Tech Briefs

Coating MCPs With AlN and GaN

Emission of electrons is increased.

A development effort underway at the time of reporting the information for this article is devoted to increasing the sensitivity of microchannel plates (MCPs) as detectors of photons and ions by coating the MCPs with nitrides of elements in period III of the periodic table. Conventional MCPs are relatively insensitive to slowly moving, large-mass ions — for example, ions of biomolecules under analysis in mass spectrometers. The idea underlying this development is to coat an MCP to reduce its work function (decrease its electron affinity) in order to increase both (1) the emission of electrons in response to impingement of low-energy, large-mass ions and (2) the multiplying effect of secondary electron emission.

Posted in: Briefs, Electronics & Computers, Product development, Coatings Colorants and Finishes, Coatings, colorants, and finishes, Reliability, Reliability

Automatic Locking of Laser Frequency to an Absorption Peak

Initial manual tuning is ordinarily not necessary.

An electronic system adjusts the frequency of a tunable laser, eventually locking the frequency to a peak in the optical absorption spectrum of a gas (or of a Fabry-Perot cavity that has an absorption peak like that of a gas). This system was developed to enable precise locking of the frequency of a laser used in differential absorption LIDAR measurements of trace atmospheric gases. This system also has great commercial potential as a prototype of means for precise control of frequencies of lasers in future dense wavelength-division-multiplexing optical communications systems.

Posted in: Briefs, Electronics & Computers, Electronic control systems, Lasers, Electronic control systems, Lasers, Gases

Noise Source for Calibrating a Microwave

This compact unit can readily be integrated into an airborne microwave instrumentation.

A correlated-noise source has been developed for use in calibrating an airborne or spaceborne Earth-observing correlation microwave polarimeter that operates in a pass band that includes a nominal frequency of 10.7 GHz. Deviations from ideal behavior of the hardware of correlation polarimeters are such as to decorrelate the signals measured by such an instrument. A correlated- noise source provides known input signals, measurements of which can be processed to estimate and correct for the decorrelation effect.

Posted in: Briefs, Electronics & Computers, Calibration, Radar, Radar, Noise, Noise

Self-Passivating Lithium/Solid Electrolyte/Iodine Cells

Passivating lithium iodide films of optimum or nearly optimum thickness form spontaneously.

Robust lithium/solid electrolyte/iodine electrochemical cells that offer significant advantages over commercial lithium/ iodine cells have been developed. At room temperature, these cells can be discharged at current densities 10 to 30 times those of commercial lithium/iodine cells. Moreover, from room temperature up to 80 °C, the maximum discharge-current densities of these cells exceed those of all other solid-electrolyte-based cells.

Posted in: Briefs, TSP, Electronics & Computers, Battery cell chemistry, Battery cell chemistry, Electrolytes, Lithium, Performance tests

Hybrid Deployable Foam Antennas and Reflectors

Compressed foam structures would be expanded to full size and shape.

Hybrid deployable radio antennas and reflectors of a proposed type would feature rigid narrower apertures plus wider adjoining apertures comprising reflective surfaces supported by open-cell polymeric foam structures (see figure). The open-cell foam structure of such an antenna would be compressed for compact stowage during transport. To initiate deployment of the antenna, the foam structure would simply be released from its stowage mechanical restraint. The elasticity of the foam would drive the expansion of the foam structure to its full size and shape.

Posted in: Briefs, TSP, Electronics & Computers, Antennas, Antennas, Storage, Foams

Gesture-Controlled Interfaces for Self-Service Machines

Potential advantages include immunity to wear and increased safety

Gesture-controlled interfaces are software-driven systems that facilitate device control by translating visual hand and body signals into commands. Such interfaces could be especially attractive for controlling self-service machines (SSMs) — for example, public information kiosks, ticket dispensers, gasoline pumps, and automated teller machines (see figure).

Posted in: Briefs, Electronics & Computers, Electronic control systems, Electronic control systems, Human machine interface (HMI), Displays, Displays

Domed, 40-cm-Diameter Ion Optics for an Ion Thruster

A modified design affords better performance without loss of service life.

Improved accelerator and screen grids for an ion accelerator have been designed and tested in a continuing effort to increase the sustainable power and thrust at the high end of the accelerator throttling range. The accelerator and screen grids are undergoing development for intended use as NASA’s Evolutionary Xenon Thruster (NEXT) — a spacecraft thruster that would have an input-power throttling range of 1.2 to 6.9 kW. The improved accelerator and screen grids could also be incorporated into ion accelerators used in such industrial processes as ion implantation and ion milling.

Posted in: Briefs, Electronics & Computers, Nuclear energy, Product development, Throttles, Performance tests, Spacecraft

User Interactive Software for Analysis of Human Physiological Data

Ambulatory physiological monitoring has been used to study human health and performance in space and in a variety of Earth-based environments (e.g., military aircraft, armored vehicles, small groups in isolation, and patients). Large, multi-channel data files are typically recorded in these environments, and these files often require the removal of contaminated data prior to processing and analyses.

Posted in: Briefs, TSP, Software, Computer software and hardware, Medical equipment and supplies, Data management, Reliability

Inferring Gear Damage From Oil-Debris and Vibration Data

Data fusion increases the reliability and reduces the difficulty of gear-damage diagnosis.

system for real-time detection of surface- fatigue-pitting damage to gears for use in a helicopter transmission is based on fuzzy-logic used to fuse data from sensors that measure oil-borne debris, referred to as “oil debris” in the article, and vibration signatures. A system to detect helicopter-transmission gear damage is beneficial because the power train of a helicopter is essential for propulsion, lift, and maneuvering, hence, the integrity of the transmission is critical to helicopter safety. To enable detection of an impending transmission failure, an ideal diagnostic system should provide real-time monitoring of the “health” of the transmission, be capable of a high level of reliable detection (with minimization of false alarms), and provide human users with clear information on the health of the system without making it necessary for them to interpret large amounts of sensor data.

Posted in: Briefs, TSP, Mechanical Components, Mechanics, On-board diagnostics, On-board diagnostics (OBD), Fatigue, Vibration, Gears, Transmission gears, Rotary-wing aircraft

Representation of Serendipitous Scientific Data

A computer program defines and implements an innovative kind of data structure than can be used for representing information derived from serendipitous discoveries made via collection of scientific data on long exploratory spacecraft missions. Data structures capable of collecting any kind of data can easily be implemented in advance, but the task of designing a fixed and efficient data structure suitable for processing raw data into useful information and taking advantage of serendipitous scientific discovery is becoming increasingly difficult as missions go deeper into space. The present software eases the task by enabling definition of arbitrarily complex data structures that can adapt at run time as raw data are transformed into other types of information. This software runs on a variety of computers, and can be distributed in either source code or binary code form. It must be run in conjunction with any one of a number of Lisp compilers that are available commercially or as shareware. It has no specific memory requirements and depends upon the other software with which it is used. This program is implemented as a library that is called by, and becomes folded into, the other software with which it is used.

Posted in: Briefs, TSP, Software, Architecture, Computer software and hardware, Data management

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