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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 451 records · Page 25
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NASA NTRS1980

Pioneer Venus Orbiter neutral gas mass spectrometer experiment

The Pioneer Venus Orbiter Neutral Mass Spectrometer (ONMS) is designed to measure the vertical and horizontal density variations of the major neutral constituents in the upper atmosphere of Venus. The mass spectrometer sensor includes a retarding potential ion source, hyperbolic quadrupole rod analyzer, and electron multiplier detector. The supporting electronic system consists of hybrid integrated circuits to reduce weight and power. The ONMS instrument was launched aboard the Pioneer Venus Orbiter on May 20, 1978, and turned on in orbit around Venus on December 4, 1978. It has operated flawlessly for over a Venus year (243 earth days) and has returned data of the composition of the major constituents in the Venus atmosphere between the altitudes of 150 and 350 km.

Niemann, H. B.↗
NASA NTRS1980

Design and operation of the Pioneer Venus Orbiter ultraviolet spectrometer

The University of Colorado's ultraviolet spectrometer instrument carried on the Pioneer Venus Orbiter spacecraft is a 125-mm f/5 Ebert-Fastie design with a 250-mm Cassegrain telescope. The instrument has extensive logic to control the grating motor drive and to adapt the basic spectrometer to the constraints and opportunities of the mission. Success has been achieved in reconciling the conflicting requirements of spectroscopic, limb profile, and imaging observations. A description of the instrument operating techniques is given together with representative results of all three types.

Stewart, A. I. F.↗
NASA NTRS1980

An airborne far-infrared spectrometer for astronomical observations

A Fabry-Perot spectrometer for airborne observations of astronomical spectral lines has been designed for use in the 50 to 200 micron region of the far-infrared. The spectrometer uses a fixed wavelength Fabry-Perot filter cooled to 4.2 K in conjunction with a high order scanning Fabry-Perot at room temperature. This arrangement provides high spectral resolution and also minimizes the thermal background radiation on the detector. The instrument has been successfully used to study all the presently detected fine structure lines between 50 and 120 microns.

Storey, J. W. V.↗
NASA NTRS1980

Design Studies for a Far Infrared Absolute Spectrometer for the Cosmic Background Explorer

Unrelenting symmetry of design is required to assure the thermal balance of a cryogenically cooled, rapid scan interferometer spectrometer to be mounted in vacuum with the Cosmic Background Explorer liquid helium dewar. The instrument receives inputs from Winston cone optical flux collectors, one open to space and a second coupled to a black body reference source. A differential instrument, the spectrometer produces outputs corresponding to the Fourier transform of the spectral radiance difference between the two inputs. The two outputs are sensed by four detectors, two optimized for shorter wavelength response, and two optimized for longer wavelengths. The optical design, detector and signal channel, system sensitivity, mechanics, thermal control and cryogenics, electronics and power systems, command and control, calibration, system test requirements, and the instrument interface are discussed. Recommendations for continued work are indicated for the superconducting reflective horns, the motor bearing and drive, and design detail.

Johnson, N. J. E.↗
NASA NTRS1980

Spacelab energetic ion mass spectrometer

Basic design criteria are given for an ion mass spectrometer for use in studying magnetospheric ion populations. The proposed instrument is composed of an electrostatic analyzer followed by a magnetic spectrometer and simultaneously measures the energy per unit and mass per unit charge of the ion species. An electromagnet is used for momentum analysis to extend the operational energy range over a much wider domain than is possible with the permanent magnets used in previous flights. The energetic ion source regions, ion energization mechanisms, field line tracing, coordinated investigations, and orbit considerations are discussed and operations of the momentum analyzer and of the electrostatic energy analyzer are examined.

Whalen, B. A.↗
NASA NTRS1981

The retarding ion mass spectrometer on dynamics Explorer-A

An instrument designed to measure the details of the thermal plasma distribution 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 directions. The retarding ion mass spectrometer, its operational modes and calibration are described as well as the data reduction plan, and the anticipated results.

Chappell, C. R.↗
NASA NTRS1981

Performance and design of the ultraviolet spectrometer and polarimeter on the solar maximum mission

The instrument observes spectral line intensity, Doppler motions, and polarization parameters. First Dopplergrams of the sun showing mass motion of prominences have been obtained. The instrument consists of a telescope, a spectrometer, a polarimeter, and five detectors. Spectral range extends from 1150 to 3600 Angstroms. The telescope is an alphanatic Gregorian capable of scanning a 256 x 256 arcsecond raster. The spectrometer is an Ebert-Fastie mount with exchangeable slits for intensity measurements and spectroscopy. Detectors are photomultipliers operating in the pulse-counting mode.

Sterk, A. A.↗
NASA NTRS1980

Interference with negative particle sampling due to formation of positive ions in a quadrupole mass spectrometer

A quadrupole mass spectrometer has been utilized to study active discharges containing Cs vapor. Production of positive ions by electron impact within the mass spectrometer and subsequent secondary electron emission from cesiated surfaces produced spurious or pseudonegative ion signals which interfered with attempts to sample negative ions from the plasma. These effects may also occur in other gas discharge systems.

Kuehn, D. G.↗
NASA NTRS1980

The HEAO 3 gamma-ray spectrometer

The third High Energy Astronomy Observatory (HEAO 3), successfully launched into low earth orbit on September 20, 1979, carries a large high-resolution gamma-ray spectrometer designed for cosmic nuclear spectroscopy. This gamma-ray spectrometer (the HEAO C-1 experiment) consists of a cluster of four coaxial high-purity germanium detectors, each with a volume of approximately 100 cu cm. Surrounding the germanium detectors is a 6.6-cm thick CsI shield operating in active anticoincidence with the central detectors and defining a field of view of about 30 deg FWHM. An initial energy resolution of 3 keV FWHM at 1.46 MeV was achieved for each detector. All valid events in the germanium detectors are individually analyzed by an 8192-channel pulse area analyzer and transmitted at a maximum rate of 15.6 evens/s for each detector. During a 6-month mission, the experiment will perform a complete sky survey for narrow cosmic gamma-ray line emission to the sensitivity level of about 0.0001 photons/sq cm s over an operating energy range of 0.05-10 MeV.

Mahoney, W. A.↗
NASA NTRS1981

Calibration of a mass spectrometer experiment for ozone

A system with which to calibrate a stratospheric mass spectrometer experiment for ozone has been developed and evaluated. The stability of ozone and the formation of impurities within the calibration volume were measured. The half-life of ozone is about 12 hours, its purity ranges from 95% to 99% and is known to within 1%. The total calibration accuracy of the mass spectrometer experiment for ozone is about + or - 2%.

Anderson, S.↗
NASA NTRS1983

Ion Mass/Velocity/Charge Spectrometer

Ion spectrometer distributes ions two-dimensionally and measures three characteristics of incident-ion beam: (1) mass/charge distribution, (2) ion velocity distribution, and (3) direction of incidence. Also useful for diagnosis in experimental plasma physics in collisionless regime. Ion spectrometer uses novel combination of standard electrostatic and magnetic deflection techniques to sort incident ions according to speed, diretion of incidence, and mass/ charge ratio.

Neugebauer, M. M.↗
NASA NTRS1981

Bulk and integrated acousto-optic spectrometers for radio astronomy

The development of sensitive heterodyne receivers (front end) in the centimeter and millimeter range, and the construction of sensitive RF spectrometers (back end) enable the spectral lines of interstellar molecules to be detected and identified. A technique was developed which combines acoustic bending of a collimated coherent light beam by a Bragg cell followed by detection by a sensitive array of photodetectors (thus forming an RF acousto-optic spectrometer (AOS). An AOS has wide bandwidth, large number of channels, and high resolution, and is compact, lightweight, and energy efficient. The thrust of receiver development is towards high frequency heterodyne systems, particularly in the millimeter, submillimeter, far infrared, and 10 micron spectral ranges.

Chin, G.↗
NASA NTRS1981

Laboratory studies on a spherically curved Bragg spectrometer for cosmic X-ray spectroscopy

A spherical array of twenty LiF 200 crystals was built to test the performances of a freestanding, self-focussing spherical crystal cosmic X-ray spectrometer. Measurements presently available show that the size of the image for a point source at infinite distance would be 3 mm (FWHM) along the focalisation axis and 2.1 mm (FWHM) along the dispersion axis. The mosaic spread on individual crystals is less than 0.1 degree. A slightly systematic deviation from the ideal bending (0.1 degree) is observed at the edges of most crystals and this appears to be the major limitation to spectrometer performance.

Cantin, M.↗
NASA NTRS1981

Cylindrical Crystal Imaging Spectrometer (CCIS) for cosmic X-ray spectroscopy

A "stigmatic" focusing, Bragg crystal spectrometer was developed and used for high spectral resolution X-ray emission line diagnostics on hot laboratory plasmas. The concept be applied at the focal plane of an orbiting X-ray telescope where it offers several advantages over conventional spectrometers, i.e., mechanical simplicity, high resolving power and sensitivity, simultaneous measurement of an extended segment of spectrum, and good imaging properties. The instrument features a simple, unambiguous, non-scanning spectrum readout that is not adversely affected by either spacecraft pointing error or source extent. The performance of the instrument is estimated in the context of the Advanced X-Ray Astrophysical Facility mission.

Schnopper, H. W.↗
NASA NTRS1981

Development of a diode laser heterodyne spectrometer and observations of silicon monoxide in sunspots

A state of the art, tunable diode laser infrared heterodyne spectrometer was designed and constructed for ground based observations throughout the 8 to 12 micron atmospheric window. The instrument was optimized for use with presently available tunable diode lasers, and was designed as a flexible field system for use with large reflecting telescopes. The instrument was aligned and calibrated using laboratory and astronomical sources. Observations of SiO fundamental (v = 1-0) and hot band (v = 2-1) absorption features were made in sunspots near 8 microns using the spectrometer. The data permit an unambiguous determination of the temperature pressure relation in the upper layers of the umbral atmosphere, and support the sunspot model suggested by Stellmacher and Wiehr.

Glenar, D. A.↗
NASA NTRS1982

Instrument manual for the retarding ion mass spectrometer on 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.

Fields, S. A.↗
NASA NTRS1982

Low intensity X-ray and gamma-ray spectrometer

A low intensity X-ray and gamma ray spectrometer for imaging, counting, and energy resolving of single invisible radiation particles is described. The spectrometer includes a converting device for converting single invisible radiation particles to visible light photons. Another converting device converts the visible light photons to photoelectrons. A fiber optics coupling device couples together the two converting devices. An intensifying device intensifies the photoelectrons by an average gain factor of between 10 to the 4th power and 10 to the 7th power. The tensifying device is an anti-ion feedback microchannel plate amplifier which is operated substantially below saturation. A displaying device displays the intensified photoelectrons. The displaying device 32 indicates the spatial position, number, and energy of the incoming single invisible radiation particles.

Yin, L. I.↗
NASA NTRS1981

Ultraviolet spectrometer and polarimeter for the Solar Maximum Mission

The detailed optical design of the Solar Maximum Mission-Ultraviolet Spectrometer and Polarimeter is discussed in conjunction with the scientific objectives that led to the design. The instrument consists of a 1.8-m effective focal length aplanatic Gregorian telescope followed by a 1-m Ebert spectrometer. The design of the Stokes polarimeter is also discussed.

Miller, M. S.↗