybrid particle-in-cell model, is used to simulate an axisymmetric cross section of the plasma acceleration zone. A set of nine HP Hall simulations are run using three different cathode positions and Bohm electron mobility coefficients to study the effects of these parameters on ion acceleration. Six additional cases were run in an attempt to better match the simulation results to the experimental data. For model validation, agreement between the numerical and experimental results is examined. The results show that it is difficult to match both the global operational parameters (i.e, thrust, discharge current, and beam current) and the ion velocity distributions. The shape of the axial velocity distributions can be closely matched by using high Bohm electron mobility values. However, this correlation comes at the expense of peak ion velocity and discharge current agreement. Radial velocity distributions are more closely matched by the simulations, but the simulations uniformly predict lower than measured inward and higher than measured outward radial velocity components (relative to the centerline) from the annular acceleration channel.
Download or read book Comparison of Numerical and Experimental Near Field Plasma Properties of the BHT 200 X3 Hall Thruster Preprint written by and published by . This book was released on 2006 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Near-field ion velocity distributions of a BusekBHT-200-X3 xenon Hall thruster obtained through numerical simulation are compared with laser-induced fluorescence measurements taken for one nominal operating condition. The numerical code Hybrid-PIC Hall, a 2D hybrid particle-in-cell model, is used to simulate an axisymmetric cross section of the plasma acceleration zone. A set of nine HP Hall simulations are run using three different cathode positions and Bohm electron mobility coefficients to study the effects of these parameters on ion acceleration. Six additional cases were run in an attempt to better match the simulation results to the experimental data. For model validation, agreement between the numerical and experimental results is examined. The results show that it is difficult to match both the global operational parameters (i.e, thrust, discharge current, and beam current) and the ion velocity distributions. The shape of the axial velocity distributions can be closely matched by using high Bohm electron mobility values. However, this correlation comes at the expense of peak ion velocity and discharge current agreement. Radial velocity distributions are more closely matched by the simulations, but the simulations uniformly predict lower than measured inward and higher than measured outward radial velocity components (relative to the centerline) from the annular acceleration channel.
Download or read book Evolution of the Ion Velocity Distribution in the Near Field of the BHT 200 X3 Hall Thruster written by and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents an analysis of near plume velocity distributions of the Busek BHT-200-X3 200 W laboratory Hall thruster derived from laser-induced fluorescence measurements of the 5d[4]7/2-6p[3]5/2 xenon ion excited state transition. The evolution of the axial and radial velocity distributions is presented from the exit plane to approximately 0.7 exit diameters downstream. It is shown that the distributions evolve significantly between the exit channel center and the inner portion of the channel where there are high frac-tions of low velocity ions. It is believed that this may be due to the slight inward focus of the xenon ion propellant colliding on the surface, recombining, and subsequently being re-ionized. Low axial velocity ions appear downstream of the thruster exit plane. While their origin is not entirely certain, the most likely explanation appears to be cross annular flow. Strong evidence of charge exchange is also evident producing high velocity wings on the primary ion velocity peak reminiscent of ion energy analyzer studies of other thrusters. A survey of the axial and radial velocity distributions along the exposed exterior boron nitride nose cone covering the central magnetic pole is performed to determine the behavior of the ions impacting this critical surface. The VDF is ideal for comparison with numerical simulations since it allows for direct comparison of the fundamental ion acceleration. External VDF data can even provide limited insight as to the internal ion formation and acceleration processes.
Download or read book Evolution of the Ion Velocity Distribution in the Near Field of a 200 W Hall Thruster Preprint written by and published by . This book was released on 2006 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents an analysis of near plume velocity distributions of the Busek BHT-200-X3 200 W laboratory Hall thruster derived from laser-induced fluorescence measurements of the 5d[4]7/2-6p[3]5/2 xenon ion excited state transition. The evolution of the axial and radial velocity distributions is presented from the exit plane to approximately 0.7 exit diameters downstream. It is shown that the distributions evolve significantly between the exit channel center and the inner portion of the channel where there are high frac-tions of low velocity ions. It is believed that this may be due to the slight inward focus of the xenon ion propellant colliding on the surface, recombining, and subsequently being re-ionized. Low axial velocity ions appear downstream of the thruster exit plane. While their origin is not entirely certain, the most likely explanation appears to be cross annular flow. Strong evidence of charge exchange is also evident producing high velocity wings on the primary ion velocity peak reminiscent of ion energy analyzer studies of other thrusters. A survey of the axial and radial velocity distributions along the exposed exterior boron nitride nose cone covering the central magnetic pole is performed to determine the behavior of the ions impacting this critical surface. The VDF is ideal for comparison with numerical simulations since it allows for direct comparison of the fundamental ion acceleration. External VDF data can even provide limited insight as to the internal ion formation and acceleration processes.
Download or read book Background Pressure Effects on Internal and Near field Ion Velocity Distribution of the BHT 600 Hall Thruster Preprint written by and published by . This book was released on 2008 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presented is a study of the effects of chamber background pressure on the ion axial velocity distribution within the discharge chamber and in the near-field of the Busek BHT-HD-600 xenon Hall effect thruster. Ion velocity distributions were measured along the acceleration channel centerline using laser-induced fluorescence of the 5d[4](sub 7/2)-6p[3](sub 5/2) xenon ion excited state transition. Measurements were taken at the lowest possible chamber background pressure and a pressure that was a factor of two higher. In addition to varying the background pressure, the magnetic field of the discharge chamber was switched between two configurations. The radial magnetic was set to a low and high strength case, which produced two different anode current oscillatory regimes. Ion axial velocity distribution function peaks were used to approximate ion energy and axial electric field strength to compare the acceleration profiles of the tested thruster operating conditions. Increasing background pressure shifted the ion acceleration region upstream in the discharge chamber. The width of the velocity distributions correlated strongly to the radial magnetic field strength. The high magnetic field case data showed narrower peaks.
Download or read book Experimental and Numerical Examination of the BHT 200 Hall Thruster Plume Postprint written by and published by . This book was released on 2007 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The plume of a Busek BHT-200 xenon Hall thruster has been characterized through measurements from various plasma electrostatic probes. Ion current flux, plasma potential, plasma density, and electron temperatures were measured in the near-field of the plume to 60 cm downstream of the exit plane. These experimentally derived measurements were compared to simulations of the thruster/vacuum chamber environment using the plasma plume code DRACO. The goals of this study were to gain understanding of the effect of the vacuum facility on the thruster plume and to determine the fidelity of the DRACO numerical simulation.
Download or read book ExB Measurements of a 200 W Xenon Hall Thruster written by and published by . This book was released on 2005 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Angularly resolved ion species fractions of Xe+1, Xe+2, and Xe+3 in the Busek BHT-200-X3 xenon Hall thruster plume were measured using an ExB probe for several operating conditions. The thruster was operated at nominal anode potential of 250 V and swept from 200 V to 325 V in 25 V increments. The ExB probe was placed 60 cm downstream of the exit plane and rotated up to 90 degrees from centerline. At the nominal anode potential, the ion species fractions of the multiply charged xenon ions were lower, while at increased discharged voltages Xe+2 and Xe+3 showed an increase in their respective species fractions. At angles beyond 35 degrees, an additional low energy peak was observed suggesting additional collisions in the far-field produce these low energy ions. Our goals are to characterize the thruster ion distribution and to verify predictions of various numerical models by investigating the effects of thruster operation and chamber backpressure on the production of charge exchange ions.
Download or read book Preliminary Plume Characterization of a Low Power Hall Thruster Cluster written by and published by . This book was released on 2002 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an effort to understand the technical issues related to running multiple Hall effect thrusters in close proximity to each other, testing of a cluster of four Busek BHT-200-X3 devices has begun in Chamber 6 at the Air Force Research Laboratory. Preliminary measurements have shown that the variations in the discharge currents of the four thrusters are synchronized, possibly due to cross talk through the thruster plumes. Measurements of plasma density, electron temperature, and plasma potential in the thruster plumes obtained using a triple Langmuir probe are presented. Anomalously high electron temperatures were recorded along the centerline of each thruster. Collisionless, magnetosonic shock waves induced by the ion-ion two-stream instability are proposed as a possible cause of the high temperatures. The unperturbed ion velocity distribution along the centerline of a Hall thruster is shown to be unstable and a simple geometric model is presented to illustrate the qualitative changes in plasma properties expected across the proposed shock. Estimates using this model show that relatively large changes in electron temperature are consistent with small changes in electron number density across a shock. Qualitative arguments are presented indicating that collisionless shocks are unlikely to form as a result of clustering multiple thrusters. In an effort to understand the technical issues related to running multiple Hall effect thrusters in close proximity to each other, testing of a cluster of four Busek BHT-200-X3 devices has begun in Chamber 6 at the Air Force Research Laboratory. Preliminary measurements have shown that the variations in the discharge currents of the four thrusters are synchronized, possibly due to cross talk through the thruster plumes. Measurements of plasma density, electron temperature, and plasma potential in the thruster plumes obtained using a triple Langmuir probe are presented.
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.
Download or read book Performance Evaluation of the SPT 140 written by and published by . This book was released on 1997 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electric Propulsion Development written by Ernst Stuhlinger and published by Elsevier. This book was released on 1963-01-01 with total page 763 pages. Available in PDF, EPUB and Kindle. Book excerpt: Progress in Astronautics and Aeronautics, Volume 9: Electric Propulsion Development covers the proceedings of the Second Electric Propulsion Conference of the American Rocker Society, held in Berkeley, California on March 14-16, 1962. The conference focuses on the existing problems in electric propulsion and their possible solutions. This book is organized into four sections encompassing 35 chapters. The first section deals with the thermodynamics of arcs; the problems of heat and momentum transfer; the chemical processes within arcs; the arc system materials; and the arc jet design problems. The second section considers the problems of ion systems, the various ion sources, and the neutralization of ion beams. This section also looks into the basic ionization processes, the production and charging of heavy particles, the corrosive properties of cesium, and the ion-optical designs. The third section describes various plasma systems, including helical transmission lines, pulsed pinch accelerators, coaxial systems, and j x B accelerators. The theoretical analyses of these systems are briefly examined. The fourth section includes papers on flight testing of electric propulsion models, on vertical rocket probes, and on satellites, This section also discusses some advanced concepts in electric propulsion, such as air scooping during ascent through the atmosphere, systems design and optimization, and planetary and interplanetary missions. This book is of great value to physicists, space engineers and designers, as well as researchers in the fields of astronautics and aeronautics.
Download or read book Laser Spectroscopy written by Wolfgang Demtröder and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 710 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impact of lasers on spectroscopy can hardly be overestimated. Lasers re present intense light sources with spectral energy densities which may exceed those of i ncoheren t sources by severa 1 orders of magnitude. Furthermore be cause of their extremely small bandwidth, single-mode lasers allow a spectral resolution which far exceeds that of conventional spectrometers. Many experi ments which could not be done before the application of lasers because of lack of intensity or insufficient resol ution are readily performed wi th lasers. Now several thousands of laser lines are known which span the whole spec tral range from the vacuum-ultraviolet to the far-infrared region. Of parti cular interest are the continuously tunable lasers which may in many cases replace wavelength-selecting elements, such as spectrometers or interferome ters. In combination with optical frequency mixing, techniques such conti nuously tunable monochromatic coherent light sources are available at nearly any desired wavelength above 100 nm.
Download or read book Fundamentals of Computational Fluid Dynamics written by H. Lomax and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chosen semi-discrete approach of a reduction procedure of partial differential equations to ordinary differential equations and finally to difference equations gives the book its distinctiveness and provides a sound basis for a deep understanding of the fundamental concepts in computational fluid dynamics.
Download or read book Atomic and Molecular Spectroscopy written by Sune Svanberg and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: A wide-ranging review of modern techniques in atomic and molecular spectroscopy. A brief description of atomic and molecular structure is followed by the relevant energy structure expressions. A discussion of radiative properties and the origin of spectra leads into coverage of X-ray and photoelectron spectroscopy, optical spectroscopy, and radiofrequency and microwave techniques. The treatment of laser spectroscopy investigates various tunable sources and a wide range of techniques characterized by high sensitivity and high resolution. Throughout this book, the relation between fundamental and applied aspects is shown, in particular by descriptions of applications to chemical analysis, photochemistry, surface characterisation, environmental and medical diagnostics, remote sensing and astrophysics.
Download or read book Advanced Space Propulsion Systems written by Martin Tajmar and published by Springer Science & Business Media. This book was released on 2012-09-08 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: Space propulsion systems have a great influence on our ability to travel to other planets or how cheap a satellite can provide TV programs. This book provides an up-to-date overview of all kinds of propulsion systems ranging from classical rocket technology, nuclear propulsion to electric propulsion systems, and further to micro-, propellantless and even breakthrough propulsion, which is a new program under development at NASA. The author shows the limitations of the present concepts and how they could look like in the future. Starting from historical developments, the reader is taken on a journey showing the amazing technology that has been put on hold for decades to be rediscovered in the near future for questions like how we can even reach other stars within a human lifetime. The author is actively involved in advanced propulsion research and contributes with his own experience to many of the presented topics. The book is written for anyone who is interested in how space travel can be revolutionized.
Download or read book Picture Processing and Digital Filtering written by T.S. Huang and published by Springer Science & Business Media. This book was released on 2013-12-11 with total page 301 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Micropropulsion for Small Spacecraft written by Michael Matthew Micci and published by AIAA. This book was released on 2000 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
