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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 1,171 records · Page 65

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NASA NTRSDate not supplied

Phase-Free Orbital Element Model Designed to Enable Rapid Assessment of Eclipse and Radiation Profiles for Low-Thrust Spiral Transfers Around the Earth

The Gateway Power and Propulsion Element (PPE) will be the first low-thrust solar electric ion propulsion mission to transfer from a highly elliptical Earth-bound orbit to a southern near-rectilinear halo orbit (NRHO) at the Earth-Moon L2 point. Due to the low thrust nature of the transfer orbit, it is desirable to locate viable trajectories that minimize the time spent in the Van Allen radiation belts to reduce solar array degradation and keep radiation dosages below design limits. In addition to radiation, low thrust trajectories which spiral around the Earth will pass through at least one or more seasons of Earth eclipses. The solar electric propulsion system relies on sunlight to generate the power necessary to operate the ion thrusters. Therefore, it is advantageous to find trajectories which also minimize the amount of time spent in eclipse and avoid excessive battery draw-down periods. We present an analytical method which rapidly approximates low-thrust spiral trajectories, fit to high-fidelity simulated data and parameterized to allow for changes in vehicle thrust characteristics, that is post-processed to determine eclipse profiles and time spent in the belts using a novel approach that estimates the geometry of the belts using a first-order dipole approximation of the Earth’s magnetic field. This method can be used to find satisfactory launch dates and orbit orientations that can serve as initial guesses when optimizing such missions in high-fidelity software.

low thrust trajectory design↗

NASA NTRS1994

Arcjet system integration development

Compatibility between an arcjet propulsion system and a communications satellite was verified by testing a Government-furnished, 1.4 kW hydrazine arcjet system with the FLTSATCOM qualification model satellite in a 9.1-meter (30-foot) diameter thermal-vacuum test chamber. Background pressure was maintained at 10(exp -5) torr during arcjet operation by cryopumping the thruster exhaust with an array of 5 K liquid helium cooled panels. Power for the arcjet system was obtained from the FLTSATCOM battery simulator. Spacecraft telemetry was monitored during each thruster firing period. No changes in telemetry data attributable to arcjet operation were detected in any of the tests. Electromagnetic compatibility data obtained included radiated emission measurements, conducted emission measurements, and cable coupling measurements. Significant noise was observed at lower frequencies. Above 500 MHz, radiated emissions were generally within limits, indicating that communication links at S-band and higher frequencies will not be affected. Other test data taken with a diagnostic array of calorimeters, radiometers, witness plates, and a residual gas analyzer evidenced compatible operation, and added to the data base for arcjet system integration. Two test series were conducted. The first series only included the arcjet and diagnostic array operating at approximately 0.1 torr background pressure. The second series added the qualification model spacecraft, a solar panel, and the helium cryopanels. Tests were conducted at 0.1 torr and 10(exp-5) torr. The arcjet thruster was canted 20 degrees relative to the solar panel axis, typical of the configuration used for stationkeeping thrusters on geosynchronous communications satellites.

Zafran, Sidney↗

NASA NTRS2012

Dynamically variable spot size laser system

A Dynamically Variable Spot Size (DVSS) laser system for bonding metal components includes an elongated housing containing a light entry aperture coupled to a laser beam transmission cable and a light exit aperture. A plurality of lenses contained within the housing focus a laser beam from the light entry aperture through the light exit aperture. The lenses may be dynamically adjusted to vary the spot size of the laser. A plurality of interoperable safety devices, including a manually depressible interlock switch, an internal proximity sensor, a remotely operated potentiometer, a remotely activated toggle and a power supply interlock, prevent activation of the laser and DVSS laser system if each safety device does not provide a closed circuit. The remotely operated potentiometer also provides continuous variability in laser energy output.

Gradl, Paul R.↗

NASA NTRS1976

Powered wheels for aircraft

Engineering details, project status, system design and specifications, and test results are presented on a powered-wheel drive system based on the Dynavector rotary actuator. The design and operation of the Dynavector system (with positive displacement very-low-inertia nonrotating vane motor) are reviewed. Feasibility studies, contract data, and findings of braking tests are described. Exploded diagrams of Dynavector details are displayed. Success in using powered wheels in lieu of aircraft main engines for on-ground movements should bring benefits in energy conservation, noise abatement, reduced pollution, and alleviated congestion in the terminal area.

Long, M. J.↗

NASA NTRS1983

Parametric study of potential early commercial power plants Task 3-A MHD cost analysis

The development of costs for an MHD Power Plant and the comparison of these costs to a conventional coal fired power plant are reported. The program is divided into three activities: (1) code of accounts review; (2) MHD pulverized coal power plant cost comparison; (3) operating and maintenance cost estimates. The scope of each NASA code of account item was defined to assure that the recently completed Task 3 capital cost estimates are consistent with the code of account scope. Improvement confidence in MHD plant capital cost estimates by identifying comparability with conventional pulverized coal fired (PCF) power plant systems is undertaken. The basis for estimating the MHD plant operating and maintenance costs of electricity is verified.

Source record↗

NASA NTRS2005

Integrated Power and Attitude Control System Demonstrated With Flywheels G2 and D1

On September 14, 2004, NASA Glenn Research Center's Flywheel Development Team experimentally demonstrated a full-power, high-speed, two-flywheel system, simultaneously regulating a power bus and providing a commanded output torque. Operation- and power-mode transitions were demonstrated up to 2000 W in charge and 1100 W in discharge, while the output torque was simultaneously regulated between plus or minus 0.8 N-m. The G2 and D1 flywheels--magnetically levitated carbon-fiber wheels with permanent magnet motors--were used for the experiment. The units were mounted on an air bearing table in Glenn's High Energy Flywheel Facility. The operational speed range for these tests was between 20,000 and 60,000 rpm. The bus voltage was regulated at 125 V during charge and discharge, and charge-discharge and discharge-charge transitions were demonstrated by changing the amount of power that the power supply provided between 300 and 0 W. In a satellite system, this would be the equivalent of changing the amount of energy that the solar array provides to the spacecraft. In addition to regulating the bus voltage, we simultaneously controlled the net torque produced by the two flywheel modules. Both modules were mounted on an air table that was restrained by a load cell. The load cell measured the force on the table, and the torque produced by the two flywheels on the table could be calculated from that measurement. This method was used to measure the torque produced by the modules, yielding net torques from -0.8 to 0.8 N-m. This was the first Glenn demonstration of the Integrated Power and Attitude Control System (IPACS) at high power levels and speeds.

Jansen, Ralph H.↗

NASA NTRS1975

System reliability analysis through corona testing

A corona vacuum test facility for nondestructive testing of power system components was built in the Reliability and Quality Engineering Test Laboratories at the NASA Lewis Research Center. The facility was developed to simulate operating temperature and vacuum while monitoring corona discharges with residual gases. The facility is being used to test various high-voltage power system components.

Lalli, V. R.↗

NASA NTRS1964

New apparatus increases ion beam power density

To increase ion engine or rocket power, an ion source and emitter, an ion beam focusing electrode, and an ion accelerator are incorporated into the system. In operation the space charge surrounding the ion emitter decreases, the ion beam density accelerates, and engine power increases.

Baldwin, L. V.↗

NASA NTRS1985

Operational performance of the photovoltaic-powered grain mill and water pump at Tangaye, Burkina Faso (formerly Upper Volta)

A photovoltaic (PV) system powering a grain mill and water pump was installed in the remote African village of Tangaye, Burkina Faso (formerly Upper Volta) under the sponsorship of the U.S. Agency for International Development (AID) and by the National Aeronautics and Space Administration (NASA) Lewis Research Center (LeRC) in early 1979. The presence reports covers the second two years of operation from April 1981 through June 1983. During this time, the grain mill and water pump were operational 96 and 88 percent of the time respectively, and the PV system generated sufficient electricity to enable the grinding of about 111 metric tons of finely ground flow and the pumping of over 5000 cm sq of water from the 10 m deep well. The report includes a description of the current configuration of the system, a review of system performance, a discussion of the socioeconomic impact of the system on the villagers and a summary of results and conclusions covering the entire four-year period.

Martz, J. E.↗

NASA NTRS1987

LERC power system autonomy program 1990 demonstration

The NASA Lewis Research Center has undertaken a program for the development of space systems automation, with a view to increased reliability, safety, payload capability, and decreased operational costs. The NASA Space Station is a primary area of application for the techniques thus developed. Attention is presently given to the activities associated with the Power Systems Autonomy Demonstration Project, which has a projected demonstration date in 1990 and will integrate knowledge-based systems into a real-time environment. Two coordinated systems under expert system control will be demonstrated.

Faymon, Karl A.↗

NASA NTRS2021

Dynamic Radioisotope Power System (DRPS) Permanently Shadowed Region (PSR) Demonstrator Rover

This conceptual design study investigated trading several Dynamic Radioisotope Power Systems (DRPS) in development to supply power to a lunar science rover which operates for long periods (months) in permanently shadowed regions (PSR) over many years. The design was conducted by the Compass team and relied heavily on the planned VIPER rover design, which is limited to only a few hours of operations in PSRs and less than a month near the south pole. As such this conceptual design shows what a DRPS can do for a follow-on type VIPER rover. In addition to the long duration, go anywhere DRPS power system, the Compass team added a communications system that utilizes the Gateway spacecraft as a relay node for nearly 24/7 communications link to the DRPS rover in lunar craters not visible from the earth. The Compass design includes a notional conops, launch and delivery, subsystem designs of power, mobility, structures, science, command and data handling, communications, guidance and control, and thermal. The thermal design was especially important due the low temperatures in PSRs where the science environment needs to be shielded from the waste heat from the DRPS.

Dynamic Radioisotope Power Systems↗

NASA NTRS1972

Telemetry remote modules

A fully operational engineering telemetry remote module is reported that forms the basis for a decentralized telemetry system which employs small low powered modules capable of distributing the multiplexer input gates around a spacecraft. The module operates mainly as a harness reducer, allowing data to be transmitted back to a central control core for inclusion in the telemetry bit stream. Each unit is capable of accepting 32 data points in various combinations.

Silverman, J. R.↗

NASA NTRS1976

Photovoltaic Test and Demonstration Project

The Photovoltaic Test and Demonstration Project was initiated by NASA in June, 1975, to develop economically feasible photovoltaic power systems suitable for a variety of terrestrial applications. Objectives include the determination of operating characteristic and lifetimes of a variety of solar cell systems and components and development of methodology and techniques for accurate measurements of solar cell and array performance and diagnostic measurements for solar power systems. Initial work will be concerned with residential applications, with testing of the first prototype system scheduled for June, 1976. An outdoor 10 kW array for testing solar power systems is under construction.

Forestieri, A. F.↗

NASA NTRS2006

Full-Duplex Digital Communication on a Single Laser Beam

A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

Hazzard, D. A.↗

NASA NTRS2017

Partially Turboelectric Aircraft Drive Key Performance Parameters

The purpose of this paper is to propose electric drive specific power, electric drive efficiency, and electrical propulsion fraction as the key performance parameters for a partially turboelectric aircraft power system and to investigate their impact on the overall aircraft performance. Breguet range equations for a base conventional turbofan aircraft and a partially turboelectric aircraft are found. The benefits and costs that may result from the partially turboelectric system are enumerated. A break even analysis is conducted to find the minimum allowable electric drive specific power and efficiency, for a given electrical propulsion fraction, that can preserve the range, fuel weight, operating empty weight, and payload weight of the conventional aircraft. Current and future power system performance is compared to the required performance to determine the potential benefit.

turbogenerator↗

NASA NTRS2012

Low Temperature Double-layer Capacitors with Improved Energy Density: An Overview of Recent Development Efforts

Electrochemical double-layer capacitors are finding increased use in a wide range of energy storage applications, particularly where high pulse power capabilities are required. Double-layer capacitors store charge at a liquid/solid interface, making them ideal for low temperature power applications, due to the facile kinetic processes associated with the rearrangement of the electrochemical double-layer at these temperatures. Potential low temperature applications include hybrid and electric vehicles, operations in polar regions, high altitude aircraft and aerospace avionics, and distributed environmental and structural health monitoring. State-of-the-art capacitors can typically operate to -40 C, with a subsequent degradation in power performance below room temperature. However, recent efforts focused on advanced electrolyte and electrode systems can enable operation to temperatures as low as -70 C, with capacities similar to room temperature values accompanied by reasonably low equivalent series resistances. This presentation will provide an overview of recent development efforts to extend and improve the wide temperature performance of these devices.

energy storage↗

NASA NTRS2012

Low Temperature Double-layer Capacitors with Improved Energy Density: An Overview of Recent Development Efforts

Supercapacitors↗

NASA NTRS2008

Thermal Expansion Studies of Selected High Temperature Thermoelectric Materials

Radioisotope thermoelectric generators (RTGs) generate electrical power by converting the heat released from the nuclear decay of radioactive isotopes (typically plutonium-238) into electricity using a thermoelectric converter. RTGs have been successfully used to power a number of space missions and have demonstrated their reliability over an extended period of time (tens of years) and are compact, rugged, radiation resistant, scalable, and produce no noise, vibration or torque during operation. System conversion efficiency for state-of-practice RTGs is about 6% and specific power less than or equal to 5.1 W/kg. Higher specific power would result in more on-board power for the same RTG mass, or less RTG mass for the same on-board power. The Jet Propulsion Laboratory has been leading, under the advanced thermoelectric converter (ATEC) project, the development of new high-temperature thermoelectric materials and components for integration into advanced, more efficient RTGs. Thermoelectric materials investigated to date include skutterudites, the Yb14MnSb11 compound, and SiGe alloys. The development of long-lived thermoelectric couples based on some of these materials has been initiated and is assisted by a thermo-mechanical stress analysis to ensure that all stresses under both fabrication and operation conditions will be within yield limits for those materials. Several physical parameters are needed as input to this analysis. Among those parameters, the coefficient of thermal expansion (CTE) is critically important. Thermal expansion coefficient measurements of several thermoelectric materials under consideration for ATEC are described in this paper. The stress response at the interfaces in material stacks subjected to changes in temperature is discussed, drawing on work from the literature and project-specific tools developed here. The degree of CTE mismatch and the associated effect on the formation of stress is highlighted.

silicon germanium↗