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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Steady state composition with low Fe(2+) concentrations for efficient O2 production by 'magma' electrolysis of lunar soils

Parameters are estimated for a hypothetical, well stirred, continuous-feed electrolytic cell that converts 20 percent of a lunar soil feedstock to O2 gas, 26 percent to Fe-Si metal, 13 percent to spinel, and 41 percent to slag. Advantages of a molten Fe-Si cathode for trapping metal on reduction, a relatively conductive steady-state composition in equilibrium with spinel (a proposed container material), and close electrodes (less than 1 cm cathode-anode distance) are discussed. To produce 1 ton of O2, about 6 MHW of energy are required for the electrolysis and IR heating within the melt, and another about 6 MHW may be introduced as waste heat through internal resistance of the electrodes. Thus, to produce 1 ton of O2 per 24 hours, about 0.5 MW of power delivered to the cell would be required.

Haskin, Larry A.↗
NASA NTRS2018

Iodine Hall-Effect Electric Propulsion System Research, Development, and System Durability Demonstration

This paper reviews recent iodine electric propulsion research and development activities at the NASA Glenn Research Center (GRC). Activities included (i) investigation of the iodine compatibility of BaO-CaO-Al2O3 impregnated tungsten hollow cathodes based on a flight heritage design, (ii) investigation of the iodine compatibility of a handful of materials common to propulsion systems, spacecraft, and ground test facilities, (iii) development of reliable iodine feed system technologies, (iv) implementation of test facility improvements in an attempt to mitigate iodine associated negative impacts, and culminated in (v) an 1,174-hour hybrid iodine-xenon propulsion system durability demonstration (iodine fed Hall-effect thruster with xenon fed cathode). Each of the activities resulted in extensive insights that shall inform future iodine electric propulsion developments. While reliable operation of a BaO-CaO-Al2O3 impregnated tungsten hollow cathode on iodine vapor was not achieved, long-term operation on xenon gas in proximity to an iodine fed thruster was demonstrated without any measurable degradation or cross-contamination of the cathode. Furthermore, iodine material corrosion investigations conducted at 300degC over 5, 15, and 30 days showed significant deterioration of all materials evaluated, although the same materials with a silicon coating proved nearly impervious to iodine so long as the coating was not mechanically damaged. Finally, the 1,174-hour durability test demonstration showed that (i) iodine feed system technologies developed at GRC delivered well-regulated uninterrupted propellant, (ii) implementation of appropriate facility improvements and procedures can limit negative impacts of iodine on test hardware and ground support equipment, although facility challenges with iodine are extensive, and (iii) a Hall-effect thruster operates with similar performance whether employing iodine or xenon propellant over long durations. The work was motivated by strong government and commercial interest in the growing capabilities of small-spacecraft (<500 kg), in combination with interest for denser low-power, high delta-v in-space propulsion systems. This work adds to a growing body of research and development efforts aimed at addressing the many anticipated challenges of implementing iodine as an in-space propellant. This work was conducted under the Advanced In-Space Propulsion (AISP) project funded through the Game Changing Development (GCD) program within NASA's Science Technology Mission Directorate (STMD).

Benavides, Gabriel F.↗
NASA NTRS2018

Iodine Hall-Effect Electric Propulsion System Research, Development, and System Durability Demonstration

This paper reviews recent iodine electric propulsion research and development activities at the NASA Glenn Research Center (GRC). Activities included (i) investigation of the iodine compatibility of BaO-CaO-Al2O3 impregnated tungsten hollow cathodes based on a flight heritage design, (ii) investigation of the iodine compatibility of a handful of materials common to propulsion systems, spacecraft, and ground test facilities, (iii) development of reliable iodine feed system technologies, (iv) implementation of test facility improvements in an attempt to mitigate iodine associated negative impacts, and culminated in (v) an 1,174-hour hybrid iodine-xenon propulsion system durability demonstration (iodine fed Hall-effect thruster with xenon fed cathode). Each of the activities resulted in extensive insights that shall inform future iodine electric propulsion developments. While reliable operation of a BaO-CaO-Al2O3 impregnated tungsten hollow cathode on iodine vapor was not achieved, long-term operation on xenon gas in proximity to an iodine fed thruster was demonstrated without any measurable degradation or cross-contamination of the cathode. Furthermore, iodine material corrosion investigations conducted at 300 C over 5, 15, and 30 days showed significant deterioration of all materials evaluated, although the same materials with a silicon coating proved nearly impervious to iodine so long as the coating was not mechanically damaged. Finally, the 1,174-hour durability test demonstration showed that (i) iodine feed system technologies developed at GRC delivered well-regulated uninterrupted propellant, (ii) implementation of appropriate facility improvements and procedures can limit negative impacts of iodine on test hardware and ground support equipment, although facility challenges with iodine are extensive, and (iii) a Hall-effect thruster operates with similar performance whether employing iodine or xenon propellant over long durations. The work was motivated by strong government and commercial interest in the growing capabilities of small-spacecraft (<500 kg), in combination with interest for denser low-power, high delta-v in-space propulsion systems. This work adds to a growing body of research and development efforts aimed at addressing the many anticipated challenges of implementing iodine as an in-space propellant. This work was conducted under the Advanced In-Space Propulsion (AISP) project funded through the Game Changing Development (GCD) program within NASA's Science Technology Mission Directorate (STMD).

Benavides, Gabriel F.↗
NASA NTRS2018

Iodine Hall-Effect Electric Propulsion System Research, Development, and System Durability Demonstration

This paper reviews recent iodine electric propulsion research and development activities at the NASA Glenn Research Center (GRC). Activities included (i) investigation of the iodine compatibility of BaO-CaO-Al2O3 impregnated tungsten hollow cathodes based on a flight heritage design, (ii) investigation of the iodine compatibility of a handful of materials common to propulsion systems, spacecraft, and ground test facilities, (iii) development of reliable iodine feed system technologies, (iv) implementation of test facility improvements in an attempt to mitigate iodine associated negative impacts, and culminated in (v) an 1,174-hour hybrid iodine-xenon propulsion system durability demonstration (iodine fed Hall-effect thruster with xenon fed cathode). Each of the activities resulted in extensive insights that shall informfuture iodine electric propulsion developments. While reliable operation of a BaO-CaO-Al2O3 impregnated tungsten hollow cathode on iodine vapor was not achieved, long-term operation on xenon gas in proximity to an iodine fed thruster was demonstrated without any measurable degradation or cross-contamination of the cathode. Furthermore, iodine material corrosion investigations conducted at 300 degrees C over 5, 15, and 30 days showed significant deterioration of all materials evaluated, although the same materials with a silicon coating proved nearly impervious to iodine so long as the coating was not mechanically damaged. Finally, the 1,174-hour durability test demonstration showed that (i) iodine feed system technologies developed at GRC delivered well-regulated uninterrupted propellant, (ii) implementation of appropriate facility improvements and procedures can limit negative impacts of iodine on test hardware and ground support equipment, although facility challenges with iodine are extensive, and (iii) a Hall-effect thruster operates with similar performance whether employing iodine or xenon propellant over long durations. The work was motivated by strong government and commercial interest in the growing capabilities of small-spacecraft (<500 kg), in combination with interest for denser low-power, high delta-v in-space propulsion systems. This work adds to a growing body of research and development efforts aimed at addressing the many anticipated challenges of implementing iodine as an in-space propellant. This work was conducted under the Advanced In-Space Propulsion (AISP) project funded through the Game Changing Development (GCD) program within NASA's Science Technology Mission Directorate (STMD).

Benavides, Gabriel F.↗
NASA NTRS1975

Studies of internal sputtering in a 30-cm ion thruster

Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have been measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power loses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

Mantenieks, M. A.↗
NASA NTRS1975

Studies of internal sputtering in a 30-cm ion thruster

Initial studies have been made of the sputtering and deposition phenomena in a 30-cm thruster. Sputtering rates, of the cathode baffle, one of the main sources of sputtered material in a thruster, have beem measured by weight loss as a function of several thruster parameters. Sputtering rates were found to increase with both cathode flow rate and beam current when constant discharge voltage of 37 volts and power losses of 185 ev/ion were maintained. Sputtering rates were reduced 24% as discharge voltage was decreased from 37 to 33 volts while keeping discharge power constant. Qualitative agreement was found between sputtering rates obtained by the weight loss and those implied by spectroscopically observed line intensities of the excited iron sputtered atoms. After the completion of the sputtering tests, deposition and sputtering sites inside the thruster were identified.

Mantenieks, M. A.↗
NASA NTRS2010

Barium Depletion in the NSTAR Discharge Cathode After 30,000 Hours of Operation

Dispenser hollow cathodes rely on a consumable supply of barium released by impregnant materials in the pores of a tungsten matrix to maintain a low work function surface. Examinations of cathode inserts from long duration ion engine tests show deposits of tungsten at the downstream end that appear to block the flow of barium from the interior. In addition, a numerical model of barium transport in the insert plasma indicates that the barium partial pressure in the insert may exceed the equilibrium vapor pressure of the dominant barium-producing reaction, and it was postulated previously that this would suppress barium loss in the upstream part of the insert. New measurements of the depth of barium depletion from a cathode insert operated for 30,352 hours reveal that barium loss is confined to a narrow region near the downstream end, confirming this hypothesis.

plasma transport↗
NASA NTRS1989

Corrosion testing of candidates for the alkaline fuel cell cathode

Current/voltage data was obtained for specially made corrosion electrodes of some oxides and of gold materials for the purpose of developing a screening test of catalysts and supports for use at the cathode of the alkaline fuel cell. The data consists of measurements of current at fixed potentials and cyclic voltammograms. These data will have to be correlated with longtime performance data in order to fully evaluate this approach to corrosion screening. Corrosion test screening of candidates for the oxygen reduction electrode of the alkaline fuel cell was applied to two substances, the pyrochlore Pb2Ru2O6.5 and the spinel NiCo2O4. The substrate gold screen and a sample of the IFC Orbiter Pt-Au performance electrode were included as blanks. The pyrochlore data indicate relative stability, although nothing yet can be said about long term stability. The spinel was plainly unstable. For this type of testing to be validated, comparisons will have to be made with long term performance tests.

Singer, Joseph↗
NASA NTRS1980

Advanced screening of electrode couples

The chromium (Cr(3+)/Cr(2+)) redox couple (electrolyte and electrode) was investigated to determine its suitability as negative electrode for the iron (Fe(3+)/Fe(2+))-chromium (Cr(3+)/Cr(2+)) redox flow battery. Literature search and laboratory investigation established that the solubility and stability of aqueous acidic solutions of chromium(3) chloride and chromium(2) chloride are sufficient for redox battery application. Four categories of electrode materials were tested; namely, metals and metalloid materials (elements and compounds), alloys, plated materials, and Teflon-bonded materials. In all, the relative performance of 26 candidate electrode materials was evaluated on the basis of slow scan rate linear sweep voltammetry in stirred solution. No single material tested gave both acceptable anodic an acceptable cathodic performance. However, the identification of lead as a good cathodic electrocatalyst and gold as a good anodic electrocatalyst led to the invention of the lead/gold combination electrocatalyst. This type of catalyst can be fabricated in several ways and appears to offer the advantages of each metal without the disadvantages associated with their use as single materials. This lead/gold electrocatalyst was tested by NASA-Lewis Research Center in complete, flowing, redox batteries comprising a stack of several cells. A large improvement in the battery's coulombic and energy efficiency was observed.

Giner, J. D.↗
NASA NTRS1987

Diode Structure for Microwave and Infrared Applications

Microwave signals switched or modulated optically. Planar diode with transparent cathode made in BaAs, Si, and InSb versions. Depending on specific configuration and material, such diode used for optical modulation of microwave signal or as infrared detector. Transparent cathode fabricated on GaAs diode so diode illuminates to generate and control short-circuit current.

Alcorn, George↗
NASA NTRS1990

Corrosion testing of candidates for the alkaline fuel cell cathode

Current/voltage data have been obtained for specially made corrosion electrodes of some oxides and of gold materials for the purpose of developing a screening test of catalysts and supports for use at the cathode of the alkaline fuel cell. The data consist of measurements of current at fixed potentials and cyclic voltammograms. These data will have to be correlated with longtime performance data in order to evaluate fully this approach to corrosion screening.

Singer, Joseph↗
NASA NTRS1992

Hollow Cathode With Multiple Radial Orifices

Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

Brophy, John R.↗
NASA NTRS1976

Long lifetime hollow cathodes for 30-cm mercury ion thrusters

An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

Mirtich, M. J.↗
NASA NTRS1976

Long lifetime hollow cathodes for 30-cm mercury ion thrusters

An experimental investigation of hollow cathodes for 30-cm Hg bombardment thrusters was carried out. Both main and neutralizer cathode configurations were tested with both rolled foil inserts coated with low work function material and impregnated porous tungsten inserts. Temperature measurements of an impregnated insert at various positions in the cathode were made. These, along with the cathode thermal profile are presented. A theory for rolled foil and impregnated insert operation and lifetime in hollow cathodes is developed. Several endurance tests, as long as 18,000 hours at emission currents of up to 12 amps were attained with no degradation in performance.

Mirtich, M. J.↗
NASA NTRS2000

Li-Ion Cell Development for Low Temperature Applications

JPL is involved in the development of rechargeable Li-ion cells for future Mars Exploration Missions. The specific objectives are to improve the Li-ion cell cycle life performance and rate capability at low temperature (<<-20 C) in order to enhance survivability of the Mars lander and rover batteries. Poor Li-ion rate capability at low temperature has been attributed to: (1) the electrolytes becoming viscous or freezing and/or (2) reduced electrode capacity that results from decreased Li diffusivity. Our efforts focus on increasing the rate capability at low temperature for Li-ion cells. In order to improve the rate capability we evaluated the following: (1) cathode performance at low temperatures, (2) electrode active material particle size on low temperature performance and (3) Li diffusivity at room temperature and low temperatures. In this paper, we will discuss the results of our study.

Huang, C.-K.↗
NASA NTRS1992

Catalysts for ultrahigh current density oxygen cathodes for space fuel cell applications

The objective was to identify promising electrocatalyst/support systems for oxygen cathodes capable of operating at ultrahigh current densities in alkaline fuel cells. Such cells will require operation at relatively high temperatures and O2 pressures. A number of materials were prepared, including Pb-Ru and Pb-Ir pyrochlores, RuO2 and Pt-doped RuO2, lithiated NiO and La-Ni perovskites. Several of these materials were prepared using techniques that had not been previously used to prepare them. Particularly interesting was the use of the alkaline solution technique to prepare Pt-doped and Pb-Ru pyrochlores in high area form. Also interesting was the use of the fusion (melt) method for preparing the Pb-Ru pyrochlore. Several of the materials were also deposited with platinum. Well-crystallized Pb2Ru2O(7-y) was used to fabricate very high performance O2 cathodes with good stability in room temperature KOH. This material was also found to be stable over a useful potential range at approx. 140 C in concentrated KOH. For some of the samples, fabrication of the gas-fed electrodes could not be fully optimized during this project period. Future work may be directed at this problem. Pyrochlores that were not well-crystallized were found to be unstable in alkaline solution. Very good O2 reduction performance and stability were observed with Pb2RuO(7-y) in a carbon-based gas-fed electrode with an anion-conducting membrane placed on the electrolyte side of the electrode. The performance came within a factor of about two of that observed without carbon. High area platinum and gold supported on several conductive metal oxide supports were examined. Only small improvements in O2 reduction performance at room temperature were observed for Pb2Ru2O(7-y) as a support because of the high intrinsic activity of the pyrochlore. In contrast, a large improvement was observed for Li-doped NiO as a support for Pt. Very poor performance was observed for Au deposited on Li-NiO at approx. 150 C. Nearly reversible behavior was observed for the O2/OH(-) couple for Li-doped NiO at approx. 200 C. The temperature dependence for the O2 reduction was examined.

Tryk, Donald A.↗
NASA NTRS2018

Design and Development of Advanced Air-Cathodes for Li-Air Battery

NASA's future missions demand high energy density batteries. Current state-of-the-art lithium-ion batteries (LIBs) reach the specific energy capacity limits (<250 Wh/kg), thus new electrochemical storage technologies are needed to meet NASA's future mission requirement of >400 Wh/kg. Battery chemistries with higher theoretical energy densities in particular, Li-metal based battery chemistries such as Li-air, are being actively pursued, but there remains a number of issues to be solved. Development of advanced and optimized air cathodes will be crucial for improving capacity retention and cycle life of Li-air battery. The microstructure of carbon substrates and the catalytic oxygen reduction of the air-cathode play critical roles in the electrochemical performance in Li-air batteries. With the development and proper design of air cathodes, the energy efficiency and energy density can be enhanced significantly. In this presentation, the results of advanced permeable air cathodes design with different substrates such as 2D carbon paper or carbon cloth, vs 3D graphene or metal foam, different high surface area carbon materials and incorporation with catalysts on oxygen reduction reactions, different porosity controlling of air cathode as well the additives in electrolyte will be presented. The cycling and rate capability performance of these air-cathodes in the Li-air cells will be discussed as well.

Wu, James J.↗
NASA NTRS1976

Development of sputtered techniques for thrust chambers

Procedures for closing out coolant passages in regeneratively cooled thrust chambers by triode sputtering, using post and hollow Cu-0.15 percent Zr cathodes are described. The effects of aluminum composite filler materials, substrate preparation, sputter cleaning, substrate bias current density and system geometry on closeout layer bond strength and structure are evaluated. High strength closeout layers were sputtered over aluminum fillers. The tensile strength and microstructure of continuously sputtered Cu-0.15 percent Zr deposits were determined. These continuous sputtered deposits were as thick as 0.75 cm. Tensile strengths were consistently twice as great as the strength of the material in wrought form.

Mullaly, J. R.↗