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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

The 30-cm ion thruster power processor

A power processor unit for powering and controlling the 30 cm Mercury Electron-Bombardment Ion Thruster was designed, fabricated, and tested. The unit uses a unique and highly efficient transistor bridge inverter power stage in its implementation. The system operated from a 200 to 400 V dc input power bus, provides 12 independently controllable and closely regulated dc power outputs, and has an overall power conditioning capacity of 3.5 kW. Protective circuitry was incorporated as an integral part of the design to assure failure-free operation during transient and steady-state load faults. The implemented unit demonstrated an electrical efficiency between 91.5 and 91.9 at its nominal rated load over the 200 to 400 V dc input bus range.

Herron, B. G.↗
NASA NTRS1985

Bearing development program for a 25 kWe solar-powered organic Rankine-cycle engine

The bearing development program is summarized for a 25-kWe power conversion subsystem (PCS) consisting of an organic Rankine-cycle engine, and permanent magnetic alternator (PMA) and rectifier to be used in a 100-kWe point-focusing distributed receiver solar power plant. The engine and alternator were hermetically sealed and used toluene as the working fluid. The turbine, alternator, and feed pump (TAP) were mounted on a single shaft operating at speeds up to 60,000 rev/min. Net thermal-to-electric efficiencies in the range of 21 to 23% were demonstrated at the maximum working fluid temperature of 400 C (750 F). A chronological summary of the bearing development program is presented. The primary causes of bearing wear problems were traced to a combination of rotordynamic instability and electrodynamic discharge across the bearing surfaces caused by recirculating currents from the PMA. These problems were resolved by implementing an externally supplied, flooded-bearing lubrication system and by electrically insulating all bearings from the TAP housing. This program resulted in the successful development of a stable, high-speed, toluene-lubricated five-pad tilting-pad journal bearing and Rayleigh step thrust bearing system capable of operating at all inclinations between horizontal and vertical.

Nesmith, B.↗
NASA NTRS2006

High Efficiency Power Combining of Ka-Band TWTs for High Data Rate Communications

Future NASA deep space exploration missions are expected in some cases to require telecommunication systems capable of operating at very high data rates (potentially 1 Gbps or more) for the transmission back to Earth of large volumes of scientific data, which means high frequency transmitters with large bandwidth. Among the Ka band frequencies of interest are the present 500 MHz Deep Space Network (DSN) band of 31.8 to 32.3 GHz and a broader band at 37-38 GHz allocated for space science [1]. The large distances and use of practical antenna sizes dictate the need for high transmitter power of up to 1 kW or more. High electrical efficiency is also a requirement. The approach investigated by NASA GRC is a novel wave guide power combiner architecture based on a hybrid magic-T junction for combining the power output from multiple TWTs [1,2]. This architecture was successfully demonstrated and is capable of both high efficiency (90-95%, depending on frequency) and high data rate transmission (up to 622 Mbps) in a two-way power combiner circuit for two different pairs of Ka band TWTs at two different frequency bands. One pair of TWTs, tested over a frequency range of 29.1 to 29.6 GHz, consisted of two 110-115W TWTs previously used in uplink data transmission evaluation terminals in the NASA Advanced Communications Technology Satellite (ACTS) program [1,2]. The second pair was two 100W TWTs (Boeing 999H) designed for high efficiency operation (greater than 55%) over the DSN frequency band of 31.8 to 32.3 GHz [3]. The presentation will provide a qualitative description of the wave guide circuit, results for power combining and data transmission measurements, and results of computer modeling of the magic-T and alternative hybrid junctions for improvements in efficiency and power handling capability. The power combiner results presented here are relevant not only to NASA deep space exploration missions, but also to other U.S. Government agency programs.

Wintucky, E. G.↗
NASA NTRSDate not supplied

Some NASA Perspectives on H2

This presentation provides the NASA perspective for government and industry technology developers world-wide who are exploring the potential for hydrogen (H2) in aviation applications including electric aircraft, airport vehicles, and airport related equipment. NASA’s H2 interest has been related to vehicle-level technology development and integration only, but NASA is keenly aware of the necessity of work focused on solving the challenges of H2 airport infrastructure. Some historical perspectives are provided on NASA efforts in H2 fuel cell development for space and aeronautics applications. NASA’s current research portfolio includes some investigation of H2 energy storage and hydrocarbon conversion for fuel cells on electric aircraft. There is no current emphasis on the other H2-related challenges. Over the years NASA has conducted research into “Quiet Green Transport” with a H2 fuel cell powered aircraft, an Emissionless Aircraft Study with Non Flow Through – Regenerative Fuel Cell (NFT-RFC) technology which captures the water, and an H2 fuel cell powered Unmanned Aerial Vehicle (UAV) study. NASA has flown a long endurance UAV using a RFC in the Low Emissions Alternative Power (LEAP) program. Recently, NASA conducted feasibility studies on hybrid SOFC with onboard hydrocarbon fuel reformation for aircraft primary propulsive power and secondary power under the Fostering Ultra-Efficient, Low-Emitting Aviation Power (FUELEAP) program. NASA currently has a multiyear program with the Center for Cryogenic High-Efficiency Electrical Technologies for Aircraft (CHEETA) to explore the benefits of using cryogenic H2 on aircraft for fuel cell propulsion and to provide superconductivity in electrical power management on the aircraft.

Power↗
NASA NTRS2002

Power-Efficient, High-Current-Density, Long-Life Thermionic Cathode Developed for Microwave Amplifier Applications

A power-efficient, miniature, easily manufactured, reservoir-type barium-dispenser thermionic cathode has been developed that offers the significant advantages of simultaneous high electron-emission current density (>2 A/sq cm) and very long life (>100,000 hr of continuous operation) when compared with the commonly used impregnated-type barium-dispenser cathodes. Important applications of this cathode are a wide variety of microwave and millimeter-wave vacuum electronic devices, where high output power and reliability (long life) are essential. We also expect it to enable the practical development of higher purveyance electron guns for lower voltage and more reliable device operation. The low cathode heater power and reduced size and mass are expected to be particularly beneficial in traveling-wave-tube amplifiers (TWTA's) for space communications, where future NASA mission requirements include smaller onboard spacecraft systems, higher data transmission rates (high frequency and output power) and greater electrical efficiency.

Wintucky, Edwin G.↗
NASA NTRSDate not supplied

Lunar Polar Exploration with Beamed Powered Rovers

Use of a laser to transmit power to a photovoltaic array has been proposed many times, including significant work done at NASA Glenn during the 1990s, but until recently the technology has lagged behind the ambitious requirements. The current NASA objective of lunar polar exploration provides the need, and evolution of higher-power and more efficient lasers provides the opportunity. Exploration of the ice-bearing craters near the lunar poles, where complete absence of sunlight precludes solar power, have been identified as a significant technology challenge for NASA’s future exploration. An approach to solve this is to use a laser to send power from the illuminated crater rim to a photovoltaic receiver on a rover inside the permanently dark region. A conceptual design was done of a prototype laser power system to be included on a proposed flight demonstration of the Kilopower space reactor. For the design, the laser transmitter is mounted on a small rover capable of moving to a location in line of sight of the receiving rover, e.g., on a crater rim with a view into the permanently dark region to be explored. A 250-watt laser diode bar transmits power at 808 nm, using a 10.5 cm optical beam director. The beam is received by a GaAs solar array mounted on the exploring rover, where it is converted into electrical power at ~50% optical to electrical efficiency. For the flight demonstration, 50 meters of laser transmission was required. The design showed a total laser mass of 7.8 kg is capable of producing the beam needed, not including the thermal control system. The demonstration design demonstrates 50-m transmission, but it would be valuable to have longer point-to-point beaming on the moon. Long beam paths require higher coherence than the diode laser bars of the demonstration system. The development of high-efficiency diode-pumped fiber lasers meets this technology need: and diode-pumped fiber lasers using the Er/Yb system can be purchased commercially with overall conversion efficiency of greater than 50% at wavelength 1.06 micrometers. Two technologies for a photovoltaic converter for this wavelength are the InGaAs photovoltaic cell, using technology developed for multi-junction space solar cells, or newly-developed high-quantum efficiency silicon cells. The next step to mature the technology would be a lunar flight demonstration. In the future, this has the potential to enhance and enable future human exploration of the moon, harvesting and utilizing the ice resources of these permanently-shadowed craters.

Geoffrey A Landis↗
NASA NTRS2014

A CubeSat Asteroid Mission: Design Study and Trade-Offs

There is considerable interest in expanding the applicability of cubesat spacecraft into lightweight, low cost missions beyond Low Earth Orbit. A conceptual design was done for a 6-U cubesat for a technology demonstration to demonstrate use of electric propulsion systems on a small satellite platform. The candidate objective was a mission to be launched on the SLS test launch EM-1 to visit a Near-Earth asteroid. Both asteroid fly-by and asteroid rendezvous missions were analyzed. Propulsion systems analyzed included cold-gas thruster systems, Hall and ion thrusters, incorporating either Xenon or Iodine propellant, and an electrospray thruster. The mission takes advantage of the ability of the SLS launch to place it into an initial trajectory of C3=0. Targeting asteroids that fly close to earth minimizes the propulsion required for fly-by/rendezvous. Due to mass constraints, high specific impulse is required, and volume constraints mean the propellant density was also of great importance to the ability to achieve the required deltaV. This improves the relative usefulness of the electrospray salt, with higher propellant density. In order to minimize high pressure tanks and volatiles, the salt electrospray and iodine ion propulsion systems were the optimum designs for the fly-by and rendezvous missions respectively combined with a thruster gimbal and wheel system For the candidate fly-by mission, with a mission deltaV of about 400 m/s, the mission objectives could be accomplished with a 800s electrospray propulsion system, incorporating a propellant-less cathode and a bellows salt tank. This propulsion system is planned for demonstration on 2015 LEO and 2016 GEO DARPA flights. For the rendezvous mission, at a ΔV of 2000 m/s, the mission could be accomplished with a 50W miniature ion propulsion system running iodine propellant. This propulsion system is not yet demonstrated in space. The conceptual design shows that an asteroid mission is possible using a cubesat platform with high-efficiency electric propulsion.

cubesat↗
NASA NTRSDate not supplied

Development of a Cold-Walled Molten Regolith Electrolysis Reactor for Lunar Oxygen Production

On the lunar surface, production of commodi-ties to support human presence, such as water, food and oxygen, and sustain the growth of a per-manent outpostwill likely require the use oflocal resources. The moon is covered almost entirely withfragmented oxide minerals known as regolithhundreds of meter thick.As a resource, it is rich in oxygen (> 42 wt.%) bound in a solid state with a variety of metals. The molten regolith electrolysis (MRE)reactor is a promising technology for the production of gaseous oxygen from the lunar reg-olithin a simple, single-stepreaction that requires minimalconsumable materials, produces oxygen and metals with high electrical efficiency and high yields from any regolithcomposition.This process involvesmelting regolith to~1600°C then electro-lyzing the molten pool to separate metal and oxy-gen ions that are then collected as liquid metal and gaseous oxygen at the respective electrodes. Lab-scale demonstrations of the MRE technology have previously reliedon external heating sources to bring the entirety of the reactor up to the operating temperaturewhich creates corrosive interfaces be-tween the molten regolith and the containment ma-terial in the reactor, limiting the overall lifespan of a reactor[1]. The Gaseous Lunar Oxygen from Regolith Electrolysis (GaLORE) project is focused on the development of a “cold-walled” or “Joule-heated” reactor design in which an internal heating source is used to selectively melt a pool of regolith between the electrodes of the reactor, leaving a shell of solidified regolith between the molten pool and the containment vessel of the reactor. This next generation reactor concept has been under development as molten oxide electrolysis (MOE) by MIT and Boston Metal for the production of iron from pure ores for terrestrial application [2]. The GaLORE project in engaged in early development of the technology for use with varying lunar regolith compositionsin the lunar environment. Thermal modelling of a proposed cold-walledreac-tor design were used as a scaffold to develop pa-rameters for a feasible reactor shape and size as well as target energy consumption[3]. The current development effort for the cold-walled reactor de-sign will be presented as a trade study of the most promising techniques for melting regolithwithin the constraints imposed by the lunar environment.Heater devices are designed to accommodate lim-ited electrical power availabilityon the moon, a wide range of regolith compositions that may be seen on the moon, limited metals available for re-placing consumed parts,and the low thermal con-ductivity of granular regolith in vacuum.Heater de-vices will be down-selectedbased on performance measurements within the above operationalcon-straints,and selected devices will be integrated into a reactor with electrodes to begin producing oxygen. [1]Sibille,L.,Sadoway, D.R.,Sirk, A., Tripathy,P.,Melendez, O., Standish, E., Dominguez, J. A., Stefanescu, D.M.,Curreri, P.A., Poizeau,S.,2009. “Recent Advancesin Scale-up Development of Molten Regolith Electrolysis for Oxygen Production in support of a Lunar Base.”AIAA 2009-659, 47th AIAA Aerospace Sciences Meeting, 5 -8 January 2009, Orlando, FL. [2] Boston Metal, https://www.boston-metal.com/moe-technology/#moe-process[3]Schreiner, S.S.,Sibille, L., Dominguez, J.A., Hoffman, J.A., 2016. "A parametric sizing model for Molten Regolith Electrolysis reactors to pro-duce oxygen on the Moon." Advances in Space Research 57.,7,1585-1603.

K D Grossman↗
NASA NTRS1962

The Analysis of a Vortex Type Magnetohydrodynamic Induction Generator

Consideration it is given to the performance to the characteristics of an AC magnetohydrodynamic power generator, A rotating magnetic field is imposed on the vortex flow of an electrically conducting fluid, which is injected tangentially into an annulus formed by two nonconducting concentric cylinders and two nonconducting end plates. A perturbation technique is used to determine the two dimensional velocity and three dimensional electromagnetic field and current distributions. Finally, the generated power, the ohmic losses, the effective power and the electrical efficiency of the converter system are calculated.

MAGNETOHYDRODYNAMIC GENERATOR↗
NASA NTRS1971

CO2 laser experiments using nuclear reactions as the ionization source.

Experimental studies show that the output of a CO2 laser is significantly increased by products of the nuclear reaction He-3 (n,p)T. Helium-3 was used in lieu of the natural helium normally present in the 1:1:8 CO2:N2:He laser gas mixture (pressure = 6 torr). The laser assembly was then exposed to a reactor thermal neutron flux of about 100 million neutrons/sq cm/sec. Power output of the laser doubled while the electrical power input decreased; electrical efficiency was thus more than doubled. Results indicate that additional ionization by the energetic charged particles may be responsible for the improved laser performance.

Rhoads, H. S.↗
NASA NTRS1974

Development of a six-man, self-contained carbon dioxide collection subsystem for spacecraft application

Life Systems, working with NASA, has developed an electrochemical, six-man, self-contained carbon dioxide concentrator subsystem (CX-6) designed to normally remove 13.2 lb/day of CO2 while maintaining the CO2 partial pressure (pCO2) of the cabin atmosphere at 3 mm Hg or less. The CX-6 was subjected to extensive parametric and endurance testing. The effects of operating conditions on CO2 removal and electrical efficiencies were determined, including effects of hydrogen (H2) flow rate, process airflow rate, pCO2, operating temperature and current density. A total of 209 days of operation was accumulated. The subsystem was designed with self-contained electronic control and monitoring instrumentation. The CX-6 was redesigned and repackaged into the CO2 collection subsystem for the air revitalization group of the space station prototype.

Schubert, F. H.↗
NASA NTRS1975

Solid state remote power controllers for 120 VDC power systems

Solid state remote power controllers can be applied to any dc power system up to 120 Vdc and distribute power up to 3.6 kW per hour. Devices have demonstrated total electrical efficiencies of 98.5 percent to 99.0 percent at rated load currents.

Sundberg, G. R.↗
NASA NTRS1975

Three types of solid state remote power controllers

Three types of solid state Remote Power Controller (RPC) circuits for 120 Vdc spacecraft distribution systems have been developed and evaluated. Both current limiting and noncurrent limiting modes of overload protection were developed and were demonstrated to be feasible. A second generation of circuits was developed which offers comparable performance with substantially less cost and complexity. Electrical efficiency for both generations is 98.5 to 99%. This paper describes various aspects of the circuit design, trade-off studies, and experimental test results. Comparisons of design parameters, component requirements, and engineering model evaluations will emphasize the high efficiency and reliability of the designs.

Baker, D. E.↗
NASA NTRS1978

The 5200 cycle test of an 8-cm diameter Hg ion thruster

An accelerated cycle test was conducted in which an 8-cm Engineering Model Thruster (EMT) prototype successfully completed 5200 on-off cycles and a total of more than 1300hours of thruster operation at a 4.5 mN thrust level. Cathode tip heater powers required for starting and keeper voltages remained well within acceptable limits. The discharge chamber utilization and electrical efficiency were nearly constant over the duration of the test. It was concluded that on-off cyclic operation by itself does not appreciably degrade starting capability or performance of the 8-cm EMT.

Mantenieks, M. A.↗
NASA NTRS1978

Low loss, flexible, lightweight corporate RF feed system for SAR antenna application

Mechanical and electrical efficiency constraints imposed by the SEASAT-A synthetic aperture radar antenna posed difficult design problems. After consideration of available standard cable and waveguide systems, it was determined that an optimum design could be obtained from a suspended substrate RF feed system. Size and mechanical flexibility constraints forced the design of a flexible, suspended substrate section capable of 180-degree flexure. Original design goal for insertion loss over power division was 1 db; measured results indicated 0.6 db maximum across the band. Multipactor testing of system components indicated system breakdown capability in excess of 4 kW compared to a specification input maximum of 1500 W.

Schiavone, F.↗
NASA NTRS1976

Interface design considerations for terrestrial solar cell modules

The need for increased solar array electrical efficiency and reliability in the achievement of future large-scale system cost goals is discussed. The relative performance of various array module designs currently on the market is evaluated, and further design improvements are suggested. The subjects of module efficiency, temperature control, and series/parallel reliability are analyzed. Applications for various combinations of array characteristics are considered.

Ross, R. G., Jr.↗
NASA NTRS1978

5200 cycle of an 8-cm diameter Hg ion thruster

An accelerated cycle test was conducted in which an 8-cm Engineering Model Thruster (EMT) prototype successfully completed 5200 on-off cycles and a total of more than 1300 hours of thruster operation at a 4.5 mN thrust level. Cathode tip heater powers required for starting and keeper voltages remained well within acceptable limits. The discharge chamber utilization and electrical efficiency were nearly constant over the duration of the test. It is concluded that on-off cyclic operation by itself does not appreciably degrade starting capability or performance of the 8-cm EMT.

Mantenieks, M. A.↗