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At least 1,225 records · Page 68
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Collection efficiency of the soot-particle aerosol mass spectrometer (SP-AMS) for internally mixed particulate black carbon

The soot-particle aerosol mass spectrometer (SP-AMS) uses an intra-cavity infrared laser to vaporize refractory black carbon (rBC) containing particles, making the particle beam–laser beam overlap critical in determining the collection efficiency (CE) for rBC and associated non-refractory particulate matter (NR-PM). This work evaluates the ability of the SP-AMS to quantify rBC and NR-PM mass in internally mixed particles with different thicknesses of organic coating. Using apparent relative ionization efficiencies for uncoated and thickly coated rBC particles, we report measurements of SP-AMS sensitivity to NR-PM and rBC, for Regal Black, the recommended particulate calibration material. Beam width probe (BWP) measurements are used to illustrate an increase in sensitivity for highly coated particles due to narrowing of the particle beam, which enhances the CE of the SP-AMS by increasing the laser beam–particle beam overlap. Assuming complete overlap for thick coatings, we estimate CE for bare Regal Black particles of 0.6 ± 0.1, which suggests that previously measured SP-AMS sensitivities to Regal Black were underestimated by up to a factor of 2. The efficacy of the BWP measurements is highlighted by studies at a busy road in downtown Toronto and at a non-roadside location, which show particle beam widths similar to, but greater than that of bare Regal Black and coated Regal Black, respectively. Further BWP measurements at field locations will help to constrain the range of CE for fresh and aged rBC-containing particles. The ability of the SP-AMS to quantitatively assess the composition of internally mixed particles is validated through measurements of laboratory-generated organic coated particles, which demonstrate that the SP-AMS can quantify rBC and NR-PM over a wide range of particle compositions and rBC core sizes.

Willis, M. D.↗
DOE OSTI2023

Design of a High Flux Beam Characterization Device for Falling Particle Receivers

This paper outlines the design and error analysis for a flux characterization device (i.e. flux wand) which traverses the aperture of a falling particle receiver cavity providing the incident power measurement needed for the calculation of receiver efficiency without significantly disrupting receiver output. The design features a linear actuator, water cooled extension arm, and refractory bar. The refractory bar/flux wand is a diffusely reflective surface which reflects light as it is translated across the receiver aperture to provide a light intensity distribution that is correlated to a measured flux. The component sizing, constrained by a typical 30 frame per second camera and a 4-point average of the measured reflectance, is presented. Simulation reveals the error that results from a 5% variation in flux wand reflectance is within 4% of the true value.

Schroeder, Nathan↗
DOE OSTI2018

black carbon mass loading, size distribution for CACTI - ground site

The Single-Particle Soot Photometer (SP2, Droplet Mea- surement Technologies) is an instrument that measures, in situ, the time-dependent scattering and incandescence signals produced by individual BC-containing particles as they travel through a continuous-wave laser beam. Any particle traversing the laser beam will scatter light, and the BC component of a BC-containing particle will absorb some of the laser energy until its temperature is raised to the point at which it incandesces (hereafter we adopt the standard terminology of the SP2 community and denote any substance determined by the SP2 to be BC as refractory black carbon (rBC)). The scattering signal provides information on particle size, and the incandescence signal is used for counting rBC-containing particles and yields the mass of the rBC component within each particle (obtained via calibration). Hence, the SP2 can determine size-resolved number and mass concentrations of rBC-containing particles and thus provides information on the rBC particle population-based mixing states within ambient aerosols rBC concentration is reported at STP conditions Time resolution: 1-min Uncertainty: ~ 30% SP2 Unit: 25 Location: Ascension Island, British Territory Location: 7° 56' S, 14° 25' W" SP2_dateTime: UTC rBC concentration is in units of ng/m^3 - dry air. Mass Equivalent Diameters [MED] used for size distribution (SP2_min; SP2_geo; and SP2_max) are in units of micrometers dN/dlogDp counts for a given size bin (SP2_geo) listed as 'SP2_cnts_0…SP2_cnts_199'. Column naming convention: 'SP2_cnts_X' are the number of particles in bin number _X. , where _X is the row number within the 'SP2_geo' size bin column that contains the mass equivalent diameter (e.g., SP2_cnts_0 = 0.01 microns; SP2_cnts_10 = 0.060 microns, etc…). The dN/dlogDp data is time-resolved where a given row is associated with the timestamp for that row. Note that the rBC column length is one field shorter than the SP2_datetime column. Last time field is not relevant to the rBC time series (see comment below on length of SP2_datetime column) Lengths for SP2_max; SP2_min; SP2_geo are one field longer then the number of SP2_cnts_XX columns . This is to provide bounds for image plots (if desired). Length for SP2_datetime is one field longer than that length of the SP2_cnts_XX columns This is to provide bounds for image plots (if desired) SP2 Calibration: Fullerene soot with corrrection applied for particle density as a function of particle size. No correction for OC content in Fullerene (recent study on SP2 sensitivity to differing black carbon types reports that non-refractory material content for fullerene soot is about 20%). Comments and/or requests are to be directed to Art Sedlacek (sedlacek@bnl.gov)

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

EPCAPE-PT-LANL Measurements: Single Particle Soot Photometer

Coastal cities offer a unique environment for studying aerosol-cloud interactions and the effects of urban emissions on cloud properties. As part of the Eastern Pacific Cloud Aerosol Precipitation Experiment (EPCAPE), the Partitioning Thrust by Los Alamos National Laboratory (EPCAPE-PT-LANL) was conducted. Our campaign focused on measuring the optical and chemical properties of aerosols and their interactions within marine stratocumulus clouds in La Jolla, California. EPCAPE-PT-LANL enhances the primary goals of EPCAPE through innovative observations of vapor-phase transitions between aerosols and cloud droplets, the impact of black carbon on aerosol-cloud dynamics, and the effects of cloud processing on aerosol optical properties. Instrument: Single Particle Soot Photometer (Droplet Measurements Technology) Data Notes: Contact us if you want additional data products from this instrument. Reported data is the black carbon (rBC) number and mass concentration with diagnostic flags. The SP2 measures incandescence from particles that is induced with a 1064 Nd-YAG laser. Particles that absorb the laser energy and then emit radiation is assumed to contain black carbon. The amount of intensity of radiation is related to the mass of absorbing material in the particle. Here, we calibrate the incandescence intensity to size selected Regal Black (Cabot) nebulized from solution. Data provided for the EPCAPE campaign used the combined broadband high-gain + low-gain channels (BHBL). Each channel has a lower threshold of detection equivalent to 2-s of the respective channel noise. Thresholding has been applied to select between the high-gain and low-gain channels. The detection limit is 80-540 nm (Deq) or 0.36- 55 fg. It is assumed that rBC is the only aerosol type that is in significant concentration in the sampled atmosphere that absorbs the laser energy. Particle data are integrated over 10 second windows to calculate a rBC number and mass concentration. QC/QA: • Diagnostic flags that impacted measured concentration: - Sample, Sheath, and Purge Flow Rates: Despite observing fluctuations in all flows, the rBC detection and mass quantification are generally observed to be stable, although large changes in sample flow rate did impact detection efficiency. A flag was implemented for sample flow deviations >12 cm3/min from the set point averaged over 30 seconds - Laser Power: Detection efficiency decreases with laser power and deviations in laser power also affect mass quantification. Flag for laser power is set for deviations in laser current from the set value >5 mA. - Primary Detector Threshold: Primary thresholding is the signal value which determines whether a “particle” is recorded. Thresholding errors occur when the threshold value is too HIGH and real particles are ignored. • Several periods without data: - 16-18 Nov: Ultra Zero Air generator failure, flows deviated significantly from set points. rBC # conc recovered but questionable. - 20-21 Nov: Offline for calibrations for several hours each day. - 25-27 Nov: Data is missing. - 30 Nov: Power outage 3 Dec: SP2 hard-drive full. - 3 Dec: Power Outage Header: - BHBL_NumbConc[#/cc]: Refers to the number concentration of refractory black carbon (rBC) measured from combined broadband high-gain and low-gain channels, expressed in particles per cubic centimeter. - BHBL_BCMass_Conc[ug/m3]: Refers to the mass concentration of refractory black carbon (rBC) measured from combined broadband high-gain and low-gain channels, expressed in micrograms per cubic meter. - NoData_Flag[bool]: A boolean flag that indicates whether no data was recorded during a measurement. - NoBC_Flag[bool]: A boolean flag indicating whether no black carbon particles were recorded during the measurement. - Laser_Flag[bool]: A boolean flag indicating deviations in laser current during the measurement. - SampleFlow_Flag[bool]: A boolean flag indicating deviations from the set sample flow rate during the measurement. - PrimThresh_Flag[bool]: A boolean flag indicating deviations from the set primary threshold during the measurement, potentially ignoring real particles. - Manual_Flag[bool]: A boolean flag indicating manual intervention or adjustments during the measurement. - CVI_Flag[bool]: A boolean flag indicating whether the Counterflow Virtual Impactor (CVI) was active or inactive during the measurement.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

BSEC Air Quality: Stationary Aerosol Composition and Mass Concentration at Baltimore

Data is 10-min average mass composition and mass concentration from the TOF-ACSM-X and Aethalometer AE33. TOF-ACSM-X reports fine (less than 2.5 um diameter) non-refractory aerosol, including organic aerosol, sulfate, nitrate, ammonium, and non-refractory chloride. Aethalometer measured the attenuation at different wavelengths for aerosol collected onto tape; one wavelength is used to convert to black carbon mass concentration. Also reported is the elemental ratios determined for organic aerosol (O/C, H/C, and organic matter to organic carbon ratio, OM/OC).

aerosol↗
DOE OSTI2025

BSEC Air Quality: Stationary Aerosol Composition and Mass Concentration at Baltimore

Data is 10-min average mass composition and mass concentration from the TOF-ACSM-X. TOF-ACSM-X reports fine (less than 2.5 um diameter) non-refractory aerosol, including organic aerosol, sulfate, nitrate, ammonium, and non-refractory chloride. Also reported is the elemental ratios determined for organic aerosol (O/C, H/C, and organic matter to organic carbon ratio, OM/OC). Finally, ion ratios of key ions used for identifying sources, ammonium balance, and fractional contribution of organic nitrate aerosol to total aerosol nitrate has been included.

aerosol↗
NASA NTRS1965

Wire winding increases lifetime of oxide coated cathodes

Refractory-metal heater base wound with a thin refractory metal wire increases the longevity of oxide-coated cathodes. The wire-wound unit is impregnated with the required thickness of metal oxide. This cathode is useful in magnetohydrodynamic systems and in electron tubes.

Kerslake, W.↗
NASA NTRS1969

Improved high-temperature silicide coatings

Special technique for applying silicide coatings to refractory metal alloys improves their high-temperature protective capability. Refractory metal powders mixed with a baked-out organic binder and sintered in a vacuum produces a porous alloy layer on the surface. Exposing the layer to hot silicon converts it to a silicide.

Klopp, W. D.↗
NASA NTRS1971

New materials for fireplace logs

Fibrous insulation and refractory concrete are used for logs as well as fireproof walls, incinerator bricks, planters, and roof shingles. Insulation is lighter and more shock resistant than fireclay. Lightweight slag bonded with refractory concrete serves as aggregrate.

Kieselback, D. J.↗
NASA NTRS1972

Development and evaluation of vacuum pressure gauge components from carbon and graphite

A prototype all carbon triode ultrahigh vacuum gage was fabricated and tested. The gage exhibited a sensitivity of 3.7 per torr for nitrogen and an X-ray background approximately 0.1 as large as would be expected of a metal gage of the same design. The gage made from these materials, showed good sensitivity and durability. A practical technique was developed for bonding carbon components together without metal fasteners. The bond is made with a cross-linked phenolic resin which is converted to vitreous carbon by a careful pyrolysis procedure. The resulting bonds are strong, electrically conductive, and can withstand repeated excursions to 2500 K in vacuum. Measurements of adsorption and outgassing characteristics of four refractory carbons have confirmed that such materials are suitable for use in ultrahigh vacuum and that some are superior refractory metals in man respects.

Benson, D. K.↗
NASA NTRS1973

Braze alloys for high temperature service

Two groups of refractory metal compositions have been developed that are very useful as high temperature brazing alloys for sealing between ceramic and metal parts. Each group consists of various compositions of three selected refractory metals which, when combined, have characteristics required of good braze alloys.

Lindberg, R. A.↗
NASA NTRS1972

Surface properties of thermionic electrodes

A quasi-equilibrium model which provides semiquantitative predictions of the oxygen reaction with refractory metals was developed at high temperature and low pressure. Extensive experimental data was obtained on adsorption and work function properties for a wide variety of adsorbates (Cs, K, Na, I, Br, Cl, and O) on several refractory metals (W, Ta, Mo, and Re). Conclusions and recommendations for research on alkali metal adsorption, oxygen adsorption, and adsorption of cesium - oxygen mixtures are included.

Stickney, R. E.↗
NASA NTRS1973

Materials interactions between the thermoelectric converter and the 5kwe reactor system

The integration of a compact thermoelectric converter with a 5-kwe reactor system is described. Material interaction uncertainties study is also presented. This includes degradation of the required austenitic - refractory metal transition joint during operation at high temperatures; loss of corrosion resistance; embrittlement by the presence of hydrogen; and loss of design margin by transport of interstitial elements. Analysis and limited experimental evidence indicate that these potential materials interactions can be adequately controlled. Group 5-2 refractory metals can be utilized without unacceptable adverse effect on system reliability.

Ferry, P. B.↗
NASA NTRS1974

Process for fabrication of stabilized aluminum phosphate fibers

Ceramic possesses ideal property combination of high refractoriness and low thermal expansion. Fiber exceeds performance of fused silica fibers at high temperatures. It shrinks less, does not devitrify into unstable cristobalite structure, and is potentially less sensitive to impurities. Might be used for high-temperature insulation, fire protection, composites, and refractories.

Ormiston, T. J.↗
NASA NTRS1974

Performance of coated columbium and tantalum alloys in plasma arc reentry simulation tests

The evaluation of coated refractory metals screened in stagnation model plasma arc tests is reported. Columbium alloys FS-85, C-129Y, and Cb-752 coated with Si-20Cr-20Fe (R512E) were tested at 1390 C. Three silicide coatings on Ta-10W were tested at 1470 C. Half-hour cycles and a 6500 N/sqm stagnation pressure were used. The best R512E coated columbium alloy was FS-85 with first local coating breakdowns occurring in 12 to 50 cycles. At coating defects, low metal recession rates (0.005 mm/min) were generally observed on coated columbium alloys while high rates (0.15 mm/min) were observed on coated Ta-10W. Coated columbium suffered large emittance losses (to below 0.7) due to surface refractory metal pentoxide formation.

Levine, S. R.↗
NASA NTRS1975

Emission spectrometric arcing procedure with minimal effect of chemical form of sample

Matrix effects related to the chemical form of analyzed materials were studied. An arc in argon was used which was buffered with silver chloride. The effect of chemical form was minimal for a variety of metals, oxides, and carbides representing the most refractory compounds and thermally stable metal-containing molecules. Only four of the most refractory materials known showed significant emission depressions due to incomplete volatilization in the arc system. These results are discussed in terms of vapor pressures of the solid materials placed on the anodes and dissociation reactions of the molecules in the gaseous environment.

Gordon, W. A.↗
NASA NTRS1975

T-111 Rankine system corrosion test loop, volume 1

Results are given of a program whose objective was to determine the performance of refractory metal alloys in a two loop Rankine test system. The test system consisted of a circulating lithium circuit heated to 1230 C maximum transferring heat to a boiling potassium circuit with a 1170 C superheated vapor temperature. The results demonstrate the suitability of the selected refractory alloys to perform from a chemical compatibility standpoint.

Harrison, R. W.↗