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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 667 records · Page 37
All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

An 8.4-GHz cryogenically cooled HEMT amplifier for DSS 13

A prototype 8.4 GHz (X-band) high electron mobility transistor (HEMT) amplifier/closed cycle refrigerator system was installed in the Deep Space Station 13 feedcone in August 1987. The amplifier is cryogenically cooled to a physical temperature of 12 K and provides 31 K antenna noise temperature (zenith) and 35 dB of gain at a frequency of 8.2 to 8.6 GHz. Antenna system noise temperature is less than 50 K from 7.2 to 9.4 MHz. The low noise HEMT amplifier system is intended for use as a radio astronomy or space communications receiver front end.

Tanida, L.↗
NASA NTRS1988

Space simulators for laser optics

Different approaches that are being utilized to test laser optical systems are described. One of the most crucial areas in the testing phase is the stability of the laser optics mounted inside the space simulator. The thermal vacuum system, the refrigeration system, and the space simulator are discussed.

Gardner, Frank H.↗
NASA NTRS1988

Studies of cryogenic propellant storage and handling for the lunar landing and launch facility (complex 39L)

A brief description of Complex 39L as it is currently conceived is presented. A brief discussion of lunar thermal history is then presented. From this follows a discussion of the current lunar thermal environment which will impact the design of cryogenic storage and handling facilities on the moon. Some previous studies are discussed. A conceptual design of liquid oxygen and hydrogen storage facilities is presented. The essential feature of this facility is that cryogens are to be stored in a number of small tanks which can serve as lander propellant tanks rather than as one large storage vessel. These tanks will be placed under a Fuel Inventory Tent (FIT) for shadow shielding. Methods of dealing with propellant boil-off are discussed. A base case cascade refrigeration system for requirements are such that it seems very feasible to construct a prototype boil-off recovery system in a laboratory environment.

Linsley, Jerald N.↗
NASA NTRS1988

Space shuttle food system summary, 1981-1986

All food in the Space Shuttle food system was precooked and processed so it required no refrigeration and was either ready-to-eat or could be prepared for consumption by simply adding water and/or heating. A gun-type water dispenser and a portable, suitcase-type heater were used to support this food system during the first four missions. On STS-5, new rehydratable packages were introduced along with a needle-injection water dispenser that measured the water as it was dispensed into the packages. A modular galley was developed to facilitate the meal preparation process aboard the Space Shuttle. The galley initially flew on STS-9. A personal hygiene station, a hot or cold water dispenser, a convection oven, and meal assembly areas were included in the galley.

Stadler, Connie R.↗
NASA NTRS1989

Measurements of complex permittivity of microwave substrates in the 20 to 300 K temperature range from 26.5 to 40.0 GHz

A knowledge of the dielectric properties of microwave substrates at low temperatures is useful in the design of superconducting microwave circuits. Results are reported for a study of the complex permittivity of sapphire (Al2O3), magnesium oxide (MgO), silicon oxide (SiO2), lanthanum aluminate (LaAlO3), and zirconium oxide (ZrO2), in the 20 to 300 Kelvin temperature range, at frequencies from 26.5 to 40.0 GHz. The values of the real and imaginary parts of the complex permittivity were obtained from the scattering parameters, which were measured using a HP-8510 automatic network analyzer. For these measurements, the samples were mounted on the cold head of a helium gas closed cycle refrigerator, in a specially designed vacuum chamber. An arrangement of wave guides, with mica windows, was used to connect the cooling system to the network analyzer. A decrease in the value of the real part of the complex permittivity of these substrates, with decreasing temperature, was observed. For MgO and Al2O3, the decrease from room temperature to 20 K was of 7 and 15 percent, respectively. For LaAlO3, it decreased by 14 percent, for ZrO2 by 15 percent, and for SiO2 by 2 percent, in the above mentioned temperature range.

Miranda, Felix A.↗
NASA NTRS1989

Operational parameters for the superconducting cavity maser

Tests of the superconducting cavity maser (SCM) ultra-stable frequency source have been made for the first time using a hydrogen maser for a frequency reference. In addition to characterizing the frequency stability, the sensitivity of the output frequency to several crucial parameters was determined for various operating conditions. Based on this determination, the refrigeration and thermal control systems of the SCM were modified. Subsequent tests showed substantially improved performance, especially at the longest averaging times.

Wang, R. T.↗
NASA NTRS1989

Radio detection of formaldehyde emission from Comet Halley

The J(K-1 K1) = -1(11) -10(10) transition of H2CO was detected in emission at 4829.659 MHz from Comet Halley. The H2CO emission line had a peak intensity of 2.66 + or - 0.78 mJy/beam with a small blueshift of -0.76 + or - 0.40 km/s, which is consistent with the anisotropic outgassing of the nucleus in the solar direction found for other cometary species. Data analysis suggests that cometary H2CO was produced from an extended source in the coma as well as directly from the nucleus and that it was not refrigerated as in interstellar dark nebulae. The derived H2CO production rate of 1.5 x 10 to the 28th molecules/s is obtained which is consistent with observational and theoretical findings.

Snyder, Lewis E.↗
NASA NTRS1990

Sensor Detects Overheating Of Perishable Material

Experimental temperature sensor changes color rapidly and irreversibly when temperature rises above pre-determined level. Based on reactions of enzymes in paraffins, blended so mixture melts at temperature considered maximum safe value. Similar devices used to detect temperature abuse, whether foods or medicines refrigerated exposed to excessive temperatures during shipment and storage. By viewing sensor, receiving clerk tells immediately whether product maintained at safe temperatures and acceptable.

Dordick, Jonathan S.↗
NASA NTRS1990

Systems Improved Numerical Fluids Analysis Code

Systems Improved Numerical Fluids Analysis Code, SINFAC, consists of additional routines added to April, 1983, version of SINDA. Additional routines provide for mathematical modeling of active heat-transfer loops. Simulates steady-state and pseudo-transient operations of 16 different components of heat-transfer loops, including radiators, evaporators, condensers, mechanical pumps, reservoirs, and many types of valves and fittings. Program contains property-analysis routine used to compute thermodynamic properties of 20 different refrigerants. Source code written in FORTRAN 77.

Costello, F. A.↗
NASA NTRS1990

Atomic hydrogen as a launch vehicle propellant

An analysis of several atomic hydrogen launch vehicles was conducted. A discussion of the facilities and the technologies that would be needed for these vehicles is also presented. The Gross Liftoff Weights (GLOW) for two systems were estimated; their specific impulses (I sub sp) were 750 and 1500 lb(sub f)/s/lb(sub m). The atomic hydrogen launch vehicles were also compared to the currently planned Advanced Launch System design concepts. Very significant GLOW reductions of 52 to 58 percent are possible over the Advanced Launch System designs. Applying atomic hydrogen propellants to upper stages was also considered. Very high I(sub sp) (greater than 750 lb(sub f)/s/lb(sub m)) is needed to enable a mass savings over advanced oxygen/hydrogen propulsion. Associated with the potential benefits of high I(sub sp) atomic hydrogen are several challenging problems. Very high magnetic fields are required to maintain the atomic hydrogen in a solid hydrogen matrix. The magnetic field strength was estimated to be 30 kilogauss (3 Tesla). Also the storage temperature of the propellant is 4 K. This very low temperature will require a large refrigeration facility for the launch vehicle. The design considerations for a very high recombination rate for the propellant are also discussed. A recombination rate of 210 cm/s is predicted for atomic hydrogen. This high recombination rate can produce very high acceleration for the launch vehicle. Unique insulation or segmentation to inhibit the propellant may be needed to reduce its recombination rate.

Palaszewski, Bryan A.↗
NASA NTRS1989

Non-destructive trace element microanalysis of as-received cometary nucleus samples using synchrotron x ray fluorescence

The Synchrotron X ray Fluorescence (SXRF) microprobe at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory, will be an excellent instrument for non-destructive trace element analyses of cometary nucleus samples. Trace element analyses of as-received cometary nucleus material will also be possible with this technique. Bulk analysis of relatively volatile elements will be important in establishing comet formation conditions. However, as demonstrated for meteorites, microanalyses of individual phases in their petrographic context are crucial in defining the histories of particular components in unequilibrated specimens. Perhaps most informative in comparing cometary material with meteorites will be the halogens and trace metals. In-situ, high spatial resolution microanalyses will be essential in establishing host phases for these elements and identifying terrestrial (collection/processing) overprints. The present SXRF microprobe is a simple, yet powerful, instrument in which specimens are excited with filtered, continuum synchrotron radiation from a bending magnet on a 2.5 GeV electron storage ring. A refrigerated cell will be constructed to permit analyses at low temperatures. The cell will consist essentially of an air tight housing with a cold stage. Kapton windows will be used to allow the incident synchrotron beam to enter the cell and fluorescent x rays to exit it. The cell will be either under vacuum or continuous purge by ultrapure helium during analyses. Several other improvements of the NSLS microprobe will be made prior to the cometary nucleus sample return mission that will greatly enhance the sensitivity of the technique.

Sutton, S. R.↗
NASA NTRS1990

Investigation of surface water behavior during glaze ice accretion

A series of experimental investigations that focused on isolating the primary factors that control the behavior of unfrozen surface water during glaze ice accretion were conducted. Detailed microvideo observations were made of glaze ice accretions on 2.54 cm diam cylinders in a closed-loop refrigerated wind tunnel. Distinct zones of surface water behavior were observed; a smooth wet zone in the stagnation region with a uniform water film, a rough zone where surface tension effects caused coalescence of surface water into stationary beads, and a zone where surface water ran back as rivulets. The location of the transition from the smooth to the rough zone was found to migrate towards the stagnation point with time. Comparative tests were conducted to study the effect of the substrate thermal and roughness properties on ice accretion. The importance of surface water behavior was evaluated by the addition of a surface tension reducing agent to the icing tunnel water supply, which significantly altered the accreted glaze ice shape. Measurements were made to determine the contact angle behavior of water droplets on ice. A simple multizone modification to current glaze ice accretion models was proposed to include the observed surface roughness behavior.

Hansman, R. John, Jr.↗
NASA NTRS1990

Thermal control system corrosion study

During the development of an expert system for autonomous control of the Space Station Thermal Control System (TCS), the thermal performance of the Brassboard TCS began to gradually degrade. This degradation was due to filter clogging by metallic residue. A study was initiated to determine the source of the residue and the basic cause of the corrosion. The investigation focused on the TCS design, materials compatibility, Ames operating and maintenance procedures, and chemical analysis of the residue and of the anhydrous ammonia used as the principal refrigerant. It was concluded that the corrosion mechanisms involved two processes: the reaction of water alone with large, untreated aluminum parts in a high pH environment and the presence of chlorides and chloride salts. These salts will attack the aluminum oxide layer and may enable galvanic corrosion between the aluminum and the more noble stainless steel and other metallic elements present. Recommendations are made for modifications to the system design, the materials used, and the operating and maintenance procedures, which should largely prevent the recurrence of these corrosion mechanisms.

Yee, Robert↗
NASA NTRS1989

A 100 micro Kelvin bolometer system for SIRTF

Progress toward a prototype of 100 mK bolometric detection system for the Space Infrared Telescope Facility (SIRTF) is described. Two adiabatic demagnetization refrigerators (ADR's) were constructed and used to investigate the capabilities necessary for orbital operation. The first, a laboratory ADR, demonstrated a hold time at 0.1 K of over 12 hours, with temperature stability approx. 3 micro-K RMS achieved by controlling the magnetic field. A durable salt pill and an efficient support system have been demonstrated. A second ADR, the SIRTF flight prototype, has been built and will be flown on a balloon. Techniques for magnetic shielding, low heat leak current leads, and a mechanical heat switch are being developed in this ADR. Plans for construction of 100 mK bolometers are discussed. Three important cosmological investigations which will be carried out by these longest wavelength SIRTF detectors are described.

Bernstein, G. M.↗
NASA NTRS1990

An 8.4-GHz dual-maser front-end system for Parkes reimplementation

An 8.4-GHz front-end system consisting of a feedhorn, a waveguide feed assembly, dual masers, and downconverters was reimplemented at Parkes as part of the Parkes Canberra Telemetry Array for the Voyager Neptune encounter. The front-end system was originally assembled by the European Space Agency and installed on the Parkes antenna for the Giotto project. It was also used on a time-sharing basis by the Deep Space Network as part of the Parkes Canberra Telemetry Array to enhance the data return from the Voyager Uranus encounter. At the conclusion of these projects in 1986, part of the system was then shipped to JPL on loan for reimplementation at Parkes for the Voyager Neptune encounter. New design and implementation required to make the system operable at Parkes included new microwave front-end control cabinets, closed-cycle refrigeration monitor system, noise-adding radiometer system, front-end controller assembly, X81 local oscillator multiplier, and refurbishment of the original dual 8.4-GHz traveling-wave masers and waveguide feed system. The front-end system met all requirements during the encounter and was disassembled in October 1989 and returned to JPL.

Trowbridge, D. L.↗
NASA NTRS1990

The effect of temperature cycling typical of low earth orbit satellites on thin films of YBa2Cu3O(7-x)

The refrigeration of superconductors in space poses a challenging problem. The problem could be less severe if superconducting materials would not have to be cooled when not in use. Thin films of the YBa2Cu3O(7-x) (YBCO) superconductor were subjected to thermal cycling, which was carried out to simulate a large number of eclipses of a low earth orbit satellite. Electrical measurements were performed to find the effect of the temperature cycling. Thin films of YBCO were formed by coevaporation of Y, BaF2, and Cu and postannealing in wet oxygen at 850 C for 3.5 h. The substrates used were (100) SrTiO3, polycrystalline alumina, and oxidized silicon; the last two have an evaporated zirconia layer. Processing and microstructure studies of these types of films have been published. THe zero resistance transition temperatures of the samples used in this study were 91, 82, and 86 K, respectively. The samples were characterized by four point probe electrical measurements as a function of temperature. The parameters measured were: the zero resistance transition temperature, the 10 to 90 percent transition width, and the room temperature resistance, normalized to that measured before temperature cycling. The results for two samples are presented. Each sample had a cumulative exposure. Cycling in atmospheric pressure nitrogen was performed at a rate of about 60 cycles per day, whereas in vacuum the rate was only about 10 cycles per day. The results indicate only little or no changes in the parameters measured. Degradation of superconducting thin films of YBCO has been reported due to storage in nitrogen. It is believed that the relatively good performance of films after temperature cycling is related to the fact that BaF2 was used as an evaporation source. The latest result on extended temperature cycling indicates significant degradation. Further tests of extended cycling will be carried out to provide additional data and to clarify this preliminary finding.

Mogro-Campero, A.↗
NASA NTRS1989

The cryogenic subsystem for the X-ray spectrometer on the Advanced X-Ray Astrophysics Facility (AXAF)

The X-ray Spectrometer (XRS) instrument on the Advanced X-ray Astrophysics Facility (AXAF) will use X-ray detectors that operate at 0.1 K. The detectors will be maintained at 0.1 K by an Adiabatic Demagnetization Refrigerator (ADR) that operates inside a liquid helium dewar. The ADR rejects approximately 2 mW of heat to the stored liquid helium. With this low instrument heat load, the liquid helium dewar will have a long lifetime if the parasitic heat load on the helium from the surrounding warm facility is minimized. Spaceborne helium dewars typically use up to 3 vapor cooled shields to intercept the parasitic heat load. The XRS will add mechanical coolers to provide additional cooling to the outer vapor cooled shield. The cryogenic system consists of an ADR, a liquid helium dewar, mechanical coolers, and a thermal strap to connect the coolers to the dewar. The lifetime of the stored cryogen is calculated to be up to 5 years. This cryogenic system is described, with particular attention given to the dewar, mechanical cooler, and ADR design, testing, and trade studies. A breadboard ADR is presently being fabricated and tested. The status of the construction and testing of this breadboard will be described.

Castles, Stephen H.↗
NASA NTRS1989

An experimental evaluation of the tensile strength of impact ice

The evaluation of the tensile strength of impact built-up ice on structural components has been prompted by such problems as electrical transmission line losses and catastrophic failures in Arctic regions, deicing problems with fixed-wing and rotary-wing aircraft, etc. It is demonstrated that the conventional tensile-testing technique furnishes adequate data on artificially refrigerated ice, and helps establish the influence of extrinsic factors on ice tensile strength.

Xian, X.↗