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Author : David Kaplan
Publisher :
ISBN 13 :
Total Pages : 88 pages
Book Rating : 4.:/5 (317 download)
Download or read book Environment of Mars, 1988 written by David Kaplan and published by . This book was released on 1988 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : OECD
Publisher : OECD Publishing
ISBN 13 : 9264099506
Total Pages : 119 pages
Book Rating : 4.2/5 (64 download)
Download or read book Improving Water Management Recent OECD Experience written by OECD and published by OECD Publishing. This book was released on 2003-02-21 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt: This publication brings together the recent work of the OECD on water management issues. It identifies the main policy challenges addressed by that work for sustainable water management.
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721531929
Total Pages : 30 pages
Book Rating : 4.5/5 (319 download)
Download or read book Ion Engine and Hall Thruster Development at the NASA Glenn Research Center written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: NASA's Glenn Research Center has been selected to lead development of NASA's Evolutionary Xenon Thruster (NEXT) system. The central feature of the NEXT system is an electric propulsion thruster (EPT) that inherits the knowledge gained through the NSTAR thruster that successfully propelled Deep Space 1 to asteroid Braille and comet Borrelly, while significantly increasing the thruster power level and making improvements in performance parameters associated with NSTAR. The EPT concept under development has a 40 cm beam diameter, twice the effective area of the Deep-Space 1 thruster, while maintaining a relatively-small volume. It incorporates mechanical features and operating conditions to maximize the design heritage established by the flight NSTAR 30 cm engine, while incorporating new technology where warranted to extend the power and throughput capability. The NASA Hall thruster program currently supports a number of tasks related to high power thruster development for a number of customers including the Energetics Program (formerly called the Space-based Program), the Space Solar Power Program, and the In-space Propulsion Program. In program year 2002, two tasks were central to the NASA Hall thruster program: 1.) the development of a laboratory Hall thruster capable of providing high thrust at high power; 2.) investigations into operation of Hall thrusters at high specific impulse. In addition to these two primary thruster development activities, there are a number of other on-going activities supported by the NASA Hall thruster program, These additional activities are related to issues such as thruster lifetime and spacecraft integration. Domonkos, Matthew T. and Patterson, Michael J. and Jankovsky, Robert S. Glenn Research Center NASA/TM-2002-211969, NAS 1.15:211969, E-13612, IMECE-2002-34444
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721607761
Total Pages : 32 pages
Book Rating : 4.6/5 (77 download)
Download or read book The Influence of Current Density and Magnetic Field Topography in Optimizing the Performance, Divergence, and Plasma Oscillations of High Specific Impulse Hall Thrusters written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent studies of xenon Hall thrusters have shown peak efficiencies at specific impulses of less than 3000 s. This was a consequence of modern Hall thruster magnetic field topographies, which have been optimized for 300 V discharges. On-going research at the NASA Glenn Research Center is investigating this behavior and methods to enhance thruster performance. To conduct these studies, a laboratory model Hall thruster that uses a pair of trim coils to tailor the magnetic field topography for high specific impulse operation has been developed. The thruster-the NASA-173Mv2 was tested to determine how current density and magnetic field topography affect performance, divergence, and plasma oscillations at voltages up to 1000 V. Test results showed there was a minimum current density and optimum magnetic field topography at which efficiency monotonically increased with voltage. At 1000 V, 10 milligrams per second the total specific impulse was 3390 s and the total efficiency was 60.8%. Plume divergence decreased at 400-1000 V, but increased at 300-400 V as the result of plasma oscillations. The dominant oscillation frequency steadily increased with voltage, from 14.5 kHz at 300 V, to 22 kHz at 1000 V. An additional oscillatory mode in the 80-90 kHz frequency range began to appear above 500 V. The use of trim coils to modify the magnetic field improved performance while decreasing plume divergence and the frequency and magnitude of plasma oscillations. Hofer, Richard R. and Jankovsky, Robert S. Glenn Research Center NASA/TM-2003-212605, E-14163, IEPC-2003-142
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721604029
Total Pages : 36 pages
Book Rating : 4.6/5 (4 download)
Download or read book Recent Results from Internal and Very-Near-Field Plasma Diagnostics of a High Specific Impulse Hall Thruster written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: Floating potential and ion current density measurements were taken on the laboratory model NASA-173Mv2 in order to improve understanding of the physical processes affecting Hall thruster performance at high specific impulse. Floating potential was measured on discharge chamber centerline over axial positions spanning 10 mm from the anode to 100 mm downstream of the exit plane. Ion current density was mapped radially up to 300 mm from thruster centerline over axial positions in the very-near-field (10 to 250 mm from the exit plane). All data were collected using a planar probe in conjunction with a high-speed translation stage to minimize probe-induced thruster perturbations. Measurements of floating potential at a xenon flow rate of 10 mg/s have shown that the acceleration layer moved upstream 3 1 mm when the voltage increased from 300 to 600 V. The length of the acceleration layer was 14 2 mm and was approximately constant with voltage and magnetic field. Ion current density measurements indicated the annular ion beam crossed the thruster centerline 163 mm downstream of the exit plane. Radial integration of the ion current density at the cathode plane provided an estimate of the ion current fraction. At 500 V and 5 mg/s, the ion current fraction was calculated as 0.77. Hofer, Richard R. and Gallimore, Alec D. and Jacobson, David (Technical Monitor) Glenn Research Center NASA/CR-2003-212604, E-14162, IEPC-2003-037
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781722016074
Total Pages : 38 pages
Book Rating : 4.0/5 (16 download)
Download or read book A Preliminary Investigation of Hall Thruster Technology written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-28 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: A three-year NASA/BMDO-sponsored experimental program to conduct performance and plume plasma property measurements on two Russian Stationary Plasma Thrusters (SPTs) has been completed. The program utilized experimental facilitates at the University of Michigan's Plasmadynamics and Electric Propulsion Laboratory (PEPL). The main features of the proposed effort were as follows: (1) Characterized Hall thruster (and arcjet) performance by measuring ion exhaust velocity with probes at various thruster conditions; (2) Used a variety of probe diagnostics in the thruster plume to measure plasma properties and flow properties including T(sub e) and n(sub e) ion current density and ion energy distribution, and electric fields by mapping plasma potential; (3) Used emission spectroscopy to identify species within the plume and to measure electron temperatures. A key and unique feature of our research was our collaboration with Russian Hall thruster researcher Dr. Sergey A Khartov, Deputy Dean of International Relations at the Moscow Aviation Institute (MAI). His activities in this program included consulting on and participation in research at PEPL through use of a MAI-built SPT and ion energy probe. Gallimore, Alec D. Glenn Research Center NAG3-1504...
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721287093
Total Pages : 34 pages
Book Rating : 4.2/5 (87 download)
Download or read book Hall Thruster Plume Measurements On-Board the Russian Express Satellites written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The operation of North-South and East-West station-keeping Hall thruster propulsion systems on-board two Russian Express-A geosynchronous communication satellites were investigated through a collaborative effort with the manufacturer of the spacecraft. Over 435 firings of 16 different thrusters with a cumulative run time of over 550 hr were reported with no thruster failures. Momentum transfer due to plume impingement was evaluated based on reductions in the effective thrust of the SPT-100 thrusters and induced disturbance torques determined based on attitude control system data and range data. Hall thruster plasma plume effects on the transmission of C-band and Ku-band communication signals were shown to be negligible. On-orbit ion current density measurements were made and subsequently compared to predictions and ground test data. Ion energy, total pressure, and electric field strength measurements were also measured on-orbit. The effect of Hall thruster operation on solar array performance over several months was investigated. A subset of these data is presented. Manzella, David and Jankovsky, Robert and Elliott, Frederick and Mikellides, Ioannis and Jongeward, Gary and Allen, Doug Glenn Research Center; Jet Propulsion Laboratory; Marshall Space Flight Center NASA/TM-2001-211217, NAS 1.15:211217, E-13069
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721674022
Total Pages : 38 pages
Book Rating : 4.6/5 (74 download)
Download or read book Efficiency Analysis of a High-Specific Impulse Hall Thruster written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: Performance and plasma measurements of the high-specific impulse NASA-173Mv2 Hall thruster were analyzed using a phenomenological performance model that accounts for a partially-ionized plasma containing multiply-charged ions. Between discharge voltages of 300 to 900 V, the results showed that although the net decrease of efficiency due to multiply-charged ions was only 1.5 to 3.0 percent, the effects of multiply-charged ions on the ion and electron currents could not be neglected. Between 300 to 900 V, the increase of the discharge current was attributed to the increasing fraction of multiply-charged ions, while the maximum deviation of the electron current from its average value was only +5/-14 percent. These findings revealed how efficient operation at high-specific impulse was enabled through the regulation of the electron current with the applied magnetic field. Between 300 to 900 V, the voltage utilization ranged from 89 to 97 percent, the mass utilization from 86 to 90 percent, and the current utilization from 77 to 81 percent. Therefore, the anode efficiency was largely determined by the current utilization. The electron Hall parameter was nearly constant with voltage, decreasing from an average of 210 at 300 V to an average of 160 between 400 to 900 V. These results confirmed our claim that efficient operation can be achieved only over a limited range of Hall parameters. Jacobson, David (Technical Monitor) and Hofer, Richard R. and Gallimore, Alec D. Glenn Research Center NASA/CR-2004-213212, E-14720, AIAA Paper 2004-3602
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721297078
Total Pages : 34 pages
Book Rating : 4.2/5 (97 download)
Download or read book Nasa's Hall Thruster Program written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: NASA's Hall thruster program has base research and focused development efforts in support of the Advanced Space Transportation Program, Space-Based Program, and various other programs. The objective of the base research is to gain an improved understanding of the physical processes and engineering constraints of Hall thrusters to enable development of advanced Hall thruster designs. Specific technical questions that are current priorities of the base effort are: (1) How does thruster life vary with operating point? (2) How can thruster lifetime and wear rate be most efficiently evaluated? (3) What are the practical limitations for discharge voltage as it pertains to high specific impulse operation (high discharge voltage) and high thrust operation (low discharge voltage)? (4) What are the practical limits for extending Hall thrusters to very high input powers? and (5) What can be done during thruster design to reduce cost and integration concerns? The objective of the focused development effort is to develop a 50 kW-class Hall propulsion system, with a milestone of a 50 kW engineering model thruster/system by the end of program year 2006. Specific program wear 2001 efforts, along with the corporate and academic participation, are described. Jankovsky, Robert S. and Jacobson, David T. and Rawlin, Vincent K. and Mason, Lee S. and Mantenieks, Maris A. and Manzella, David H. and Hofer, Richard R. and Peterson, Peter Y. Glenn Research Center NASA/TM-2001-211215, E-13067, NAS 1.15:211215, AIAA Paper 2001-3888
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721610686
Total Pages : 32 pages
Book Rating : 4.6/5 (16 download)
Download or read book Ion Voltage Diagnostics in the Far-Field Plume of a High-Specific Impulse Hall Thruster written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: The effects of the magnetic field and discharge voltage on the far-field plume of the NASA 173Mv2 laboratory-model Hall thruster were investigated. A cylindrical Langmuir probe was used to measure the plasma potential and a retarding potential analyzer was employed to measure the ion voltage distribution. The plasma potential was affected by relatively small changes in the external magnetic field, which suggested a means to control the plasma surrounding the thruster. As the discharge voltage increased, the ion voltage distribution showed that the acceleration efficiency increased and the dispersion efficiency decreased. This implied that the ionization zone was growing axially and moving closer to the anode, which could have affected thruster efficiency and lifetime due to higher wall losses. However, wall losses may have been reduced by improved focusing efficiency since the total efficiency increased and the plume divergence decreased with discharge voltage. Hofer, Richard R. and Haas, James M. and Gallimore, Alec D. Glenn Research Center NASA/CR-2003-212895, AIAA Paper 2003-4556, E-14313
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721261611
Total Pages : 32 pages
Book Rating : 4.2/5 (616 download)
Download or read book Inter-Cusp Ion and Electron Transport in a Nstar-Derivative Ion Thruster written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: Diffusion of electrons and ions to anode surfaces between the magnetic cusps of a NASA Solar Electric Propulsion Technology Application Readiness ion thruster has been characterized. Ion flux measurements were made at the anode and at the screen grid electrode. The measurements indicated that the average ion current density at the anode and at the screen grid were approximately equal. Additionally, it was found that the electron flux to the anode between cusps is best described by the classical cross-field diffusion coefficient. Foster, John E. Glenn Research Center NASA/TM-2001-210669, NAS 1.15:210669, E-12535
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721192823
Total Pages : 30 pages
Book Rating : 4.1/5 (928 download)
Download or read book Internal Plasma Properties and Enhanced Performance of an 8 Cm Ion Thruster Discharge written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is a need for a lightweight, low power ion thruster for space science missions. Such an ion thruster is under development at NASA Glenn Research Center. In an effort to better understand the discharge performance of this thruster. a version of this thruster with an anode containing electrically isolated electrodes at the cusps was fabricated and tested. Discharge characteristics of this ring cusp ion thruster were measured without ion beam extraction. Discharge current was measured at collection electrodes located at the cusps and at the anode body itself. Discharge performance and plasma properties were measured as a function of discharge power, which was varied between 20 and 50 W. It was found that ion production costs decreased by as much as 20 percent when the two most downstream cusp electrodes were allowed to float. Floating the electrodes did not give rise to a significant increase in discharge power even though the plasma density increased markedly. The improved performance is attributed to enhanced electron containment. Foster, John E. and Patterson, Michael J. Glenn Research Center NASA/TM-1999-209386, E-11813, NAS 1.15:209386
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721294336
Total Pages : 32 pages
Book Rating : 4.2/5 (943 download)
Download or read book A Hall Thruster Performance Model Incorporating the Effects of a Multiply-Charged Plasma written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Hall thruster performance model that predicts anode specific impulse, anode efficiency, and thrust is discussed. The model is derived as a function of a voltage loss parameter, an electron loss parameter, and the charge state of the plasma. Experimental data from SPT and TAL type thrusters up to discharge powers of 21.6 kW are used to determine the best fit for model parameters. General values for the model parameters are found, applicable to high power thrusters and irrespective of thruster type. Performance of a 50 kW thruster is calculated for an anode specific impulse of 2500 seconds or a discharge current of 100 A. Hofer, Richard R. and Jankovsky, Robert S. Glenn Research Center NASA/TM-2002-211214, E-13066, NAS 1.15:211214, AIAA Paper 2001-3322
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721527458
Total Pages : 30 pages
Book Rating : 4.5/5 (274 download)
Download or read book Ferroelectric Emission Cathodes for Low-Power Electric Propulsion written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low- or no-flow electron emitters are required for low-power electric thrusters, spacecraft plasma contactors, and electrodynamic tether systems to reduce or eliminate the need for propellant/expellant. Expellant-less neutralizers can improve the viability of very low-power colloid thrusters, field emission electric propulsion devices, ion engines, Hall thrusters, and gridded vacuum arc thrusters. The NASA Glenn Research Center (GRC) is evaluating ferroelectric emission (FEE) cathodes as zero expellant flow rate cathode sources for the applications listed above. At GRC, low voltage (100s to approx. 1500 V) operation of FEE cathodes is examined. Initial experiments, with unipolar, bipolar, and RF burst applied voltage, have produced current pulses 250 to 1000 ns in duration with peak currents of up to 2 A at voltages at or below 1500 V. In particular, FEE cathodes driven by RF burst voltages from 1400 to 2000 V peak to peak, at burst frequencies from 70 to 400 kHz, emitted average current densities from 0.1 to 0.7 A/sq cm. Pulse repeatability as a function of input voltage has been initially established. Reliable emission has been achieved in air background at pressures as high as 10(exp -6) Torr. Kovaleski, Scott D. and Burke, Tom (Technical Monitor) Glenn Research Center NASA/CR-2002-211872, E-13554, NAS 1.26:211872, AIAA Paper 2002-4242
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781721507290
Total Pages : 26 pages
Book Rating : 4.5/5 (72 download)
Download or read book Carbon-Based Ion Optics Development at NASA Grc written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-21 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: With recent success of the NSTAR ion thruster on Deep Space 1, there is continued interest in long term, high propellant throughput thrusters to perform energetic missions. This requires flight qualified thrusters that can operate for long periods at high beam density, without degradation in performance resulting from sputter induced grid erosion. Carbon-based materials have shown nearly an order of magnitude improvement in sputter erosion resistance over molybdenum. NASA Glenn Research Center (GRC) has been active over the past several years pursuing carbon-based grid development. In 1995, NASA GRC sponsored work performed by the Jet Propulsion Laboratory to fabricate carbon/carbon composite grids using a machined panel approach. In 1999, a contract was initiated with a commercial vendor to produce carbon/carbon composite grids using a chemical vapor infiltration process. In 2001, NASA GRC purchased pyrolytic carbon grids from a commercial vendor. More recently, a multi-year contract was initiated with North Carolina A&T to develop carbon/carbon composite grids using a resin injection process. The following paper gives a brief overview of these four programs. Haag, Thomas and Patterson, Michael and Rawlin, Vince and Soulas, George Glenn Research Center; Jet Propulsion Laboratory; Marshall Space Flight Center NASA/TM-2002-211501, NAS 1.15:211501, IEPC-01-94, E-13241
