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Author : Brian Peters
Publisher :
ISBN 13 :
Total Pages : 116 pages
Book Rating : 4.:/5 (64 download)
Download or read book Magnetic Field Penetration and Enhanced Diffusion in Pulsed Plasma Thrusters written by Brian Peters and published by . This book was released on 2005 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Christian Thomas Dum
Publisher :
ISBN 13 :
Total Pages : 288 pages
Book Rating : 4.:/5 (251 download)
Download or read book Nonlinear Stabilization and Enhanced Diffusion of a Turbulent Plasma in a Magnetic Field written by Christian Thomas Dum and published by . This book was released on 1968 with total page 288 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 17 pages
Book Rating : 4.:/5 (742 download)
Download or read book PPT Research at AFRL: Material Probes to Measure the Magnetic Field Distribution in a Pulsed Plasma Thruster written by and published by . This book was released on 1998 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of the PPT basic research program at AFRL has now shifted to understanding the sources of the low energy efficiency. Based on previous research modifications such as changing the electrode geometry, discharge frequency, and discharge energy may all result in moderate increases to the energy efficiency. What is required from a basic research standpoint is a diagnostic capability that can acquire information with sufficient accuracy to enable PPT designers to understand why certain influences increase performance - and then design PPTs which maximize these effects. To model a fluid description of the PPT plasma, the critical measurements are magnetic field and density. Temperature, composition and charge state also become critical as the models become more detailed. This paper describes a magnetic field probe array used at AFRL to map the magnetic fields in a laboratory model PPT. The paper focuses on determining to what extent the probe perturbs the plasma, the measurement limitations. Also discussed are options towards making this critical measurement with increased accuracy.
Author :
Publisher :
ISBN 13 :
Total Pages : 456 pages
Book Rating : 4.:/5 (3 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Author :
Publisher :
ISBN 13 :
Total Pages : 29 pages
Book Rating : 4.:/5 (742 download)
Download or read book Electromagnetic Effects in the Near Field Plume Exhaust of a Micro-Pulsed Plasma Thruster written by and published by . This book was released on 2002 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work we present a model of the near field plasma plume of a Pulsed Plasma Thruster (PPT). As a working example we consider a micro-PPT developed at the Air Force Research Laboratory. This is a miniaturized design of the axisymmetric PPT with a thrust in the 10 micro-N range that utilizes Teflon(Trademark(sup Trademark)) as a propellant. The plasma plume is simulated using a hybrid fluid-PIC-DSMC approach. The plasma plume model is combined with Teflon(Trademark) ablation and plasma generation models that provide boundary conditions for the plume. This approach provides a consistent description of the plasma flow from the surface into the near plume. The magnetic field diffusion into the plume region is also considered and plasma acceleration by the electromagnetic mechanism is studied. Teflon(Trademark) ablation and plasma generation analyses show that file Teflon(Trademark) surface temperature and plasma parameters are strongly non-uniform in the radial direction. The plasma density near the propellant surface peaks at about 10(exp 24)/cu m in the middle of the propellant face while the electron temperature peaks at about 4 eV near the electrodes. The plume simulation shows that a dense plasma focus is developed at a few millimeters from the thruster exit plane at the axis. This plasma focus exists during the entire pulse, but the plasma density in the focus decreases from about 2x10(exp 22)/cu m at the beginning of the pulse down to 0.3x10(exp 22)/cu m at 5 microsec. The velocity phase is centered at about 20 km/s in the axial direction. At later stages of the pulse there are two ion populations with positive and negative radial velocity. Electron densities predicted by file plume model are compared with near field measurements using a Herriot Cell technique and very good agreement is obtained.
Author : Allan J. Cohen
Publisher :
ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (31 download)
Download or read book An Electron Bombardment Thruster Operated with a Cusped Magnetic Field written by Allan J. Cohen and published by . This book was released on 1969 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : C. L. Dailey
Publisher :
ISBN 13 :
Total Pages : 39 pages
Book Rating : 4.:/5 (227 download)
Download or read book Magnetic Field Annihilation of Plasmas for Advanced Plasma Engine Design written by C. L. Dailey and published by . This book was released on 1971 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ejection of energetic streams of plasma from the sun during solar flares indicates the action of a powerful acceleration process. This mechanism has been explained in terms of the rapid release of magnetic field energy resulting from the collision of streams of plasma carrying oppositely directed magnetic fields. In such a collison the field is annihilated and the corresponding energy is converted to kinetic energy of the ejected plasma. A two-coil pulsed inductive machine has been built at TRW Systems which makes use of this process to accelerate and heat a plasma. In one region of the machine the solar flare process is produced and the energy released by magnetic field annihilation is converted to kinetic energy. The information obtained from experiments in this region of the machine can be applied to the design of a high performance pulsed plasma thruster. In a different region of the device the magnetic field energy is converted to ion heating and compression. The application of the field annihilation mechanism may be useful for controlled thermonuclear fusion. This report describes the two-coil accelerator and reviews the background upon which the experimental investigation is based. Construction of the machine is finished and testing of the control circuitry is proceeding. (Author).
Author :
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ISBN 13 :
Total Pages : 218 pages
Book Rating : 4.:/5 (317 download)
Download or read book The Effects of Magnetic Nozzle Configurations on Plasma Thrusters written by and published by . This book was released on 1997 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : C. L. Dailey
Publisher :
ISBN 13 :
Total Pages : 46 pages
Book Rating : 4.:/5 (227 download)
Download or read book Pulsed Plasma Acceleration in Strong Bias Magnetic Fields for Electric Propulsion Application written by C. L. Dailey and published by . This book was released on 1978 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is shown that ohmic efficiency is limited to 50% for self-field quasi-steady plasma acceleration and for impulsive acceleration in small scale devices. This limit also applies when a constant bias field is added to the self-field but it can be removed by using a bias field that decreases in the acceleration direction. Tests were conducted with a bias field thruster in an attempt to demonstrate increased efficiency. It consisted of a V-shaped channel placed between pole pieces of a permanent magnet having the same divergence angle as the channel; electrodes were located in the upper and lower surfaces of the channel. Operation was quasi-steady for a current discharge period of 800 microseconds. Gas injection was continuous and was done in two ways - in one mode it was introduced through hollow electrodes, in the other it entered the channel through a narrow slit. In the final version tested the channel was made of alumina and tungsten electrodes were used. Impulse enhancement due to the bias field was determined by suspending the magnet from piano wires and measuring its deflection when the thruster was fired. For argon injection through the electrodes, the current was carried down-stream from the magnet in the usual self-field discharge mode and no magnet deflection occurred. For axial injection of argon a large magnet deflection occurred. This was found to be due to current carried on the sidewalls which was stabilized by the sidewalls and which produced severe ablation of the alumina. When a mixture of hydrogen and nitrogen was substituted for argon, no magnet deflection occurred.
Author : Dan M. Goebel
Publisher : John Wiley & Sons
ISBN 13 : 0470436263
Total Pages : 528 pages
Book Rating : 4.4/5 (74 download)
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.
Author : Ron Armale
Publisher :
ISBN 13 :
Total Pages : 198 pages
Book Rating : 4.:/5 (341 download)
Download or read book Fast Magnetic Field Penetration Into a Plasma written by Ron Armale and published by . This book was released on 1994 with total page 198 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 69 pages
Book Rating : 4.:/5 (742 download)
Download or read book Breakthrough to Optimized Pulsed Plasma Thrusters written by and published by . This book was released on 2004 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analytic models predict the possibility of extending the range of performance parameters of Pulsed Plasma Thrusters (PPT) by using propellants other than the traditionally used Teflon. A theoretical and experimental effort was initiated at The Ohio State University to investigate the use of alternative propellants for PPT. Analytical and numerical calculations (MACH2) indeed indicate a significant broadening of the obtainable range of specific impulse and thrust-to-power ratios when alternative propellants such as lithium or water are utilized. Consequently, in an effort to investigate changes in physical phenomena and thruster performance experimentally, a hybrid thruster was designed and built, facilitating the use of alternatively water or Teflon. The thruster design includes a unique water propellant feed system, allowing the supply of the water propellant without detrimentally affecting the inherent simplicity of the PPT system. The thruster operation and performance was investigated by several different diagnostic methods, including current and voltage measurements, Langmuir probes, and magnetic field probes. Furthermore, impact pressure measurements in the plume of the thruster allowed new insight into the plume structure and the accurate evaluation of impulse bits. Employment of the diagnostic methods for Teflon and water propellant enabled the unambiguous identification of propellant related effects such as reduced electron temperature and higher exhaust velocities in the case of water propellant.
Author :
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (946 download)
Download or read book Plasma Processes in Pulsed Plasma Microthrusters written by and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This final technical report summarizes research on low-power pulsed Teflon(Trademark) plasma propulsion for satellites. Section I discusses a compact thrust stand used to make thrust and impulse bit measurements. Section II describes experimental measurements on a gasdynamic-type PPT in which measurements of magnetic field, electron number density, electron temperature, ion speed ratio and gas velocity are carried out by magnetic and advanced Langmuir probes. This section also describes thrust and heat-loss measurements. Section III outlines research with an electromagnetic-type PPT, intended to achieve very high specific impulse and efficiency.
Author : Lyman Spitzer
Publisher :
ISBN 13 :
Total Pages : 12 pages
Book Rating : 4.:/5 (713 download)
Download or read book Diffusion of a Plasma Across a Magnetic Field written by Lyman Spitzer and published by . This book was released on 1957 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Nicole J. Meckel
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (11 download)
Download or read book Improved Pulsed Plasma Thruster Systems for Satellite Propulsion written by Nicole J. Meckel and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Michael Lane Garrett
Publisher :
ISBN 13 :
Total Pages : 120 pages
Book Rating : 4.:/5 (871 download)
Download or read book Fluctuation Induced Cross-field Transport in Hall Thrusters and Tokamaks written by Michael Lane Garrett and published by . This book was released on 2013 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: One area of fundamental plasma physics which remains poorly understood is the transport of particles across magnetic field lines at rates significantly higher than predicted by theory exclusively based on collisions. This "anomalous" transport is observed in many different classes of plasma experiment. Notably, both magnetic confinement fusion devices and Hall thrusters exhibit anomalous cross-field particle diffusion. This higher than predicted "loss" of particles has significant practical implications for both classes of experiment. In the case of magnetic confinement fusion experiments, such as tokamaks, the Lawson criterion nT[tau]E >/= 1021 [keV. s. M- 3] dictates that the reactant particles in a fusion plasma must be confined for a sufficient time to fuse. Higher than predicted cross-field transport decreases the effectiveness of the magnetic confinement and makes fusion more difficult to achieve. For Hall thrusters, enhanced cross-field electron mobility reduces the efficiency of the thruster. As a result, more propellant and power is required to achieve the same thrust. The goal of this thesis is to review observed and predicted fluctuation induced particle transport in Hall thrusters and tokamaks. To date, significant work has been done within both the tokamak and propulsion communities to attempt to quantify the effect of turbulent fluctuations of plasma parameters on anomalous cross-field transport. However, our understanding of the fundamental physical processes that lead to anomalously high cross-field transport remains incomplete. These two regimes of plasma physics are very different in several important ways. The magnetic field strength and field orientation, the device size, the collisionality of different species, the ion mass, and the presence of neutrals are all areas with significant differences between tokamaks and Hall thrusters. However, there are similarities as well. For example, the edge density and temperature in a tokamak are similar to those found in Hall thrusters, both have magnetized electrons, drift waves occur in both regimes and many of the observed fluctuations are of similar scale. Generally, research on cross-field transport within the tokamak community is isolated from work done within the thruster community. However, analysis of physics within both regimes reveals a rich set of complex fluctuations across a broad frequency spectrum, which contribute to cross-field transport. By studying the relevant phenomena in tandem, we can reveal fundamental processes present in both regimes. Hopefully, this will lead to a global explanation for these elusive physical processes.
Author :
Publisher :
ISBN 13 :
Total Pages : 102 pages
Book Rating : 4.:/5 (946 download)
Download or read book Physics and Dynamics of Current Sheets in Pulsed Plasma Thrusters written by and published by . This book was released on 2002 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this final report we present the results of our AFOSR-sponsored studies of the physics and dynamics of current sheets in electronmagnetic, pulsed, plasma thrusters (PPTs). The research project focused on the fundamental aspects of the physics and dynamics that are most relevant to improving the performance of PPTs. In particular, we focused on the problems of current sheet canting and current sheet initiation, both of which can lead to adverse effects on the mass utilization and propulsive efficiencies of PPTs operating in the electromagnetic mode.
