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At least 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Time-resolved velocity and ion sound speed measurements from simultaneous bow shock imaging and inductive probe measurements

We present a technique to measure the time-resolved velocity and ion sound speed in magnetized, supersonic high-energy-density plasmas. We place an inductive (“b-dot”) probe in a supersonic pulsed-power-driven plasma flow and measure the magnetic field advected by the plasma. As the magnetic Reynolds number is large (R M > 10), the plasma flow advects a magnetic field proportional to the current at the load. This enables us to estimate the flow velocity as a function of time from the delay between the current at the load and the signal at the probe. The supersonic flow also generates a hydrodynamic bow shock around the probe, the structure of which depends on the upstream sonic Mach number. By imaging the shock around the probe with a Mach–Zehnder interferometer, we determine the upstream Mach number from the shock Mach angle, which we then use to determine the ion sound speed from the known upstream velocity. We use the sound speed to infer the value of Z̄T e , where Z̄ is the average ionization and T e is the electron temperature. We use this diagnostic to measure the time-resolved velocity and sound speed of a supersonic (M S ~ 8), super-Alfvénic (M A ~ 2) aluminum plasma generated during the ablation stage of an exploding wire array on the Magpie generator (1.4 MA, 250 ns). The velocity and Z̄T e measurements agree well with the optical Thompson scattering measurements reported in the literature and with 3D resistive magnetohydrodynamic simulations in GORGON.

47 OTHER INSTRUMENTATION↗
DOE OSTI2023

Measurements and Model Improvement: Insight into NWP Model Error Using Doppler Lidar and Other WFIP2 Measurement Systems

Abstract Doppler-lidar wind-profile measurements at three sites were used to evaluate NWP model errors from two versions of NOAA’s 3-km-grid HRRR model, to see whether updates in the latest version 4 reduced errors when compared against the original version 1. Nested (750-m grid) versions of each were also tested to see how grid spacing affected forecast skill. The measurements were part of the field phase of the Second Wind Forecasting Improvement Project (WFIP2), an 18-month deployment into central Oregon–Washington, a major wind-energy-producing region. This study focuses on errors in simulating marine intrusions, a summertime, 600–800-m-deep, regional sea-breeze flow found to generate large errors. HRRR errors proved to be complex and site dependent. The most prominent error resulted from a premature drop in modeled marine-intrusion wind speeds after local midnight, when lidar-measured winds of greater than 8 m s −1 persisted through the next morning. These large negative errors were offset at low levels by positive errors due to excessive mixing, complicating the interpretation of model “improvement,” such that the updates to the full-scale versions produced mixed results, sometimes enhancing but sometimes degrading model skill. Nesting consistently improved model performance, with version 1’s nest producing the smallest errors overall. HRRR’s ability to represent the stages of sea-breeze forcing was evaluated using radiation budget, surface-energy balance, and near-surface temperature measurements available during WFIP2. The significant site-to-site differences in model error and the complex nature of these errors mean that field-measurement campaigns having dense arrays of profiling sensors are necessary to properly diagnose and characterize model errors, as part of a systematic approach to NWP model improvement. Significance Statement Dramatic increases in NWP model skill will be required over the coming decades. This paper describes the role of major deployments of accurate profiling sensors in achieving that goal and presents an example from the Second Wind Forecast Improvement Program (WFIP2). Wind-profile data from scanning Doppler lidars were used to evaluate two versions of HRRR, the original and an updated version, and nested versions of each. This study focuses on the ability of updated HRRR versions to improve upon predicting a regional sea-breeze flow, which was found to generate large errors by the original HRRR. Updates to the full-scale HRRR versions produced mixed results, but the finer-mesh versions consistently reduced model errors.

Meteorology & Atmospheric Sciences↗
DOE OSTI2021

UNESE Argon-39 Measurement Techniques: Developing an above-ground Argon-39 Measurement Capability

The Underground Nuclear Explosion Signatures Experiment (UNESE) sought to use 37 Ar as a tracer for measuring noble-gas migration in the soil surrounding historic Underground Nuclear Explosions (UNE). One unexpected observation was the presence of the much longer-lived isotope 39 Ar from historic UNEs. Quantifying the activity of 39 Ar proved difficult due to the lack of capability to measure significantly-above-background levels of 39 Ar and a general discomfort to repeatedly expose Ultra-Low-Background Proportional Counters (ULBPCs) to significant radioactivity. Because the whole-air samples collected for the 37 Ar tracer measurement were already being measured on the above-ground argon capability, it was decided to expand that capability to include 39 Ar. This document describes the efforts required to achieve quantitative reporting of the 39 Ar backgrounds measured during experiments at the sites of the historic Barnwell and Disko Elm UNEs.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2024

Comparison of the sensitivity of 236 U measurements in environmental samples by MC-ICP-MS and ATONA based high precision U TIMS measurements

The ATONA project is focused upon exploring the improvements in uranium isotope ratio measurements by thermal ionization mass spectrometry (TIMS) provided by a new, capacitor-based, amplifier technology. These “ATONA” Faraday amplifiers (Isotopx Ltd, UK) promise accurate, low-noise measurements of very small signals (< 1 femto-amp) in a traditional Faraday cup, which was only previously possible using an ion counter. This report outlines a series of experiments that were performed to assess the performance of the system in samples that test our rapid analysis procedures, and then compare the results against other mass spectrometry techniques currently available for environmental analyses. The following major goals were achieved: (1) illustrated the importance of 236 U measurements for the screening and analysis of environmental samples; (2) improved sensitivity for 236 U, and then identified 236 U in the 4350B standard at ultra-trace levels (3) Provided comparison of the 236 U sensitivity to multi-collector inductively coupled mass spectrometry techniques (4) Illustrated high TRL for the ATONA based measurement technique. This completes the reporting requirements for task 4 in the project LCP and highlights the utility of the system to make highly sensitive 236 U measurements in programmatically relevant sample matrices and at relevant uranium concentrations.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2025

Fast and sensitive measurements of sub-3 nm particles using Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM)

New particle formation (NPF) is the atmospheric process whereby gas molecules react and nucleate to form detectable particles. NPF has a strong impact on Earth's radiative balance as it produces roughly half of global cloud condensation nuclei. However, the time resolution and sensitivity of current instrumentation are inadequate in measuring the size distribution of sub-3 nm particles, the particles critical for understanding NPF. Here we present the Condensation Particle Counters For Atmospheric Rapid Measurements (CPC FARM), a method to measure the concentrations of freshly nucleated particles. The CPC FARM consists of five CPCs operating in parallel, each configured to operate at different detectable particle sizes between 1–3 nm. This study explores two methods to calculate the size distribution from the differential measurements across the CPC channels. The performance of both inversion methods was tested against the size distribution measured by a pair of stepping particle mobility sizers (SMPSs) during an ambient air sampling study in Pittsburgh, PA. Observational results indicate that the CPC FARM is more accurate with higher time resolution and sensitivity in the sub-3 nm range compared to the SMPS.

Cheng, Darren [Carnegie Mellon Univ., Pittsburgh, ↗
NASA NTRS1972

Measurement component technology. Volume 1: Cryogenic pressure measurement technology, high pressure flange seals, hydrogen embrittlement of pressure transducer material, close coupled versus remote transducer installation and temperature compensation of pressure transducers

The results are presented of an investigation into the availability and performance capability of measurement components in the area of cryogenic temperature, pressure, flow and liquid detection components and high temperature strain gages. In addition, technical subjects allied to the components were researched and discussed. These selected areas of investigation were: (1) high pressure flange seals, (2) hydrogen embrittlement of pressure transducer diaphragms, (3) The effects of close-coupled versus remote transducer installation on pressure measurement, (4) temperature transducer configuration effects on measurements, and (5) techniques in temperature compensation of strain gage pressure transducers. The purpose of the program was to investigate the latest design and application techniques in measurement component technology and to document this information along with recommendations for upgrading measurement component designs for future S-2 derivative applications. Recommendations are provided for upgrading existing state-of-the-art in component design, where required, to satisfy performance requirements of S-2 derivative vehicles.

Hayakawa, K. K.↗
NASA NTRS1976

Experimental research in the use of electrets in measuring effluents from rocket exhaust and a review of standard air quality measuring devices

Seven standard types of measuring devices used to obtain the chemical composition of rocket exhaust effluents were discussed. The electrets, a new measuring device, are investigated and compared with established measuring techniques. The preliminary results obtained show that electrets have multipollutant measuring capabilities, simplicity of deployment, speed of assessment or analysis, and may be an important and valuable tool in measuring pollutants from space vehicle rocket exhaust.

Susko, M.↗
NASA NTRS1986

Advanced optical measuring systems for measuring the properties of fluids and structures

Four advanced optical models are reviewed for the measurement of visualization of flow and structural properties. Double-exposure, diffuse-illumination, holographic interferometry can be used for three-dimensional flow visualization. When this method is combined with optical heterodyning, precise measurements of structural displacements or fluid density are possible. Time-average holography is well known as a method for displaying vibrational mode shapes, but it also can be used for flow visualization and flow measurements. Deflectometry is used to measure or visualize the deflection of light rays from collimation. Said deflection occurs because of refraction in a fluid or because of reflection from a tilted surface. The moire technique for deflectometry, when combined with optical heterodyning, permits very precise measurements of these quantities. The rainbow schlieren method of deflectometry allows varying deflection angles to be encoded with colors for visualization.

Decker, A. J.↗
NASA NTRS1988

Comparison of in situ aerosol measurements with SAGE 2 and SAM 2 aerosol measurements during the airborne Antarctic ozone experiment

Models indicate that stratospheric aerosols play a major role in the destruction of ozone during the Austral winter. Although many in situ measurements of stratospheric aerosols were made during the Airborne Antarctic Ozone Experiment, changes of aerosol concentration and size distributions across the polar vortex are important to understanding changes of chemical species taking place during this time. Therefore comparing the in situ measurements with measurements made by satellites scanning wider areas will give a clearer picture of the possible role played by aerosols during this period. The wire impactor size distributions are compared to those from the aerosol spectrometers and a best fit size distribution determined. Aerosol extinctions are calculated from the in situ measurements and compared to the extinctions measured by the satellites. Five comparisons are made with SAGE 2 and four with SAM 2. Extinctions agree as close as a factor of two.

Ferry, G. V.↗
NASA NTRS1990

Comparison of NOAA-9 ERBE measurements with Cirrus IFO satellite and aircraft measurements

Earth Radiation Budget Experiment (ERBE) measurements onboard the NOAA-9 are compared for consistency with satellite and aircraft measurements made during the Cirrus Intensive Field Observation (IFO) of October 1986. ERBE scene identification is compared with NOAA-9 TIROS Operational Vertical Sounder (TOVS) cloud retrievals; results from the ERBE spectral inversion algorithms are compared with High resolution Interferometer Sounder (HIS) measurements; and ERBE radiant existance measurements are compared with aircraft radiative flux measurements.

Ackerman, Steven A.↗
NASA NTRS1995

Dielectric property measurements in the Electromagnetic Properties Measurement Laboratory

The capability to measure the dielectric properties of various materials has been developed in the Electromagnetic Properties Measurement Laboratory (EPML) of the Electromagnetics Research Branch (ERB). Two measurement techniques which have been implemented in the EPML to characterize materials are the dielectric probe and waveguide techniques. Several materials, including some for which the dielectric properties are well known, have been measured in an attempt to establish the capabilities of the EPML in determining dielectric properties. Brief descriptions of the two techniques are presented in this report, along with representative results obtained during these measurements.

Cravey, Robin L.↗
NASA NTRS1997

W-Band Transmission MeasurementS and X-Band Dielectric Properties Measurements for a Radome Material Sample

This paper describes measurements which were performed on a sample of radome material in the Electromagnetic Properties Measurements Laboratory (EPML). The purpose of the measurements described in this paper was to determine the one-way transmission loss through the flat panel of radome material for a frequency range of 84 to 94 GHz, for varying incidence angles. The panel, which was manufactured by Norton Performance Plastics Corporation, was provided to the EPML by TRW. The size of the panel is 40 in x 36 in x 0.422 in and consists of a foam material with one side coated with a smooth white coating (this side will be referred to as the front side). The dielectric properties of the foam material from the inside of the panel were also determined at X-band (8.2-12.4 GHz). The W-band free space measurements are presented first, followed by the X-band dielectric properties measurements.

Cravey, Robin L.↗
NASA NTRS2001

ACE-Asia Aerosol Optical Depth and Water Vapor Measured by Airborne Sunphotometers and Related to Other Measurements and Calculations

In the Spring 2001 phase of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia), the 6-channel NASA Ames Airborne Tracking Sunphotometer (AATS-6) operated on 15 of the 19 research flights of the NCAR C-130, while its 14-channel counterpart (AATS- 14) flew successfully on all 18 research flights of the CIRPAS Twin Otter. ACE-Asia studied aerosol outflow from the Asian continent to the Pacific basin. It was designed to integrate suborbital and satellite measurements and models so as to reduce the uncertainty in calculations of the climate forcing due to aerosols. AATS-6 and AATS-14 measured solar beam transmission at 6 and 14 wavelengths (380-1021 and 354-1558 nm, respectively), yielding aerosol optical depth (AOD) spectra and column water vapor (CWV). Vertical differentiation in profiles yielded aerosol extinction spectra and water vapor concentration. The wavelength dependence of these AOD and extinction spectra indicates that supermicron dust was often a major component of the ACE-Asia aerosol. Frequently this dust-containing aerosol extended to high altitudes. For example, in AATS- 14 profiles analyzed to date, 36% of full-column AOD at 525 nm was above 3 km. In contrast, only 10% of CWV was above 3 km. Analyses and applications of AATS-6 and AATS-14 data to date include comparisons to (i) extinction products derived using in situ measurements, (ii) extinction profiles derived from lidar measurements, and (iii) AOD retrievals from the Multi-angle Imaging Spectro-Radiometer (MISR) aboard the TERRA satellite. Other planned collaborative studies include comparisons to results from size spectrometers, chemical measurements, other satellite sensors, flux radiometers, and chemical transport models. Early results of these studies will be presented.

Livingston, John M.↗
NASA NTRS2002

Evaluation of SAGE II and Balloon-Borne Stratospheric Aerosol Measurements: Evaluation of Aerosol Measurements from SAGE II, HALOE, and Balloonborne Optical Particle Counters

Stratospheric aerosol measurements from the University of Wyoming balloonborne optical particle counters (OPCs), the Stratospheric Aerosol and Gas Experiment (SAGE) II, and the Halogen Occultation Experiment (HALOE) were compared in the period 1982-2000, when measurements were available. The OPCs measure aerosol size distributions, and HALOE multiwavelength (2.45-5.26 micrometers) extinction measurements can be used to retrieve aerosol size distributions. Aerosol extinctions at the SAGE II wavelengths (0.386-1.02 micrometers) were computed from these size distributions and compared to SAGE II measurements. In addition, surface areas derived from all three experiments were compared. While the overall impression from these results is encouraging, the agreement can change with latitude, altitude, time, and parameter. In the broadest sense, these comparisons fall into two categories: high aerosol loading (volcanic periods) and low aerosol loading (background periods and altitudes above 25 km). When the aerosol amount was low, SAGE II and HALOE extinctions were higher than the OPC estimates, while the SAGE II surface areas were lower than HALOE and the OPCS. Under high loading conditions all three instruments mutually agree to within 50%.

Hervig, Mark↗
NASA NTRS1986

Method for contact resistivity measurements on photovoltaic cells and cell adapted for such measurement

A method is disclosed for scribing at least three grid contacts of a photovoltaic cell to electrically isolate them from the grid contact pattern used to collect solar current generated by the cell, and using the scribed segments for determining parameters of the cell by a combination of contact end resistance (CER) measurements using a minimum of three equally or unequally spaced lines, and transmission line modal (TLM) measurements using a minimum of four unequally spaced lines. TLM measurements may be used to determine sheet resistance under the contact, R.sub.sk, while CER measurements are used to determine contact resistivity, .rho..sub.c, from a nomograph of contact resistivity as a function of contact end resistance and sheet resistivity under the contact. In some cases, such as the case of silicon photovoltaic cells, sheet resistivity under the contact may be assumed to be equal to the known sheet resistance, R.sub.s, of the semiconductor material, thereby obviating the need for TLM measurements to determine R.sub.sk.

Burger, Dale R.↗
NASA NTRS2006

Use of In Situ Cloud Condensation Nuclei, Extinction, and Aerosol Size Distribution Measurements to Test a Method for Retrieving Cloud Condensation Nuclei Profiles From Surface Measurements

If the aerosol composition and size distribution below cloud are uniform, the vertical profile of cloud condensation nuclei (CCN) concentration can be retrieved entirely from surface measurements of CCN concentration and particle humidification function and surface-based retrievals of relative humidity and aerosol extinction or backscatter. This provides the potential for long-term measurements of CCN concentrations near cloud base. We have used a combination of aircraft, surface in situ, and surface remote sensing measurements to test various aspects of the retrieval scheme. Our analysis leads us to the following conclusions. The retrieval works better for supersaturations of 0.1% than for 1% because CCN concentrations at 0.1% are controlled by the same particles that control extinction and backscatter. If in situ measurements of extinction are used, the retrieval explains a majority of the CCN variance at high supersaturation for at least two and perhaps five of the eight flights examined. The retrieval of the vertical profile of the humidification factor is not the major limitation of the CCN retrieval scheme. Vertical structure in the aerosol size distribution and composition is the dominant source of error in the CCN retrieval, but this vertical structure is difficult to measure from remote sensing at visible wavelengths.

Ghan, Stephen J.↗
NASA NTRSDate not supplied

Measurement System Analysis of a Novel Phase-Based Ultrasonic NDE Technique for Bond Strength Measurement

Fiber reinforced polymer parts have shown tremendous benefits in aerospace structural applications, but their qualification and certification for use in safety critical areas are currently hindered by the lack of a capable non-destructive evaluation (NDE) method or technique for the inspection of these adhesively bonded parts. Conventional NDE methods and techniques typically detect gross bond defects in a qualitative (Pass/Fail) manner. These techniques struggle to detect weak or kissing bonds. Also, there are no widely adopted NDE methods or techniques for measuring interfacial bond strength or detecting kissing bonds. Bond strength is currently ensured by process control and semi-destructive testing. Results from recent research from other authors, including but not limited to mechanical testing, have shown an excellent correlation between interfacial stiffness of an adhesively bonded joint and the adhesive bond strength of that joint. In this paper, a measurement system analysis (MSA) of a novel phase-based ultrasonic NDE Technique, developed at NASA Langley Research Center, is presented for bond strength measurement to assess at an increased level the measurement process and identify components of variation in that measurement process.

Ultrasound↗
DOE OSTI2024

Mass measurement systems and related methods for measuring mass of solids within a liquid

A measurement system includes a vessel for containing a fluid and at least one solid material and a probe assembly for disposing partially into the fluid within the vessel. The probe assembly includes a hollow tube having an open lower longitudinal end and at least one pressure sensor within the hollow tube, the at least one pressure sensor configured to measure pressures of the fluid within the hollow tube at at least two different elevations. A method of measuring a mass of suspended solids within a fluid, the method includes receiving pressure measurements representing two different elevations of the fluid within a hollow tube and substantially free of the suspended solids and based at least partially on the received pressure measurements, determining a mass of the suspended solids.

Galbreth, Gregory G.↗