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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

NASA Ames Research Center 60 MW Power Supply Modernization

The NASA Ames Research Center 60 MW DC Power Supply was built in 1974 to provide controlled DC power for the Thermophysics Facility Arc Jet Laboratory. The Power Supply has gradually losing reliability due to outdated technology and component life limitation. NASA has decided to upgrade the existing rectifier modules with contemporary high-power electronics and control equipment. NASA plans to complete this project in 2001. This project includes a complete replacement of obsolete thyristor stacks in all six rectifier modules and rectifier bridge control system. High power water-cooled thyristors and freewheeling diodes will be used. The rating of each of the six modules will be 4000 A at 5500 V. The control firing angle signal will be sent from the Facility Control System to six modules via fiberoptic cable. The Power Supply control and monitoring system will include a Master PLC in the Facility building and a Slave PLC in each rectifier module. This system will also monitor each thyristor level in each stack and the auxiliary equipment.

Choy, Yuen Ching↗
NASA NTRSDate not supplied

Health Monitoring and Prognostics in Li-ion Batteries

Space applications need to overcome a very critical challenge of predicting remaining useful life of its critical systems/subsystems, with batteries being one of them. Batteries, power electronics conditioning system and motors and one of the most critical systems. Similarly in case of electric aircrafts, computing remaining flying time is safety-critical, since an aircraft that runs out of power (battery charge) while in the air will eventually lose control leading to catastrophe. To tackle and solve the prediction problem, it is essential to have awareness of the current state and health of the system, especially since it is necessary to perform condition-based predictions. To be able to accurately predict the future state of any system, it is required to possess knowledge of its current and future operations. Given models of the current and future system behavior, the general approach of model-based prognostics can be employed as a solution to the prior stated prediction problem. Two approaches are presented with battery prognostics application. The first approach presentation covers a physics based-modeling approach implemented for battery prognostics. Given models of the current and future system behavior, a general approach of model-based prognostics can be employed as a solution to the prediction problem and further for decision making. A second hybrid framework for fusing information from physics-based performance models along with deep learning algorithms for prognostics of complex safety critical systems i.e. batteries is presented. In this framework, physics-based performance models infer unobservable model parameters related to the system's components health solving a calibration problem in the deep learning approach.

Batteries↗
NASA NTRSDate not supplied

Health Monitoring and Prognostics in Li-ion Batteries

Space applications need to overcome a very critical challenge of predicting remaining useful life of its critical systems/subsystems, with batteries being one of them. Batteries, power electronics conditioning system and motors and one of the most critical systems. Similarly in case of electric aircrafts, computing remaining flying time is safety-critical, since an aircraft that runs out of power (battery charge) while in the air will eventually lose control leading to catastrophe. To tackle and solve the prediction problem, it is essential to have awareness of the current state and health of the system, especially since it is necessary to perform condition-based predictions. To be able to accurately predict the future state of any system, it is required to possess knowledge of its current and future operations. Given models of the current and future system behavior, the general approach of model-based prognostics can be employed as a solution to the prior stated prediction problem. Two approaches are presented with battery prognostics application. The first approach presentation covers a physics based-modeling approach implemented for battery prognostics. Given models of the current and future system behavior, a general approach of model-based prognostics can be employed as a solution to the prediction problem and further for decision making. A second hybrid framework for fusing information from physics-based performance models along with deep learning algorithms for prognostics of complex safety critical systems i.e. batteries is presented. In this framework, physics-based performance models infer unobservable model parameters related to the system's components health solving a calibration problem in the deep learning approach.

Battery Prognostics↗
NASA NTRS1972

Mechanisms for the adhesion of silver to glow discharge sensitized perfluorinated ethylene propylene (PEP)

Details are given for the deposition of silver onto FEP for a batch coater capable of handling 864 square inches at a time. The effectiveness of the glow discharge is shown to be optimum when the FEP faces the anode. Using solid state theory based upon the work function difference, and the heuristic assumption that the surface of FEP is populated with fluoride ions, it is argued that an anode sensitized surface develops states receptive to electron transfer from silver, whereas a cathode sensitized surface is polarized only, and as a result cannot permanently trap charge. Thermodynamic arguments given show that an order of magnitude of 10 to the 9th power electrons are transferred into states to a depth of 10 nm.

Schutt, J. B.↗
NASA NTRS1978

Annealing of GaAs solar cells damaged by electron irradiation

Measurements of thermal annealing of GaAlAs/GaAs solar cells damaged by 1 MeV electron irradiation are reported, and the magnitude of the short-circuit current recovery is discussed. The damaged cells are annealed in a vacuum at 200 C. A cell irradiated at 10 to the 13th power electrons per sq cm recovers all its lost short-circuit current after 15 hours of annealing. Possible application of the annealing process to solar cells in space is also considered.

Walker, G. H.↗
NASA NTRS1977

Radiation tests of SEP solar cells

Solar cells specially designed for Solar Electric Propulsion (SEP) were tested with radiation fluences up to 10 to the 12th power protons having energies of 1.5, 1.0, and 0.5 MeV, and with fluences up to 10 to the 16th power electrons having 1.0 MeV energy. Spectrolab cells having a back-surface field were also irradiated with the same particles and fluences. Cell performances are described by curves in which normalized and absolute values of maximum power, maximum-power voltage, short-circuit current, and open-circuit voltage are plotted as a function of fluence.

Oman, H.↗
NASA NTRS2002

A Large-Magnitude Biological Source of H2 to the Archaean Atmosphere?

The appearance of photosynthetic microbial communities on Earth was a critical juncture in the chemical evolution of the oceans and atmosphere. The use of sunlight as an energy source frees life from a dependence on geochemical energy sources; global biospheric productivity, as well as the biological influence on planetary chemistry, can be greatly enhanced as a result. To understand the potential biogeochemical impacts of the transition to a photosynthetic biosphere, we examined chemical cycling in potential modern analogs of these Archaean photosynthetic communities - microbial mats from Baja California, Mexico. The primary role of photosynthetic members in the mat community is to extract reducing power (electrons) from water and use it to 'fix' carbon dioxide into organic carbon (biomolecules); however, when exposed to a simulated Archaean atmosphere of very low oxygen content, these organisms divert a substantial fraction of the captured reducing power into the production of molecular hydrogen. Globally, this mechanism of hydrogen production could have outstripped geologic sources by 2 to 4 orders of magnitude. A large-magnitude H2 flux to the environment offers the potential to enhance the global distribution and productivity of H2-consuming organisms, and also to contribute significantly to oxidation of the oceans and atmosphere by via escape to space.

Hoehler, Tori M.↗
NASA NTRS1977

Spacecraft transformer and inductor design

The conversion process in spacecraft power electronics requires the use of magnetic components which frequently are the heaviest and bulkiest items in the conversion circuit. This handbook pertains to magnetic material selection, transformer and inductor design tradeoffs, transformer design, iron core dc inductor design, toroidal power core inductor design, window utilization factors, regulation, and temperature rise. Relationships are given which simplify and standardize the design of transformers and the analysis of the circuits in which they are used. The interactions of the various design parameters are also presented in simplified form so that tradeoffs and optimizations may easily be made.

Mclyman, W. T.↗
NASA NTRS2019

Prognostics and Health Monitoring in Li-Ion Batteries and Capacitors Using Physics-Based Modeling Approach

In order to tackle and solve the prediction problem of the lifetime of Li-ion batteries, it is essential to have awareness of the current state and health of the battery pack. To be able to accurately predict the future state of any system, one must possess knowledge of its current and future operations. Using derived models of the current and future system behavior, a model-based prognostics approach can be implemented as a solution to the prediction problem. As more and more autonomous electric vehicles progressively emerge in our daily life, a very critical challenge lies in accurate prediction of remaining useful life of the systems/subsystems. Batteries, power electronics conditioning systems, and motors are integrated to form the powertrain in electric vehicles; one of the most critical systems. In the case of electric aircrafts, computing remaining flying time is critical for safety, since an aircraft that runs out of power (battery charge) while in the air will eventually lose control leading to catastropheThis presentation covers a physics-based modeling approach implemented for case studies in capacitor and battery prognostics which are an integral part of an electrical powertrain system. The general approach of model-based prognostics will be examined as a potential solution for safety critical problems related to battery state of charge and state of health.

Physics based modeling↗
NASA NTRS2010

Development of SiC Large Tapered Crystal Growth

Majority of very large potential benefits of wide band gap semiconductor power electronics have NOT been realized due in large part to high cost and high defect density of commercial wafers. Despite 20 years of development, present SiC wafer growth approach is yet to deliver majority of SiC's inherent performance and cost benefits to power systems. Commercial SiC power devices are significantly de-rated in order to function reliably due to the adverse effects of SiC crystal dislocation defects (thousands per sq cm) in the SiC wafer.

Neudeck, Phil↗
NASA NTRSDate not supplied

Selection of Alternator Voltage for Dynamic Radioisotope Power Systems

In this paper, we present a study to select an appropriate alternator voltage of the free-piston Stirling convertors (FPSC) for efficient and light Dynamic Radioisotope Power Systems (DRPS). With a system thermal-to-electrical efficiency 3-4 times greater than radioisotope thermoelectric generator (RTG) systems and a higher power density than Brayton systems in the power range of interest for radioisotope-powered systems, Stirling-based DRPS is uniquely suited to benefit upcoming NASA missions. Much effort has been invested in the design and optimization of the thermal, mechanical, and materials aspects of FPSCs, but the electrical aspect has been more nebulous. Therefore, in this paper, a preliminary study will be presented to select the appropriate Stirling alternator voltage to develop a light and efficient system using available flight components. Power conversion systems face a trade between efficiency and system volume/mass with the optimal trade being determined by the application. Neglecting non-idealities related to insulation thickness and winding packing factor and assuming a constant winding area, alternator efficiency is independent of alternator voltage. Because wire size and alternator current can be traded against turn count and alternator voltage without impacting efficiency, the guidance on the optimal design comes from analysis of the controller power electronics and the remainder of the system. Properties of available flight-qualified electrical components, such as rated voltage/current and on-resistance, typically come in discrete values instead of a continuous range of values. With multiple components being required to form the power conversion stage of the controller, each limited to incremental values, a continuous optimization is of little benefit. Instead of a continuous optimization, a random process using properties of the available components can be used to develop a Pareto design front indicating the optimized trade space. The most advantageous trade between system efficiency and mass for the system at hand can then be selected from the range of feasible designs. In the final paper, the design process, assumptions, and preliminary results will be presented.

Free-Piston Stirling Convertor Controller, Dynamic↗
NASA NTRS2003

Flywheels Upgraded for Systems Research

With the advent of high-strength composite materials and microelectronics, flywheels are becoming attractive as a means of storing electrical energy. In addition to the high energy density that flywheels provide, other advantages over conventional electrochemical batteries include long life, high reliability, high efficiency, greater operational flexibility, and higher depths of discharge. High pulse energy is another capability that flywheels can provide. These attributes are favorable for satellites as well as terrestrial energy storage applications. In addition to energy storage for satellites, the several flywheels operating concurrently can provide attitude control, thus combine two functions into one system. This translates into significant weight savings. The NASA Glenn Research Center is involved in the development of this technology for space and terrestrial applications. Glenn is well suited for this research because of its world-class expertise in power electronics design, rotor dynamics, composite material research, magnetic bearings, and motor design and control. Several Glenn organizations are working together on this program. The Structural Mechanics and Dynamics Branch is providing magnetic bearing, controls, and mechanical engineering skills. It is working with the Electrical Systems Development Branch, which has expertise in motors and generators, controls, and avionics systems. Facility support is being provided by the Space Electronic Test Engineering Branch, and the program is being managed by the Space Flight Project Branch. NASA is funding an Aerospace Flywheel Technology Development Program to design, fabricate, and test the Attitude Control/Energy Storage Experiment (ACESE). Two flywheels will be integrated onto a single power bus and run simultaneously to demonstrate a combined energy storage and 1-degree-of-freedom momentum control system. An algorithm that independently regulates direct-current bus voltage and net torque output will be experimentally demonstrated.

Jansen, Ralph H.↗
NASA NTRS1975

Experiment definition phase shuttle laboratory: LDRL-10.6 experiment

Progress is reported in the development of the space shuttle laboratory laser data relay link. The system transmittance of various surfaces was considered in order to examine the coating tradeoffs for the beryllium mirrors. The results of six coating combinations considered are summarized. It is recommended that silver coatings be used throughout the system. Design of the pre-expander and a preliminary alignment procedure implemented to align all optical elements to the reference mechanical axis (the rotational axis of the outer gimbal bearing located between the two Gregorian telescopes) are included. The local oscillator subsystem, consisting of the laser, Stark cell, Stark cell electronics, power supply, starting circuit, and conditioning optics were completed and installed in the optimechanical subsystem and operation against a 10.6 micrometer source was attempted. Preliminary measurements of the HgCdTe mixer showed that this critical element was inoperative and in subsequent tests the receiver front end electronics had also failed. Possible reasons for these failures and corrective action and steps to prevent future recurrence are discussed.

Source record↗
NASA NTRS2010

High-Efficiency K-Band Space Traveling-Wave Tube Amplifier for Near-Earth High Data Rate Communications

The RF performance of a new K-Band helix conduction cooled traveling-wave tube amplifier (TWTA) is presented in this paper. A total of three such units were manufactured, tested and delivered. The first unit is currently flying onboard NASA s Lunar Reconnaissance Orbiter (LRO) spacecraft and has flawlessly completed over 2000 orbits around the Moon. The second unit is a proto-flight model. The third unit will fly onboard NASA s International Space Station (ISS) as a very compact and lightweight transmitter package for the Communications, Navigation and Networking Reconfigurable Testbed (CoNNeCT), which is scheduled for launch in 2011. These TWTAs were characterized over the frequencies 25.5 to 25.8 GHz. The saturated RF output power is >40 W and the saturated RF gain is >46 dB. The saturated AM-to- PM conversion is 3.5 /dB and the small signal gain ripple is 0.46 dB peak-to-peak. The overall efficiency of the TWTA, including that of the electronic power conditioner (EPC) is as high as 45 percent.

Simons, Rainee N.↗
NASA NTRS1981

High voltage cabling for high power spacecraft

Studies by NASA have shown that many of the space missions proposed for the time period 1980 to 2000 will require large spacecraft structures to be assembled in orbit. Large antennas and power systems up to 2.5 MW size are predicted to supply the electrical/electronic subsystems, solar electric subsystems, solar electric propulsion, and space processing for the near-term programs. Platforms of 100 meters/length for stable foundations, utility stations, and supports for these multi-antenna and electronic powered mechanisms are also being considered. This paper includes the findings of an analytic and conceptual design study for large spacecraft power distribution, and electrical loads and their influence on the cable and connector requirements for these proposed large spacecraft.

Dunbar, W. G.↗
NASA NTRS1993

Computer simulation of a 20-kHz power system for advanced launch systems

The performance of two 20-kHz actuator power systems being built for an advanced launch system are evaluated for typical launch senario using an end-to-end system simulation. Aspects of system performance ranging from the switching of the power electronic devices to the vehicle aerodynamics are represented in the simulation. It is shown that both systems adequately stabilize the vehicle against a wind gust during launch. However, it is also shown that in both cases there are bus voltage and current fluctuations which make system power quality a concern.

Sudhoff, S. D.↗
NASA NTRS2020

Ultrafast Melting at Metal-Semiconductor Interfaces: A Molecular Dynamics Study

Quantifying the thermodynamics of interfacial melting is important for several applications such as laser machining and designing radiation hardened electronic devices. Due to the short time and length scales that are involved in the process, molecular simulations provide an ideal path for understating the interfacial melting phenomena. In this work we investigate tungsten (W) – silicon carbide (SiC) interfaces which are relevant in modern high-power electronic devices. Classical molecular dynamics simulations along with the two-temperature model (TTM) were used to study the radiation induced melting of the interface while a neural network-based machine learning framework was used to track the transient re-crystallization process. The damage endured by the semiconductor at the interface following the radiation event is discussed in detail while the re-crystallization of the metal is described in terms of the classical nucleation theory.

Ashwin Ravichandran↗
NASA NTRS2003

Microcalorimeters for High Resolution X-Ray Spectroscopy of Laboratory and Astrophysical Plasmas

The proposal has three major objectives. The first focuses on advanced neutron-transmutation-doped (NTD)-based microcalorimeter development. Our goal is to develop an array of microcalorimeters with sub- 5 eV energy resolution that can operate with pile-up-free throughput of at least 100 Hz per pixel. The second objective is to establish our microcalorimeter as an essential x-ray diagnostic for laboratory astrophysics studies. We propose to develop a dedicated microcalorimeter spectrometer for the EBIT (electron beam ion trap). This instrument will incorporate the latest detector and cryogenic technology that we have available. The third objective is to investigate innovative ideas related to possible flight opportunities. These include compact, long lived cryo-systems, ultra-low temperature cold stages, low mass and low power electronics, and novel assemblies of thin windows with high x-ray transmission.

Silver, E.↗