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Magnetostrictive Heat Switches Actuated by Flux Tubes

A switch would remain "open" or "closed" until actuated to change its state. In a proposed improvement on the basic concept of a magnetostrictive heat switch for cryogenic applications, the magnetic field needed for actuation would be generated by a superconducting flux tube (SFT). A closely related concept for a magnetostrictive heat switch was presented in "Magnetostrictive Heat Switch for Cryogenic Use" (NPO-20274), NASA Tech Briefs, Vol. 23, No. 8, (August, 1999), p.48. To recapitulate: The main thermal contact in the heat switch would be made or broken by making or breaking, respectively, the mechanical contact between (1) the moving end of a rod of magnetostrictive material and (2) a fixed contact pad. The magnetic field needed for actuation would be generated by use of a superconducting solenoid.

Posted in: Briefs, TSP, Physical Sciences

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Liquid Shell Insulation

At high temperatures and pressures, probes would last just long enough to take readings. A new concept called "liquid shell insulation" has been proposed as a means of temporary thermal protection for scientific instrument probes that are required to operate for short times in hot, high-pressure environments. Liquid shell insulation was conceived to protect probes that would be dropped from spacecraft to great depths in the atmospheres of the outer planets. For example, at a depth of 1,000 km on Jupiter, a probe would have to withstand a pressure of about 4,000 Earth atmospheres (≈0.4 GPa) and a temperature of about 1,800 K. On Earth, liquid shell insulation might be useful for protecting probes that would be inserted in undersea volcanic vents or deep oil wells.

Posted in: Briefs, TSP, Physical Sciences

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Magnetostrictive Valves Actuated by Flux Tubes

Power would be applied during toggling only. Magnetostrictive valves for cryogenic applications would be actuated by superconducting flux tubes (SFTs), according to a proposal. The reasoning behind this proposal closely tracks that of the proposal to use SFTs in magnetostrictive heat switches, as reported in the preceding article.

Posted in: Briefs, TSP, Physical Sciences

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Fluorometer for Analysis of Photosynthesis in Phytoplankton

Measurements could be made in situ and in vivo. An instrument that measures the characteristic lifetime of fluorescence of chlorophyll has been invented for in situ, real-time oceanographic studies of photosynthesis in phytoplankton. The basic design and principle of operation lend themselves to development of the instrument as a relatively inexpensive, sensitive, compact, rugged, portable, low-power-consumption, hand-held, shipboard unit. Similar units with designs adapted to agricultural applications (e.g., assessment of physiological statuses of crops) are also envisioned.

Posted in: Briefs, TSP, Physical Sciences

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Modifications of a Hydrazine Fueling Procedure and Equipment

Workers could safely wear less-restrictive protective garments. A combination of procedure and equipment for loading liquid hydrazine into a spacecraft fuel tank that contains a diaphragm or bladder would be modified, according to a proposal. The purpose of the modifications is to enable fueling technicians to work safely, during all but a small part of the loading process, in less-restrictive protective attire.

Posted in: Briefs, TSP, Physical Sciences

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Ultrasonic Bubble-Sizing Instrument

Bubbles associated with decompression sickness can be detected noninvasively. An ultrasonic instrument has been developed for measuring the sizes of bubbles in the human body. A primary example is that of bubbles associated with decompression sickness (the "bends"); these bubbles consist mostly of nitrogen and can occur in both blood vessels and extravascular tissues. The bubbles can lodge (embolize) in vessels in the lungs and elsewhere, causing any of a variety of pathological conditions. Gaseous emboli that cause decompression sickness pose a serious risk of injury to aviators, astronauts, divers, and other individuals who are exposed to varying environmental pressures. Gaseous emboli can also be serious complications of cardiopulmonary bypass operations, introduction of air during cardiotomy, and cavitation bubbles generated by replacement heart valves.

Posted in: Briefs, Physical Sciences

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Surface and Gas Temperatures via Multiwavelength Pyrometry

A report describes experiments using multiwavelength pyrometry to determine the surface temperature of the end tip inside a BeO cylinder that is part of a probe designed to measure high-temperature gases. The cylinder is heated by the gas into which it is inserted, and the gas temperature is related to the tip temperature via a mathematical model of the probe. The probe was tested in two atmospheric burner experiments. The measured interior temperatures were 1,360 and 1,745 K. Available temperature information on the burner flame is lower, being at 1,300 and 1,580 K, respectively. This was so because the thermocouples performing the measurement were positioned at the cooler periphery of the jet to avoid being destroyed by hot gases at the burner's central flow, the hot temperature of which the BeO probe was successful in measuring.

Posted in: Briefs, Physical Sciences

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