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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

The 27-28 October 1986 FIRE IFO cirrus case study - Cloud optical properties determined by High Spectral Resolution Lidar

The High Spectral Resolution Lidar (HSRL) was operated from a roof-top site in Madison, Wisconsin. The transmitter configuration used to acquire the case study data produces about 50 mW of ouput power and achieved eye-safe, direct optical depth, and backscatter cross section measurements with 10 min averaging times. A new continuously pumped, injection seeded, frequency doubled Nd:YAG laser transmitter reduces time-averaging constraints by a factor of about 10, while improving the aerosol-molecular signal separation capabilities and wavelength stability of the instrument. The cirrus cloud backscatter-phase functions have been determined for the October 27-28, 1986 segment of the HSRL FIRE dataset. Features exhibiting backscatter cross sections ranging over four orders of magnitude have been observed within this 33 h period. During this period, cirrus clouds were observed with optical thickness ranging from 0.01 to 1.4. The altitude relationship between cloud top and bottom boundaries and the optical center of the cloud is influenced by the type of formation observed.

Grund, C. J.↗
NASA NTRS1993

Chromospheric and coronal observations with multilayer optics

The first high resolution X-ray images of an astronomical object (the solar corona) formed with normal incidence multilayer optics, were obtained in late 1987. We review the developments which have occurred in multilayer optics technology since 1987, and discuss the advantages that these developments present for solar observations. The most significant advantages of multilayer optics are: (1) telescopes with modest apertures (about 0.1-0.5 meters) can achieve images with very high (about 0.1-0.3 arcsec) resolution; and (2) the spectral selectivity of multilayers permits the investigation of thermal structures with resolution T/(Delta)T is about 5-10. We describe the analysis of polar plumes observed in 1987 and of small X-ray emitting regions called 'bright points' observed in 1991 to illustrate the power of multilayer optics for astronomical studies.

Walker, Arthur B. C., Jr.↗
NASA NTRS2015

Experimental Estimation of CLASP Spatial and Spectral Resolutions: Results of the Instrument's Optical Alignment

The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding rocket experiment design to measure for the first time the polarization signal of the Lyman-Alpha line (121.6nm), emitted in the solar upper-chromosphere and transition region. This instrument aims to detect the Hanle effect's signature hidden in the Ly-alpha polarization, as a tool to probe the chromospheric magnetic field. Hence, an unprecedented polarization accuracy is needed ((is) less than 10 (exp -3). Nevertheless, spatial and spectral resolutions are also crucial to observe chhromospheric feature such as spicules, and to have precise measurement of the Ly-alpha line core and wings. Hence, this poster will present how the telescope and the spectrograph were separately aligned, and their combined spatial and spectral resolutions.

spatial resolution↗
NASA NTRS2009

Differential Deposition Technique for Figure Corrections in Grazing Incidence X-ray Optics

A differential deposition technique is being developed to correct the low- and mid-spatial-frequency deviations in the axial figure profile of Wolter type grazing incidence X-ray optics. These deviations arise due to various factors in the fabrication process and they degrade the performance of the optics by limiting the achievable angular resolution. In the differential deposition technique, material of varying thickness is selectively deposited along the length of the optic to minimize these deviations, thereby improving the overall figure. High resolution focusing optics being developed at MSFC for small animal radionuclide imaging are being coated to test the differential deposition technique. The required spatial resolution for these optics is 100 m. This base resolution is achievable with the regular electroform-nickel-replication fabrication technique used at MSFC. However, by improving the figure quality of the optics through differential deposition, we aim at significantly improving the resolution beyond this value.

Kilaru, Kiranmayee↗
NASA NTRS1982

Solar corona at high resolution

The earth's surface is shielded from solar X rays almost completely by the atmosphere. It is, therefore, necessary to place X-ray detectors on rockets or orbiting satellites. Solar rays were detected for the first time in the late 1940's, using V-2 rockets. In 1960, the first true X-ray images of the sun were obtained with the aid of a simple pinhole camera. The spatial resolution of the X-ray images could be considerably improved by making use of reflective optics, operating at grazing incidence. Aspects of X-ray mirror developments are discussed along with the results obtained in coronal studies utilizing the new devices for the observation of solar X-ray emission. It is pointed out that the major achievements of the Skylab missions were due primarily to the unique opportunity to obtain data over an extended period of time. Attention is given to normal incidence X-ray optics, achievements possible by making use of high spatial resolution optics, and details of improved mirror design.

Golub, L.↗
NASA NTRS1986

Composition of faint comets

The study uses an emission line, differential imaging camera built by the Science Operations Branch. This instrument allows photometric data to be obtained over a large area of a comet in a large number of resolution elements. The detector is a 100x100 Reticon array which with interchangeable optics can give resolutions from 2" to 30" over a field of 1' to 15'. The camera through its controlling computer can simultaneously take images in on-line and continuum filters and through computer subtraction and calibration present a photometric image of the comet produced by only the emission of the molecule under study. Initial work has shown two significant problems. First the auxiliary equipment of the telescope has not allowed the unambiguous location of faint comets so that systematic observations could be made, and secondly initial data has not shown much molecular emission from the faint comets which were located. Work last year on a software and hardware display system and this year on additional guide motors on the 36-inch telescope has allowed the differential camera to act as its own finder and guide scope. Comet IRAS was observed in C2 and CO+, as well as an occultation by the comet of SAO029103. The perodic comet Giacobini-Zinner was also observed in C2.

Brown, L. W.↗
NASA NTRS1991

NGC 1068 - Resolution of nuclear structure in the optical continuum

The HST Planetary Camera has been used to obtain an optical continuum image of the Seyfert galaxy NGC 1068. The image reveals a bright nucleus embedded in an irregular cloudlike structure which is well-differentiated against the background of the galaxy. The nucleus is resolved, with an FWHM of about 0.15 arcsec, or 11 pc. There is no evidence for any unresolved nuclear component. The precise geometry of the scattering region cannot yet be inferred. The cloud surrounding the nucleus is elongated in the NE-SSW direction and has extreme dimensions of 3.5 arcsec x 1.7 arcsec. The brightness centroid is situated 0.4 arcsec SW of the nucleus. It is concluded that the light from the cloud is contributed largely by stars, but that the appearance of the cloud is distinctly dissimilar to what is expected from young or old stellar systems and bears to simple relationship to the numerous features that have heretofore been resolved at other wavelengths.

Lynds, Roger↗
NASA NTRS2012

Flight Programs and X-ray Optics Development at MSFC

The X-ray astronomy group at the Marshall Space Flight Center is developing electroformed nickel/cobalt x-ray optics for suborbital and orbital experiments. Suborbital instruments include the Focusing X-ray Solar Imager (FOXSI) and Micro-X sounding rocket experiments and the HERO balloon payload. Our current orbital program is the fabrication of a series of mirror modules for the Astronomical Roentgen Telescope (ART) to be launched on board the Russian-German Spectrum Roentgen Gamma Mission (SRG.) The details and status of these various programs are presented. A second component of our work is the development of fabrication techniques and optical metrology to improve the angular resolution of thin shell optics to the arcsecond-level. The status of these x-ray optics technology developments is also presented.

Gubarev, M.↗
NASA NTRS1971

Optical and infrared masers

High resolution studies of atoms and molecules applied to optical and infrared maser experimentation

Source record↗
NASA NTRS2007

Single-Shot Rotational Raman Thermometry for Turbulent Flames Using a Low-Resolution Bandwidth Technique

An alternative optical thermometry technique that utilizes the low-resolution (order 10(exp 1)/cm) pure-rotational spontaneous Raman scattering of air is developed to aid single-shot multiscalar measurements in turbulent combustion studies. Temperature measurements are realized by correlating the measured envelope bandwidth of the pure-rotational manifold of the N2/O2 spectrum with a theoretical prediction of a species-weighted bandwidth. By coupling this thermometry technique with conventional vibrational Raman scattering for species determination, we demonstrate quantitative spatially resolved, single-shot measurements of the temperature and fuel/oxidizer concentrations in a high-pressure turbulent Cf4-air flame. Our technique provides not only an effective means of validating other temperature measurement methods, but also serves as a secondary thermometry technique in cases where the anti-Stokes vibrational N2 Raman signals are too low for a conventional vibrational temperature analysis.

Kojima, Jun↗
NASA NTRS2002

Diffraction Effects in a Grating Spectrometer

This paper describes a numerical study of diffraction effects in the AIRES optical system using GLAD by Applied Optics Research. AIRES (or Airborne Infrared Echelle Spectrometer) employs two gratings in series. The small, first-order (i.e., predisperser) grating sorts orders for the large, high-order echelle grating, thus providing moderately high spectral resolution over 3.6 octaves in wavelength. The AIRES' optical design includes three field stops (i.e., a circular aperture and two long, narrow slits) and four pupil stops. A detailed diffraction analysis is required to evaluate critical trade-offs between spectral resolution, optical throughput, detector background, scattered light, and system size and weight. Such an analysis must consider diffraction effects at the pupil stops (edge diffraction), at the field stops (spatial filtering), and at intermediate positions where other optical elements are located. The effects of slit width, slit length, oversizing of the second slit relative to the first, baffling at the Lyot stop and subsequent pupil stops, and the necessity for oversizing other optical elements are presented and discussed. It is found that for narrow slits, the downstream energy distribution is significantly broadened relative to that for large slits, where telescope diffraction dominates, leading to significantly more light loss than anticipated, unless other key optical elements are oversized. The importance of performing a proper diffraction analysis is emphasized and the suitability of GLAD for this task is discussed.

Haas, Michael R.↗
NASA NTRS2012

The Transition-Edge-Sensor Array for the Micro-X Sounding Rocket

The Micro-X sounding rocket program will fly a 128-element array of transition-edge-sensor microcalorimeters to enable high-resolution X-ray imaging spectroscopy of the Puppis-A supernova remnant. To match the angular resolution of the optics while maximizing the field-of-view and retaining a high energy resolution (< 4 eV at 1 keV), we have designed the pixels using 600 x 600 sq. micron Au/Bi absorbers, which overhang 140 x 140 sq. micron Mo/Au sensors. The data-rate capabilities of the rocket telemetry system require the pulse decay to be approximately 2 ms to allow a significant portion of the data to be telemetered during flight. Here we report experimental results from the flight array, including measurements of energy resolution, uniformity, and absorber thermalization. In addition, we present studies of test devices that have a variety of absorber contact geometries, as well as a variety of membrane-perforation schemes designed to slow the pulse decay time to match the telemetry requirements. Finally, we describe the reduction in pixel-to-pixel crosstalk afforded by an angle-evaporated Cu backside heatsinking layer, which provides Cu coverage on the four sidewalls of the silicon wells beneath each pixel.

Eckart, M. E.↗
NASA NTRS1983

Feasibility study of an optically coherent telescope array in space

Numerical methods of image construction which can be used to produce very high angular resolution images at optical wavelengths of astronomical objects from an orbiting array of telescopes are discussed and a concept is presented for a phase-coherent optical telescope array which may be deployed by space shuttle in the 1990's. The system would start as a four-element linear array with a 12 m baseline. The initial module is a minimum redundant array with a photon-counting collecting area three times larger than space telescope and a one dimensional resolution of better than 0.01 arc seconds in the visible range. Later additions to the array would build up facility capability. The advantages of a VLBI observatory in space are considered as well as apertures for the telescopes.

Traub, W. A.↗
NASA NTRS1992

Optical spectroscopy of Z Canis Majoris, V1057 Cygni, and FU Orionis - Accretion disks and signatures of disk winds

High resolution, high SNR optical spectra have been used to investigate the hypothesis that in outburst, FU Ori objects are self-luminous accretion disks whose light dominates at optical and near-IR wavelengths. Strong evidence has been found for linewidth versus wavelength correlation in good agreement with model predictions for Z CMa and V1057 Cyg, but not for FU Ori itself. Linewidth varies continuously with wavelength at optical wavelengths in the former two objects, In the case of FU Ori, it is argued that a combination of strong wind components to spectral lines, and surface gravity possibly being lower than that of supergiants, conceals the underlying linewidth versus wavelength relationship. A marginal correlation is found between linewidth and lower excitation potential in all three objects. Synthetic disk spectra are subtracted from observed spectral, and remarkably good fits are found for all three objects for wavelengths longer than about 5000 A.

Welty, Alan D.↗
NASA NTRS1981

Stability of magnetically suspended optics in a vibration environment

The improving resolution capabilities of large spaceborne optical experiments are placing ever-increasing demands on platform stability in a vibration environment. The present paper discusses the principles of magnetic suspension systems as a promising alternative to conventional methods. The disadvantages of various conventional pointing mount geometrics are discussed, including the CG-mount approach and end-mount pointing, and advantages of a system whereby the payload has a high degree of isolation from the carrier in translation are pointed out. The Annular Suspension and Pointing System Vernier System is then presented as a hardware realization of a complete magnetic suspension system consisting of six magnetic bearing assemblies controlling six degrees of freedom of payload motion in a standardized end-mount configuration. A model of a simplified two-degrees-of-freedom isolation and pointing unit is considered and the transfer function from carrier translation to payload pointing is derived. The function is evaluated for several degenerate cases corresponding to conventional mounting techniques and magnetic suspension. Analytical performance predictions show a stability of better than 0.01 arcsec for a wide range of payloads in the worst-case shuttle disturbance environment.

Hamilton, B. J.↗
NASA NTRS2012

Very High Resolution Solar X-ray Imaging Using Diffractive Optics

This paper describes the development of X-ray diffractive optics for imaging solar flares with better than 0.1 arcsec angular resolution. X-ray images with this resolution of the greater than or equal to 10 MK plasma in solar active regions and solar flares would allow the cross-sectional area of magnetic loops to be resolved and the coronal flare energy release region itself to be probed. The objective of this work is to obtain X-ray images in the iron-line complex at 6.7 keV observed during solar flares with an angular resolution as fine as 0.1 arcsec - over an order of magnitude finer than is now possible. This line emission is from highly ionized iron atoms, primarily Fe xxv, in the hottest flare plasma at temperatures in excess of approximately equal to 10 MK. It provides information on the flare morphology, the iron abundance, and the distribution of the hot plasma. Studying how this plasma is heated to such high temperatures in such short times during solar flares is of critical importance in understanding these powerful transient events, one of the major objectives of solar physics.We describe the design, fabrication, and testing of phase zone plate X-ray lenses with focal lengths of approximately equal to 100 m at these energies that would be capable of achieving these objectives. We show how such lenses could be included on a two-spacecraft formation-flying mission with the lenses on the spacecraft closest to the Sun and an X-ray imaging array on the second spacecraft in the focal plane approximately equal to 100 m away. High resolution X-ray images could be obtained when the two spacecraft are aligned with the region of interest on the Sun. Requirements and constraints for the control of the two spacecraft are discussed together with the overall feasibility of such a formation-flying mission.

Dennis, B. R.↗
NASA NTRS1993

Investigation of solar active regions at high resolution by balloon flights of the solar optical universal polarimeter, extended definition phase

Technical studies of the feasibility of balloon flights of the former Spacelab instrument, the Solar Optical Universal Polarimeter, with a modern charge-coupled device (CCD) camera, to study the structure and evolution of solar active regions at high resolution, are reviewed. In particular, different CCD cameras were used at ground-based solar observatories with the SOUP filter, to evaluate their performance and collect high resolution images. High resolution movies of the photosphere and chromosphere were successfully obtained using four different CCD cameras. Some of this data was collected in coordinated observations with the Yohkoh satellite during May-July, 1992, and they are being analyzed scientifically along with simultaneous X-ray observations.

Tarbell, Theodore D.↗
NASA NTRS1995

An X-ray and optical study of the interaction of the Cygnus Loop supernova remnant with an interstellar cloud

We have used the ROSAT high-resolution imager and optical emission line data to study the structure of a bright optical knot on the southeastern rim of the Cygnus Loop supernova remnant. This knot has been identified as an encounter between the blast wave and a small isolated cloud. The knot appears in projection just behind the blast wave, which is traced by Balmer line filaments which bound the X-ray emission. The knot is a prominent X-ray feature, consisting of a numerb of filaments which are correlated with the optical line emission. These data permit a detailed view of the blast wave interaction. By combining the optical and X-ray data it is possible to trace the blast wave as a continuous surface from its southern edge around the western side of the cloud that then continues on to the north. The southeastern knot is an indentation on the surface of the blast wave. Thus the southeastern knot is not a small cloud that has been overrun by the blast wave, but the tip of a larger cloud. Bright X-ray emission is associated with bright radiative filaments. The location of this emission, upstream of the radiative shocks, implies that the enhanced X-rays come from a reverse shock. The presence of a reverse shock is further evidence that the southeastern knot represents an early stage of a blast wave encountering a large cloud. A consistent picture of the Cygnus Loop as an explosion within a preexisting cavity is emerging. These observations agree with that picture.

Graham, James, R.↗