SEARCH · Search NASA

Results for “ELECTRONIC FILTER”

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.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8

All sources NASA NTRS DOE OSTI

NASA NTRS2005

High-Resolution Electron Energy-Loss Spectroscopy (HREELS) Using a Monochromated TEM/STEM

A 200 keV FEI TF20 XT monochromated (scanning) transmission electron microscope funded by NASA's SRLIDAP program is undergoing installation at Lawrence Livermore National Laboratory. Instrument specifications in STEM mode are Cs =1.0 mm, Cc =1.2 mm, image resolution =0.18 nm, and in TEM mode Cs =1.3 mm, Cc =1.3 mm, information limit =0.14 nm. Key features of the instrument are a voltage-stabilized high tension (HT) supply, a monochromator, a high-resolution electron energy-loss spectrometer/energy filter, a high-resolution annular darkfield detector, and a solid-state x-ray energy-dispersive spectrometer. The high-tension tank contains additional sections for 60Hz and high frequency filtering, resulting in an operating voltage of 200 kV plus or minus 0.005V, a greater than 10-fold improvement over earlier systems. The monochromator is a single Wien filter design. The energy filter is a Gatan model 866 Tridiem-ERS high resolution GIF spec d for less than or equal to 0.15 eV energy resolution with 29 pA of current in a 2 nm diameter probe. 0.13 eV has already been achieved during early installation. The x-ray detector (EDAX/Genesis 4000) has a take-off angle of 20 degrees, an active area of 30 square millimeters, and a solid angle of 0.3 steradians. The higher solid angle is possible because the objective pole-piece allows the detector to be positioned as close as 9.47 mm from the specimen. The voltage-stabilized HT supply, monochromator and GIF enable high-resolution electron energy-loss spectroscopy (HREELS) with energy resolution comparable to synchrotron XANES, but with approximately 100X better spatial resolution. The region between 0 and 100 eV is called the low-loss or valence electron energy-loss spectroscopy (VEELS) region where features due to collective plasma oscillations and single electron transitions of valence electrons are observed. Most of the low-loss VEELS features we are detecting are being observed for the first time in IDPs. A major focus of our research is to understand the origin and significance of these features and how they might be exploited to gain insight about IDPs and other meteoritic materials.

Sai, Z. R.↗

NASA NTRS1977

Design, fabrication and performance of two grazing incidence telescopes for celestial extreme ultraviolet astronomy

The design and performance of grazing incidence telescopes for celestial extreme ultraviolet (EUV) astronomy are described. The telescopes basically consist of a star tracker, collimator, grazing incidence mirror, vacuum box lid, vacuum housing, filters, a ranicon detector, an electronics box, and an aspect camera. For the survey mirror a Wolter-Schwarzschild type II configuration was selected. Diamond-turning was used for mirror fabrication, a technique which machines surfaces to the order of 10 microns over the required dimensions. The design of the EUV spectrometer is discussed with particular reference to the optics for a primarily spectroscopic application and the fabrication of the f/10 optics.

Lampton, M.↗

NASA NTRS1982

An incursion of dust in the southwestern United States from April 1980 eruptions of Mount St. Helens

An intrusion of volcanic dust occurred over the northern Mojave Desert, one month before the explosive eruption of 18 May 1980. Visibility was reduced to 15 to 30 miles during meteorological conditions that should have yielded a visibility in excess of 100 miles. This intrusion was documented by particle size distributions, scanning electron microscope analysis of Nuclepore filter samples, insolation measurements, observations by Navy and NASA aircraft, and meteorological data. No further incidents have been observed to date because of a lack of simultaneous volcanic activity with the particular wind patterns that existed in April. Therefore, under certain meteorological conditions, the desert of the southwestern United States could be significantly affected by volcanic ash from an eruption of Mount St. Helens.

Mathews, L. A.↗

NASA NTRS1989

An astronomy camera for low background applications in the 1.0 to 2.5 micron spectral region

A description is given of a low-background astronomy camera system based on a short wavelength (1.0-2.5 micron) 128 x 128 focal plane array. The camera is designed to accept either a HgCdTe array for the 1-2.5 micron spectral region or an InSb array for the 3-5 micron spectral region. A cryogenic folded optical system is utilized to control excess stray light along with a cold eight-position filter wheel for spectral filtering. The camera head and electronics will also accept a 256 x 256 focal plane. Engineering evaluation of the system and two engineering runs at the JPL Table Mountain Observatory have been completed. System design, engineering performance, and sample imagery are presented.

Kaki, Said A.↗

NASA NTRS1989

Fiber-optic three axis magnetometer prototype development

The goal of this research program was to develop a high sensitivity, fiber optic, interferometric, three-axis magnetometer for interplanetary spacecraft applications. Dynamics Technology, Inc. (DTI) has successfully integrated a low noise, high bandwidth interferometer with high sensitivity metallic glass transducers. Also, DTI has developed sophisticated signal processing electronics and complete data acquisition, filtering, and display software. The sensor was packaged in a compact, low power and weight unit which facilitates deployment. The magnetic field sensor had subgamma sensitivity and a dynamic range of 10(exp 5) gamma in a 10 Hz bandwidth. Furthermore, the vector instrument exhibited the lowest noise level when only one axis was in operation. A system noise level of 1 gamma rms was observed in a 1 Hz bandwidth. However, with the other two channels operating, the noise level increased by about one order of magnitude. Higher system noise was attributed to cross-channel interference among the dither fields.

Wang, Thomas D.↗

NASA NTRS1995

Yohkoh/SXT x-ray synoptic maps of coronal brightness and temperature

The Yohkoh soft X-ray telescope (SXT) records on the order of 50 solar images per day in two different color filters. These provide material for the generation of synoptic maps, which compress the 3-dimensional data cube into two dimensions. We are creating synoptic maps from strips of data both at disk center and at different heights, including limb maps that are analogous to those produced by ground-based coronagraphs. The ratios of intensities in images taken in two filters provide estimates of the electron temperature in the range 1 - 3 x 10(exp 6) K. These are broad-band temperature maps; rather than maps created with discrete sampling as in the case of the coronal green and red lines. We discuss the properties of these maps and their application to the study of energy release in the corona.

Slater, G. L.↗

NASA NTRS2001

A Second Generation Multi-Angle Imaging SpectroRadiometer (MISR-2)

The Multi-angle Imaging SpectroRadiometer (MISR) has been in Earth orbit since December 1999 on NASA's Terra spacecraft. This instrument provides new ways of looking at the Earth's atmosphere, clouds, and surface for the purpose of understanding the Earth's ecology, environment, and climate. To facilitate the potential future continuation of MISR's multi-angle observations, a study was undertaken in 1999 and 2000 under the Instrument Incubator Program (IIP) of NASA Code Y's Earth Science Technology Office (ESTO) to investigate and demonstrate the feasibility of a successor to MISR that will have greatly reduced size and mass. The kernel of the program was the design, construction, and testing of a highly miniaturized camera, one of the nine that would probably be used on a future space borne MISR-like instrument. This demonstrated that the size and mass reduction of the optical system and camera electronics are possible and that filters can be assembled to meet the miniaturized packaging requirements. An innovative, reflective optics design was used, enabling the wavelength range to be extended into the shortwave infrared. This was the smallest all-reflective camera ever produced by the contractor. A study was undertaken to determine the feasibility of implementing nine (multi-angle) cameras within a single structure. This resulted in several possible configurations. It would also be possible to incorporate one of the cameras into an airborne instrument.

spectroradiometers↗

NASA NTRS2010

Single sensor processing to obtain high resolution color component signals

A method for generating color video signals representative of color images of a scene includes the following steps: focusing light from the scene on an electronic image sensor via a filter having a tri-color filter pattern; producing, from outputs of the sensor, first and second relatively low resolution luminance signals; producing, from outputs of the sensor, a relatively high resolution luminance signal; producing, from a ratio of the relatively high resolution luminance signal to the first relatively low resolution luminance signal, a high band luminance component signal; producing, from outputs of the sensor, relatively low resolution color component signals; and combining each of the relatively low resolution color component signals with the high band luminance component signal to obtain relatively high resolution color component signals.

Glenn, William E.↗

NASA NTRS2007

Predicting the Blast of Lunar Soil Under a Rocket's Exhaust Jet

The blast of lunar soil represents a problem for the future missions planned for the moon. When the lander approached the ground during the Apollo missions, huge showers of dust particles were sent in all directions at extremely high velocities - including upwards towards the landing spacecraft. This represents a clear danger to the lander because the loss of visibility and the damage that can be produced to the vehicle itself. If there had been equipment on the ground, these showers of particles would have created a sand blasting effect over the equipment, possibly damaging optics and contaminating the equipment and depending on the size and velocity of the particles maybe even more extensive damage as the particles penetrated the outer surface of the equipment. Since the there is no air on the moon to slow down the particles, they can travel large distances at high speeds, in fact in some instances they can reach near escape velocity and go into an orbit around the moon and come all the way back to almost the same point where they were at the beginning; meaning that some of the lunar dust that came up during landing will shower back over the site. Once on the surface, the extremely fine dust had a habit of getting itself everywhere. During the Apollo missions it not only covered the astronauts' suits, but managed to work its way inside, damaging airtight joints and scratching up glass visors. The dust found its way inside the spacecraft, contaminating the floor and electronic systems inside, clogging air filters in the process. This is due to the fact that the lunar soil is extremely cohesive. The Lunar soil causes all of the same problems as sand does on Earth but unlike sand particles on Earth, which have smooth spherical shapes, the dust on the Moon is more like small particles of glass with sharper edges since there is no erosion on the lunar surface. During the Apollo missions the dust problem did not cause a big problem due to the fact of the length of duration of the missions. But as NASA plans to have long term missions to the moon the dust problem becomes an issue, due to multiple landings and the equipment that will be accumulated on the site. In order to mitigate these problems it is needed first to understand the physics of the problem in order to find the most suitable solution to protect equipment and vehicles during the next lunar missions..

Diaz, Carlos J. Sanchez↗

NASA NTRS2020

Progress in the Development of Frequency-Domain Multiplexing for the X-ray Integral Field Unit on Board the Athena Mission

Frequency-domain multiplexing (FDM) is the baseline readout system for the X-ray Integral Field Unit on board the Athena mission. Under the FDM scheme, TESs are coupled to a passive LC filter and biased with alternating current (AC bias) at MHz frequencies. Using high-quality-factor LC filters and room-temperature electronics developed at SRON and low-noise two-stage SQUID amplifiers provided by VTT, we have recently demonstrated good performance with the FDM readout of Mo/Au TES calorimeters with Au/Bi absorbers. We have achieved a performance requested for the demonstration model with the single-pixel AC bias ( ΔE = 1.8 eV ) and nine-pixel multiplexing ( ΔE = 2.6 eV ) modes. We have also demonstrated 14-pixel multiplexing with an average energy resolution of 3.3 eV, which is limited by nonfundamental issues related to FDM readout in our laboratory setup.

H. Akamatsu↗

NASA NTRS1997

Spatial and Temporal Energy Characterization of Precipitating Electrons for the January 10th, 1997 Magnetic Cloud Event

The January 10-11, 1997 magnetic cloud event provided a rare opportunity to study auroral energy deposition under varying but intense IMF conditions. The Wind spacecraft located about 100 RE upstream monitored the IMF and plasma parameters during the passing of the cloud. The Polar Ultraviolet Imager (UVI) observed the aurora[ precipitation during the first encounter of the cloud with Earth's magnetosphere and during several subsequent substorm events. The UVI has the unique capability of measuring the energy flux and characteristic energy of the precipitating electrons through the use of narrow band filters that distinguish short and long wavelength molecular nitrogen emissions. The spatial and temporal characteristics of the precipitating electron energy will be discussed beginning with the inception of the event at the Earth early January 1 Oth and continuing through the subsidence of auroral activity on January 11th.

Spann, J. F., Jr.↗

NASA NTRS1975

Atmospheric particulate measurements in Norfolk, Virginia

Characterization of atmospheric particulates was conducted at a site near the center of Norfolk, Virginia. Air quality was measured in terms of atmospheric mass loading, particle size distribution, and particulate elemental composition for a period of 2 weeks. The objectives of this study were (1) to establish a mean level of air quality and deviations about this mean, (2) to ascertain diurnal changes or special events in air quality, and (3) to evaluate instrumentation and sampling schedules. Simultaneous measurements were made with the following instruments: a quartz crystal microbalance particulate monitor, a light-scattering multirange particle counter, a high-volume air sampler, and polycarbonate membrane filters. To assess the impact of meteorological conditions on air quality variations, continuous data on temperature, relative humidity, wind speed, and wind direction were recorded. Particulate elemental composition was obtained from neutron activation and scanning electron microscopy analyses of polycarbonate membrane filter samples. The measured average mass loading agrees reasonably well with the mass loadings determined by the Virginia State Air Pollution Control Board. There are consistent diurnal increases in atmospheric mass loading in the early morning and a sample time resolution of 1/2 hour seems necessary to detect most of the significant events.

Storey, R. W., Jr.↗

NASA NTRS1997

Using Superconducting Thin Films in Microwave Lines

High temperature superconductors(HTS) and microwaves devices form the ideal partnership. The application of superconductors in microwave devices, components and systems allows the reduction in size, power consumption and insertion loss. The surface resistance of high-Tc superconductors has been found to be two orders of magnitude lower than normal conducting copper materials. The reduction in size and power requirements, which together both lead to a reduction in system mass, coupled with reasonably accessible operating temperatures, suggest that HTS microwave components should find ready application in satellite communications systems. At present, multi- channeling communication networks demand filters with narrow bandwidth in order to allow the available RF frequency spectrum to be partitioned into small frequency bands, -and possible variation of dielectric constant from substrate to substrate is undesirable. Microwave multiplexers demand the fabrication of two identical filters in each channel. Thus, the filter with tuning function is preferable. Tunable filters are the critical component for phased array antennas in order to electronically steer the radiated beam. To fabricate a tunable filter that uses an electric field for operation, one would like a material that provides a large change on dielectric constant for a given electric field, yet has a relatively low tangent in order to minimize the insertion loss of the device. Ferroelectrics have been the materials of choice. Their large dielectric constant sufficiently increases the coupling between microwave resonators and its dependence on electric field provides timability. Development of technology promises to diminish tangent loss. The use of thin ferroelectric films sufficiently decreases insertion losses keeping considerable potential for applications. NASA Lewis Research Center is the one of the leading centers in investigation of superconductors/ferroelectric tunable components for microwave devices. A large number of possible microwave devices were fabricated and tested on the basis of thin film multilayer superconductor-ferroelectric structures. In major cases the systems with edge-coupling scheme were investigated. Dr. Genkin has recently focused on the new potentialities which implements the using of thin ferroelectric films in filters fabricated with end-coupled microstrip lines. Numerical modeling shows that these systems have large potential for application in tunable narrow- and wide-bandpass filters in the frequency range 10-20 GHz. The phase shifter with end-coupled resonant sections was fabricated and tested. Experimental results show large tunability, particular in low voltages. The possible optimization of this structure promises to improve the obtained result and to reach the low level of insertion losses.

Genkin, Varery↗

NASA NTRS1999

Effects of Hydrogen on Tantalum Nitride Resistors

This document is a presentation about the investigation of drift reported in static frequency output from the analog circuit of a Multichannel Microwave Integrated circuit hybrid microelectronic filter module for space flight application. Electron Dispersion X-Ray Detector )EDAX) Analysis of the 35k ohm thin film Tantalum Nitride Chip resistors identified Palladium in the film. A catalytic reaction of Palladium and hydrogen produces mono atomic hydrogen. When the filter module cavities were filled with a 4 % hydrogen 96 % Nitrogen gas mixture at 25C and monitored the electrical performance for 24 hours. Some channels drifted in a similar pattern as the channel being investigated. Palladium was found on the resistors. The corrective actions taken are reviewed, which resulted in a stable circuit.

Weiler, James↗

NASA NTRS1973

A Comparison of Near Simultaneous Lidar Returns and Particulate Collections on Filters Flown at Six Stratospheric Altitudes

Collections of particulates on both Los Alamos Scientific Laboratory (LASL) and National Center for Atmospheric Research (NCAR) filter systems were made from an RB 57F aircraft flown at one tropospheric and six stratospheric altitudes over the Boulder, Colorado, area. This daytime flight was spanned by lidar returns on evenings before and after the flight. Scanning electron microscope examination of the LASL filters showed no evidence of solid particulates greater than 2 micrometers (the instrumental resolving power). Quantitative analysis of the NCAR filters yielded chemical composition and mass. The mass values were normalized to the total air flow through the filters to yield mass mixing ratios at the various altitudes. The lidar returns, normalized to molecular densities obtained from sonde data, were put in the form of particulate scattering divided by molecular scattering, i. e., an optical mixing ratio. A plot of the optical mixing ratio versus mass mixing ratio, in the stratosphere, yielded linear relationship, for five of the six data points, going through the origin.

Schuster, Burton G.↗

NASA NTRS2016

Development and Performance of a Suprathermal Electron Spectrometer to Study Auroral Precipitations

The design, development, and performance of Medium-energy Electron SPectrometer (MESP), dedicated to the in situ observation of suprathermal electrons in the auroral ionosphere, are summarized in this paper. MESP employs a permanent magnet filter with a light tight structure to select electrons with proper energies guided to the detectors. A combination of two avalanche photodiodes and a large area solid-state detector (SSD) provided 46 total energy bins (1 keV resolution for 3-20 keV range for APDs, and 7 keV resolution for greater than 20 keV range for SSDs). Multi-channel ultra-low power application-specific integrated circuits are also verified for the flight operation to read-out and analyze the detector signals. MESP was launched from Poker F1at Research Range on 3 March 2014 as a part of ground-to-rocket electrodynamics-electrons correlative experiment (GREECE) mission. MESP successfully measured the precipitating electrons from 3 to 120 keV in 120-ms time resolution and characterized the features of suprathermal distributions associated with auroral arcs throughout the flight. The measured electrons were showing the inverted-V type spectra, consistent with the past measurements. In addition, investigations of the suprathermal electron population indicated the existence of the energetic non-thermal distribution corresponding to the brightest aurora.

Ogasawara, Keiichi↗

NASA NTRSDate not supplied

Experimental Demonstration and Characterization of a Ceramic Sintered Wick Heat Pipe Evaporator

As electrified aircraft propulsion (EAP) matures and power electronics, electric machines, and batteries achieve higher power density, the thermal management of these devices becomes ever more critical. In this paper, a heat pipe made from a dielectric ceramic material is proposed, which enables its use in the thermal management of a high frequency filter inductor for an EAP power electronics application. The manufacturing process for the sintered powder wick was developed and its performance characterized. The heat pipe is further experimentally demonstrated via an open evaporator test and shown to behave analogous to a constant conductance heat pipe.

Thermal Management↗

NASA NTRSDate not supplied

Experimental Demonstration and Characterization of a Ceramic Sintered Wick Heat Pipe Evaporator

Thermal management↗