Search NASA⌕ Search

SEARCH · Search NASA

Results for “Sampling device”

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.

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

At least 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Identification of dislocation-related and point-defects in III-As layers for silicon photonics applications

Abstract The aim of this paper is to identify, analyze and compare the defects present in III-As, as a function of dislocation density, and as a function of the presence/absence of quantum dots (QDs). Such materials are of fundamental importance for the development of lasers and photodiodes for silicon photonics. The study is based on an extensive deep-level transient spectroscopy investigation, carried out on GaAs pin diodes grown on Si and on GaAs (that differ in the dislocation density), with and without embedded QDs. The original results described in this paper demonstrate that: (a) we were able to identify four different defects within the device grown on Si (three electron and one hole traps) and one defect (hole trap) in the device on GaAs, common to both samples; (b) all the majority carrier traps identified are located near midgap, i.e. are efficient non-radiative recombination centers; (c) such defects are absent (or non-detectable) in the sample grown on GaAs substrate, having a very low dislocation density; (d) the presence of QDs does not result in additional defects within the semiconductor material; (e) the analysis of the capture kinetics revealed that two of the identified traps are related to point defects, whereas the other two traps can be associated with point defects located near a dislocation; (f) a comparison with previous reports indicate that the detected traps are related to native III-As defects, or to oxygen-related complexes.

Physics↗
DOE OSTI2025

A 291-day Evaluation of the Performance of a Consumer-grade Temporal Radon Detector

Affordable, accurate, and robust temporal measurement devices are desirable for screening and assessment of radon levels in private homes and workplaces. This research expands upon prior research, using the RadonFTlab RadonEye device through a comparison of multiple samples of this instrument with a laboratory-grade instrument, the Saphymo AlphaGUARD, over a more extensive period than reported previously. Data were collected over 291 d in a poorly ventilated basement space in an occupied building. Environmental conditions varied naturally, changing both the radon source term and radon entry into the space approximating typically deployed conditions. The R-squared linear regression correlation coefficient and relative sensitivities of each RadonEye with the AlphaGUARD were computed. Altogether temporal and diurnal variations were also studied. The sensitivities of all RadonEyes and the AlphaGUARD agreed to within 22% throughout the entire deployment period.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Handheld Raman Spectrometers: Assessment Report

In April 2022 the National Urban Security Technology Laboratory’s System Assessment and Validation for Emergency Responders program conducted an operational assessment of ten commercially available handheld Raman spectrometers. Additionally, prior to the operational assessment, the Pacific Northwest National Laboratory conducted laboratory testing of the devices, including scanning a number of samples in various containers. This report summarizes the results of the assessment.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1980

JANTX1N645-1 diode

Samples manufactured by Semtech were tested. Devices showed excessine reverse leakage currents during each of three test phases. Results of testing suggest that failures occurred because of static charge on surface of encapsulant, caused by thermal decomposition of paint.

Source record↗
NASA NTRS1980

Ultraviolet /UV/ emission line mapping of selected regions in the Orion Nebula

Digital processing of data from the International Ultraviolet Explorer (IUE) satellite are used to obtain monochromatic mosaic images of the most prominent UV spectra lines at 35 locations in the central region of the Orion Nebula. The image processing techniques include calculations of the spectrograph orientation and the thermal effects, normalization for exposure time, background subtraction, correction for sensitivity variation within the IUE spectrograph aperture, correction to an absolute flux scale, sample interpolation, and display on graphic devices. The resulting UV emission line intensity maps may be used in conjunction with observations of other wavelength regions to determine the spatial distribution of ionization and abundance levels of carbon and oxygen in Orion.

Turnrose, B. E.↗
NASA NTRS1980

Applications of acoustics in the measurement of coal slab thickness

The determination of the possibility of employing acoustic waves at ultrasonic frequencies for measurements of thicknesses of slabs of coal backed by shale is investigated. Fundamental information concerning the acoustical properties of coal, and the relationship between these properties and the structural and compositional parameters used to characterize coal samples was also sought. The testing device, which utilizes two matched transducers, is described.

Hadden, W. J., Jr.↗
NASA NTRS1990

Central activity in 60 micron peakers

The authors present charge coupled device (CCD) imaging results of their sample of Infrared Astronomy Satellite (IRAS) galaxies with spectral energy distributions peaking at 60 microns (Vader et al 1988). The results support the author's suggestion that the activity in 60 micron peaking galaxies is centrally concentrated, and represents an early stage of dust-embedded nuclear activity. This activity is probably triggered by a recent interaction/merger event as indicated by their peculiar optical morphologies. The authors propose that 60 micron peakers are the precursors of SO's in the case of amorphous systems, and ellipticals in the case of interacting galaxies.

Heisler, Charlene A.↗
NASA NTRS1991

Atmospheric pressure flow reactor: Gas phase chemical kinetics under tropospheric conditions without wall effects

A flow reactor for simulating the interaction in the troposphere is set forth. A first reactant mixed with a carrier gas is delivered from a pump and flows through a duct having louvers therein. The louvers straighten out the flow, reduce turbulence and provide laminar flow discharge from the duct. A second reactant delivered from a source through a pump is input into the flowing stream, the second reactant being diffused through a plurality of small diffusion tubes to avoid disturbing the laminar flow. The commingled first and second reactants in the carrier gas are then directed along an elongated duct where the walls are spaced away from the flow of reactants to avoid wall interference, disturbance or turbulence arising from the walls. A probe connected with a measuring device can be inserted through various sampling ports in the second duct to complete measurements of the first and second reactants and the product of their reaction at selected XYZ locations relative to the flowing system.

Koontz, Steven L.↗
NASA NTRS1994

The EMSS catalog of X-ray-selected clusters of galaxies. 1: An atlas of CCD images of 41 distant clusters

An atlas of deep, wide-field R-band charge coupled device (CCD) images of a complete sample of distant, X-ray-selected clusters of galaxies is presented. These clusters are the 41 most distant (z is greater than or equal to 0.15) and most X-ray-luminous (L(sub x) is greater than or equal to 2 x 10(exp 44) ergs/s) clusters in the Einstein Observatory Extended Medium Sensitivity Survey (EMSS) catalog that are observable from Mauna Kea (delta is greater than -40 deg). The sample spans a redshift range of 0.15 is less than or equal to z is less than or equal to 0.81 and includes at least two and possibly as many as six rich clusters with z is greater than 0.5. For the most part, the data are of superior quality, with a median seeing of 0.8 sec full width half-maximum (FWHM) and coverage of at least 1 Mpc x 1 Mpc in the cluster frame (H(sub 0) = 50; q(sub 0) = 1/2). In addition, we update the available optical, X-ray, and radio data on the entire EMSS sample of 104 clusters. We outline the cluster selection criteria in detail and emphasize that X-ray-selected cluster samples may prove to be more useful for cosmological studies than optically selected samples. The EMSS cluster sample in particular can be exploited for diverse cosmological investigations, as demonstrated by the detection of evolution in the X-ray luminosity function previously reported, and more recently by the discovery of a large number of gravitationally lensed images in these clusters.

Gioia, I. M.↗
NASA NTRS2000

Hierarchical Statistical 3D ' Atomistic' Simulation of Decanano MOSFETs: Drift-Diffusion, Hydrodynamic and Quantum Mechanical Approaches

When MOSFETs are scaled to deep submicron dimensions the discreteness and randomness of the dopant charges in the channel region introduces significant fluctuations in the device characteristics. This effect, predicted 20 year ago, has been confirmed experimentally and in simulation studies. The impact of the fluctuations on the functionality, yield, and reliability of the corresponding systems shifts the paradigm of the numerical device simulation. It becomes insufficient to simulate only one device representing one macroscopical design in a continuous charge approximation. An ensemble of macroscopically identical but microscopically different devices has to be characterized by simulation of statistically significant samples. The aims of the numerical simulations shift from predicting the characteristics of a single device with continuous doping towards estimating the mean values and the standard deviations of basic design parameters such as threshold voltage, subthreshold slope, transconductance, drive current, etc. for the whole ensemble of 'atomistically' different devices in the system. It has to be pointed out that even the mean values obtained from 'atomistic' simulations are not identical to the values obtained from continuous doping simulations. In this paper we present a hierarchical approach to the 'atomistic' simulation of aggressively scaled decanano MOSFETs. A full scale 3D drift-diffusion'atomostic' simulation approach is first described and used for verification of the more economical, but also more restricted, options. To reduce the processor time and memory requirements at high drain voltage we have developed a self-consistent option based on a thin slab solution of the current continuity equation only in the channel region. This is coupled to the Poisson's equation solution in the whole simulation domain in the Gummel iteration cycles. The accuracy of this approach is investigated in comparison with the full self-consistent solution. At low drain voltage only single solution of the nonlinear Poisson equation is sufficient to extract the current with satisfactory accuracy. A pilot version of a hydrodynamic 'atomistic' simulator has been developed in order to study the effect of the nonequilibrium, non local transport in decanano MOSFETs on the random dopant induced current fluctuations. For the first time we have also applied the density gradient approach in 3D to investigate the effect of the quantum confinement on the threshold voltage fluctuations. The developed 'atomistic' simulation techniques have been applied to study various fluctuation resistant MOSFET architectures including epitaxial and delta doped devices.

Asenov, Asen↗
NASA NTRS2014

Microorganisms in the Stratosphere (MIST): In-flight Sterilization with UVC Leds

The stratosphere (10 km to 50 km above sea level) is a unique place on Earth for astrobiological studies of microbes in extreme environments due to the combination of harsh conditions (high ultraviolet radiation, low pressure, desiccation, and low temperatures). Microorganisms in the Stratosphere (MIST) will attempt to characterize the diversity of microbes at these altitudes using a balloon collection device on a meteorological weather balloon. A major challenge of such an aerobiology study is the potential for ground contamination that makes it difficult to distinguish between collected microbes and contaminants. One solution is to use germicidal ultraviolet light emitting diodes (UV LEDs) to sterilize the collection strip. To use this solution, an optimal spatial arrangement of the lights had to be determined to ensure the greatest chance of complete sterilization within the 30 to 60 minute time of balloon ascent. A novel, 3D-printed test stand was developed to experimentally determine viable Bacillus pumilus SAFR-032 spore reduction after exposure to ultraviolet radiation at various times, angles, and distances. Taken together, the experimental simulations suggested that the UV LEDs on the MIST flight hardware should be active for at least 15 minutes and mounted within 4 cm of the illuminated surface at any angle to achieve optimal sterilization. These findings will aid in the production of the balloon collection device to ensure pristine stratospheric microbial samples are collected. Flight hardware capable of in-flight self-sterilization will enable future life detection missions to minimize both forward contamination and false positives.

Exobiology↗
NASA NTRS2015

Passive, Collapsible Contingency Urinal for Human Space Flight

Fluid transport systems for spacecraft face acute challenges because of the persistently unfamiliar and unforgiving low-gravity environment. IRPI, LLC, has developed a contingency wastewater collection and processing device that provides passive liquid collation, containment, bubble separation, and droplet coalescence functions. The lightweight, low-volume, low-cost, and potentially disposable device may be used for subsequent sampling, metering, storage, disposal, and/or reuse. The approach includes a fractal wetting design that incorporates smart capillary fluidics. This work could have a broad impact on capillary-based fluid management on spacecraft and on Earth.

Jenson, Ryan↗
NASA NTRS2017

Towards a Qualification Data Set: Expanded SEE Data on the P2020 Processor

Earlier P2020 SEE data are compared and expanded to a recent die revision, significantly increasing samples tested by protons by five devices, and by heavy ions by five devices. Earlier tested SEE types are found to be fairly similar in register, L1 cache, L2 cache, and CPU crashes. New test methods give SEE performance for the flash memory controller, watchdog circuit, and a built-in Ethernet port on the P2020 processor. Results from heavy ion and proton tests are presented, with data separated over a large number of specific error types and test programs.

Vartanian, Sargeh↗
DOE OSTI2023

A Comprehensive Analysis of Real-World Accelerometer Data Quality in a Global Smartphone-based Seismic Network

The proliferation of low-cost sensors in smartphones has facilitated numerous applications; however, large-scale deployments often encounter performance issues. Sensing heterogeneity, which refers to varying data quality due to factors such as device differences and user behaviors, presents a significant challenge. In this research, we perform an extensive analysis of 3-axis accelerometer data from the MyShake system, a global seismic network utilizing smartphones. We systematically evaluate the quality of approximately 22 million 3-axis acceleration waveforms from over 81 thousand smartphone devices worldwide, using metrics that represent sampling rate and noise level. We explore a broad range of factors influencing accelerometer data quality, including smartphone and accelerometer manufacturers, phone specifications (release year, RAM, battery), geolocation, and time. Our findings indicate that multiple factors affect data quality, with accelerometer model and smartphone specifications being the most critical. In addition, we examine the influence of data quality on earthquake parameter estimation and show that removing low-quality accelerometer data enhances the accuracy of earthquake magnitude estimation.

58 GEOSCIENCES↗
NASA NTRS2013

Genesis Ultrapure Water Megasonic Wafer Spin Cleaner

A device removes, with high precision, the majority of surface particle contamination greater than 1-micron-diameter in size from ultrapure semiconductor wafer materials containing implanted solar wind samples returned by NASA's Genesis mission. This cleaning device uses a 1.5-liter/minute flowing stream of heated ultrapure water (UPW) with 1- MHz oscillating megasonic pulse energy focused at 3 to 5 mm away from the wafer surface spinning at 1,000 to 10,000 RPM, depending on sample size. The surface particle contamination is removed by three processes: flowing UPW, megasonic cavitations, and centripetal force from the spinning wafer. The device can also dry the wafer fragment after UPW/megasonic cleaning by continuing to spin the wafer in the cleaning chamber, which is purged with flowing ultrapure nitrogen gas at 65 psi (.448 kPa). The cleaner also uses three types of vacuum chucks that can accommodate all Genesis-flown array fragments in any dimensional shape between 3 and 100 mm in diameter. A sample vacuum chuck, and the manufactured UPW/megasonic nozzle holder, replace the human deficiencies by maintaining a consistent distance between the nozzle and wafer surface as well as allowing for longer cleaning time. The 3- to 5-mm critical distance is important for the ability to remove particles by megasonic cavitations. The increased UPW sonication time and exposure to heated UPW improve the removal of 1- to 5-micron-sized particles.

Allton, Judith H.↗
NASA NTRS1975

Measurement of sputtered efflux from 5-, 8-, and 30-cm diameter mercury ion thrusters

A technique has been developed which uses spectral transmittance of samples exposed to thruster efflux to determine and characterize the effect of the efflux on spacecraft surfaces and optical devices. An investigation of facility backsputter revealed that efflux samples must be protected (e.g., by small shield boxes) from materials from tank walls and targets. The composition of the sputter efflux deposited on the samples was mostly molybdenum with trace amounts of tantalum, iron and/or mercury. The efflux from a 5-cm diameter thruster was deposited on samples located in the plane of the accelerator grid; the 8-cm diameter thruster efflux results showed that the location of ion beam sputtering and efflux deposition equilibrium occurred at 57 deg with respect to the thruster axis; and the 30-cm diameter thruster had an ion beam erosion-efflux deposition equilibrium at 45 deg.

Weigand, A. J.↗