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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Coded aperture devices for viewing extended objects from space

Coded aperture sensors for photons or energetic neutral atoms (ENAs), which incorporate FOV limiters and subdivide the object field into a number of elements which is smaller than the number of detector pixels, are described. A least squares fit to the data is made in reconstructing the object field. To evaluate the optics and reconstruction algorithms, two 'breadboard' sensors have been constructed, one based on a film camera and the other upon a UV-light sensitive microchannel plate detector system. Results obtained thus far show that the concept is viable, and no special difficulties should be encountered in adapting the detector geometries to neutral particle imaging systems. Charged particle deflection plates could be incorporated into the region between the FOV limiter and the aperture, or installed ahead of the limiter.

Curtis, C. C.↗
NASA NTRS2000

Performance of The Far Ultraviolet Spectroscopic Explorer Mirror Assemblies

The Far Ultraviolet Spectroscopic Explorer is a NASA astrophysics satellite which produces high-resolution spectra in the far-ultraviolet (90.5-118.7 nm bandpass) using a high effective area and low background detectors. The observatory was launched on its three-year mission from Cape Canaveral Air Station on 24 June 1999. The instrument contains four coaligned, normal incidence, off-axis parabolic mirrors which illuminate separate Rowland circle spectrograph channels equipped with holographically ruled diffraction gratings and delay line microchannel plate detectors. The telescope mirrors have a 352 x 387 mm aperture and 2245 mm focal length and are attached to actuator assemblies, which provide on-orbit, tip, tilt, and focus control. Two mirrors are coated with silicon carbide (SiC) and two are coated with lithium fluoride over aluminum (Al:LiF). We describe mirror assembly in-flight optical and mechanical performance. On-orbit measurements of the far-ultraviolet point spread function associated with each mirror are compared to expectations based on pre-flight laboratory measurements and modeling using the Optical Surface Analysis Code and surface metrology data. On-orbit imaging data indicate that the mirrors meet their instrument-level requirement of 50 percent and 95 percent slit transmission for the high- and mid-resolution spectrograph entrance slits, respectively. The degradation of mirror reflectivity during satellite integration and test is also discussed. The far-ultraviolet reflectivity of the SiC- and AlLiF-coated mirrors decreased about six percent and three percent, respectively, between coating and launch. Each mirror is equipped with three actuators, which consist of a stepper motor driving a ball screw via a two-stage planetary gear train. We also discuss the mechanical performance of the mirror assemblies, including actuator performance and thermal effects.

Ohi, Raymond G.↗
DOE OSTI2024

Single-shot ionization-based monitor for pulsed electron beams

In this work, we present an experimental demonstration of a single-shot, nondestructive electron beam diagnostic based on the ionization of a low-density pulsed gas jet. In our study, 7 MeV electron bunches from a radio-frequency photoinjector, carrying up to 100 pC of charge, traversed a localized distribution of nitrogen gas (N 2 ). The interaction of the electron bunches with the N 2 gas generated a correlated signature in the ionized particle distribution, which was spatially magnified using a series of electrostatic lenses and recorded with a microchannel-plate detector. Various modalities, including point-to-point imaging and velocity mapping, are investigated. A temporal trace of the detector current enabled the identification of single- and double-ionization events. The characteristics of the ionization distribution, dependence on gas density, total bunch charge, and other parameters, are described. Approaches to scaling to higher electron bunch density and energy are suggested. Additionally, the instrument proves useful for comprehensive studies of the ionization process itself.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

High Yield Xray Imager Final Design Review

The High Yield Xray Imager (HYXI) is a new NIF target diagnostic system currently under development. The goal of HYXI is to provide high-fidelity, high temporal resolution x-ray imaging capability on high yield NIF implosions at 10MJ and above. The HYXI instrument design concept is based on the combination of two technologies that have been successfully utilized at the NIF on previous instruments, electron pulse-dilation and hybrid-CMOS sensor imaging. The combination of these two techniques will give HYXI sufficient data quality to ascertain differences in hot spot formation dynamics between high and low yield implosions. This information will highlight the critical hot spot conditions needed for ignition and burn. The HYXI design leverages the successful operation of the PDIXI x-ray imager at the NIF on multi MJ yield shots. A new radiation tolerant CMOS imaging array (HYPERION) is being developed to eliminate the significant background noise which limits the data quality of PDIXI. We successfully placed the contract with Advanced hCMOS Systems (AHS) to develop the HYPERION sensor, which fulfils our criteria to place long lead time item procurements by end of FY24. The HYXI Final Design Review was completed at the end of Q4 FY24 (Sep 24 th and Sep 30 th ). The HYXI project is a multi-year effort with a phased approach to be bring up system functionality over time in parallel with the development and fabrication effort of the HYPERION CMOS imaging array. In Phase 1, time-integrated x-ray images on NIF DT experiments will be collected starting in Q3 FY25. In Phase 2 of the project, time-resolved imaging with HYXI utilizing a spare microchannel plate detector back-end will begin in Q3 FY26. Phase 3 concludes the project with the installation of the HYPERION sensor array and the final performance qualification of the HYXI instrument which is scheduled for Q3 FY27 as discussed in the PDR and MRT report on this project in FY23.

42 ENGINEERING↗
NASA NTRS1976

Spectroscopic survey of the far-ultraviolet /1160-1700 A/ emissions of Capella

A far-ultraviolet spectral survey of Capella (Alpha Aur, G5 III + G0 III) has been obtained using a highly sensitive rocketborne spectrograph with a microchannel plate detector. The spectral distribution is very similar to that of the sun; however, if the line surface fluxes are due to the primary (G5 III), then, except for Ly-alpha, they are about an order of magnitude greater than those of the quiet sun

Vitz, R. C.↗
NASA NTRS1978

A rocket observation of the far-ultraviolet spectrum of Saturn

Far-ultraviolet (1160-1750 A) spectra of the Saturnian disk and the ring system have been obtained by using a very sensitive rocket-borne spectrograph with a microchannel plate detector. The use of two apertures of different diameter in the telescope focal plane permitted the separation of the contribution of the planetary disk from that of the rings. H I lambda 1216 was the only atomic spectral line emission detected in the planet and the rings. A weak signal from the disk between 1300 A and 1500 A was observed. Geometric disk albedos, averaged over 50 A, were determined from 1500 A to 1700 A. Measurements of the ring reflectivity longward of 1650 A are compatible with H2O frost but not NH3 frost.

Weiser, H.↗
NASA NTRS1981

The Johns Hopkins Ultraviolet Telescope for Shuttle astronomy

The Hopkins Ultraviolet Telescope (HUT) is a 90-cm f/2 prime focus telescope and spectrometer with a photon-counting microchannel plate detector designed to obtain moderate resolution (wavelength interval, approximately 4 A) spectrophotometry of faint (visual magnitude, less than approximately 17) objects in the far-ultraviolet spectral region (approximately 900-1700 A). The HUT will be mounted on the Spacelab Instrument Pointing System and will be operated by a Payload Specialist using a field acquisition TV system to assist in locating targets. The initial flight of the HUT, expected in 1984 or 1985, will be devoted primarily to the study of quasars and active galactic nuclei, emphasizing the 900-1200 A spectral region which is inaccessible with other existing or currently planned orbiting instruments.

Davidson, A. F.↗
NASA NTRS1981

A wide-field soft X-ray camera

A wide-field soft X-ray camera (WFSXC) sensitive in the 50 to 250 eV band is described. The camera features Wolter-Schwarzschild optics with an 8 degree field of view and 300 cu cu collecting area. The focal plane instrument is a microchannel plate detector. Broad-band energy discrimination is provided by thin-film filters mounted immediately in front of the focal plane. The WFSXC is capable of detecting sources with intensities greater than 5 percent of HZ 43 during typical sounding rocket exposures, and it would approach the same sensitivity range as EUVE during a typical exposure from the Shuttle.

Petre, R.↗
NASA NTRS1982

Energetic ion mass spectrometer

A new type of spectrometer for space application has been developed to measure separately mass/charge and the three-dimensional velocity distribution of incident ions. The instrument has relatively high resolution and allows rapid measurement of the four-dimensional set of mass/charge, speed, elevation angle, and azimuth angle. The instrument includes a sector magnet, an electrostatic deflector, microchannel plate detectors with position sensitive readout, and a set of grids with variable applied voltage.

Neugebauer, M.↗
NASA NTRS1983

Observational evidence for solar wind acceleration at the base of coronal holes

An EUV spectrometer with a microchannel plate detector was developed to measure Doppler shifts of coronal and transition region lines. The results of three sounding rocket fights of this instrument indicate that EUV resonance emission lines are systematically shifted toward shorter wavelength within coronal holes. This "blue-shift" signature, first identified within compact low latitude holes, was also observed in a well developed polar coronal hole. The maximum measured shift within these coronal holes corresponds to a velocity relative to the remaining solar disc of 12 km/s in lambda 625 Mg X T to the approximately 10 to the 6.15 K power and 7 km /s/ in lambda 629 OV (T to the approximately 10 to the 5.4 K power). The existing data indicate that these blue-shifts are a common (and possibly universal) signature of coronal holes. These data provide important information on the acceleration of coronal plasma in open magnetic field regions, although the interpretation of observed Doppler shifts to derive a systematic mass flux is to some extent model dependent. A straightforward hypothesis is that the blueshift signature is a direct manifestation of the high speed solar wind deep within the transition region and inner corona.

Rottman, G. J.↗
NASA NTRS1984

An extreme ultraviolet spectrometer experiment for the Shuttle Get Away Special Program

An extreme ultraviolet (EUV) spectrometer experiment operated successfully during the STS-7 mission in an experiment to measure the global and diurnal variation of the EUV airglow. The spectrometer is an F 3.5 Wadsworth mount with mechanical collimator, a 75 x 75 mm grating, and a bare microchannel plate detector providing a spectral resolution of 7 X FWHM. Read-out of the signal is through discrete channels or resistive anode techniques. The experiment includes a microcomputer, 20 Mbit tape recorder, and a 28V, 40 Ahr silver-zinc battery. It is the first GAS payload to use an opening door. The spectrometer's 0.1 x 4.2 deg field of view is pointed vertically out of the shuttle bay. During the STS-7 flight data were acquired continuously for a period of 5 hours and 37 minutes, providing spectra of the 570 A to 850 A wavelength region of the airglow. Five diurnal cycles of the 584 A emission of neutral helium and the 834 A emission of ionized atomic oxygen were recorded. The experiment also recorded ion events and pressure pulses associated with thruster firings. The experiment is to fly again on Mission 41-F.

Conway, R. R.↗
NASA NTRS1984

Measuring EUV Line Emission from the Hot Interstellar Medium

In the local interstellar medium, the presence of hot gas was inferred from measurements of oxygen VI absorption in the ultraviolet, and from diffuse emission in the extreme ultraviolet (EUV) and soft X-ray regions. A spectrometer that is very sensitive to gas in this temperature range is described. The spectrometer uses an array of plane ruled gratings at grazing incidence in the extreme off plane mount. A set of Kirkpatrick-Baez mirrors focuses the conically diffracted light on to one of two microchannel plate detectors. The field of view of the instrument is 0.2 deg by 12 deg. The predicted sensitivity ranges from 50 to 200 ph/(sq cm sec str) with a resolving power of 15 to 50 over the 50 to 700 angstrom wavelength band.

Labov, S.↗
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 NTRS1985

The Hopkins ultraviolet telescope

The Shuttle is scheduled to carry the Hopkins UV Telescope (HUT) aloft in 1986. HUT will be one of three telescopes on the mission and will be sensitive to the 450-1800 A interval. Its primary goals will be observations of Halley's Comet, the planets, distant galaxies and quasars. It will be controlled by Spacelab personnel and features a 0.9 m primary mirror, a spectrograph on the focal plane, and an Si intensified image television camera for on-line image monitoring. The main component of the spectrograph will be a 1024 channel self-scanning Reticon photodiode array coupled by optic fibers to the microchannel detector plates. HUT is presently undergoing qualification testing.

Davidsen, A. F.↗
NASA NTRS1986

Operational characteristics of Wedge and Strip image readout systems

Application of the Wedge and Strip readout system in microchannel plate detectors for the Extreme Ultraviolet Explorer and FAUST space astronomy programs is discussed. Anode designs with high resolution (greater than 600 x 600 pixels) in imaging and spectroscopy applications have been developed. Extension of these designs to larger formats (100 mm) with higher resolution (3000 x 3000 pixels) are considered. It is shown that the resolution and imaging are highly stable, and that the flat field performance is essentially limited by photon statistics. Very high speed event response has also been achieved with output pulses having durations of less than 10 nanoseconds.

Siegmund, O. H. W.↗
NASA NTRS1986

A spectrometer to measure the diffuse, astronomical extreme ultraviolet background

The present grazing incidence spectrometer for measuring the diffuse astronomical background between 80 and 650 A uses a wire grid collimator to define a 40-arcmin by 15-deg field of view. After passing through the collimator, radiation impinges on an array of plane reflection gratings. An array of mirrors then focuses the diffracted light through a thin filter onto a microchannel plate detector. The resulting system focuses to a few arcmin and produces spectra with 10 to 20 A resolution. Performance characteristics of the spectrometer are discussed.

Labov, Simon↗
NASA NTRS1986

The design of an echelle spectrometer for diffuse extreme ultraviolet/far ultraviolet astronomy

The novel, relatively high-resolution nebular spectrometer design presented incorporates a mechanical precollimator with an objective echelle grating that proceeds to a cross-dispensing Wadsworth configuration; the minimum feasible number of reflections is employed in order to maximize EUV sensitivity. The configuration, which is noted to be capable of yielding a comparatively large field of view for optimal diffuse emission sensitivity, is compact and employs conventionally fabricated optical components and available microchannel plate detectors. The sensitivities obtainable approach the limit stipulated by Liouville's theorem.

Martin, Christopher↗
NASA NTRS1987

Experimental tests of a toroidal electrostatic analyzer

A toroidal electrostatic analyzer of a design suitable for space plasma instrumentation has been constructed and tested. Experimental results are compared with second-order ion optical theory and are in good agreement. Verifying the ion optics of the toroid was simplified by use of a position-sensing microchannel-plate detector mounted on a positioning system with three translational degrees of freedom located at the toroid exit. The toroidal analyzer described here is the first optical element in a fully toroidal mass spectrograph intended for analysis of kilovolt magnetospheric plasmas.

Young, D. T.↗