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At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Electromagnetic Transient Modeling of Data Centers

This report serves as a user manual for the accompanying EMT model library developed by the National Laboratory of the Rockies (NLR) for various equipment in large data centers. The EMT model library enables detailed modeling of large data center loads for conducting grid stability studies. The EMT model library for data centers include detailed models of a 5.5 kW power supply unit (PSU), a 2.5 uninterruptible power supply (UPS), a 260 MW gas turbine-generator, a 500 kW motor load, and a 33 kW IT rack. These components represent all major equipment in data centers that need to be modeled for performing grid stability studies for data centers.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS1965

DSIF - Woomera

DSIF tracking antenna, signal transmission, and data acquisition and processing facilities at Woomera, Australia

AUSTRALIA↗
NASA NTRS1974

Characteristics and performance of several mass spectrometer residual gas analyzers

The operation and properties of various mass-spectrometer residual gas analyzers for use in vacuum measurements were analyzed in terms of efficiencies of ion extraction, ion separation and transmission, and ion collection. Types of instruments studied were magnetic sector, omegatron, quadrupole, and monopole. Experimental results presented include absolute sensitivity to argon, relative sensitivity to 10 gases, and cracking patterns for these gases. It is shown that the properties are strongly dependent on instrument range, resolution, and the particular voltages, currents, or field intensities used to control the instrument.

Hultzman, W. W.↗
NASA NTRS1978

Multiple wavelength geodesy

An apparatus is being constructed which should be able to measure baselines up to 50 km long with a fractional uncertainty of about 5 x 10 to the -8 power. The instrument will measure both the optical length and the required correction due to the refractivity of the atmosphere, using three wavelengths transmitted in one direction over the path to an active receiver. The three wavelengths are 632.8 nm, 441.6 nm and 3.7 cm. The two endpoint instruments are synchronized using subsidiary return transmissions at 632.8 nm and another telemetry signal. The one-way nature of the system allows an increase in range over existing round-trip systems.

Levine, J.↗
NASA NTRS1989

Halogen occultation experiment (HALOE) optical witness-plate program

An optical witness plate program was implemented to monitor buildup of molecular contamination in the clean room during the assembly and testing of the Halogen Occulation Experiment (HALOE) instrument. Travel plates to monitor molecular contamination when the instrument is not in the clean room are also measured. The instrument technique is high-resolution transmission spectroscopy in the 3 micron spectral region using a Fourier transform spectrometer. Witness specimens of low index of refraction, infrared transmitting material are used for contaminant monitoring and for spectral signature analysis. Spectral signatures of possible molecular contamination are presented. No condensible volatile material contamination of HALOE optical witness specimens have yet been found.

Harvey, Gale A.↗
NASA NTRS2000

Solar Physics

The areas of emphasis are: (1) develop theoretical models of the transient release of magnetic energy in the solar atmosphere, e.g., in solar flares, eruptive prominences, coronal mass ejections, etc.; (2) investigate the role of the Sun's magnetic field in the structuring of solar corona by the development of three-dimensional numerical models that describe the field configuration at various heights in the solar atmosphere by extrapolating the field at the photospheric level; (3) develop numerical models to investigate the physical parameters obtained by the ULYSSES mission; (4) develop numerical and theoretical models to investigate solar activity effects on the solar wind characteristics for the establishment of the solar-interplanetary transmission line; and (5) develop new instruments to measure solar magnetic fields and other features in the photosphere, chromosphere transition region and corona. We focused our investigation on the fundamental physical processes in solar atmosphere which directly effect our Planet Earth. The overall goal is to establish the physical process for the Sun-Earth connections.

Wu, S. T.↗
NASA NTRS2003

Designer Infrared Filters using Stacked Metal Lattices

We have designed and fabricated infrared filters for use at wavelengths greater than or equal to 15 microns. Unlike conventional dielectric filters used at the short wavelengths, ours are made from stacked metal grids, spaced at a very small fraction of the performance wavelengths. The individual lattice layers are gold, the spacers are polyimide, and they are assembled using integrated circuit processing techniques; they resemble some metallic photonic band-gap structures. We simulate the filter performance accurately, including the coupling of the propagating, near-field electromagnetic modes, using computer aided design codes. We find no anomalous absorption. The geometrical parameters of the grids are easily altered in practice, allowing for the production of tuned filters with predictable useful transmission characteristics. Although developed for astronomical instrumentation, the filters arc broadly applicable in systems across infrared and terahertz bands.

Smith, Howard A.↗
NASA NTRS2012

Analysis of Suomi - NPP VIIRS Vignetting Functions Based on Yaw Maneuver Data

The Suomi NPP Visible Infrared Imager Radiometer Suite (VIIRS) reflective bands are calibrated on-orbit via reference to regular solar observations through a solar attenuation screen (SAS) and diffusely reflected off a Spectralon (Registered Trademark) panel. The degradation of the Spectralon panel BRDF due to UV exposure is tracked via a ratioing radiometer (SDSM) which compares near simultaneous observations of the panel with direct observations of the sun (through a separate attenuation screen). On-orbit, the vignetting functions of both attenuation screens are most easily measured when the satellite performs a series of yaw maneuvers over a short period of time (thereby covering the yearly angular variation of solar observations in a couple of days). Because the SAS is fixed, only the product of the screen transmission and the panel BRDF was measured. Moreover, this product was measured by both VIIRS detectors as well as the SDSM detectors (albeit at different reflectance angles off the Spectralon panel). The SDSM screen is also fixed; in this case, the screen transmission was measured directly. Corrections for instrument drift and degradation, solar geometry, and spectral effects were taken into consideration. The resulting vignetting functions were then compared to the pre-launch measurements as well as models based on screen geometry.

Xiong, Xiaoxiong↗
NASA NTRS1977

Advances in laser technology for the atmospheric sciences; Proceedings of the Seminar, San Diego, Calif., August 25, 26, 1977

These papers deal with recent research, developments, and applications in laser and electrooptics technology, particularly with regard to atmospheric effects in imaging and propagation, laser instrumentation and measurements, and particle measurement. Specific topics include advanced imaging techniques, image resolution through atmospheric turbulence over the ocean, an efficient method for calculating transmittance profiles, a comparison of a corner-cube reflector and a plane mirror in folded-path and direct transmission through atmospheric turbulence, line-spread instrumentation for propagation measurements, scaling laws for thermal fluctuations in the layer adjacent to ocean waves, particle sizing by laser photography, and an optical Fourier transform analysis of satellite cloud imagery. Other papers discuss a subnanosecond photomultiplier tube for laser application, holography of solid propellant combustion, diagnostics of turbulence by holography, a camera for in situ photography of cloud particles from a hail research aircraft, and field testing of a long-path laser transmissometer designed for atmospheric visibility measurements.

Trolinger, J. D.↗
NASA NTRS1973

Worldwide variations in atmospheric transmission. I - Baseline results from Smithsonian observations.

The spectrobolometer used in the studies is discussed, giving attention to instrument design, the method of recording, and the spectral resolution. The atmospheric transmission for each wavelength was determined by making observations over a range of air masses. The precipitable water vapor values were found from the spectrobolograms by measurement of the depths of water vapor bands at 0.935, 1.13, and 1.47 microns. The results of the studies are discussed together with seasonal variations, long term trends, and the nature of the aerosols.

Roosen, R. G.↗
NASA NTRS1981

Calibration of a turbidity meter for making estimates of total suspended solids concentrations and beam attenuation coefficients in field experiments

Management of water resources such as a reservoir requires using analytical models which describe such parameters as the suspended sediment field. To select or develop an appropriate model requires making many measurements to describe the distribution of this parameter in the water column. One potential method for making those measurements expeditiously is to measure light transmission or turbidity and relate that parameter to total suspended solids concentrations. An instrument which may be used for this purpose was calibrated by generating curves of transmission measurements plotted against measured values of total suspended solids concentrations and beam attenuation coefficients. Results of these experiments indicate that field measurements made with this instrument using curves generated in this study should correlate with total suspended solids concentrations and beam attenuation coefficients in the water column within 20 percent.

Usry, J. W.↗
NASA NTRS1985

Tethered nuclear power for the Space Station

A nuclear space power system the SP-100 is being developed for future missions where large amounts of electrical power will be required. Although it is primarily intended for unmanned spacecraft, it can be adapted to a manned space platform by tethering it above the station through an electrical transmission line which isolates the reactor far away from the inhabited platform and conveys its power back to where it is needed. The transmission line, used in conjunction with an instrument rate shield, attenuates reactor radiation in the vicinity of the space station to less than one-one hundredth of the natural background which is already there. This combination of shielding and distance attenuation is less than one-tenth the mass of boom-mounted or onboard man-rated shields that are required when the reactor is mounted nearby. This paper describes how connection is made to the platform (configuration, operational requirements) and introduces a new element the coaxial transmission tube which enables efficient transmission of electrical power through long tethers in space. Design methodology for transmission tubes and tube arrays is discussed. An example conceptual design is presented that shows SP-100 at three power levels 100 kWe, 300 kWe, and 1000 kWe connected to space station via a 2 km HVDC transmission line/tether. Power system performance, mass, and radiation hazard are estimated with impacts on space station architecture and operation.

Bents, D. J.↗
NASA NTRS1985

Tethered nuclear power for the space station

A nuclear space power system the SP-100 is being developed for future missions where large amounts of electrical power will be required. Although it is primarily intended for unmanned spacecraft, it can be adapted to a manned space platform by tethering it above the station through an electrical transmission line which isolates the reactor far away from the inhabited platform and conveys its power back to where it is needed. The transmission line, used in conjunction with an instrument rate shield, attenuates reactor radiation in the vicinity of the space station to less than one-one hundredth of the natural background which is already there. This combination of shielding and distance attenuation is less than one-tenth the mass of boom-mounted or onboard man-rated shields that are required when the reactor is mounted nearby. This paper describes how connection is made to the platform (configuration, operational requirements) and introduces a new element the coaxial transmission tube which enables efficient transmission of electrical power through long tethers in space. Design methodology for transmission tubes and tube arrays is discussed. An example conceptual design is presented that shows SP-100 at three power levels 100 kWe, 300 kWe, and 1000 kWe connected to space station via a 2 km HVDC transmission line/tether. Power system performance, mass, and radiation hazard are estimated with impacts on space station architecture and operation.

Bents, D. J.↗
NASA NTRS1993

Shuttle PRCS plume contamination analysis for Astro-2 mission

The Astro-2 mission scheduled for Jan. 1995 flight is co-manifested with the Spartan experiment. The Astro instrument array consists of several telescopes operating in the UV spectrum. To obtain the desired 300 observations with the telescope array in a shorter time than the Astro-1 mission, it will be necessary to use the primary reaction control system (PRCS) rather than just the Vernier reaction control system. The high mass flow rate of the PRCS engines cause considerable concern about contamination due to PRCS plume return flux. Performance of these instruments depends heavily on the environment they encounter. The ability of the optical system to detect a remote signal depends not only on the intensity of the incoming signal, but also on the ensuing transmission loss through the optical train of the instrument. Performance of these instruments is thus dependent on the properties of the optical surface and the medium through which it propagates. The on-orbit contamination environment will have a strong influence on the performance of these instruments. The finding of a two-month study of the molecular contamination environment of the Astro-2 instruments due to PRCS thruster plumes during the planned Astro-2 mission are summarized.

Wang, Francis C.↗
NASA NTRS2006

Temperature-dependent Refractive Index of Silicon and Germanium

Silicon and germanium are perhaps the two most well-understood semiconductor materials in the context of solid state device technologies and more recently micromachining and nanotechnology. Meanwhile, these two materials are also important in the field of infrared lens design. Optical instruments designed for the wavelength range where these two materials are transmissive achieve best performance when cooled to cryogenic temperatures to enhance signal from the scene over instrument background radiation. In order to enable high quality lens designs using silicon and germanium at cryogenic temperatures, we have measured the absolute refractive index of multiple prisms of these two materials using the Cryogenic, High-Accuracy Refraction Measuring System (CHARMS) at NASA's Goddard Space Flight Center, as a function of both wavelength and temperature. For silicon, we report absolute refractive index and thermo-optic coefficient (dn/dT) at temperatures ranging from 20 to 300 K at wavelengths from 1.1 to 5.6 pin, while for germanium, we cover temperatures ranging from 20 to 300 K and wavelengths from 1.9 to 5.5 microns. We compare our measurements with others in the literature and provide temperature-dependent Sellmeier coefficients based on our data to allow accurate interpolation of index to other wavelengths and temperatures. Citing the wide variety of values for the refractive indices of these two materials found in the literature, we reiterate the importance of measuring the refractive index of a sample from the same batch of raw material from which final optical components are cut when absolute accuracy greater than k5 x 10" is desired.

Frey, Bradley J.↗