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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Solar energy recorder

A serious obstacle to the large-scale terrestrial application of solar energy lies in the scarcity of reliable data on the amount of solar energy at candidate converter sites. This paper describes a system designed to monitor and record, automatically, the values of the direct and total (sun and sky) solar radiation which would be seen by either tracking or fixed-type solar converters. A further pressing need addressed by the system is the means for efficiency testing and evaluation of solar cells, solar collectors and solar concentrator systems, under outdoor exposure to natural sunlight and weather conditions for extended periods. The design was accomplished in support of the Marshall Space Flight Center, NASA, where design concepts and materials for large-scale terrestrial solar energy converters are currently being evaluated.

Lollar, R. B.↗
NASA NTRS2016

An Overview of Power, Energy Storage, and Conversion Efforts for 2014 SBIR Phases I and II

Technological innovation is the overall focus of NASA's Small Business Innovation Research (SBIR) program. The program invests in the development of innovative concepts and technologies to help NASA's mission directorates address critical research and development needs for agency projects. NASA's Small Business Innovation Research (SBIR) program focuses on technological innovation by investing in development of innovative concepts and technologies to help NASA mission directorates address critical research needs for Agency programs. This report highlights 15 of the innovative SBIR 2014 Phase I and II projects that focus on one of NASA Glenn Research Center's six core competencies-Power, Energy Storage and Conversion. The technologies cover a wide spectrum of applications such as high-radiation-tolerant ceramic voltage isolators, development of hermetic sealing glasses for solid oxide fuel cells, rechargeable lithium metal cells, high-efficiency direct methane solid oxide fuel cell systems, Li metal protection for high-energy space batteries, isolated bidirectional direct current converters for distributed battery energy applications, and high-efficiency rad-hard ultrathin Si photovoltaic cell technology for space. Each article describes an innovation and technical objective and highlights NASA commercial and industrial applications. This report provides an opportunity for NASA engineers, researchers, and program managers to learn how NASA SBIR technologies could help their programs and projects, and lead to collaborations and partnerships between the small SBIR companies and NASA that would benefit both.

flywheels↗
NASA NTRS1990

Quasilinear saturation of forced current sheet tearing modes

Numerical studies of tearing modes in a nearly singular forced current sheet equilibrium (Liewer and Payne, 1990) show that the modes saturate quasilinearly when the width of the magnetic island formed by the reconnection is on the order of several times the linear mode width which scales as approximately (kS) exp -2/5, where S is the Lundquist number and k is the wavenumber. The modes saturate quasilinearly by flattening the current profile, converting magnetic energy into plasma energy. The longer wavelength modes, which saturate at higher levels, release the most energy. These modes may, nonlinearly, play a role in coronal heating when sharp current sheets form as a result of global magnetic stresses.

Liewer, Paulett C.↗
NASA NTRS1993

A direct current rectification scheme for microwave space power conversion using traveling wave electron acceleration

The formation of the Vision-21 conference held three years ago allowed the present author to reflect and speculate on the problem of converting electromagnetic energy to a direct current by essentially reversing the process used in traveling wave tubes that converts energy in the form of a direct current to electromagnetic energy. The idea was to use the electric field of the electromagnetic wave to produce electrons through the field emission process and accelerate these electrons by the same field to produce an electric current across a large potential difference. The acceleration process was that of cyclotron auto-resonance. Since that time, this rather speculative ideas has been developed into a method that shows great promise and for which a patent is pending and a prototype design will be demonstrated in a potential laser power beaming application. From the point of view of the author, a forum such as Vision-21 is becoming an essential component in the rather conservative climate in which our initiatives for space exploration are presently formed. Exchanges such as Vision-21 not only allows us to deviate from the 'by-the-book' approach and rediscover the ability and power in imagination, but provides for the discussion of ideas hitherto considered 'crazy' so that they may be given the change to transcend from the level of eccentricity to applicability.

Manning, Robert M.↗
NASA NTRS1980

Design of energy-storage reactors for single-winding constant-frequency dc-to-dc converters operating in the discontinuous-reactor-current mode

This paper presents an algorithm and equations for designing the energy-storage reactor for dc-to-dc converters which are constrained to operate in the discontinuous-reactor-current mode. This design procedure applied to the three widely used single-winding configurations: the voltage step-up, the current step-up, and the voltage-or-current step-up converters. A numerical design example is given to illustrate the use of the design algorithm and design equations.

Chen, D. Y.↗
NASA NTRS1992

Coronal loops - Current-based heating processes

Based on new observations, a theoretical model of magnetic-field related heating processes in the solar corona is given. In this model, field-aligned currents are induced along coronal loops in thin current sheaths. Excitation of instabilities involving magnetic reconnection converts the energy associated with the current-related magnetic field directly into particle energy, where the heating process proceeds via short bursts corresponding to an intermittent disruption of the current sheath configuration. Because of the relatively low transverse thermal conduction, only a small fraction of the loop volume is heated to a much higher temperature than the average value. This is consistent with experimental observations of low filling factors of hot plasmas in coronal loops. Thus the model involves a repeated sequence of dynamic events taking into account the observed loop topology, the differential emission measure distribution in the 10 exp 6 - 10 exp 7 K range, the energy balance requirements in the loop, and the probable duty cycles involved in the heating processes.

Beaufume, P.↗
NASA NTRS2013

Feasibility of Traveling Wave Direct Energy Conversion of Fission Reaction Fragments

Fission fragment direct energy conversion has been considered in the past for the purpose of increasing nuclear power plant efficiency and for advanced space propulsion. Since the fragments carry electric charge (typically in the order of 20 e) and have 100 MeV-range kinetic energy, techniques utilizing very high-voltage DC electrodes have been considered. This study is focused on a different approach: the kinetic energy of the charged fission fragments is converted into alternating current by means of a traveling wave coupling scheme (Traveling Wave Direct Energy Converter, TWDEC), thereby not requiring the utilization of high voltage technology. A preliminary feasibility analysis of the concept is introduced based on a conceptual level study and on a particle simulation model of the beam dynamics.

Tarditi, A. G.↗
NASA NTRS1993

Solid-state Isotopic Power Source for Computer Memory Chips

Recent developments in materials technology now make it possible to fabricate nonthermal thin-film radioisotopic energy converters (REC) with a specific power of 24 W/kg and a 10 year working life at 5 to 10 watts. This creates applications never before possible, such as placing the power supply directly on integrated circuit chips. The efficiency of the REC is about 25 percent which is two to three times greater than the 6 to 8 percent capabilities of current thermoelectric systems. Radio isotopic energy converters have the potential to meet many future space power requirements for a wide variety of applications with less mass, better efficiency, and less total area than other power conversion options. These benefits result in significant dollar savings over the projected mission lifetime.

Brown, Paul M.↗
NASA NTRS1979

Thermal power systems, point-focusing distributed receiver technology project. Volume 2: Detailed report

Thermal or electrical power from the sun's radiated energy through Point-Focusing Distributed Receiver technology is the goal of this Project. The energy thus produced must be economically competitive with other sources. The Project supports the industrial development of technology and hardware for extracting energy from solar power to achieve the stated goal. Present studies are working to concentrate the solar energy through mirrors or lenses, to a working fluid or gas, and through a power converter change to an energy source useful to man. Rankine-cycle and Brayton-cycle engines are currently being developed as the most promising energy converters for our near future needs.

Lucas, J.↗
NASA NTRS1982

Analysis of transistor and snubber turn-off dynamics in high-frequency high-voltage high-power converters

Dc to dc converters which operate reliably and efficiently at switching frequencies high enough to effect substantial reductions in the size and weight of converter energy storage elements are studied. A two winding current or voltage stepup (buck boost) dc-to-dc converter power stage submodule designed to operate in the 2.5-kW range, with an input voltage range of 110 to 180 V dc, and an output voltage of 250 V dc is emphasized. In order to assess the limitations of present day component and circuit technologies, a design goal switching frequency of 10 kHz was maintained. The converter design requirements represent a unique combination of high frequency, high voltage, and high power operation. The turn off dynamics of the primary circuit power switching transistor and its associated turn off snubber circuitry are investigated.

Wilson, P. M.↗
NASA NTRS2009

T-Rex: A Japanese Space Tether Experiment

Electrodynamic tether (EDT) thrusters work by virtue of the force a magnetic field exerts on a wire carrying an electrical current. The force, which acts on any charged particle moving through a magnetic field (including the electrons moving in a current-carrying wire), were concisely expressed by Lorentz in 1895 in an equation that now bears his name. The force acts in a direction perpendicular to both the direction of current flow and the magnetic field vector. Electric motors make use of this force: a wire loop in a magnetic field is made to rotate by the torque the Lorentz Force exerts on it due to an alternating current in the loop times so as to keep the torque acting in the same sense. The motion of the loop is transmitted to a shaft, thus providing work. Although the working principle of EDT thrusters is not new, its application to space transportation may be significant. In essence, an EDT thruster is just a clever way of getting an electrical current to flow in a long orbiting wire (the tether) so that the Earth s magnetic field will accelerate the wire and, consequently the payload attached to the wire. The direction of current flow in the tether, either toward or away from the Earth along the local vertical, determines whether the magnetic force will raise or lower the orbit. The bias voltage of a vertically deployed metal tether, which results just from its orbital motion (assumed eastward) through Earth s magnetic field, is positive with respect to the ambient plasma at the top and negative at the bottom. This polarization is due to the action of the Lorentz force on the electrons in the tether. Thus, the natural current flow is the result of negative electrons being attracted to the upper end and then returned to the plasma at the lower end. The magnetic force in this case has a component opposite to the direction of motion, and thus leads to a lowering of the orbit and eventually to re-entry. In this generator mode of operation the Lorentz Force serves both to drive the current and then to act on the current to decelerate the system. One of the most important features of tether thrusters is that they use renewable energy sources to drive the electrical current flow in either the orbit-raising or orbit-lowering modes. Sources inherent to Earth orbit are used. To raise the orbit, sunlight can be converted to the electrical energy required to drive the tether current. To lower the orbit, the orbital energy itself (supplied by the Earth-to-orbit launcher when it raises the system into orbit) is the energy source of the tether current via the action of the Lorentz Force. Electrodynamic tethers can be directly applied to a wide spectrum of uses in space. As a propulsion system, they include satellite de-orbit, transfer of a satellite from one orbit to another, altitude maintenance for large spacecraft such as the International Space Station, and since it works wherever there is a magnetic field and an ionosphere planetary exploration missions. An electrodynamic tether upper stage could be used as an Orbit Transfer Vehicle (OTV) to move payloads within low earth orbit. The OTV would rendezvous with the payload and launch vehicle, grapple the payload and maneuver it to a new orbital altitude or inclination without the use of boost propellant. The tug could then lower its orbit to rendezvous with the next payload and repeat the process. Conceivably, such a system could perform several orbital maneuvering assignments without resupply, making it relatively inexpensive to operate.

Johnson, Les↗
NASA NTRS1976

Pulsed thermionic converter study

A nuclear electric propulsion concept using a thermionic reactor inductively coupled to a magnetoplasmadynamic accelerator (MPD arc jet) is described, and the results of preliminary analyses are presented. In this system, the MPD thruster operates intermittently at higher voltages and power levels than the thermionic generating unit. A typical thrust pulse from the MPD arc jet is characterized by power levels of 1 to 4 MWe, a duration of 1 msec, and a duty cycle of approximately 20%. The thermionic generating unit operates continuously but with a lower power level of approximately 0.4 MWe. Energy storage between thrust pulses is provided by building up a large current in an inductor using the output of the thermionic converter array. Periodically, the charging current is interrupted, and the energy stored in the magnetic field of the inductor is utilized for a short duration thrust pulse. The results of the preliminary analysis show that a coupling effectiveness of approximately 85 to 90% is feasible for a nominal 400 KWe system with an inductive unit suitable for a flight vehicle.

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