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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Pulsed plasma microthruster for synchronous meteorological satellite /SMS/

Two completely self contained variable thrust flight prototype plasma propulsion systems using solid teflon as propellant were designed, built and laboratory tested. The impulse bit amplitude of each thruster is 25 micro lb-sec. Impulse bits can be provided at rates varying from 50 ppm to 110 ppm. The total impulse capability is 400 lb-sec. Only 23 watts of bus power are required at maximum pulse rate. The system was subjected and passed the required vibration schedule and thermal vacuum test after a minor change in capacitor end face material. A 13 million discharge life test of the system was subsequently performed.

Guman, W. J.↗
NASA NTRS1975

CdS thin film solar cells for terrestrial power

The development of very low cost long lived Cu2S/CdS thin film solar cells for large scale energy conversion is reported. Excellent evaporated metal grid patterns were obtained using a specially designed aperture mask. Vacuum evaporated gold and copper grids of 50 lines per inch and 1 micron thickness were adequate electrically for the fine mesh contacting grid. Real time roof top sunlight exposure tests of encapsulated CdS cells showed no loss in output after 5 months. Accelerated life testing of encapsulated cells showed no loss of output power after 6 months of 12 hour dark-12 hour AMI illumination cycles at 40 C, 60 C, 80 C and 100 C temperatures. However, the cells changed their basic parameters, such as series and shunt resistance and junction capacitance.

Shirland, F. A.↗
NASA NTRS1976

Advanced very high resolution radiometer

The advanced very high resolution radiometer development program is considered. The program covered the design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical structural model, and a life test model. Special bench test and calibration equipment was also developed for use on the program.

Source record↗
NASA NTRS1982

Testing and failure analysis to improve screening techniques for hermetically sealed metallized film capacitors for low energy applications

Effective screening techniques are evaluated for detecting insulation resistance degradation and failure in hermetically sealed metallized film capacitors used in applications where low capacitor voltage and energy levels are common to the circuitry. A special test and monitoring system capable of rapidly scanning all test capacitors and recording faults and/or failures is examined. Tests include temperature cycling and storage as well as low, medium, and high voltage life tests. Polysulfone film capacitors are more heat stable and reliable than polycarbonate film units.

Source record↗
NASA NTRS1989

Characterization testing of a 40 AHR bipolar nickel-hydrogen battery

Extensive characterization testing has been done on a second 40 amp-hour (Ahr), 10-cell bipolar nickel-hydrogen (Ni-H2) battery to study the effects of such operating parameters as charge and discharge rates, temperature, and pressure, on capacity, Ahr and watt-hour (Whr) efficiencies, end-of-charge (EOC) and mid-point discharge voltages. Testing to date has produced many interesting results, with the battery performing well throughout all of the test matrix except during the high-rate (5C and 10C) discharges, where poorer than expected results were observed. The exact cause of this poor performance is, as yet, unknown. Small scale 2 x 2 inch battery tests are to be used in studying this problem. Low earth orbit (LEO) cycle life testing at a 40 percent depth of discharge (DOD) and 10 C is scheduled to follow the characterization testing.

Brewer, Jeffrey C.↗
NASA NTRS1991

Low cost battery designs for small satellite applications

The topics are presented in viewgraph form and include the following: EPI nickel-hydrogen flight history; designs developed and tested; 3.5 inch diameter common pressure vessel (CPV); nickel-hydrogen system advantages; 2.5 inch diameter individual pressure vessel (IPV) and CPV; 5 AH CPV charge voltage/pressure; 5 AH CPV cell design; RNH-5-1 charge retention test; nickel-hydrogen cell specifications; sealed prismatic nickel metal hydride; nickel metal hydride life test; nickel-hydride cell specifications; and nickel metal hydride system advantages.

Brill, Jack↗
NASA NTRS2002

Numerical Propulsion System Simulation (NPSS): An Award Winning Propulsion System Simulation Tool

The Numerical Propulsion System Simulation (NPSS) is a full propulsion system simulation tool used by aerospace engineers to predict and analyze the aerothermodynamic behavior of commercial jet aircraft, military applications, and space transportation. The NPSS framework was developed to support aerospace, but other applications are already leveraging the initial capabilities, such as aviation safety, ground-based power, and alternative energy conversion devices such as fuel cells. By using the framework and developing the necessary components, future applications that NPSS could support include nuclear power, water treatment, biomedicine, chemical processing, and marine propulsion. NPSS will dramatically reduce the time, effort, and expense necessary to design and test jet engines. It accomplishes that by generating sophisticated computer simulations of an aerospace object or system, thus enabling engineers to "test" various design options without having to conduct costly, time-consuming real-life tests. The ultimate goal of NPSS is to create a numerical "test cell" that enables engineers to create complete engine simulations overnight on cost-effective computing platforms. Using NPSS, engine designers will be able to analyze different parts of the engine simultaneously, perform different types of analysis simultaneously (e.g., aerodynamic and structural), and perform analysis in a more efficient and less costly manner. NPSS will cut the development time of a new engine in half, from 10 years to 5 years. And NPSS will have a similar effect on the cost of development: new jet engines will cost about a billion dollars to develop rather than two billion. NPSS is also being applied to the development of space transportation technologies, and it is expected that similar efficiencies and cost savings will result. Advancements of NPSS in fiscal year 2001 included enhancing the NPSS Developer's Kit to easily integrate external components of varying fidelities, providing the initial Visual-Based Syntax (VBS) capability, and developing additional capabilities to support space transportation. NPSS was supported under NASA's High Performance Computing and Communications Program. Through the NASA/Industry Cooperative Effort agreement, NASA Glenn and its industry and Government partners are developing NPSS. The NPSS team consists of propulsion experts and software engineers from GE Aircraft Engines, Pratt & Whitney, The Boeing Company, Honeywell, Rolls-Royce Corporation, Williams International, Teledyne Continental Motors, Arnold Engineering Development Center, Wright Patterson Air Force Base, and the NASA Glenn Research Center. Glenn is leading the way in developing NPSS--a method for solving complex design problems that's faster, better, and cheaper.

Stauber, Laurel J.↗
NASA NTRS2006

Microthruster Propulsion for the Space Technology 7 (ST7) Technology Demonstration Mission

For future applications to precision formation flying missions, NASA's New Millennium Program is scheduled to test colloid micro-Newton thrusters (CMNTs) on the ST7 technology demonstration mission. These CMNTs are part of a disturbance reduction system (DRS) on the ESA SMART-2 Spacecraft or LISA Pathfinder. The goal of the ST7 DRS is to demonstrate technologies necessary to meet the nanometer precision positioning control requirements of the LISA mission. In order to achieve these goals, the CMNTs are required to demonstrate a thrust resolution of less than 0.1 micro-N and a thrust noise of less than 0.1 micro-N/[square root]Hz for thrust levels between 5 and 30 micro-N. Developed by Busek Co. with support from JPL in testing an design, the CMNT has been developed over the last four years into a flight-ready microthrust system. The development, validation testing, and flight unit production of the CMNTs are described. Development tests and analysis include preliminary wear tests, propellant loading process verification, flow testing, and performance verification. Validation and flight unit verification includes thermal and structural analysis, life testing, thermal and dynamic load testing, and performance verification. Final delivery of the units is planned in 2007 with and planned launch and flight demonstration 2009.

microthruster↗
NASA NTRS2008

Assessments of Hollow Cathode Wear in the Xenon Ion Propulsion System (XIPs(c)) by Numerical Analyses and Wear Tests

The standard approach presently followed by NASA to qualify electric propulsion for the required mission throughput has been based largely on life tests, which can be costly and time consuming. Revised electric propulsion lifequalification approaches are being formulated that combine analytical and/or computational methods with (shorter-duration) wear tests. As a model case, a wear test is being performed at JPL to assess the lifetime of the discharge hollow cathode in the Xenon Ion Propulsion System (XIPS(c)), a 25-cm ion engine developed by L-3 Communications Electron Technologies, Inc. for commercial applications. Wear and plasma data accumulated throughout this life-assessment program are being used to validate the existing 2-D hollow cathode code OrCa2D. We find that the OrCa2D steady-state solution predicts very well the time-averaged plasma data and the keeper voltage after 5500 hrs of operation in high-power mode. When the wave motion that occurs naturally in these devices is accounted for, based on an estimate of the maximum wave amplitude, the molybdenum-keeper erosion profile observed in the XIPS(c) discharge cathode is also reproduced within a factor of two of the observation. When the same model is applied to predict the erosion of a tantalum keeper we find that erosion is reduced by more than two orders of magnitude compared to the molybdenum keeper due the significantly lower sputtering yield of tantalum. A tantalum keeper would therefore allow keeper lifetimes that greatly exceed the present requirements for deep-space robotic missions considered by NASA. Moreover, such large reduction of the erosion renders the largest uncertainties in the models, which are associated with the wave amplitude estimates and the electron transport model, negligible.

plasma simulations↗
NASA NTRS1977

Experimental and analytical load-life relation for AISI 9310 steel spur gears

Life tests were conducted at three different loads with three groups of 8.9 cm, pitch diameter spur gears made of vacuum arc remelted AISI 9310 steel. Life was found to vary inversely with load to the 4.3 and 5.1 power at the L-10 and L-50 life levels, respectively. The Weibull slope varied linearly with maximum Hertz contact stress, having an average value of 2.5. The test data when compared to AGMA standards showed a steeper slope for the load-life diagram.

Townsend, D. P.↗
NASA NTRS1977

Experimental and Analytical Load-Life Relation for AISI 9310 Steel Spur Gears

Life tests were conducted at three different loads with three groups of 8.9 cm pitch diameter spur gears made of vacuum arc remelted VAR AISI 9310 steel. Life was found to vary inversely with load to the 4.3 and 5.1 power at the L10 sub and L50 sub life levels, respectively. The Weibull slope varied linearly with maximum Hertz contact stress, having an average value of 2.5. The test data when compared to AGMA standards showed a steeper slope for the load-life diagram.

Townsend, D. P.↗
NASA NTRS1983

Reliability of constricted double-heterojunction AlGaAs diode lasers

Constricted double-heterojunction diode lasers have been life tested at 70 C heatsink temperature and 3-4 mW/facet in CW operation. A median life of 7800 h is obtained at 70 C, which extrapolates to 400,000 h median life at room temperature. The extrapolated mean time to failure at room temperature is in excess of 1,000,000 h. Single-longitudinal-mode CW operation is maintained after 10,000 h of accelerated aging at 70 C.

Botez, D.↗
NASA NTRS1984

Ni-cd Battery Life Expectancy in Geosynchronous Orbit

The feasibility of using nickel cadmium batteries as an alternate if flight qualified NiH2 batteries are not available is explored. Battery life expectancy data being a key element of power system design, an attempt is made to review the literature, life test data and in orbit performance data to develop an up to date estimate of life expectancy for NiCd batteries in a geosynchronous orbit.

Broderick, R. J.↗
NASA NTRS1993

Plasma contactor technology for Space Station Freedom

Hollow cathode plasma contactors have been baselined for Space Station Freedom to control the electrical potentials of surfaces to eliminate/mitigate damaging interactions with the space environment. The system represents a dual-use technology which is a direct outgrowth of the NASA electric propulsion program and in particular the technology development effort on ion thruster systems. Specific efforts include optimizing the design and configuration of the contactor, validating its required lifetime, and characterizing the contactor plume and electromagnetic interference. The plasma contactor subsystems include the plasma contactor unit, a power electronics unit, and an expellant management unit. Under this program these will all be brought to breadboard and engineering model development status. New test facilities have been developed, and existing facilities have been augmented, to support characterizations and life testing of contactor components and systems. This paper discusses the magnitude, scope, and status of the plasma contactor hardware development program now under way and preliminary test results on system components.

Patterson, Michael J.↗
NASA NTRS2004

Reducing the Time and Cost of Testing Engines

Producing a new aircraft engine currently costs approximately $1 billion, with 3 years of development time for a commercial engine and 10 years for a military engine. The high development time and cost make it extremely difficult to transition advanced technologies for cleaner, quieter, and more efficient new engines. To reduce this time and cost, NASA created a vision for the future where designers would use high-fidelity computer simulations early in the design process in order to resolve critical design issues before building the expensive engine hardware. To accomplish this vision, NASA's Glenn Research Center initiated a collaborative effort with the aerospace industry and academia to develop its Numerical Propulsion System Simulation (NPSS), an advanced engineering environment for the analysis and design of aerospace propulsion systems and components. Partners estimate that using NPSS has the potential to dramatically reduce the time, effort, and expense necessary to design and test jet engines by generating sophisticated computer simulations of an aerospace object or system. These simulations will permit an engineer to test various design options without having to conduct costly and time-consuming real-life tests. By accelerating and streamlining the engine system design analysis and test phases, NPSS facilitates bringing the final product to market faster. NASA's NPSS Version (V)1.X effort was a task within the Agency s Computational Aerospace Sciences project of the High Performance Computing and Communication program, which had a mission to accelerate the availability of high-performance computing hardware and software to the U.S. aerospace community for its use in design processes. The technology brings value back to NASA by improving methods of analyzing and testing space transportation components.

Source record↗
NASA NTRS1987

KOH concentration effect on cycle life of nickel-hydrogen cells

A cycle life test of Ni/H2 cells containing electrolytes of various KOH concentrations and a sintered type nickel electrode was carried out at 23 C using a 45 min accelerated low Earth orbit (LEO) cycle regime at 80 percent depth of discharge. One of three cells containing 26 percent KOH has achieved over 28,000 cycles, and the other two 19,000 cycles, without a sign of failure. Two other cells containing 31 percent KOH electrolyte, which is the concentration presently used in aerospace cells, failed after 2,979 and 3,620 cycles. This result indicates that the cycle life of the present type of Ni/H2 cells may be extended by a factor of 5 to 10 simply by lowering the KOH concentration. Long cycle life of a Ni/H2 battery at high depth-of-discharge operation is desired, particularly for an LEO spacecraft application. Typically, battery life of about 30,000 cycles is required for a five year mission in an LEO. Such a cycle life with presently available cells can be assured only at a very low depth-of-discharge operation. Results of testing already show that the cycle life of an Ni/H2 cell is tremendously improved by simply using an electrolyte of low KOH concentration.

Lim, Hong S.↗