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At least 883 records · Page 49

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NASA NTRS1984

Ion mass spectrometer

An ion mass spectrometer is described which detects and indicates the characteristics of ions received over a wide angle, and which indicates the mass to charge ratio, the energy, and the direction of each detected ion. The spectrometer includes a magnetic analyzer having a sector magnet that passes ions received over a wide angle, and an electrostatic analyzer positioned to receive ions passing through the magnetic analyzer. The electrostatic analyzer includes a two dimensional ion sensor at one wall of the analyzer chamber, that senses not only the lengthwise position of the detected ion to indicate its mass to charge ratio, but also detects the ion position along the width of the chamber to indicate the direction in which the ion was traveling.

Neugebauer, M.↗

NASA NTRS1984

Imaging X-ray spectrometer

An X-ray spectrometer for providing imaging and energy resolution of an X-ray source is described. This spectrometer is comprised of a thick silicon wafer having an embedded matrix or grid of aluminum completely through the wafer fabricated, for example, by thermal migration. The aluminum matrix defines the walls of a rectangular array of silicon X-ray detector cells or pixels. A thermally diffused aluminum electrode is also formed centrally through each of the silicon cells with biasing means being connected to the aluminum cell walls and causes lateral charge carrier depletion between the cell walls so that incident X-ray energy causes a photoelectric reaction within the silicon producing collectible charge carriers in the form of electrons which are collected and used for imaging.

Grant, P. A.↗

NASA NTRS1977

Portable reflectance spectrometer

A portable reflectance spectrometer is disclosed. The spectrometer essentially includes an optical unit and an electronic recording unit. The optical unit includes a pair of thermoelectrically-cooled detectors, for detecting total radiance and selected radiance projected through a circular variable filter wheel, and is capable of operating to provide spectral data in the range 0.4 to 2.5 micrometers without requiring coventional substitution of filter elements. The electronic recording unit includes power supplies, amplifiers, and digital recording electronics designed to permit recordation of data on tape casettes. Both the optical unit and electronic recording unit are packaged to be manually portable.

Goetz, A. F. H.↗

NASA NTRS1984

A cryogenically cooled, multidetector spectrometer for infrared astronomy

A liquid helium-cooled, 24 detector grating spectrometer was developed and used for low resolution astronomical observations in the 5 to 14 micron spectral range. The instrument operated on the 91 cm Kuiper Airborne Observatory, the 3 m IRTF (Mauna Kea), the 3 m Shane telescope Observatory, the 3 m Shane telescope (Lick Observatory), and the 152 cm NASA and University of Arizona telescope. The detectors are discrete Si:Bi photoconductors with individual metal oxide semiconductor field effect transistor preamplifiers operating at 4 K. The system uses a liquid helium-cooled slit, order-sorter filter, collimator mirror, grating, and camera mirror arranged in a Czerny-Turner configuration with a cold stop added between the collimator mirror and the grating. The distances between components are chosen so that the collimator mirror images the secondary mirror of the telescope onto the cold stop, thus providing a very effective baffle. Scattered radiation is effectively reduced by using liquid helium-cooled, black baffles to divide the spectrometer into three separate compartments. The system noise-equivalent flux density, when used on the 152 cm telescope from 8 to 13 microns with a resolving power of 50, is 4.4 x 10 to the minus 17th power W/sq cm micron square root of Hz. The main applications are for measuring continuum radiation levels and solid state emission and absorption features in regions of star and planet formation.

Witteborn, F. C.↗

NASA NTRS1982

Imaging spectrometer technologies for advanced earth remote sensing

A major requirement of multispectral imaging systems for advanced earth remote sensing is the provision for greater spectral resolution and more versatile spectral band selection. The imaging spectrometer instrument concept provides this versatility by the combination of pushbroom imaging and spectrally dispersing optics using area array detectors in the focal plane. The shuttle imaging spectrometer concept achieves 10- and 20-meter ground instantaneous fields of view with 20-nanometer spectral resolution from earth orbit. Onboard processing allows the selection of spectral bands during flight; this, in turn, permits the sensor parameters to be tailored to the experiment objectives. Advances in optical design, infrared detector arrays, and focal plane cooling indicate the feasibility of the instrument concept and support the practicability of a validation flight experiment for the shuttle in the late 1980s. Previously announced in STAR as N83-28542

Wellman, J. B.↗

NASA NTRS1983

Mass spectrometer

The quadrupole Mass Spectrometer of the Induced Environment Contamination Monitor (IECM) operates in the range from 2 to 150 amu. It is pointed out that the Mass Spectrometer on STS-2 performed very well. It was found that the column density of H2O effluent from the Shuttle reached a maximum of 1 x 10 to the 13th per sq cm at 7 hr, 30 min and decreased by a factor of 7.5 during the subsequent 40 hrs. The count rate response of H2O could be correlated with mission-related events, taking into account the dumping of supply water, the operation of the Flash Evaporator System, and the firing of a primary reaction control system engine.

Miller, E. R.↗

NASA NTRS1984

Double focusing ion mass spectrometer of cylindrical symmetry

A mass spectrometer consisting of an electric sector followed by a magnetic sector is described. The geometry is a cylindrically symmetric generalization of the Mattauch-Herzog spectrometer (1934). With its large annular entrance aperture and a position-sensitive detector, the instrument provides a large geometric factor and 100-percent duty factor, making it appropriate for spacecraft experiments.

Coplan, M. A.↗

NASA NTRS1985

Imaging Spectrometer for Geophysical Surveys

Airborne spectrometer combines technologies of television imaging and spectroscopy to produce data for geophysical surveys, agricultural assessments, forest and land management, and exploration for oil and minerals. Designed for Small Size, infrared imaging spectrometer uses folded telescope and passes input and output of its monochromator through hole in monochromator grating. Instrument permits analysis of terrain at many infrared wavelengths.

Labaw, C. C.↗

NASA NTRS1986

Compact Imaging Spectrometer

Imaging spectrometer for use in crop and mineral resource-mapping experiments is scaled-down version. Compact imaging spectrometer uses Schmidt/Littrow optics with single spherical primary mirror. Radiation from scene strikes reflecting Schmidt corrector plate located near center of curvature of primary spherical mirror.

Wellman, J. B.↗

NASA NTRS1986

Mass Spectrometer for Airborne Micro-Organisms

Bacteria and other micro-organisms identified continously with aid of new technique for producing samples for mass spectrometer. Technique generates aerosol of organisms and feeds to spectrometer. Given species of organism produces characteristic set of peaks in mass spectrum and thereby identified. Technique useful for monitoring bacterial makeup in environmental studies and in places where cleanliness is essential, such as hospital operating rooms, breweries, and pharmaceutical plants.

Sinha, M. P.↗

NASA NTRS1984

A cometary ion mass spectrometer

The development of flight suitable analyzer units for that part of the GIOTTO Ion Mass Spectrometer (IMS) experiment designated the High Energy Range Spectrometer (HERS) is discussed. Topics covered include: design of the total ion-optical system for the HERS analyzer; the preparation of the design of analyzing magnet; the evaluation of microchannel plate detectors and associated two-dimensional anode arrays; and the fabrication and evaluation of two flight-suitable units of the complete ion-optical analyzer system including two-dimensional imaging detectors and associated image encoding electronics.

Shelley, E. G.↗

NASA NTRS1984

Application of Fabry-perot Spectrometers for Measurement of Upper Atmosphere Temperatures and Winds

The mechanisms giving rise to certain airglow and auroral emissions and their height distribution are briefly surveyed. The basic principles of operation of scanning Fabry-Perot spectrometers are outlined in order to illustrate the calibration and use of such instruments to measure Doppler broadening and shift of atomic emission lines in the spectrum of the airglow and aurora and hence to infer atmospheric temperatures and wind velocities. Technical details of some specific instruments are given. Brief mention is made of the use of wide angle Michelson interferometers for the same application. Emphasis is given to the future importance of imaging Fabry-Perot spectrometers to permit the detailed mapping of temperature and wind velocity, especially in the auroral regions.

F Jacka↗

NASA NTRS1984

A 150 Micron Heterodyne Spectrometer for Airborne Astronomy

The advantages of heterodyne detection for high resolution spectroscopy were long known to radio astronomers. Heterodyne spectroscopy was productive at submillimeter wavelengths, but its extension to shorter submillimeter and far-infrared (FIR) wavelengths was hampered by inadequate mixers and local oscillators. A significant advance in FIR receiver technology was demonstrated using an optically-pumped FIR laser and a Schottky-diode mixer. Any similar spectrometer intended for airborne observations at shorter wavelengths must be compatible with the more restrictive aircraft environment. The effectiveness of the design of a FIR heterodyne spectrometer was verified in ground-based observations with a prototype version. The airborne successor is even more compact, and has a much broader spectral coverage. Flight tests are scheduled for the new instrument.

Betz, A.↗

NASA NTRS1984

Geometric error analysis for shuttle imaging spectrometer experiment

The demand of more powerful tools for remote sensing and management of earth resources steadily increased over the last decade. With the recent advancement of area array detectors, high resolution multichannel imaging spectrometers can be realistically constructed. The error analysis study for the Shuttle Imaging Spectrometer Experiment system is documented for the purpose of providing information for design, tradeoff, and performance prediction. Error sources including the Shuttle attitude determination and control system, instrument pointing and misalignment, disturbances, ephemeris, Earth rotation, etc., were investigated. Geometric error mapping functions were developed, characterized, and illustrated extensively with tables and charts. Selected ground patterns and the corresponding image distortions were generated for direct visual inspection of how the various error sources affect the appearance of the ground object images.

Wang, S. J.↗

NASA NTRS1985

A retarding ion mass spectrometer for the Dynamics Explorer-1

The Retarding Ion Mass Spectrometer (RIMS) for Dynamics Explorer-1 is an instrument designed to measure the details of the thermal plasma distribution. It combines the ion temperature determining capability of the retarding potential analyzer with the compositional capabilities of the mass spectrometer and adds multiple sensor heads to sample all directions relative to the spacecraft ram direction. This manual provides a functional description of the RIMS, the instrument calibration, and a description of the commands which can be stored in the instrument logic to control its operation.

Wright, W.↗

NASA NTRS1985

Results of a search for deuterium at 25-50 GC/c using a magnetic spectrometer

A method is presented for separately identifying isotopes using a Cerenkov detector and a magnet spectrometer. Simulations of the method are given for separating deuterium from protons. The simulations are compared with data gathered from the 1979 flight of the New Mexico State University balloonborne magnet spectrometer. The simulation and the data show the same general characteristics lending credence to the technique. The data show an apparent deuteron signal which is (11 + or - 3)% of the total sample in the rigidity region 38.5 to 50 GV/c. Until further background analysis and subtraction is performed this should be regarded as an upper limit to the deuteron/(deuteron+proton) ratio.

Golden, R. L.↗

NASA NTRS1985

The Gamma-Ray Imaging Spectrometer (GRIS): A new balloon-borne experiment for gamma-ray line astronomy

High resolution gamma-ray spectroscopy is a relatively new field that holds great promise for further understanding of high energy astrophysical processes. When the high resolution gamma-ray spectrometer (GRSE) was removed from the GRO payload, a balloon program was initiated to permit continued development and improvement of instrumentation in this field, as well as continued scientific observations. The Gamma-Ray Imaging Spectrometer (GRIS) is one of the experiments selected as part of this program. The instrument contains a number of new and innovative features that are expected to produce a significant improvement in source location accuracy and sensitivity over previous balloon and satellite experiments.

Teegarden, B. J.↗

NASA NTRS1985

Noiseless coding for the Gamma Ray spectrometer

The payload of several future unmanned space missions will include a sophisticated gamma ray spectrometer. Severely constrained data rates during certain portions of these missions could limit the possible science return from this instrument. This report investigates the application of universal noiseless coding techniques to represent gamma ray spectrometer data more efficiently without any loss in data integrity. Performance results demonstrate compression factors from 2.5:1 to 20:1 in comparison to a standard representation. Feasibility was also demonstrated by implementing a microprocessor breadboard coder/decoder using an Intel 8086 processor.

Rice, R.↗