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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Solutions for discharge chamber sputtering and anode deposit spalling in small mercury ion thrusters

Small electron bombardment mercury ion thrusters are considered for attitude-control and station-keeping operations in the case of earth synchronous satellites. The required operational lifetimes of the order of 20,000 hours could present problems because of the occurrence of sputter erosion of thruster discharge chamber components. The investigation reported is concerned with a study of these problems and the development of approaches for overcoming them.

Power, J. L.↗
NASA NTRS1977

Anodic growth of niobium oxide

Report documents experimental examination of growth kinetics of niobium oxide, using current transient technique.

Davidson, M. C.↗
NASA NTRS1977

Multi-anode microchannel arrays

A development program is currently being undertaken to produce photon-counting detector arrays which are suitable for use in both ground-based and space-borne instruments and which utilize the full sensitivity, dynamic range and photometric stability of the microchannel array plate (MCP). The construction of the detector arrays and the status of the development program are described.

Timothy, J. G.↗
NASA NTRS1978

A progress report on multi-anode microchannel arrays

A development program is currently being undertaken to produce photon-counting detector arrays which are suitable for use in both ground-based and space-borne instruments and which utilize the full sensitivity, dynamic range and photometric stability of the microchannel array plate (MCP). The construction of the detector arrays and the status of the development program are briefly described.

Timothy, J. G.↗
NASA NTRS1979

Effects of 1-MeV gamma radiation on a multi-anode microchannel array detector tube

A multianode microchannel array (MAMA) detector tube without a photocathode was exposed to a total dose of 1,000,000 rads of 1-MeV gamma radiation from a Co-60 source. The high-voltage characteristic of the microchannel array plate, average dark count, gain, and resolution of pulse height distribution characteristics showed no degradation after this total dose. In fact, the degassing of the microchannels induced by the high radiation flux had the effect of cleaning up the array plate and improving its characteristics.

Timothy, J. G.↗
NASA NTRS1983

The development and test of multi-anode microchannel array detector systems. 2: Soft X-ray detectors

The techniques and procedures for producing very-large-format pulse-counting array detector systems for use in forthcoming high-energy astrophysics facilities were defined, and the structures and performance characteristics of high-sensitivity photocathodes for use at soft X-ray wavelengths between 100 and 1 A were determined. The progress made to date in each of these areas are described and the tasks that will be undertaken when the program is continued are summarized.

Timothy, J. G.↗
NASA NTRS1984

Research on oxidation by air and tempering of Raney nickel electrocatalysts for the H2 anodes of alkali combustion materials cells

The controlled oxidation in air of Raney nickel electrocatalysts was studied, with special attention paid to the quantitative analysis of nickel hydroxide. The content of the latter was determined through X-ray studies, thermogravimetric measurements, and spectral photometric examinations. The dependence of the content on the drying of activated catalyst is determined. The influence of nickel hydroxide on the electrochemical parameters of the catalyst, such as diffusion polarization, is studied, including a measurement of the exchange current density using the potential drop method. Conservation by oxidation in air with ancillary stabilization of the oxide in an H2 flow at 300 C is explored, including reduction by H2, the influence of tempering time, and structural studies on conserved and stabilized catalyst, long term research on the catalyst, including the influence of aging on the reduced catalyst, and the results of impedance measurements are presented.

Selbach, H. J.↗
NASA NTRS1984

Photometry with Multi-anode Microchannel Arrays (mamas) and Charge Injection Devices (cids)

The characteristics of two kinds of detectors are summarized with emphasis on those aspects that would affect their use in high accuracy astronomical photometry. The first type, the multianode microchannel arrays (MAMA), are a family of pulse counting array detectors. Components and operation principles are reviewed and quantum efficiency, noise characteristics, and dynamic range characteristics are described. The second type, charge injection devices (CID), are discussed in reference to their applicability to photometric detection at optical wavelengths.

Timothy, J. G.↗
NASA NTRS1986

The development and test of multi-anode microchannel array detector systems. Part 2: Soft X-ray detectors

Detector systems based on the high gain microchannel plate (MCP) electron multiplier were used extensively for imaging at soft X-ray wavelengths both on the ground and in space. The latest pulse counting electronic readout systems provide zero readout noise, spatial resolutions (FWHM) of 25 microns or better and can determine the arrival times of detected photons to an accuracy of the order of 100 ns. These systems can be developed to produce detectors with active areas of 100 nm in diameter or greater. The use of CsI photocathodes produces very high detective quantum efficiencies at wavelengths between about 100 and 1A (approximately 0.1 to 10 keV) with moderate energy resolution. The operating characteristics of the different types of soft X-ray MCP detector systems are described and the prospects for future developments are discussed.

Timothy, J. G.↗
NASA NTRS1986

Mathematical modelling of solar ultraviolet radiation induced optical degradation in anodized aluminum

In the design of spacecraft for proper thermal balance, accurate information on the long-term optical behavior of the spacecraft outer skin materials is necessary. A phenomenological model for such behavior is given. The underlying principles are explained and some examples are given of the model's fit to actual measurements under simulated Earth-orbit conditions. Comments are given on the applicability of the model to materials testing and thermal modelling.

Ruley, John D.↗
NASA NTRS1989

Delay-Line Anode For Microchannel-Plate Spectrometer

Photon-counting read-out system for microchannel-plate spectrometer includes delay line and timing circuit to measure wavelength coordinate and wedge/wedge charge-division system to measure orthogonal spatial coordinate. System proves advantageous for portable two-dimensional spectrometers having large image planes and for which design requirements include simplicity, reliability, low power consumption, and low mass.

Lampton, M.↗
NASA NTRS1993

Chemical Strips Anodic Film From Aluminum

Phosphoric acid solution offers advantages over other stripping solutions. More effective than other strippers and safer to use. Relatively environmentally benign, phosphoric acid stripper ceases its chemical attack so less process control is needed in its use.

Eichinger, Eric C.↗
NASA NTRS1993

Corrosion Of Anodized 2219-T87 Aluminum

Report describes electrochemical studies of effectiveness of three surface treatments in protecting 2219-T87 aluminum alloy against corrosion.

Danford, M. D.↗
NASA NTRS1993

High-resolution Y-axis readout for delay-line microchannel anodes

We have devised a method to obtain a high-resolution Y-axis event position determination from microchannel plate delay-line detectors. The method is based on the double-delay-line wedge-wedge charge partition principle of Lampton et al. (1990), where the X axis is read out by a pair of side-by-side delay lines and the Y-axis coordinate is determined by comparing the charges on the two parallel delay lines. However, our new method abandons the common field return path of the two delay lines, and splits them into two adjacent but independent transformer coupled timing circuits having no common ground connection except via the charge-measurement amplifiers. Thus we eliminate the large electrostatic capacitance of the delay lines from the input of the charge-measuring system. Over its limited working field, the spatial resolution in the Y coordinate can easily equal the resolution provided in the X coordinate by the delay line. Applications to extreme and FUV photon-counting spectroscopy are envisioned.

Raffanti, R.↗