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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 847 records · Page 47
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Channel Temperature Model for Microwave AlGaN/GaN HEMTs on SiC and Sapphire MMICs in High Power, High Efficiency SSPAs

A key parameter in the design trade-offs made during AlGaN/GaN HEMTs development for microwave power amplifiers is the channel temperature. An accurate determination can, in general, only be found using detailed software; however, a quick estimate is always helpful, as it speeds up the design cycle. This paper gives a simple technique to estimate the channel temperature of a generic microwave AlGaN/GaN HEMT on SiC or Sapphire, while incorporating the temperature dependence of the thermal conductivity. The procedure is validated by comparing its predictions with the experimentally measured temperatures in microwave devices presented in three recently published articles. The model predicts the temperature to within 5 to 10 percent of the true average channel temperature. The calculation strategy is extended to determine device temperature in power combining MMICs for solid-state power amplifiers (SSPAs).

Freeman, Jon C.↗
NASA NTRS2001

The Evolution of the VASIMR Engine

Our future deep space explorers face many daunting challenges but three of these loom high above the rest: Physiological debilitation, radiation sickness and psychological stress. Many countermeasures are presently being considered to ameliorate these difficulties however, in the long run, two important new developments are required: abundant space power and advanced propulsion. The development of the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) addresses these important areas of need. The VASIMR is a high power, radio frequency-driven magneto plasma rocket, capable of very high exhaust velocities. In addition, its unique architecture allows in-flight mission-optimization of thrust and specific impulse to enhance performance and reduce trip time. A NASA-led, research team, involving industry, academia and government facilities is pursuing the development of this concept in the United States. The technology can be validated, in the near term, in venues such as the International Space Station, where it can also serve as both a drag compensation device and a plasma contactor for the orbital facility. Other near-Earth applications in the commercial and scientific satellite sectors are also envisioned. This presentation covers the present status of the technology, plans for its near term deployment and a vision for its future evolution.

Chang-Diaz, F. R.↗
NASA NTRS1979

Development of high reliability, high frequency power conditioning models of converter regulators

High efficiency conversion, regulation, and filtering techniques are discussed for power using high conversion frequencies; i.e., in the order of 1 to 5 MHz for converters having total output power capability in the order of 20 watts and 200 to 500 KHz for converters having total output powers in excess of 200 watts. Work centered on areas of component selection, material selection, optimization of the various types of circuits required, and the selection of materials for and design of magnetic components. These techniques were then applied to the design of two sample converters, one a medium power instrument type converter and the second a high power converter representative of a primary spacecraft converter regulator. The configuration and performance of the two converters is reported and discussed.

Rochussen, A. W.↗
NASA NTRS1979

Photovoltaic power systems for rural areas of developing countries

Systems technology, reliability, and present and projected costs of photovoltaic systems are discussed using data derived from NASA, Lewis Research Center experience with photovoltaic systems deployed with a variety of users. Operating systems in two villages, one in Upper Volta and the other in southwestern Arizona are described. Energy cost comparisons are presented for photovoltaic systems versus alternative energy sources. Based on present system technology, reliability, and costs, photovoltaics provides a realistic energy option for developing nations.

Rosenblum, L.↗
NASA NTRS1986

Resistojet- and arcjet-propulsion power processing

Power-processing unit (PPU) designs for resistojet and arcjet propulsion systems were developed. Various PPU power converter and power circuit technologies were considered. Arcjet, resistojet and chemical propulsion system performance were compared. Significant propellant mass reductions are enabled with electric propulsion.

Palaszewski, Bryan↗
NASA NTRS1987

Space station electrical power system

The purpose of this paper is to describe the design of the Space Station Electrical Power System. This includes the Photovoltaic and Solar Dynamic Power Modules as well as the Power Management and Distribution System (PMAD). In addition, two programmatic options for developing the Electrical Power System will be presented. One approach is defined as the Enhanced Configuration and represents the results of the Phase B studies conducted by the NASA Lewis Research Center over the last two years. Another option, the Phased Program, represents a more measured approach to reaching about the same capability as the Enhanced Configuration.

Labus, Thomas L.↗
NASA NTRS1987

Overview of free-piston Stirling engine technology for space power application

An overview is presented of free-piston Stirling engine activities, directed toward space power applications. One of the major elements of the program is the development of advanced power conversion. Under this program the status of the 25 kWe opposed-piston Space Power Demonstrator Engine (SPDE) is presented. Initial differences between predicted and experimental power outputs and power output influenced by variations in regenerators are discussed. Technology work was conducted on heat-exchanger concepts to minimize the number of joints as well as to enhance the heat transfer in the heater. Design parameters and conceptual design features are also presented for a 25 kWe, single-cylinder free-piston Stirling space power converter. Projections are made for future space power requirements over the next few decades along with a recommendation to consider the use of dynamic power conversion systems, either solar or nuclear. A cursory comparison is presented showing the mass benefits of a Stirling system over a Brayton system for the same peak temperature and output power. A description of a study to investigate the feasibility of scaling a single-cylinder free-piston Stirling space power module to the 150 kWe power range is presented.

Slaby, Jack G.↗
NASA NTRS1987

Space Station Electrical Power System

The purpose of this paper is to describe the design of the Space Station Electrical Power System. This includes the Photovoltaic and Solar Dynamic Power Modules as well as the Power Management and Distribution System (PMAD). In addition, two programmatic options for developing the Electrical Power System will be presented. One approach is defined as the Enhanced Configuration and represents the results of the Phase B studies conducted by the NASA Lewis Research Center over the last two years. Another option, the Phased Program, represents a more measured approach to reaching about the same capability as the Enhanced Configuration.

Labus, Thomas L.↗
NASA NTRS1989

Development of parallel algorithms for electrical power management in space applications

The application of parallel techniques for electrical power system analysis is discussed. The Newton-Raphson method of load flow analysis was used along with the decomposition-coordination technique to perform load flow analysis. The decomposition-coordination technique enables tasks to be performed in parallel by partitioning the electrical power system into independent local problems. Each independent local problem represents a portion of the total electrical power system on which a loan flow analysis can be performed. The load flow analysis is performed on these partitioned elements by using the Newton-Raphson load flow method. These independent local problems will produce results for voltage and power which can then be passed to the coordinator portion of the solution procedure. The coordinator problem uses the results of the local problems to determine if any correction is needed on the local problems. The coordinator problem is also solved by an iterative method much like the local problem. The iterative method for the coordination problem will also be the Newton-Raphson method. Therefore, each iteration at the coordination level will result in new values for the local problems. The local problems will have to be solved again along with the coordinator problem until some convergence conditions are met.

Berry, Frederick C.↗
NASA NTRS1988

Future spacecraft propulsion

Propulsion requirements for launch vehicles, upper stages, satellites and platforms, and planetary spacecraft are described from a functional perspective and compared on an energy basis. Mission velocity requirements for a range of missions are presented. A simple model relating optimum exhaust velocity and maximum system delta-V as a function of system-specific energy is developed, which provides insight into the relationship between system performance and various power and propulsion subsystem characteristics. Based on this model, various advanced propulsion options, e.g., the solid-core nuclear rocket and nuclear electric propulsion, are evaluated, and the implications of this analysis for propulsion and power system technology development programs are discussed. The objective of this paper is to provide an overview of future propulsion requirements for the nonspecialist.

Garrison, P. W.↗
NASA NTRS2011

Development of a Novel Wireless Electric Power Transfer System for Space Applications

This paper will introduce a new implementation for wireless electric power transfer systems: space applications. Due to the risks that constitute the use of electrical connector for some space missions/applications, a simple wireless power system design approach will be evaluated as an alternative for the use of electrical connectors. This approach takes into consideration the overall system performance by designing the magnetic resonance elements and by verifying the overall system electrical behavior. System characterization is accomplished by executing circuit and analytical simulations using Matlab(TradeMark) and LTSpiceIV(TradeMark) software packages. The design methodology was validated by two different experiments: frequency consideration (design of three magnetic elements) and a small scale proof-ofconcept prototype. Experiment results shows successful wireless power transfer for all the cases studied. The proof-of-concept prototype provided approx.4 W of wireless power to the load (light bulb) at a separation of 3 cm from the source. In addition. a resonant circuit was designed and installed to the battery terminals of a handheld radio without batteries, making it tum on at a separation of approx.5 cm or less from the source. It was also demonstrated by prototype experimentation that multiple loads can be powered wirelessly at the same time with a single electric power source.

VazquezRamos, Gabriel↗
NASA NTRSDate not supplied

Materials for Power Transmission in Extreme Environments

NASA’s goal for a sustained human presence on the Moon and a future Lunar economy requires the development of novel power transmission materials for extreme environments. As an increasing number of public and private entities set their sights towards a future on the Moon, the demand for surface power will dramatically increase – potentially up to megawatt levels. A Lunar economy is envisioned to include a human habitat, manned and unmanned science exploration assets, excavation rovers and systems, and large-scale infrastructure construction such as solar arrays and power grids. A NASA trade study estimated that 1 to 3 km of power transmission lines (1 to 3 KV ac and dc) will be needed over time. Current high power and voltage SOA cables/wire can easily exceed 1 kg/m where mass is not as critical. Connectors, deployment spools and robots further increase the subsystem mass significantly increasing costs. On the other hand, advances in aeronautics provides path towards space missions. The operating environment on the Moon presents substantial risk to safe and reliable power transmission due to space weathering and degradation. These challenges include cosmic and UV radiation, extreme temperatures swings, the electrostatic Lunar exosphere, and the electrostatic and abrasive lunar regolith. The critical need for lightweight, safe and reliable power cables/wires materials is evident. In this presentation, the extreme high altitude and lunar environments and recent materials development from NASA Glenn Research Center’s High Voltage Materials team towards meeting NASA’s objectives and goals for aeronautics and space missions.

Cu/CNT conductors↗
NASA NTRSDate not supplied

Establishing a Lunar Surface Power Grid

The National Aeronautics and Space Administration (NASA) is seeking to develop a lunar surface power system for its Artemis missions as well as for planned future commercial lunar surface activities. This power system is composed of a number of assets which contain electrical loads and many of these contain energy resources. These assets can be connected to form a grid, which allows power to be shared between the system’s distributed energy resources. This grid can provide backup power to existing assets as well as primary power to future assets. A trade study was conducted for an Artemis scale grid, which has identified 3 kV AC as an ideal transmission voltage. Development work has also begun for a universal modular interface converter (UMIC) which connects assets and microgrids operating at 120 V DC space power to the grid. Products from this grid definition and UMIC development work will enable highly reliable and available power for Artemis and future planetary surface missions, which is key to achieving NASA’s long term vision of space exploration.

Planetary surface power↗