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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 NTRS1994

Ultra high purity, dimensionally stable INVAR 36

An INVAR 36 material having long-term dimensional stability is produced by sintering a blend of powders of nickel and iron under pressure in an inert atmosphere to form an alloy containing less than 0.01 parts of carbon and less than 0.1 part aggregate and preferably 0.01 part individually of Mn, Si, P, S and Al impurities. The sintered alloy is heat treated and slowly and uniformly cooled to form a material having a coefficient of thermal expansion of less than 1 ppm/C and a temporal stability of less than 1 ppm/year.

Sokolowski, Witold M.↗
NASA NTRS1995

The control of purity and stoichiometry of compound semiconductors by high vapor pressure transport

In this report we summarize the results of a three year research program on high pressure vapor transport (HPVT) of compound semiconductors. Most of our work focused onto pnictides, in particular ZnGeP2, as a model system. Access to single crystals of well controlled composition of this material is desired for advancing the understanding and control of its point defect chemistry in the contest of remote, real-time sensing of trace impurities, e.g., greenhouse gases, in the atmosphere by ZnGeP2 optical parametric oscillators (OPO's).

Bachmann, Klaus J.↗
NASA NTRS1995

Ultra high purity, dimensionally stable INVAR 36

An INVAR 36 material having long-term dimensional stability is produced by sintering a blend of powders of nickel and iron under pressure in an inert atmosphere to form an alloy containing less than 0.01 parts of carbon and less than 0.1 part aggregate and preferably 0.01 part individually of Mn, Si, P, S and Al impurities. The sintered alloy is heat treated and slowly and uniformly cooled to form a material having a coefficient of thermal expansion of less than 1 ppm/C and a temporal stability of less than 1 ppm/year.

Sokolowski, Witold M.↗
NASA NTRS1995

Fabrication of large-area CCD detectors on high-purity, float-zone silicon

In this report on the fabrication of a 1024 x 1024 charge coupled device (CCD) imager to be used as a soft x-ray sensor onboard the Advanced X-ray Astronomical Facility (AXAF), the following conclusions were found: the dislocations that limited the performance of the high resistivity imager were characterized; the sources of stress were identified and the dislocations found were eliminated; and a charge transfer inefficiency (CTI) of 10(exp -6) and read noise as low as 1.3/e was demonstrated. This sensor must have low noise and a low CTI and must be radiation hardened to withstand any radiation damage from a space environment.

Gregory, J. A.↗
NASA NTRS1994

Purity and Cleanness of Aeorgel as a Cosmic Dust Capture Medium

The capability for capturing micrometeoroids intact through laboratory simulations [Tsou 1988] and in space [Tsou 1993] in passive underdense silica aerogel offers a valuable tool for cosmic dust research. The integrity of the sample handling medium can substantially modify the integrity of the sample. Intact capture is a violent hypervelocity event: the integrity of the capturing medium can cause even greater modification of the sample.

micrometeoroids cosmic dust silica aerogel↗
NASA NTRS2011

Use of Aquaporins to Achieve Needed Water Purity On ISS for the EMU Space Suit System

With the U.S. Space Shuttle fleet retired, the supply of extremely high-quality water 'super-Q' - required for the EMU Space suit cooling on this ISS - will become a significant operational hardware challenge in the very near future. A proposed potential solution is the use of a filtration system consisting of a semi-permeable membrane embedded with aquaporin proteins. Aquaporins are a special class of trans-membrane proteins that facilitate passive transport of water and other substances across a membrane. The specificity of these proteins is such that only water is allowed through the protein structure, and this novel property invites their adaptation for use in water filtration systems, specifically usage on the ISS for the EMU space suit system. These proteins are found in many living systems and have been developed for commercial use today.

Hill, Terry R.↗
NASA NTRS2003

Curved Focal-Plane Arrays Using Back-Illuminated High-Purity Photodetectors

Curved-focal-plane arrays of back-illuminated silicon-based photodetectors are being developed. The basic idea is to improve the performance of an imaging instrument and simplify the optics needed to obtain a given level of performance by making an image sensor (e.g., a photographic film or an array of photodetectors) conform to a curved focal surface, instead of following the customary practice of designing the optics to project an image onto a flat focal surface. Eyes are natural examples of optical systems that have curved focal surfaces on which image sensors (retinas) are located. One prior approach to implementation of this concept involves the use of curved-input-surface microchannel plates as arrays of photodetectors. In comparison with microchannel plates, these curved-focal-plane arrays would weigh less, operate at much lower voltages, and consume less power. It should also be possible to fabricate the proposed devices at lower cost. It would be possible to fabricate an array of photodetectors and readout circuitry in the form of a very-large-scale integrated (VLSI) circuit on a curved focal surface, but it would be difficult and expensive to do so. In a simple and inexpensive alternate approach, a device (see figure) would have (1) a curved back surface, onto which light would be focused; and (2) a flat front surface, on which VLSI circuitry would be fabricated by techniques that are well established for flat surfaces. The device would be made from ultrapure silicon, in which it is possible to form high-resistivity, thick photodetectors that are fully depleted through their thicknesses. (As used here, "thick means having a thickness between a fraction of a millimeter and a few millimeters.) The back surface would be polished to the curvature of the focal surface of the intended application. To enable the collection of charge carriers excited by photons near the back surface or in the bulk of the device, it would be necessary to form a transparent or semitransparent back-surface electrode, possibly by delta doping. [Delta doping is so named because its density-vs.-depth characteristic is reminiscent of the Dirac function (impulse function): the dopant is concentrated in a very thin layer - nominally, a single atomic layer.]

Nikzad, Shouleh↗
NASA NTRS2012

Use of Aquaporins to Achieve Needed Water Purity on the International Space Station for the Extravehicular Mobility Unit Space Suit System

With the retirement of the U.S. Space Shuttle fleet, the supply of extremely high quality water required for the Extravehicular Mobility Unit (EMU) space suit cooling on the International Space Station (ISS) will become a significant operational hardware challenge in the very near future. One proposed solution is the use of a filtration system consisting of a semipermeable membrane embedded with aquaporin proteins, a special class of transmembrane proteins that facilitate passive, selective transport of water in vivo. The specificity of aquaporins is such that only water is allowed through the protein structure, and it is this novel property that invites their adaptation for use in water filtration systems, specifically those onboard the ISS for the EMU space suit system. These proteins are also currently being developed for use in terrestrial filtration systems.

Hill, Terry R.↗
NASA NTRS2020

NASA Engineering and Safety Center Technical Bulletin No. 20-08: Assessment of Ketazine Derived High Purity Hydrazine for Spacecraft Propellant Systems

Hydrazine and its derivatives have dominated the class of hypergolic liquid propellants for bipropellant propulsion systems in rockets such as the Titan, MX Missile, and Ariane; it has also been widely utilized as a monopropellant in auxiliary power units and in thrusters for altitude and in-orbit control of satellites and spacecraft. With continued use of hydrazine in current and future spacecraft and payloads, it is necessary to understand the historical and current states of synthesis for the commodity and possible implications that may arise from changes in production processes for the United States stock.

Ketazine↗