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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS2002

Ultralow-Background Large-Format Bolometer Arrays

In the coming decade, work will commence in earnest on large cryogenic far-infrared telescopes and interferometers. All such observatories - for example, SAFIR, SPIRIT, and SPECS - require large format, two dimensional arrays of close-packed detectors capable of reaching the fundamental limits imposed by the very low photon backgrounds present in deep space. In the near term, bolometer array architectures which permit 1000 pixels - perhaps sufficient for the next generation of space-based instruments - can be arrayed efficiently. Demonstrating the necessary performance, with Noise Equivalent Powers (NEPs) of order 10-20 W/square root of Hz, will be a hurdle in the coming years. Superconducting bolometer arrays are a promising technology for providing both the performance and the array size necessary. We discuss the requirements for future detector arrays in the far-infrared and submillimeter, describe the parameters of superconducting bolometer arrays able to meet these requirements, and detail the present and near future technology of superconducting bolometer arrays. Of particular note is the coming development of large format planar arrays with absorber-coupled and antenna-coupled bolometers.

Benford, Dominic↗
NASA NTRS1989

Microwave oscillator with reduced phase noise by negative feedback incorporating microwave signals with suppressed carrier

Oscillator configurations which reduce the effect of 1/f noise sources for both direct feedback and stabilized local oscillator (STALO) circuits are developed and analyzed. By appropriate use of carrier suppression, a small signal is generated which suffers no loss of loop phase information or signal-to-noise ratio. This small signal can be amplified without degradation by multiplicative amplifier noise, and can be detected without saturation of the detector. Together with recent advances in microwave resonator Qs, these circuit improvements will make possible lower phase noise than can be presently achieved without the use of cryogenic devices.

Dick, G. J.↗
NASA NTRS2004

Arrays of Bolometers for Far-infrared and Submillimeter Astronomy

We describe 12 x 32 arrays of semiconducting cryogenic bolometers designed for use in far-infrared and submillimeter cameras. These 12 x 32 arrays are constructed from 1 x 32 monolithic pop-up detectors developed at NASA Goddard Space Flight Center. The pop-up technology allows the construction of large arrays with high filling factors that provide efficient use of space in the focal planes of far-infrared and submillimeter astronomical instruments. This directly leads to a significant decrease in observing time. The prototype array is currently operating in SHARC II, a facility instrument in use at the Caltech Submillimeter Observatory (CSO). The elements of this array employ a bismuth absorber coating and quarter wave backshort to optimize the bolometer absorption for a passband centered at 350 microns. However, this resonant structure also provides good bolometer performance at 450 and 850 microns, the two additional SHARC II passbands. A second array is to be installed in the High-resolution Airborne Widebandwidth Camera (HAWC), a far-infrared imaging camera for the Stratospheric Observatory for Infrared Astronomy (SOFIA). This array is currently in the final stage of construction, and its completion is expected in early 2004. HAWC is scheduled for commissioning in 2005. The HAWC array employs titanium-gold absorbers and is optimized for uniform absorption from 40 to 300 microns to accommodate all four of its far-infrared passbands. We describe the details of the array construction including the mechanical design and electrical characterization of the constituent linear arrays, comparing the SHARC II and HAWC cases. We also summarize the overall characteristics of the final two-dimensional arrays. Finally, we show examples of array performance in the form of images obtained with SHARC II.

Chuss, D. T.↗
NASA NTRS2006

Cryogenic Cooling for Myriad Applications-A STAR Is Born

Cryogenics, the science of generating extremely low temperatures, has wide applicability throughout NASA. The Agency employs cryogenics for rocket propulsion, high-pressure gas supply, breathable air in space, life support equipment, electricity, water, food preservation and packaging, medicine, imaging devices, and electronics. Cryogenic liquid oxygen and liquid hydrogen systems are also replacing solid rocket motor propulsion systems in most of the proposed launch systems, a reversion to old-style liquid propellants. In the late 1980s, NASA wanted a compact linear alternator/motor with reduced size and mass, as well as high efficiency, that had unlimited service life for use in a thermally driven power generator for space power applications. Prior development work with free-piston Stirling converters (a Stirling engine integrated with a linear actuator that produces electrical power output) had shown the promise of that technology for high-power space applications. A dual use for terrestrial applications exists for compact Stirling converters for onsite combined heat and power units. The Stirling cycle is also usable in reverse as a refrigeration cycle suitable for cryogenic cooling, so this Stirling converter work promised double benefits as well as dual uses. The uses for cryogenic coolers within NASA abound; commercial applications are similarly wide-ranging, from cooling liquid oxygen and nitrogen, to cryobiology and bio-storage, cryosurgery, instrument and detector cooling, semiconductor manufacturing, and support service for cooled superconducting power systems.

Source record↗
NASA NTRS2008

Electrical NEP in Hot-Electron Titanium Superconducting Bolometers

We are presenting the current progress on the titanium (Ti) hot-electron transition-edge devices. The ultimate goal of this work is to develop a submillimeter Hot-Electron Direct Detector (HEDD) with the noise equivalent power NEP = 10(sup -1) - 10(sup -20) W/Hz(sup 1/2) for the moderate resolution spectroscopy and Cosmic Microwave Background (CMB) studies on future space telescope (e.g., SPICA, SAFIR, SPECS, CMBPol) with cryogenically cooled (approximately 4-5 K) mirrors. Recently, we have achieved the extremely low thermal conductance (approximately 20 fW/K at 300 mK and approximately 0.1 fW/K at 40 mK) due to the electron-phonon decoupling in Ti nanodevices with niobium (Nb) Andreev contacts. This thermal conductance translates into the "phonon-noise" NEP approximately equal to 3 x 10(sup -21) W/Hz(sup 1/2) at 40 mK and NEP approximately equal to 3 x 10(sup -19) W/Hz(sup 1/2) at 300 mK. These record data indicate the great potential of the hot-electron detector for meeting many application needs. Beside the extremely low phonon-noise NEP, the nanobolometers have a very low electron heat capacitance that makes them promising as detectors of single THz photons. As the next step towards the practical demonstration of the HEDD, we fabricated and tested somewhat larger than in Ref.1 devices (approximately 6 micrometers x 0.35 micrometers x 40 nm) whose critical temperature is well reproduced in the range 300-350 mK. The output electrical noise measured in these devices with a low-noise dc SQUID is dominated by the thermal energy fluctuations (ETF) aka "phonon noise". This indicates the high electrothermal loop gain that effectively suppresses the contributions of the Johnson noise and the amplifier (SQUID) noise. The electrical NEP = 6.7 x 10(sup -18) W/Hz(sup 1/2) derived from these measurements is in good agreement with the predictions based on the thermal conductance data. The very low NEP and the high speed (approximately microns) are a unique combination not found in other detectors.

transition-edge sensor↗
NASA NTRS2020

Fitting Leak Test Report

Many Human Landing System flight elements are anticipated to implement mechanically connected joints in cryogenic fluid lines to simplify system assembly. These joints will need to survive launch vibration, while cold, and remain as leak‐free as possible to minimize commodity loss. Threaded fluid fittings should be qualified for use in their expected environments to reduce risk and ensure mission success. A new ground‐based test apparatus was developed and validated to obtain quantifiable low leak rate test data for a small component, such as a pressurized threaded fluid fitting, while in the temperature range of liquid hydrogen. A cryocooler is used to attain the cold test temperature and helium leakage from a pressurized fitting mounted within a vacuum test chamber is measured using a mass spectrometer leak detector. Two different sizes of Swagelok VCR fittings with three different types of seal rings were selected as the test articles for the initial proof of concept testing. Each fitting configuration was subjected to two consecutive cryogenic thermal cycles and cold leak measurement tests, followed by exposure to a high vibration test profile at ambient temperature on a shaker table, and then two additional cold leak measurement tests. Very low leak rates, below the acceptable leak rate threshold, were measured at the pressures tested. Several enhancements to the test hardware are discussed that would facilitate a comprehensive fitting qualification test campaign by enabling a higher test throughput rate and ensuring a repeatable test profile.

Cryogenic Fluid Management↗
NASA NTRS2003

Progress Toward a Compact 0.05 K Magnet Refrigerator Operating from 10 K

Much of the most interesting information regarding our universe is hidden in the sub-millimeter, infrared, and x-rays bands of the spectrum, to which our atmosphere is largely opaque. Thus, missions exploring these bands are a very important part of NASA s Space Science program. Coincidentally, the most sensitive detectors in these spectral regions operate at extremely low temperatures, typically 0.05 - 0.10 K. Generally these temperatures will be achieved using magnetic refrigerators, also know as Adiabatic Demagnetization Refrigerators, or ADRs. Current ADRs, such as the one used in the XRS-II instrument on the Astro-E2 satellite, use a single-stage to cool detectors from 1.3 K to 0.06 K. The ADR is designed so that it can absorb the heat on the detector stage for at least 24 hours before it must stop, warm up to the helium bath temperature (1.3 K), and dump the accumulated heat. Future detector arrays will be much larger and will have higher heat dissipation. Furthermore, future missions will use mechanical cryocoolers to provide upper stage cooling, but they can only reach 4 - 10 K. Trying to scale heavy (-15 kg) single stage ADRs up to the higher heat loads and higher heat rejection temperatures required leads to unacceptably large systems. The GSFC Cryogenics Branch has developed the Continuous ADR (CADR) to solve this problem. The CADR consists of a series of ADR stages that sequentially pass heat from the load up to the high temperature heat sink. The stage connected to the load remains at a constant temperature. The continuous stage effectively decouples detector operation from ADR operation, allowing the ADR stages to be cycled much more rapidly. Rapid cycling leads to higher cooling power density. The cascading, multistage arrangement allows the magnetic refrigerant of each stage to be optimized for its own temperature swing. In the past year, we have made good progress toward a 0.05 to 10K system. A four-stage system that operates from 4.2 K was demonstrated. Magnetic shielding was added to eliminate inter-stage coupling. Improvements were made to superconducting and passive gas-gap heat switches. A second type of passive gas gap switch, one meant for use at higher temperature, was demonstrated. The presentation will focus primarily on these recent design improvements, and on the challenges that remain on the progress toward a system that will operate from 10 K or higher.

Canavan, Edgar↗
NASA NTRS1990

Fiber-coupled high resolution infrared array spectrometer for the Kuiper Airborne Observatory

A novel cryogenic grating spectrometer (FCAS) is being designed for observations of volatiles in cometary and planetary atmospheres, and in newly forming planetary systems. The instrument features two-dimensional detector arrays coupled to a high-dispersion echelle by infrared fibers, and will achieve a spectral resolving power of about 40,000. The primary observational platform for this instrument will be the Kuiper Airborne Observatory, but it will also be configured for use at ground-based observatories. Initially, the spectrometer will use a 58 x 62, 1- to 5-micron InSb array. Larger-format IR arrays and arrays of different composition, will later be incorporated as they become available. The instrument will be used in two modes. The first uses a large format IR array in the spectral image plane for the customary one-dimensional spectral-one-dimensional spatial coverage. In the second mode, a massive, coherent bundle of infrared transmitting ZrF4 fibers will be installed after the dispersive element, to reformat the two-dimensional array into an elongated one-dimensional array for wide spectral coverage, allowing multiple lines to be measured in a single integration with high sensitivity. The overall instrument design is discussed, and the system sensitivity is estimated.

Glenar, D. A.↗
NASA NTRS2003

A 10 Kelvin 3 Tesla Magnet for Space Flight ADR Systems

Many future space flight missions are expected to use adiabatic demagnetization refrigerators (ADRs) to reach detector operating temperatures well below one Kelvin. The goal is to operate each ADR with a mechanical cooler as its heat sink, thus avoiding the use of liquid cryogens. Although mechanical coolers are being developed to operate at temperatures of 6 Kelvin and below, there is a large efficiency cost associated with operating them at the bottom of their temperature range. For the multi-stage ADR system being developed at Goddard Space Flight Center, the goal is to operate with a 10 Kelvin mechanical cooler heat sink. With currently available paramagnetic materials, the highest temperature ADR stage in such a system will require a magnetic field of approximately three Tesla. Thus the goal is to develop a small, lightweight three Tesla superconducting magnet for operation at 10 Kelvin. It is important that this magnet have a low current/field ratio. Because traditional NbTi magnets do not operate safely above about six Kelvin, a magnet with a higher Tc is required. The primary focus has been on Nb3Sn magnets. Since standard Nb3Sn wire must be coated with thick insulation, wound on a magnet mandrel and then reacted, standard Nb,Sn magnets are quite heavy and require high currents Superconducting Systems developed a Nb3Sn wire which can be drawn down to small diameter, reacted, coated with thin insulation and then wound on a small diameter coil form. By using this smaller wire and operating closer to the wire s critical current, it should be possible to reduce the mass and operating current of 10 Kelvin magnets. Using this "react-then-wind" technology, Superconducting Systems has produced prototype 10 Kelvin magnets. This paper describes the development and testing of these magnets and discusses the outlook for including 10 Kelvin magnets on space-flight missions.

Tuttle, Jim↗
NASA NTRS2005

Temperature-dependent optical properties of Cd(1-x),Zn(x),Te substitute material

In this study, we report cryogenic optical properties of Cd(l-x), Zn(x), Te wafers that are used as substrate seed layers in the manufacturing of HgCdTe focal-plane array detectors. These studies are motivated by the fact that the substrate optical properties influence the overall detector performance. The studies consist of measuring the substrate frequency dependent transmittance T(W) and reflectance R(W) above and below the optical band-gap in the UV/Visible and infrared frequency ranges, and with temperature variation of the sample from 5 to 300 K. Determination of the optical absorption from these measurements show that the optical absorption energy gap near 1.6 eV shows a substantial increase as the temperature is reduced from 300 to 5 K. Furthermore, we observe the presence of infrared-active optical phonons whose peak frequency shifts as the temperature of the sample is varied over the measured temperature range. The theoretical frequency dependent optical conductivity, with allowance for redistribution of spectral weight among the interband transition charge carriers, will be discussed.

Quijada, Manuel A.↗
NASA NTRS2008

Wavefront Sensing with the Fine Guidance Sensor for James Webb Space Telescope

An analysis is presented that utilizes the Fine Guidance Sensor (FGS) for focal-plane wavefront sensing (WFS) for the James Webb Space Telescope (JWST). WFS with FGS increases the number of wavefront measurements taken in field of the telescope, but has many challenges over the other JWST instruments that make it unique, such as; less sampling of the Point Spread Function (PSF), a smaller diversity-defocus range, a smaller image detector size, and a polychromatic object or source. Additionally, presented is an analysis of sampling for wavefront sensing. Results are shown based on simulations of flight and the cryogenic optical testing at NASA Johnson Space Center.

Smith, J. Scott↗
NASA NTRS1976

A telescope for the Infrared Astronomical Satellite /IRAS/

The Infrared Astronomical Satellite (IRAS) will be used to survey the 8 to 120 micron spectrum of the entire sky to the faintest flux levels possible by using state-of-the-art detectors and preamplifiers. As a result of a recently completed study of the telescope and focal plane, a concept has been devised that demonstrates the feasibility of using stored cryogen to cool the telescope for one year of operation in a polar twilight orbit at an altitude of 900 km. Predictions regarding noise equivalent flux density, cryogenic lifetime, and the number of noise spikes caused by Van Allen belt radiation are presented. The telescope is cooled both by supercritical and by superfluid helium. The on-board signal processing includes provisions for suppressing noise spikes.

Hedden, R. L.↗
NASA NTRS1983

Life test performance of a Philips rhombic-drive refrigerator with bellows seals

In February 1979, tour Stirling cycle cryogenic refrigerators, developed by Philips Laboratories for the John Hopkins University/Applied Physics Laboratory, were launched into orbit aboard the P78-1 spacecraft. The refrigerators were designed to cool the detectors of two identical gamma-ray spectrometers to 77 K reliably for one year. Since launch, the refrigerators, still in orbit, have individually accumulated from 5,000 to over 20,000 hours of operation. As part of those efforts, a refrigerator identical to those in orbit was built, with one significant modification: flexible metal bellows between the crankcase and the working volume to prevent possible contaminants from migrating into the cold region. During the life test of the modified refrigerator, the temperature increase during the first three month run was 0.022 k/day, a negligible level. As of October 1982, the unit has accumulated over 12,300 hours of operation.

Lindale, E.↗
NASA NTRS1984

Temperature stability limits for an isothermal demagnetization refrigerator

It is pointed out that magnetic refrigeration can provide additional cooling for infrared detectors on space missions, taking into account the Shuttle Infrared Telescope Facility (SIRTF) and the Large Deployable Reflector (LDR). From a temperature of 2 K provided by the primary cryogens, magnetic refrigerators could cool bolometers or pumped photoconductors to 0.1 K or below. Such a reduction in operating temperature would increase the sensitivity for bolometers, while the response at longer wavelengths for pumped photoconductors would be improved. Two types of magnetic refrigeration cycles have been proposed. One type uses a complete demagnetization. The present investigation is concerned with the second type, which uses a feedback-controlled isothermal demagnetization, taking into account the temperature stability limits. Attention is given to control system resolution, thermometer noise, reaction time, and thermal time constants.

Kittel, P.↗
NASA NTRS2003

Integration, Testing and Performance of the Infrared Multi-Object Spectrometer

The Infrared Multi-Object Spectrometer (IRMOS) is a principle investigator-class instrument for the Kitt Peak National Observatory 2.1 m and Mayall 3.8 m telescopes. IRMOS is a near-IR (0.8 - 2.5 micron) spectrometer with low-to mid-resolving power (R = lambda/delta lambda = 300 - 3000). On the 3.8 m telescope, IRMOS produces simultaneous spectra of approximately 100 objects in its approximately 3 x 2 arcmin field of view using a commercial micro electro-mechanical systems (MEMS) digital micro-mirror device (DMD) from Texas Instruments. The multi-mirror array DMD operates as a real-time programmable slit mask. The all-reflective optical design consists of two imaging subsystems. The focal reducer images the focal plane of the telescope onto the DMD field stop, and the spectrograph images the DMD onto a large-format detector. The instrument operates at approximately 80 K, cooled by a single electro-mechanical cryocooler. The bench and all components are made from aluminum 6061-T651. There are three cryogenic mechanisms. We describe laboratory integration and test of IRMOS before shipment to Kitt Peak. We give an overview of the optical alignment technique and integration of optical, mechanical, electrical and cryogenic subsystems. We compare optical test results to model predictions of point spread function size and morphology, contrast, and stray light. We discuss some lessons learned and conclude with a prediction for performance on the telescope.

Ohl, Raymond G.↗
NASA NTRS1995

The development of infrared detectors and mechanisms for use in future infrared space missions

The environment above earth's atmosphere offers significant advantages in sensitivity and wavelength coverage in infrared astronomy over ground-based observatories. In support of future infrared space missions, technology development efforts were undertaken to develop detectors sensitive to radiation between 2.5 micron and 200 micron. Additionally, work was undertaken to develop mechanisms supporting the imaging and spectroscopy requirements of infrared space missions. Arsenic-doped-Silicon and Antimony-doped-Silicon Blocked Impurity Band detectors, responsive to radiation between 4 micron and 45 micron, were produced in 128x128 picture element arrays with the low noise, high sensitivity performance needed for space environments. Technology development continued on Gallium-doped-Germanium detectors (for use between 80 micron and 200 micron), but were hampered by contamination during manufacture. Antimony-doped-Indium detectors (for use between 2.5 micron and 5 micron) were developed in a 256x256 pixel format with high responsive quantum efficiency and low dark current. Work began on adapting an existing cryogenic mechanism design for space-based missions; then was redirected towards an all-fixed optical design to improve reliability and lower projected mission costs.

Houck, James R.↗
NASA NTRS1978

Infrared Astronomical Satellite /IRAS/ and Shuttle Infrared Telescope Facility /SIRTF/ - Implications of scientific objectives on focal plane sensitivity requirements

The full potential of infrared astronomy can be realized only through observations made with space-based telescopes cooled to cryogenic temperatures. The paper outlines the scientific mission, system description, and focal plane requirements for two cryogenic telescopes: the Infrared Astronomical Satellite (IRAS) and the Shuttle Infrared Telescope Facility (SIRTF). IRAS, a 60-cm superfluid-helium-cooled telescope system, will perform a one-year 8-120-micron IR sky survey; it will provide results of high reliability and sensitivity, produce the first complete survey data for the 30-120-micron region, and fill in missing portions (spectrally and spatially) of previous surveys short of 30 microns; its focal plane assembly is being designed to approach background-limited performance with an array of 62 discrete detectors. The SIRTF design will allow detailed follow-up studies in the 1-1000-micron range with a 116-160-cm observatory-class instrument. The Shuttle sortie capability introduces the unique SIRTF concept of an easily refurbishable or replaceable focal plane instrument complement in an orbiting cryogenic telescope.

Mccreight, C. R.↗
NASA NTRS1993

The SIRTF mission

This paper describes the status of NASA's Space Infrared Telescope Facility (SIRTF) program. SIRTF will be a cryogenically cooled observatory for infrared astronomy from space and is planned for launch early in the next decade. We discuss a newly modified baseline SIRTF mission and review the state of the detector technology which will provide the heart of SIRTF's scientific advances.

Werner, M. W.↗