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Results for “Temperature Control”

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 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Results from the cascaded variable conductance heatpipe experiment on LDEF

A Variable Conductance Heat Pipe Experiment (CVCHPE) was successfully flown onboard the LDEF and demonstrated temperature control better than +/- 0.3 C during 50 days of on-orbit data collection in a widely varying external environment. The experiment used two series connected, dry reservoir variable conductance heat pipes which require no electrical power for operation. The heat pipes used a central artery design with ammonia working fluid and nitrogen control gas.

Grote, Michael G.↗
NASA NTRS1989

Quantitative computer simulations of extraterrestrial processing operations

The automation of a small, solid propellant mixer was studied. Temperature control is under investigation. A numerical simulation of the system is under development and will be tested using different control options. Control system hardware is currently being put into place. The construction of mathematical models and simulation techniques for understanding various engineering processes is also studied. Computer graphics packages were utilized for better visualization of the simulation results. The mechanical mixing of propellants is examined. Simulation of the mixing process is being done to study how one can control for chaotic behavior to meet specified mixing requirements. An experimental mixing chamber is also being built. It will allow visual tracking of particles under mixing. The experimental unit will be used to test ideas from chaos theory, as well as to verify simulation results. This project has applications to extraterrestrial propellant quality and reliability.

Vincent, T. L.↗
NASA NTRS1991

Thermal design of the Cosmic Background Explorer cryogenic optical assembly

The Cosmic Background Explorer (COBE) is a satellite which is designed to study the 3-K cosmic background radiation. Two cryogenic instruments and a common support structure comprise the Cryogenic Optical Assembly (COA). In order to make definitive measurements of the low-energy FIR radiation, the temperature of the COA must be maintained below 3 K. Temperature control of the COA elements is achieved by the use of a superfluid helium dewar. The thermal design also minimizes power dissipation, transient operational effects, and thermal gradients within the COA. This is accomplished by isolating selected components and heat-sinking others to various locations on the cryogen tank. The thermal design was developed primarily through analysis. Analytical models were created to perform parametric design studies. Ground testing was performed to correlate the thermal models and validate the thermal design. Both test and flight data confirmed that all design requirements were either met or exceeded.

Mosier, Carol L.↗
NASA NTRS1990

Test results of a diffraction grating beam combiner

A laser diode beam combiner employing diffraction gratings has been fabricated and tested. The Grating Laser Beam Combiner (GLBC) uses two holographic diffraction gratings to incoherently combine the first order diffraction components of four 35 mW AlGaAs lasers. The grating rhomb design minimizes the transmitter sensitivity to the inherent frequency instability of laser diodes. The overall throughput of the combiner is 74 percent. Each laser was temperature controlled to 0.1 C and modulated with 110 Mbps QPPM data. Two lasers under modulation were coaligned to within 76 microrad with a combined average power of 45 mW.

Rall, Jonathan A.↗
NASA NTRS1992

Condensation Of Volatile Contaminant In An Instrument

Report describes investigation of deposition of contaminant of cooled optical detectors in Wide-Field/Planetary Camera (WF/PC), an instrument in Hubble Space Telescope. To understand phenomenon, initially thought to be deposition of water from graphite/epoxy optical-bench material in instrument, researchers mounted several diagnostic instruments on access plate to monitor interior of WF/PC housing and optical bench. Temperature-controlled quartz-crystal microbalance (TQCM) measures adsorbed and desorbed volatile condensible material on surfaces in WF/PC.

Hansen, Patricia A.↗
NASA NTRS1991

Thermal design and test results for SUNLITE ultra-stable reference cavity

SUNLITE (Stanford University-NASA Laser In-Space Technology Experiment) is a space-based experiment which uses a reference cavity to provide a stable frequency reference for a terahertz laser oscillator. Thermal stability of the cavity is a key factor in attaining a stable narrow-linewidth laser beam. The mount which is used to support and align the cavity will provide thermal isolation from the environment. The baseline requirement for thermal stability of the cavity is 0.025 C/min, but the design is directed toward achieving stability well beyond this requirement to improve the science data gained. A prototype of the cavity mount was fabricated and tested to characterize the thermal performance. The thermal vacuum test involved stable high-resolution temperature measurements and stable baseplate temperature control over long durations. Based on test data, the cavity mount design satisfies the severe requirement for the cavity thermal stability.

Amundsen, Ruth M.↗
NASA NTRS1992

Thermal conductance of two interface materials and their applications in space systems

The temperature control of spacecraft and instrument systems and subsystems requires heat transfer interface materials that possess good thermal and structural characteristics, among other properties, to respond to the vacuum environment of space. These materials must be easy to apply to, and remove from, the surfaces where they are applied, and must be able to withstand power dissipation extremes, and be used for different clamping configurations and pressures. Silicone based greases, used in the past, tend to migrate and to contaminate nearby surfaces. Bare metal to metal contact offers low thermal conductance and difficulties in estimating the actual heat transfer. Several polymeric materials containing different thermal conductive compounds and structural reinforcements were prepared to overcome grease and metal problems. Two polymeric materials were evaluated: Cho-Therm 1671 elastomer; and the CV-2946, a conductive RTV silicone. Tests were done to learn more about these products. Results indicate that the tightly bolted, torqued fixtures did not buckle or distort, and provided optimum thermal conductance. Fixtures simulating actual spacecraft configuration suffered bowing and separating.

Scialdone, J. J.↗
NASA NTRS1992

Injection seeding of a Q-switched alexandrite laser: Study of frequency stabilization

AlGaAs diode lasers were used to injection seed a pulsed Q-switched alexandrite laser which produces a narrowband of radiation. Injection seeding is a method for achieving linewidths of less than 500 mega-Hz in the output of the broadband, tunable solid state laser. When the laser was set at a current of 59.8 milli-A and a temperature of 14.04 C, the wavelength was 767.6 nano-m. The Q-switched alexandrite laser was injection seeded and frequency stabilization was studied. The linewidth requirement was met, but the stability requirement was not due to drifting in the feedback voltage. Improvements on injection seeding should focus on increasing the feedback voltage to the laser diode, filtering the laser diode by using temperature controlled narrowband filters, and the use of diamond (SiC) grating placed inside the alexandrite laser's resonator cavity.

Brown, Lamarr A.↗
NASA NTRS1992

Results from the LDEF/A0076 cascaded variable conductance heatpipe experiment

The A0076 Variable Conductance Heat Pipe Experiment (CVCHPE) on the Long Duration Exposure Facility (LDEF) demonstrated temperature control better than +/- 0.3 C during fifty days on on-orbit data collection in a widely varying external environment. The experiment used two series connected, dry reservoir variable conductance heat pipes which require no electrical power for operation. The heat pipes used a central artery design with ammonia working fluid and nitrogen control gas. The LDEF was in orbit for almost six years rather than the planned one year mission. Although no additional data were taken during this extended period, post-test data indicated that the set point drifted upward less than 1 C per year. There were significant changes to the appearance of all external thermal control surfaces primarily due to atomic oxygen degradation, and one small anomaly in the electronics. These changes, though, had little effect on the CVCHPE performance.

Grote, Michael G.↗
NASA NTRS1990

Superfluid helium on-orbit resupply

The requirements for superfluid helium (SFHe) resupply were investigated, and the results were used to develop a conceptual design for a superfluid helium tanker (SFHT) which is designed to meet a 50-mission requirement. The SFHT design uses a conventional dewar approach with multiple vapor cooled shields, and a porous-plug phase separator for on-orbit temperature control. An open loop refrigeration approach is used for ground conversion of normal He to SFHe, allowing near-total fill of the supply tank. Design diagrams of the SFHT concept and of various SFHT subsystems are presented.

Eberhardt, Ralph N.↗
NASA NTRS1991

Performance of the Research Animal Holding Facility (RAHF) and General Purpose Work Station (GPWS) and other hardware in the microgravity environment

This paper discusses the performance of the Research Animal Holding Facility (RAHF) and General Purpose Work Station (GPWS) plus other associated hardware during the recent flight of Spacelab Life Sciences 1 (SLS-1). The RAHF was developed to provide proper housing (food, water, temperature control, lighting and waste management) for up to 24 rodents during flights on the Spacelab. The GPWS was designed to contain particulates and toxic chemicals generated during plant and animal handling and dissection/fixation activities during space flights. A history of the hardware development involves as well as the redesign activities prior to the actual flight are discussed.

Hogan, Robert P.↗
NASA NTRS1992

Growing protein crystals in microgravity - The NASA Microgravity Science and Applications Division (MSAD) Protein Crystal Growth (PCG) program

In collaboration with a medical researcher at the University of Alabama at Birmingham, NASA's Marshall Space Flight Center in Huntsville, Alabama, under the sponsorship of the Microgravity Science and Applications Division (MSAD) at NASA Headquarters, is continuing a series of space experiments in protein crystal growth which could lead to innovative new drugs as well as basic science data on protein molecular structures. From 1985 through 1992, Protein Crystal Growth (PCG) experiments will have been flown on the Space Shuttle a total of 14 times. The first four hand-held experiments were used to test hardware concepts; later flights incorporated these concepts for vapor diffusion protein crystal growth with temperature control. This article provides an overview of the PCG program: its evolution, objectives, and plans for future experiments on NASA's Space Shuttle and Space Station Freedom.

Herren, B.↗
NASA NTRS1993

Environmental monitors in the Midcourse Space Experiments (MSX)

The Midcourse Space Experiment (MSX) is an SDIO sponsored space based sensor experiment with a full complement of optical sensors. Because of the possible deleterious effect of both molecular and particulate contamination on these sensors, a suite of environmental monitoring instruments are also being flown with the spacecraft. These instruments are the Total Pressure Sensor based on the cold-cathode gauge, a quadrupole mass spectrometer, a Bennett-type ion mass spectrometer, a cryogenic quartz crystal microbalance (QCM), four temperature-controlled QCM's, and a Xenon and Krypton Flash Lamp Experiment. These instruments have been fully space-qualified, are compact and low cost, and are possible candidate sensors for near-term planetary and atmospheric monitoring. The philosophy adopted during design and fabrication, calibration and ground testing, and modeling will be discussed .

Uy, O. M.↗
NASA NTRS1992

A high sensitivity real-time NVR monitor

The use of a temperature-controlled 200-MHz SAW resonator piezoelectric mass microbalance to monitor the mass of nonvolatile residue (NVR) deposited on its surface in real time is reported. The fundamental frequency of this device is mainly dependent on the configuration of the transducers and not on the thickness of the substrate. Therefore, higher operating frequencies can be achieved without reducing the thickness of the crystal. The real-time instrument was integrated onto a conventional stainless steel NVR plate and operated flawlessly over a 14-d period at Kennedy Space Center and successfully measured less than 1 ng/sq cm d NVR contamination. Contamination episodes detected by the instrument were correlated with scheduled activities on the test stand. Under the assumption of a baseline noise level of +/- 2 Hz, the absolute mass lower limit of detection would be 0.065 ng/sq cm. This would enable the detection of a daily NVR deposition rate of less than 0.1 ng/sq cm d.

Bowers, William D.↗
NASA NTRS1992

Space Station external thermal control system design and operational overview

The driving design requirements and resulting design characteristics for a two-phase ammonia system of the Space Shuttle are reviewed with particular attention given to operational and station assembly issues related to system activation and steady-state operation. Design is described at an overall system level and an orbit replaceable unit level. It is concluded that a system flow network must be designed and ammonia pressures must be controlled to acquire waste heat efficiently from all contributing heat sources at a controlled temperature.

Raetz, John↗
NASA NTRS1929

Investigation of damping liquids for aircraft instruments

This report covers the results of an investigation carried on at the Bureau of Standards under a research authorization from, and with the financial assistance of, the National Advisory Committee for Aeronautics. The choice of a damping liquid for aircraft instruments is difficult owing to the range of temperature at which aircraft operate. Temperature changes affect the viscosity tremendously. The investigation was undertaken with the object of finding liquids of various viscosities otherwise suitable which had a minimum change in viscosity with temperature. The new data relate largely to solutions. The effect of temperature on the kinematic viscosity of the following liquids and solutions was determined in the temperature interval -18 degrees to +30 degrees C. (1) solutions of animal and vegetable oils in xylene. These were poppy-seed oil, two samples of neat's-foot oils, castor oil, and linseed oil. (2) solutions of mineral oil in xylene. These were Squibb's petrolatum of naphthene base and transformer oil. (3) glycerine solutions in ethyl alcohol and in mixture of 50-50 ethyl alcohol and water. (4) mixtures of normal butyl alcohol with methyl alcohol. (5) individual liquids, kerosene, mineral spirits, xylene, recoil oil. The apparatus consisted of four capillary-tube viscometers, which were immersed in a liquid bath in order to secure temperature control. The method of calibration and the related experimental data are presented.

Keulegan, G H↗
NASA NTRS1994

Improved Thermoelectrically Cooled Laser-Diode Assemblies

Cooling decreases wavelength and increases efficiency and lifetime. Two improved thermoelectrically cooled laser-diode assemblies incorporate commercial laser diodes providing combination of both high wavelength stability and broad wavelength tuning which are broadly tunable, highly stable devices for injection seeding of pulsed, high-power tunable alexandrite lasers used in lidar remote sensing of water vapor at wavelengths in vicinity of 727 nanometers. Provide temperature control needed to take advantage of tunability of commercial AlGaAs laser diodes in present injection-seeding application.

Glesne, Thomas R.↗
NASA NTRS1993

Performance of low-cost commercial fiber-optic transceivers for reference frequency distribution

Precision time and frequency reference signals were effectively disseminated using high-quality intricate fiber-optic distribution systems. The quality of signals distributed by such systems is excellent, but the cost of these systems makes them unavailable to many potential users. A study of signal quality maintained using inexpensive commercial transmitter/receiver pairs is undertaken. Seven different transmitter/receiver pairs obtained from four different manufacturers were thoroughly tested using a 5 MHz sinusoid derived from a precision, temperature controlled, crystal-controlled oscillator. The electrical signal output from each fiber-optic receiver was tested for spectral purity, single-sideband phase noise, and AM noise, and the results are tabulated and discussed without identification of the manufacturer or the equipment model number.

Dragonette, Richard↗