Download or read book Propellant Inefficiency Due to Particulates in a Pulsed Plasma Thruster written by and published by . This book was released on 1997 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Propellant inefficiency resulting from the ejection of propellant material in particulate form is characterized in a Pulsed Plasma Thruster (PPT). Exhaust deposits are collected and analyzed using a combination of Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis. (EDAX), and microscopic imaging. Teflon particulates are observed with sizes ranging from over 100 mum down to less than 1 mum. Estimates of the mass entrained in this form show that the particulates may account for up to 30% of the total propellant mass used, indicating that methods of ameliorating this loss mechanism would result in significant improvements in the PPT thrust efficiency.
Download or read book Propellant Losses Because of Particulate Emission in a Pulsed Plasma Thruster written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Propellant inefficiency material in particulate form is characterized in a laboratory pulsed plasma thruster (PPT) operating at 1 Hz with a 204 discharge energy (20 W). Exhaust deposits are collected and analyzed using a combination of a scanning electron microscope with energy dispersive x-ray analysis and microscopic imaging. Teflon(trademark) particulates are observed with characteristic dianietens ranging from over 100 micrometers down to less than 1 micrometer.
Download or read book Particulate Emission from a Pulsed Plasma Thruster written by Gregory G. Spanjers and published by . This book was released on 1996 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Propellant inefficiency resulting from the ejection of propellant material in particulate form is characterized in a Pulsed Plasma Thruster (PPT). Exhaust deposits are collected and analyzed using a combination of Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis (EDAX), and microscopic imaging. Teflon particulates are observed with sizes ranging from over 100 microns down to less than 1 microns. Estimates of the mass entrained in this form show that the particulates may account for up to 20% of the total propellant mass used, indicating that methods of ameliorating this loss mechanism would result in significant improvements in the PPT thrust efficiency.
Download or read book Effect of Propellant Temperature on Efficiency in the Pulsed Plasma Thruster written by and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A pulsed plasma thruster (PPT) benefits from the inherent engineering simplicity-and reduced tankage fraction gained by storing the propellant as a solid. The solid is converted to the gaseous state and accelerated by an electric discharge across the propellant face. Previous research has concluded that as little as 10% of the consumed propellant is converted to plasma and efficiently accelerated. The remaining propellant is consumed in the form of late-time vaporization and particulate emission, creating minimal thrust. Critical to improving the PPT performance is improving the propellant utilization. The present work demonstrates one possible method of increasing the PPT propellant efficiency. By measuring the PPT thrust, propellant consumption, and propellant temperature while varying the power level, duration of the experimental run, and total propellant mass, a correlation is established between decreased propropellant temperature and increased propellant efficiency. The method is demonstrated by performance measurements at 60 W and S W, which show a 25% increase in thrust efficiency, while the propellant temperature decreases from 135 to 42 deg C. Larger increases in the efficiency may be realized on-orbit where operating temperatures are commonly subzero. The dependence of propellant consumption on temperature also creates systematic errors in laboratory measurements with short experimental runs, and orbit analyses where the PPT performance measured at one power level is linearly scaled to the power available on the spacecraft.
Download or read book The Effect of Propellant Temperature on Efficiency in a Pulsed Plasma Thruster written by Gregory G. Spanjers and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Propellant Inefficiencies in a Pulsed Plasma Thruster written by and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Pulsed Plasma Thruster (PPT) benefits from the inherent engineering simplicity and reduced tankage fraction gained by storing the propellant as a solid. The solid is converted to the gaseous state during an electric surface discharge. Previous research has concluded that the bulk of the propellant expands gas-dynamically from the chamber at low directed velocity, with possibly as little as 10% ionized and efficiently accelerated to high velocity using electromagnetic forces. The two velocity components result in a low propellant utilization efficiency. Critical to improving the PPT efficiency is preventing the formation of the low-velocity propellant and/or developing a means of accelerating it electromagnetically. In the present work measurements are made of the solid propellant conversion to the gaseous state with the intent of better understanding the formation process. By better understanding the propellant conversion it is hoped that future PPTs can be designed with significantly increased propellant efficiencies.
Download or read book Pulsed Plasma Thruster Using Water Propellant written by Carsten A. Scharlemann and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Performance Study on Liquid Propellant Pulsed Plasma Thruster written by Akira Kakami and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Performance of Gas fed Pulsed Plasma Thrusters Using Water Vapor Propellant written by John K. Ziemer and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Basic Research in Electric Propulsion Part I Pulsed Plasma Thruster Propellant Efficiency and Contamination Part II Arcjet Remote Plume Measurement and Hydrogen Density written by and published by . This book was released on 2002 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Pulsed Plasma Thrusters (PPT) have been the major technology under investigation for the Small Satellite Electric Propulsion Thruster Research program. Arcjet technology is also under investigation with Electric Propulsion Space Experiment Optical Signature experiments underway and Multiphoton Laser Induced Fluorescence Measurements of Ground State Atomic Hydrogen have been performed in an arcjet plume. At present PPTs are being tested in the laboratory environment with investigations under way to determine exact inefficiency mechanisms that can be corrected. This work has already identified previously unknown physical behavior in the PPT. The Electric Propulsion Space Experiment is a flight demonstration of a 30 kW ammonia arcjet propulsion system. Optical measurements of the arcjet plume were performed using on-board optical equipment ground observatories and other space platforms. Low power arcjet technology provided definitive work on atomic species plume concentrations in low power hydrogen arcjet plumes. This work applied a flame diagnostic Multiphoton Laser Induced Fluorescence to the excited-state plasma environment to investigate concentration levels of atomic ground-state hydrogen.
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 Alternate Propellant Evaluation for 100 joule Class Pulsed Plasma Thrusters written by Eric J. Pencil and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transport Processes in Pulsed Plasma Thrusters written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The simplicity of the pulsed plasma microthruster (PPT) allowed its selection for space flight application, even with low efficiency relative to other concepts. Improvements to PPT thrust efficiency and specific impulse represent today's challenges for research and development. Self consistent modeling of PPT behavior requires a description of the flow composition as it changes from complex molecular forms to highly ionized, constituent atoms. Heat flux from the plasma discharge to the solid propellant, (traditionally, Teflon), depends on transport coefficients for electrical and thermal conductivity in the partially ionized flow. Numerical simulations now use an existing, single temperature equation of state for Teflon (from the SESAME tables) along with classical transport formulas based on Coulomb collisions. The principal effort under the present grant has been to develop a two-temperature, LTE model for Teflon in the regime of interest for PPTs. This model includes 25 species (atoms, molecules, ions and electronics) and allows separates heavy-particle and electron temperatures. An idealized analysis, limited to one-dimensional, quasi-steady MHD flow, but incorporating resistive heating and thermal diffusion, has also been developed and provides useful guidance on PPT operation and propellant behavior.
Download or read book Investigation of Thrust Mechanisms in a Water Fed Pulsed Plasma Thruster written by Carsten A. Scharlemann and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: 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. ii 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 unambigous identification of propellant related effects such as reduced electron temperature and higher exhaust velocites in the case of water propellant. The electromagnetic nature of the water thruster was clearly identified. For 30 J discharge energy, the water thruster requires only 5% of the mass bit of a Teflon thruster to produce an impulse bit 30% of the magnitude of the Teflon thruster, suggesting greatly increased propellant efficiencies. In agreement with the plasma diagnostic results, a specific impulse for the water thruster of up to 8000 s and efficiencies of up to 16% were evaluated.
Download or read book Propellant and Central Electrode Optimization of a Coaxial Pulsed Plasma Thruster written by Julia Katherine Laystrom and published by . This book was released on 2004 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Numerical Analysis of the Effect of Propellant Material Properties on Pulsed Plasma Thruster Performance written by Ronald Lynn Corey and published by . This book was released on 2000 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Study of a Dual Stage Solid Propellant Pulsed Plasma Thruster written by Clémence Royer and published by . This book was released on 2018 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt:
