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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

Thermal modeling of the Shuttle Infrared Telescope Facility

The Shuttle Infrared Telescope Facility (SIRTF) is a cryogenically cooled telescope in the one-meter aperture class designed for sensing in the infrared from 2-200 microns. This facility is currently planned for multiple missions onboard the Space Shuttle with varying instrument complements. All components of the SIRTF within the field of view of the optics are cryogenically cooled. The baseline primary coolant is supercritical helium which is stored in an external tank and routed through the telescope-cooling the instruments, the optical components and the baffles. For detector cooling below 6 K, small reservoirs of superfluid helium (HeII) are provided. The SIRTF was thermally modeled on the SINDA computer program both for steady state and transient solutions. The analysis shows that the baseline configuration has a large capacity for growth in cryogen requirements. A proportional controller model was developed for transient operations. The control system maintained the optics within all prescribed temperature limits except for certain combinations of transients involving a large step change in the power dissipation in the secondary mirror assembly and/or when the primary mirror was assumed to be constructed of quartz. The baseline SIRTF will perform the mission for which it was designed.

Gier, H. L.↗
NASA NTRS1991

The X-ray Spectrometer - A cryogenic instrument on the Advanced X-ray Astrophysics Facility

The X-ray Spectrometer (XRS) is an instrument on the Advanced X-ray Astrophysics Facility (AXAF), the third of NASA's Great Observatories scheduled for launch in 1998. The XRS detectors have a resolution of approximately 10 eV over the range 0.3 - 10 keV. To achieve this resolution, the detectors are maintained at or below 0.1 Kelvin using an adiabatic demagnetization refrigerator inside a superfluid helium dewar. In addition, split-Stirling-cycle mechanical coolers are used to extend the anticipated on-orbit helium lifetime to a minimum of 4 years. This paper describes the challenges of developing this hybrid cryogenic system and presents an overview of the current design of the system.

Breon, Susan R.↗
NASA NTRS1988

Cryogenic, polar lunar observatories

In a geological vein, it is noted that some permanently shadowed regions on the Moon could provide natural passive cooling environments for astronomical detectors. A telescope located in one of the low, dark, polar regions could operate with only passive cooling at 40 K or perhaps lower, depending on how well it could be insulated from the ground and surrounded by radiation shields to block heat and light from any nearby warm or illuminated objects.

Burke, J. D.↗
NASA NTRS1975

A two-degree Kelvin refrigerator

Open-cycle cryogenic refrigerator maintains temperature as low as 2K for periods up to six months. Designed to cool an infrared detector, refrigerator can be used in cooling Josephson-junction devices, magnetic bubble domains, and superconducting devices.

Stephens, J. B.↗
NASA NTRS1992

Low earth orbiting Nadir Etalon Sounding Spectrometer instrument concept for temperature, moisture and trace species, LeoNESS

A concept for a low earth orbiting nadir etalon spectrometer sounder (LeoNESS) is described which can achieve retrieval of temperature, H2O, surface, boundary conditions, cloudiness, and trace species with an accuracy that meets or exceeds the AIRS specifications. Options employing 65-K and 30-K detectors are examined; the former may be implemented via passive radiative cooling. The concept, which is derived from the Cryogenic Limb Array Etalon Spectrometer, has the potential for improving the horizontal and vertical resolution.

Kumer, J. B.↗
NASA NTRS2017

Cryogenic Thermal Emittance Measurements on Small-Diameter Stainless Steel Tubing

The Mid Infrared Instrument aboard the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 K operating temperature. The refrigerant flows through several meters of 2 mm diameter 304L stainless steel tubing, with some sections gold plated, and some not, which are exposed to their environment. An issue of water freezing onto the tube surfaces is mitigated by running a warm gas through the lines to sublimate the frozen water. To model the effect of this process on nearby instruments, an accurate measure of the tube emittance is needed. Previously we reported the absorptance of the gold plated stainless steel tubing as a function of source temperature (i.e. its environment). In this work the thermal emittance of the uncoated tubing is measured as a function of its temperature between 100 and 280 K. These values lead to an accurate prediction of the minimum length of time required to thermally recycle the system. We report the technique and present the results.

stainless steel↗
NASA NTRS1994

Potential aerospace applications of high temperature superconductors

The recent discovery of High Temperature Superconductors (HTS) with superconducting transition temperature, T(sub c), above the boiling point of liquid nitrogen has opened the door for using these materials in new and practical applications. These materials have zero resistance to electric current, have the capability of carrying large currents and as such have the potential to be used in high magnetic field applications. One of the space applications that can use superconductors is electromagnetic launch of payloads to low-earth-orbit. An electromagnetic gun-type launcher can be used in small payload systems that are launched at very high velocity, while sled-type magnetically levitated launcher can be used to launch larger payloads at smaller velocities. Both types of launchers are being studied by NASA and the aerospace industry. The use of superconductors will be essential in any of these types of launchers in order to produce the large magnetic fields required to obtain large thrust forces. Low Temperature Superconductor (LTS) technology is mature enough and can be easily integrated in such systems. As for the HTS, many leading companies are currently producing HTS coils and magnets that potentially can be mass-produced for these launchers. It seems that designing and building a small-scale electromagnetic launcher is the next logical step toward seriously considering this method for launching payloads into low-earth-orbit. A second potential application is the use of HTS to build sensitive portable devices for the use in Non Destructive Evaluation (NDE). Superconducting Quantum Interference Devices (SQUID's) are the most sensitive instruments for measuring changes in magnetic flux. By using HTS in SQUID's, one will be able to design a portable unit that uses liquid nitrogen or a cryocooler pump to explore the use of gradiometers or magnetometers to detect deep cracks or corrosion in structures. A third use is the replacement of Infra-Red (IR) sensor leads on Earth Orbit Systems (EOS) with HTS leads. IR detectors on these EOS missions are cooled to a 4.2K to improve their signal to noise ratio. They are connected to data acquisitions systems using manganin wires (low thermal conductors) to reduce the heat load on the cryogen. Replacing these wires with HTS leads will increase the lifetime of these missions by about 50 percent. This is a promising application that is ready for actual implementation on such systems. The analysis also show that an the number of IR detectors increase in larger EOS systems, substantial increase in the lifetime of each mission will be realized by using HTS leads instead of the manganin ones.

Selim, Raouf↗
NASA NTRS2011

NIRCam: Development and Testing of the JWST Near-Infrared Camera

The Near Infrared Camera (NIRCam) is one of the four science instruments of the James Webb Space Telescope (JWST). Its high sensitivity, high spatial resolution images over the 0.6 - 5 microns wavelength region will be essential for making significant findings in many science areas as well as for aligning the JWST primary mirror segments and telescope. The NIRCam engineering test unit was recently assembled and has undergone successful cryogenic testing. The NIRCam collimator and camera optics and their mountings are also progressing, with a brass-board system demonstrating relatively low wavefront error across a wide field of view. The flight model?s long-wavelength Si grisms have been fabricated, and its coronagraph masks are now being made. Both the short (0.6 - 2.3 microns) and long (2.4 - 5.0 microns) wavelength flight detectors show good performance and are undergoing final assembly and testing. The flight model subsystems should all be completed later this year through early 2011, and NIRCam will be cryogenically tested in the first half of 2011 before delivery to the JWST integrated science instrument module (ISIM).

Greene, Thomas↗
NASA NTRS1994

FPA Needs for NASA Missions

NASA has identified needs for a broad range of specialized, optimized infrared detectors and IR detector arrays to meet its future mission requirements. Space infrared missions will be conducted in a number of discipline areas, including astrophysics, earth and atmospheric science, planetary systems, and space physics. To allow investigators to meet scientific goals, specific technical requirements for infrared detectors have been developed. These challenging and often unique requirements include, for example, achieving background-limited performance in a cryogenic space telescope; developing long-wave IR arrays which achieve near background-limited performance at elevated (approximately 60 kelvin) operating temperatures; achieving IR arrays with large two-dimensional formats, excellent uniformity and linearity, and low power dissipation; demonstrating an imaging array technology for very long-wavelength (less than 100 microns) IR sensing, and IR devices with extremely low dark current levels; and demonstrating stable, low-noise, low-dissipation readouts. These requirements can in some cases be met by adaptation or extension of technologies originally developed by DoD. In other cases, the novel spectral range or other characteristics require unique solutions. Examples are given of recent scientific results which have been made possible with IR arrays. These serve as a preview of the kinds of science return which can be enabled by advanced IR focal plane technology from space platforms.

McCreight, Craig R.↗
NASA NTRS1991

Small Business Innovations (Photodetector)

Epitaxx, Inc. of Princeton, NJ, developed the Epitaxx Near Infrared Room Temperature Indium-Gallium-Arsenide (InGaAs) Photodetector based on their Goddard Space Flight Center Small Business Innovation Research (SBIR) contract work to develop a linear detector array for satellite imaging applications using InGaAs alloys that didn't need to be cooled to (difficult and expensive) cryogenic temperatures. The photodetectors can be used for remote sensing, fiber optic and laser position-sensing applications.

Source record↗
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 NTRS1975

A large cooled infrared telescope facility for Spacelab

An optimized cooled IR telescope of 1 m aperture diameter will offer sensitivities over the 1 micron to 1 mm spectrum at least 1000 times greater than can be achieved from the ground in the atmospheric windows, and comparable sensitivities at wavelengths that are outside the windows. A study has shown that a cryogenically-cooled telescope of up to 1.6 m aperture diameter for Spacelab is feasible without new technology, although some development of detectors and scientific instruments to take advantage of the extreme sensitivity is indicated.-

Mccarthy, S. G.↗
NASA NTRS1980

Laser angle sensor development

Electrical and optical parameters were developed for a two axis (pitch/roll) laser angle sensor. The laser source and detector were mounted in the plenum above the model. Two axis optical distortion measurements of flow characteristics in a 0.3 transonic cryogenic tunnel were made with a shearing interferometer. The measurement results provide a basis for estimating the optical parameters of the laser angle sensor. Experimental and analytical information was generated on model windows to cover the reflector. A two axis breadboard was assembled to evaluate different measurement concepts. The measurement results were used to develop a preliminary design of a laser angle sensor. Schematics and expected performance specifications are included.

Pond, C. R.↗
NASA NTRS1986

A faint object spectrometer for the infrared

A cryogenic astronomical spectrometer for the NASA Infrared Telescope Facility is described. This spectrometer will employ an array of at least 20 detectors and provide a resolving power of 100 to 1500 at 1-5 microns. The resolving power will be adjustable by changing gratings.

Tokunaga, A. T.↗
NASA NTRS1981

Low thermal conductance rigidizer for reducing torsional oscillations in cryogenic Dewars

A rigidizer, which provides greater rigidity against torsional oscillations, is highly resistant to radial motions, and has low thermal conductivity, has been developed to decrease vibrational levels affecting infrared detectors operated in cryostats (e.g., HD-3L Dewar) in aircraft such as NASA's Kuiper Airborne Observatory. The rigidizer is composed of two triangular elements and an intermediate support structure which joins them at the centers of their sides. The reentrant design provides a long heat path, while the triangular truss structure provides high rigidity in the horizontal plane. The structure is relatively compliant in the vertical direction, a desirable feature since the internal structure of the Dewar contracts as it cools. Rigidity in the vertical direction is provided by the neck tube. The support structure is quite compact. Several variants of the rigidizer have been fabricated, using flat sheets of G-10 fiberglass epoxy in thicknesses between 0.75-1.5 mm for the upper and lower truss assemblies, and either G-10 or stainless steel for the intermediate structure.

Harper, D. A.↗
NASA NTRS1991

High resolution, low energy avalanche photodiode X-ray detectors

Silicon avalanche photodiodes have been fabricated, and their performance as X-ray detectors has been measured. Photon sensitivity and energy resolution were measured as a function of size and operating parameters. Noise thresholds as low as 212 eV were obtained at room temperature, and backscatter X-ray fluorescence data were obtained for aluminum and other light elements. It is concluded that the results with the X-ray detector are extremely encouraging, and the performance is challenging the best available proportional counters. While not at the performance level of either cryogenic silicon or HgI2, these device operate at room temperature and can be reproduced in large numbers and with much larger areas than typically achieved with HgI2. In addition, they are rugged and appear to be indefinitely stable.

Farrell, R.↗
NASA NTRS1993

Measurements of atmospheric carbonyl sulfide during the NASA Chemical Instrumentation Test and Evaluation Project: Implications for the global COS budget

Atmospheric carbonyl sulfide COS concentrations were measured by three analytical systems during the Chemical Instrumentation Test and Evaluation (CITE 3) project. The three systems all used cryogenic sample preconcentration and gas chromatographic (GC) separation but differed in the method of detection. The FPD system used a flame photometric detector, the MS system used a mass selective detector, and the ECD-S system used a fluorinating catalyst followed by an electron capture detector. With the FPD system, we found a mean COS concentration of 510 ppt over the North Atlantic and 442 ppt over the Tropical Atlantic. With the ECD-S system, we found a mean COS concentration of 489 ppt over the North Atlantic and 419 ppt over the Tropical Atlantic. All three systems registered a latitudinal gradient in atmospheric COS of between 1.6 and 2.0 ppt per degree of latitude, with increasing COS concentrations northward which was similar to the gradient measured by Bingemer et al. (1990). It is difficult to reconcile the measured latitudinal concentration gradient with present theories of the global COS budget since the largest sink of COS is thought to be a flux to land plants, most of which are in the northern hemisphere.

Johnson, James E.↗
NASA NTRS1987

Infrared spectroscopy of the lower stratosphere with a balloon-borne cryogenic Fourier spectrometer

The IR limb emission of the lower stratosphere has been measured using a balloon-borne liquid nitrogen-cooled Michelson interferometer with liquid helium-cooled Si:Ga detectors. Portions of the thermal emission spectrum have been recorded between 650 and 2000/cm with an unapodized spectral resolution of 0.03/cm. This is the highest spectral resolution limb emission thus far obtained. A preliminary description is given of these data along with a discussion of the significant features. Species identified to date include CO2, O3, CFCl3, CF2Cl2, H2O, CH4, HNO3, N2O, NO2, and ClONO2. A tentative identification is made for NO, representing the first direct spectroscopic detection of NO in emission.

Kunde, Virgil G.↗