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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Distributed Fiber Optic Sensing to Identify Locations of Resistive Transitions in REBCO Conductors and Magnets

High-temperature superconductors such as REBa 2 Cu 3 O 7-x (REBCO, RE = rare earth) can generate strong magnetic fields that are promising for applications in particle accelerators and compact fusion reactors. Traditionally, voltage taps are installed in superconducting magnets to measure the voltage signals due to resistive transitions. The voltage-tap-based diagnostics is important for the development of magnet technology as it can help pinpoint the locations in the magnet windings that limit the magnet performance. The architecture of the multi-tape REBCO cable such as CORC wires, however, makes it difficult to apply the voltage-tap-based diagnostics to identify the locations of resistive transitions. Distributed fiber optic sensing (DFOS) has the potential to address this issue. In this paper, we report the measurements of thermal strain along a CORC wire based on optical frequency domain reflectometry with a maximum spatial resolution of 0.65 mm and a temporal resolution of 10 Hz. The optical fiber is co-wound with the CORC wire that is epoxy impregnated. During the test, current was increased until a resistive transition occurred in the conductor. The spectrum shift of the reflected light along the fiber was recorded. The results suggested that with proper thermal isolation from the cryogen, DFOS can be used to identify the locations of resistive transitions in CORC wires and magnets. In conclusion, the results will allow a better understanding of the causes of resistive transitions in REBCO conductors and magnets, which will help improve the REBCO magnet technology.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Direct quantification of ion composition and mobility in organic mixed ionic-electronic conductors

Ion transport in organic mixed ionic-electronic conductors (OMIECs) is crucial due to its direct impact on device response time and operating mechanisms but is often assessed indirectly or necessitates extra assumptions. Operando x-ray fluorescence (XRF) is a powerful, direct probe for elemental characterization of bulk OMIECs and was used to directly quantify ion composition and mobility in a model OMIEC, poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS), during device operation. The first cycle revealed slow electrowetting and cation-proton exchange. Subsequent cycles showed rapid response with minor cation fluctuation (~5%). Comparison with optical-tracked electrochromic fronts revealed mesoscale structure–dependent proton transport. The calculated effective ion mobility demonstrated thickness-dependent behavior, emphasizing an interfacial ion transport pathway with a higher mobile ion density. The decoupling of interfacial effects on bulk ion mobility and the decoupling of cation and proton migration elucidate ion transport in conventional and emerging OMIEC-based devices and has broader implications for other ionic conductors writ large.

42 ENGINEERING↗
DOE OSTI2022

Mechanical, Microstructural, and Electrochemical Characterization of NaSICON Sodium Ion Conductors [Poster]

The DOE Office of Electricity views sodium batteries as a priority in pursuing a safe, resilient, and reliable grid. Improvements in solid-state electrolytes are key to realizing the potential of these large-scale batteries. NaSICON structure consists of SiO 4 or PO 4 tetrahedra sharing common corners with ZrO 6 octahedra. Structure forms “tunnels” in three dimensions that can transport interstitial sodium ion. 3D structure provides higher ionic conductivity than other conductors (β’’-alumina), particularly at low temperature. Lower temperature (cheaper) processing compared to β’’-alumina. Our objective was to identify fundamental structure-processing-property relationships in NaSICON solid electrolytes to inform design for use in sodium batteries. In this work, the mechanical properties of NaSICON sodium ion conductors are affected by sodium conduction. Electrochemical cycling can alter modulus and hardness in NaSICON. Excessive cycling can lead to secondary phases and/or dendrite formation that change mechanical properties in NaSICON. Mechanical and electrochemical properties can be correlated with topographical features to further inform design decisions

25 ENERGY STORAGE↗
NASA NTRS1966

Special tool seals conductors with combination of plastic sleeves

Special tool seals electrical conductors connecting instrumentation within space vehicle cryogenic fuel tanks and oxidizer tanks. An inner sleeve of fluorinated ethylene-propylene and an outer sleeve of tetrafluoroethylene enclose a bundle of conductors and are heated with the tool to form a tight seal of the bundle and each individual wire.

Young, S.↗
NASA NTRS1971

Parallel-gap welding for joints between copper conductors and Kovar

Welding technique produces more reliable joints than soldering. Investigation used different sizes of copper conductors and component lead ribbons, corrosion protection platings, and melting points of metals being joined. Optimum combination is gold-plated component lead ribbons and solder-plated copper conductors.

Mc Daniel, G. E.↗
NASA NTRS1972

Termination of flat conductor cable to NASA/MSFC plugs

Data, supplemented with artwork, are presented on the major steps involved with terminating flat conductor cable (FCC) to MSFC's FCC plugs. Cable and shield preparation steps include material cutting, insulation stripping, and plating of exposed conductors. Methods and equipment required to terminate FCC to each of four MSFC plugs are described.

Angele, W.↗
NASA NTRS1974

Testing of flat conductor cable to Underwriters Laboratory standards UL719 and UL83

The flat conductor cable (FCC) which was tested consisted of three AWG No. 12 flat copper conductors laminated between two films of polyethylene terephthalate (Mylar) insulation with a self-extinguishing polyester adhesive. Results of the tests conducted on this cable, according to specifications, warrants the use of this FCC for electrical interconnections in a surface nonmetallic protective covering.

Loggins, R. W.↗
NASA NTRS1976

High-temperature flat-conductor cable

Temperature limit of 25-conductor signal cable and 3-conductor power cable, fabricated using woven and roll laminated technique, increased from 200 C to 350 C when polyimide/fluorinated ethylene propylene or polytetrafluoroethylene insulation films and fluorinated ethylene propylene as adhesive medium is applied.

Rigling, W. S.↗
NASA NTRS1979

Cryostatic influence of Formvar coatings on sizing of the stabilizer in superconductive NbTi-Cu - Conductor bundle effects

In continuation of single-conductor studies, quench onset data of quasi-steady operation are reported for a Formvar-coated composite (Nb48Ti/Cu) in bundle geometry (conductor thickness about 0.2 cm, approximately square cross section). Overall thermal conductances of the heater simulation technique applied are of the order 0.1 W/(sq cm-K), comparable to single-specimen results, around 4 K and below the lambda transition in agreement with model predictions. Considerable deterioration, however, occurs below 3 K and down to the lambda temperature during operation in near-saturated He I. Consequences for magnets of intermediate energy density are discussed with emphasis on the modifications necessitated by coatings.

Caspi, S.↗
NASA NTRS1981

Shielded conductor cable system

A cable system carries one or more insulated conductors completely enclosed within a shield having one end connected to ground. A lightning protector network connects the other end of the shield to ground. The protector network is normally open circuited and becomes only short circuited in response to a momentary abnormal surge voltage induced in the shield. The protector network's open to short impedance change completes a conductive circuit path between the shield and the two grounded ends for conducting a shield current which has the desired effect of protecting the signal carrying conductors in the cable from the large surge voltage.

Castle, K. D.↗
NASA NTRS1980

A base-metal conductor system for silicon solar cells

Solder, copper, and silver are evaluated as conductor layer metals for silicon solar cell metallization on the basis of metal price stability and reliability under operating conditions. Due to its properties and cost, copper becomes an attractive candidate for the conductor layer. It is shown that nickel operates as an excellent diffusion barrier between copper and silicon while simultaneously serving as an electrical contact and mechanical contact to silicon. The nickel-copper system may be applied to the silicon by plating techniques utilizing a variety of plating bath compositions. Solar cells having excellent current-voltage characteristics are fabricated to demonstrate the nickel-copper metallization system.

Coleman, M. G.↗
NASA NTRS1981

Numerical simulation of sheath structure and current-voltage characteristics of a conductor-dielectric disk in a plasma

A computer program is being developed to simulate the interaction of a plasma with a conducting disk. Two configurations are examined: (1) the conductor is a 'button' in the center of a larger dielectric disk, and (2) the conducting disk is covered by a dielectric disk to the same size with a circular hole in the center of the dielectric, exposing a region of conductor. Results of the electrostatic plasma simulation are presented both with and without secondary electron emission from the dielectric; characteristic curves and voltage profiles are included.

Chaky, R. C.↗
NASA NTRS1984

Shielded Aluminum Flat-Conductor Cable

Thin wiring harness stores compactly. Flat aluminum conductors glued between layers of polyimide. Aluminum shield surrounds insulated conductors. Outer layer polyimide. Aluminum shield reduces flexibility of cable and cable withstand only limited number of repetitions of sharp bending at same spot.

Farina, S.↗
NASA NTRS1986

Carbon Shields for Intercalated Fiber Conductors

Stability in air increased by depositing amorphous carbon. Initially graphite fibers intercalated (insertion of atoms or molecules between graphite layers). Next, conductor coated with diamondlike amorphous carbon. Coating applied in same chamber as intercalation reaction or alternate deposichamber is used. Deposition of carbon accomplished by any number of techniques. tion Ion-beam sputter-deposition and RF plasma techniques have been used, but dc plasma and others work also. Potential uses include conductive epoxy composites, tether conductors, signal wire, and power cables.

Banks, B. A.↗
NASA NTRS1986

Design and fabrication of the 20 km/10 kV electromechanical tether for TSS-1 using high impact conductor (Hiwire)

The development of a 20-km electromechanical tether for the tethered satellite system (TSS) is described. The basic design requirements for electromagnetic cables and for conductors in cables subject to stresses and cyclic loading are discussed. The tether fabricatioon procedures involve: (1) conductor twisting around the core, (2) insulation extrusion, (3) strength member braiding, and (4) protective jacket braiding.

Scala, E.↗
NASA NTRS1989

The physics of positively biased conductors surrounded by dielectrics in contact with a plasma

The physics of a positively biased conductor surrounded by dielectrics in contact with plasma is investigated. It is shown that because of the presence of secondary emission from the surrounding dielectrics, the voltage of the surfaces near the conductor has three solutions. The high- and low-voltage solutions are stable, while the intermediate-voltage solution is unstable. This theory is applied to explain the snapover effect observed on high-voltage solar arrays that involve the use of highly biased surfaces in contact with the space environment.

Hastings, Daniel E.↗
NASA NTRS1990

Low frequency electrical noise across contacts between a normal conductor and superconducting bulk YBa2Cu3O7

Virtually every device that makes use of the new ceramic superconductors will need normal conductor to supercondutor contacts. The current-voltage and electrical noise characteristics of these contacts could be become important design considerations. I-V and low frequency electrical noise measurements are presented on contacts between a normal conductor and superconducting polycrystalline YBa2Cu3O7. The contacts were formed by first sputtering gold palladium pads onto the surface of the bulk superconductor and then using silver epoxy to attach a wire(s) to each pad. Voltage across the contacts was found for small current densities. The voltage spectral density, S sub v(f), a quanity often used to characterize electrical noise, very closely followed an empirical relationship given by, S sub v(f) = C(VR)sq/f, where V is the DC voltage across the contact, R is the contact resistance, F is frequency, and C is a contant found to be 2 x 10(exp -10)/Omega sq at 78 K. This relationship was found to be independent of contact area, contact geometry, sample fabrication technique, and sample density.

Hall, J.↗