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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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An all-electronic crossbar switch consisting of FET series-shunt switches inside the feedback loops of operational amplifiers was designed and constructed. Time-shared solution of five different differential equations was obtained by using four integrators on ASTRAC 2, with a new solution being generated 250 times per second.
A simple technique for sequentially Q-switching molecular lasers is discussed in which an optical scanner is used as an optical folding element in a laser cavity consisting of a stationary diffraction grating and partially reflecting mirror. Sequential Q-switching of a conventional CO2 laser is demonstrated in which over sixty-two transitions between 9.2 and 10.8 microns are observed. Rapid repetition rates (200 Hz) and narrow laser pulses (less than 5 microsec) allow conventional signal processing techniques to be used with this multiwavelength laser source which is a versatile tool for laser propagation studies, absorption spectroscopy, and gain measurements. Results of a preliminary experiment demonstrating the utility of measuring selective absorption of CO2 laser wavelengths by C2H4 are shown.
Description of a new scheme using parabolic switching boundaries as opposed to the current method of linear switching to improve the fuel consumption of manned orbital space vehicles. Fuel consumption during error recovery and limit cycle phases are both considered.
Continuous-wave laser can achieve higher rate of emission through Q-switching. Technique keeps Q, energy storage rating, of laser cavity at low value while ion population inversion is being built up. Then Q is suddenly switched to high value just before instability occurs.
Solid state switch has following capabilities: (1) Hybrid or IC from compatible with direct mounting on solar array substrate; (2) Continuous signal is not required to hold it in either on or off state; (3) Separate signal lines for on and off control; (4) Electrically isolated from input signals; and (5) Current surges will not cause switch failure.
Thermal switch maintains temperature of planetary lander, within definite range, by transferring heat. Switch produces relatively large stroke and force, uses minimum electrical power, is lightweight, is vapor pressure actuated, and withstands sterilization temperatures without damage.
Switch presently provides remote control switching, by radio signals, or pollution sampling devices. Can be used for remote weather station interrogation, firing of pyrotechnics, control of dangerous equipment, or control of device in location where it is impractical to run metallic conductors because of time limitations, distance, or terrain.
A preliminary evaluation of environmental capabilities was undertaken on toggle switches and on Apollo-type toggle switches. The purpose of this evaluation was to take a first look at their tested capabilities for the purpose of determining whether the candidate hardware appears to have a good chance of successfully completing a detailed envrionmental qualification test program.
A compact high-current pulse-forming network capacitor bank using paralleled silicon controlled rectifiers as switches is described. The maximum charging voltage of the bank is 1kV and maximum load current is 20 kA. The necessary switch equalization criteria and performance with dummy load and an arc plasma generator are described.
Printed-circuit process produces ordnance-initiated start/stop switches. Method is faster and less costly than fabriction by hand, and produces switches of uniform quality.
Switching devices using various circuits of electronic or mechanical elements depending on the operating conditions and purpose of the switching were investigated and their uses are discussed.
A high power ferrite microwave switch was developed along with associated electronic driver circuits for operation in a spaceborne high power microwave transmitter in geostationary orbit. Three units were built and tested in a space environment to demonstrate conformance to the required performance characteristics. Each unit consisted of an input magic-tee hybrid, two non-reciprocal latching ferrite phase shifters, an out short-slot 3 db quadrature coupler, a dual driver electronic circuit, and input logic interface circuitry. The basic mode of operation of the high power ferrite microwave switch is identical to that of a four-port, differential phase shift, switchable circulator. By appropriately designing the phase shifters and electronic driver circuits to operate in the flux-transfer magnetization mode, power and temperature insensitive operation was achieved. A list of the realized characteristics of the developed units is given.
A unique microcircuit intended for use as a shorting switch for large extraterrestrial solar cell arrays is described. The packaging design for the 5 kV isolated hybrid switch is different from most hybrid microcircuits in that it utilizes a compartmentalized plastic case (a portion of which is encapsulated), is not hermetic, and is designed for high voltage operation.
Consisting of NAND gates, switch can be expanded to multipole input and can switch at frequencies up to 30MHz. Device uses digital integrated circuits to provide isolation between inputs and between input and output ports.
Switch achieves high isolation and continuous input/output matching by using resonant coupling structure of diplexer. Additionally, dc bias network used to control switch is decoupled from RF input and output lines. Voltage transients in external circuits are thus minimized.
A new class of high-voltage power transistors has been achieved by adapting present interdigitated thyristor processing techniques to the fabrication of NPN Si transistors. Present devices are 2.3 cm in diameter. The electrical performance obtained is consistent with the predictions of an optimum design theory specifically developed for power switching transistors. The forward safe operating area of the experimental transistors shows a significant improvement over commercially available devices. The report describes device design, wafer processing, and various measurements which include dc characteristics, forward and reverse second breakdown limits, and switching times.
Mechanical parts used in conventional switches to index stepper motor that drives switch elements are replaced by optoelectronic indexing device that controls magnetic-detent motor. Unit eliminates major source of wear and maintains detent accuracy longer. Design of device achieves reduction of insertion loss, crosstalk, and wave guide reflections when receiving and transmitting.
Device performs same switching functions as mechanical switches, occupies same or less panel space, requires only one power source (which is compatible with the load), and operates under severe conditions of temperature, vibration, and shock.