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At least 163 records · Page 9

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NASA NTRS1979

Low intensity X-ray and gamma-ray imaging device

A radiation to visible light converter is combined with a visible light intensifier. The converter is a phosphor or scintillator material which is modified to block ambient light. The intensifier includes fiber optics input and output face plates with a photocathode-microchannel plate amplifier-phosphor combination. Incoming radiation is converted to visible light by the converter which is piped into the intensifier by the input fiber optics face plate. The photocathode converts the visible light to electrons which are amplified by a microchannel plate amplifier. The electrons are converted back to light by a phosphor layer and piped out for viewing by the output fiber optics faces plate. The converter-intensifier combination may be further combined with its own radiation source or used with an independent source.

Yin, L. I.↗

NASA NTRS1981

Applications study of advanced power generation systems utilizing coal-derived fuels. Volume 1: Executive summary

The technology status of phosphoric acid and molten carbon fuel cells, combined gas and steam turbine cycles, and magnetohydrodynamic energy conversion systems was assessed and the power performance of these systems when operating with medium-Btu fuel gas whether delivered by pipeline to the power plant or in an integrated mode in which the coal gasification process and power system are closely coupled as an overall power plant was evaluated. Commercially available combined-cycle gas turbine systems can reach projected required performance levels for advanced systems using currently available technology. The phosphoric acid fuel cell appears to be the next most likely candidate for commercialization. On pipeline delivery, the systems efficiency ranges from 40.9% for the phosphoric acid fuel cell to 63% for the molten carbonate fuel cell system. The efficiencies of the integrated power plants vary from approximately 39-40% for the combined cycle to 46-47% for the molden carbonate fuel cell systems. Conventional coal-fired steam stations with flue-gas desulfurization have only 33-35% efficiency.

Robson, F. L.↗

NASA NTRS1983

Advanced coal gasifier-fuel cell power plant systems design

Two advanced, high efficiency coal-fired power plants were designed, one utilizing a phosphoric acid fuel cell and one utilizing a molten carbonate fuel cell. Both incorporate a TRW Catalytic Hydrogen Process gasifier and regenerator. Both plants operate without an oxygen plant and without requiring water feed; they, instead, require makeup dolomite. Neither plant requires a shift converter; neither plant has heat exchangers operating above 1250 F. Both plants have attractive efficiencies and costs. While the molten carbonate version has a higher (52%) efficiency than the phosphoric acid version (48%), it also has a higher ($0.078/kWh versus $0.072/kWh) ten-year levelized cost of electricity. The phosphoric acid fuel cell power plant is probably feasible to build in the near term: questions about the TRW process need to be answered experimentally, such as weather it can operate on caking coals, and how effective the catalyzed carbon-dioxide acceptor will be at pilot scale, both in removing carbon dioxide and in removing sulfur from the gasifier.

Heller, M. E.↗

NASA NTRS1983

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. A theoretical expression for the rotating ring-disk electrode technique; the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; oxygen reduction mechanism in trifluoromethanesulfonic acid (TFMSA), considered as an alternate electrolyte for the acid fuel cells; and transport properties of the phosphoric acid electrolyte at high concentrations and temperatures are covered.

Chin, D. T.↗

NASA NTRS1984

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. The areas covered were: (1) development of a theoretical expression for the rotating ring disk electrode technique; (2) determination of the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; (3) determination of oxygen reduction mechanism in trifluoreomethanesulfonic acid (TFMSA) which was considered as an alternate electrolyte for the acid fuel cells; and (4) the measurement of transport properties of the phosphoric acid electrolyte at high concentrations and temperatures.

Chin, D. T.↗

NASA NTRS1990

X ray sensitive area detection device

A radiation sensitive area detection device is disclosed which comprises a phosphor-containing film capable of receiving and storing an image formed by a pattern of incoming x rays, UV, or other radiation falling on the film. The device is capable of fluorescing in response to stimulation by a light source in a manner directly proportional to the stored radiation pattern. The device includes: (1) a light source capable of projecting light or other appropriate electromagnetic wave on the film so as to cause it to fluoresce; (2) a means to focus the fluoresced light coming from the phosphor-containing film after light stimulation; and (3) at least one charged coupled detector or other detecting element capable of receiving and digitizing the pattern of fluoresced light coming from the phosphor-containing film. The device will be able to generate superior x ray images of high resolution from a crystal or other sample and will be particularly advantageous in that instantaneous near-real-time images of rapidly deteriorating samples can be obtained. Furthermore, the device can be made compact and sturdy, thus capable of carrying out x ray or other radiation imaging under a variety of conditions, including those experienced in space.

Carter, Daniel C.↗

NASA NTRS1997

A High Temperature Vapor Phase Lubrication Study Utilizing a Thioether Liquid Lubricant

Much of the experimental work on vapor phase lubrication has employed certain organo phosphorous compounds as the vapor phase lubricant. Graham and Klaus, for instance, used tricresyl phosphate (TCP) and tributyl phosphate to vapor phase lubricate a four-ball wear tester using M50 steel balls at 370 C. Makki and Graham were able to vapor phase lubricate a reciprocating pin on plate tribometer using 1018 steel at 280 C with TCP vapor. Although a few organo phosphorous compounds, such as TCP, have been successfully used as vapor phase lubricants in many laboratory experiments, many problems remain unsolved. Two areas of concern relate to the 'durability' of phosphate deposited films and to the ability of the lubricating system to "self-recover" when vapor phase lubricated with an organo phosphorous compound. Durability refers to the ability of the deposited film to provide effective lubrication, for a period of time, after the vapor flow to the lubricating surfaces has been interrupted. Vapor phase lubrication tests, conducted at Cleveland State University with their high temperature tribometer, revealed that when TCP vapor flow to the lubricating surfaces was interrupted the frictional coefficient of the system rapidly increased from a value less than 0.1 to a value of 0.3 which was selected as our failure point. Self-recovery means the ability of the vapor phase lubricant to reduce the frictional coefficient of the lubricating system back down to value less than 0.1 after startup of the interrupted vapor flow. Lubrication tests conducted at Cleveland State University revealed that the high temperature tribometer could not self-recover after startup of the interrupted TCP vapor flow.

Morales, Wilfredo↗

NASA NTRS1998

Measurement of heat conduction through stacked screens

This paper describes the experimental apparatus for the measurement of heat conduction through stacked screens as well as some experimental results taken with the apparatus. Screens are stacked in a fiberglass-epoxy cylinder, which is 24.4 mm in diameter and 55 mm in length. The cold end of the stacked screens is cooled by a Gifford-McMahon (GM) cryocooler at cryogenic temperature, and the hot end is maintained at room temperature. Heat conduction through the screens is determined from the temperature gradient in a calibrated heat flow sensor mounted between the cold end of the stacked screens and the GM cryocooler. The samples used for these experiments consisted of 400-mesh stainless steel screens, 400-mesh phosphor bronze screens, and two different porosities of 325-mesh stainless steel screens. The wire diameter of the 400-mesh stainless steel and phosphor bronze screens was 25.4 micrometers and the 325-mesh stainless steel screen wire diameters were 22.9 micrometers and 27.9 micrometers. Standard porosity values were used for the experimental data with additional porosity values used on selected experiments. The experimental results showed that the helium gas between each screen enhanced the heat conduction through the stacked screens by several orders of magnitude compared to that in vacuum. The conduction degradation factor is the ratio of actual heat conduction to the heat conduction where the regenerator material is assumed to be a solid rod of the same cross sectional area as the metal fraction of the screen. This factor was about 0.1 for the stainless steel and 0.022 for the phosphor bronze, and almost constant for the temperature range of 40 to 80 K at the cold end.

NASA Discipline Environmental Health↗

NASA NTRS1968

Preparation of silver-activated zinc sulfide thin films

Silver improves luminescence and reduces contamination of zinc sulfide phosphors. The silver is added after the zinc sulfide phosphors are deposited in thin films by vapor evaporation, but before calcining, by immersion in a solution of silver salt.

Feldman, C.↗

NASA NTRS1972

Improved photoetching fabrication method

Photoetching method producing well-defined lines with minimum undercutting was developed for etching coolant passages in nickel sheet. Phosphate coating is applied over conventional silver plate maskant and phosphoric acid solution is used to remove silver maskant. Phosphoric acid prevents etching of silver edges and mask has sharply-defined lines.

Kistler, C. L.↗

NASA NTRS1971

CRT image recording evaluation

Performance capabilities and limitations of a fiber optic coupled line scan CRT image recording system were investigated. The test program evaluated the following components: (1). P31 phosphor CRT with EMA faceplate; (2). P31 phosphor CRT with clear clad faceplate; (3). Type 7743 semi-gloss dry process positive print paper; (4). Type 777 flat finish dry process positive print paper; (5). Type 7842 dry process positive film; and (6). Type 1971 semi-gloss wet process positive print paper. Detailed test procedures used in each test are provided along with a description of each test, the test data, and an analysis of the results.

Source record↗

NASA NTRS1971

High contrast cathode ray tube

A layer of material is described, which contains fine grains of phosphor material stimulated by electrons to produce visible radiation. The layer, which also contains fine grains of cobalt oxide, is deposited on the glass screen of a cathode ray tube to provide high contrast, by absorbing most of the visible radiation which is directed to the layer through the screen, while not materially affecting the visible light which the phosphor material produces in response to the electron stimulation.

Lisovicz, E. J.↗

NASA NTRS1972

The Lick Observatory image-dissector scanner.

A scanner that uses an image dissector to scan the output screen of an image tube has proven to be a sensitive and linear detector for faint astronomical spectra. The image-tube phosphor screen acts as a short-term storage element and allows the system to approach the performance of an ideal multichannel photon counter. Pulses resulting from individual photons, emitted from the output phosphor and detected by the image dissector, trigger an amplifier-discriminator and are counted in a 24-bit, 4096-word circulating memory. Aspects of system performance are discussed, giving attention to linearity, dynamic range, sensitivity, stability, and scattered light properties.

Robinson, L. B.↗

NASA NTRS1972

Cathodochromic cathode ray tube: An operations manual

A cathodochromic (CC) storage and display system capable of storing full TV resolution images has been built. The images are derived from standard TV signals: composite video, composite sync, composite blanking, horizontal drive, and vertical drive. Image storage takes place in the CC CRT; the fixed image is written for several TV frames for the contrast to be usable. Once stored on the CC CRT, the image can be read out in one of three modes: with the eye, a 35-mm camera, or a TV camera. Incoming information may also be stored in a storage tube similar to the CC CRT but with a phosphor layer behind the CC layer. By exciting the phosphor layer with a standard raster scan it is possible to read out an image stored in the CC layer in one of three modes: direct viewing, photography, or flying-spot readout using a photomultiplier.

Heyman, P. M.↗

NASA NTRS1972

The smoothing dissector.

A technique for adding a form of buffer store to an image dissector is described that increases markedly the photoelectron-detecting ability of the image dissector. The buffer-store function is accomplished in the phosphor screen of an image intensifier tube by the metastable electronic excitation states resulting in the phosphor screen from high-energy photoelectron bombardment. The addition of this image intensifier to an image dissector is shown to cause no nonlinearity in the input/output characteristics of the image dissector.

Eberhardt, E. H.↗

NASA NTRS1969

Cathodochromic storage device

A memory and display device has been developed by combing a fast phosphor layer with a cathodochromic layer in a cathode ray tube. Images are stored as patterns of electron beam induced optical density in the cathodo-chromic material. The stored information is recovered by exciting the backing, fast phosphor layer with a constant current electron beam and detecting the emitted radiation which is modulated by absorption in the cathodochromic layer. The storage can be accomplished in one or more TV frames (1/30 sec each). More than 500 TV line resolution and close to 2:1 contrast ratio are possible. The information storage time in a dark environment is approximately 24 hours. A reconstituted (readout) electronic video signal can be generated continuously for times in excess of 10 minutes or periodically for several hours.

Bosomworth, D. R.↗

NASA NTRS1977

Determination of trace amounts of POF3

Approach takes advantage of fact that phosphorous oxyfluoride (POF3) and phosphorous oxychloride (POC13) both belong to same molecular symmetry group and should have extinction coefficients that are approximately the same. Extinction coefficient of reagent-grade POC13 is measured, and this coefficient is employed to calculate POF3 concentrations.

Foster, J. N.↗

NASA NTRS1977

X-ray sensitive oblique imaging device

Instrument employs light reflecting surface (evaporated aluminum coating or minor substrate) behind phosphor screen to improve effective quantum efficiency in dual process: fraction of incoming X-rays are converted to photoelectrons at photocathode; and X-rays that pass through photocathode and thin X-ray transparent membrane enter phosphor screen.

Hallam, K. L.↗