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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.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2012

Development and assessment of solar-thermal-activated fuel production: Phase 1, summary

Sandia National Laboratories has for many years been engaged in investigating and developing the science and technology of solar thermochemistry for solar fuel applications under the banner “Sunshine to Petrol.” This report summarizes BP‐funded solar thermochemical work performed from November 2011 through May 2012. This “phase one” effort centered on performance mapping of the Counter‐Rotating‐Ring Receiver Reactor Recuperator (CR5) prototype, a thermochemical heat engine for splitting CO 2 (and/or H 2 O) to produce CO (H 2 ) and O 2 . The bulk of the on‐sun testing effort was performed with 8 ceria‐finned rotating rings. During operation, argon is injected into the reduction side of the CR5 while CO 2 is provided to the oxidation side.

Miller, James Edward↗
DOE OSTI2012

In Vitro Dissolution Tests of Plutonium and Americium Containing Contamination Originating From ZPPR Fuel Plates

Assessing the extent of internal dose is of concern whenever workers are exposed to airborne radionuclides or other contaminants. Internal dose determinations depend upon a reasonable estimate of the expected biological half-life of the contaminants in the respiratory tract. One issue with refractory elements is determining the dissolution rate of the element. Actinides such as plutonium (Pu) and Americium (Am) tend to be very refractory and can have biological half-lives of tens of years. In the event of an exposure, the dissolution rates of the radionuclides of interest needs to be assessed in order to assign the proper internal dose estimates. During the November 2011 incident at the Idaho National Laboratory (INL) involving a ZPPR fuel plate, air filters in a constant air monitor (CAM) and a giraffe filter apparatus captured airborne particulate matter. These filters were used in dissolution rate experiments to determine the apparent dissolution half-life of Pu and Am in simulated biological fluids. This report describes these experiments and the results. The dissolution rates were found to follow a three term exponential decay equation. Differences were noted depending upon the nature of the biological fluid simulant. Overall, greater than 95% of the Pu and 93% of the Am were in a very slow dissolving component with dissolution half-lives of over 10 years.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2012

Independent Confirmatory Survey Results of Soils Associated with the Argyle Street Sewer Line at the United Nuclear Corporation Naval Products Site, New Haven, Connecticut (Letter Report)

Oak Ridge Institute for Science and Education (ORISE) personnel visited the United Nuclear Corporation (UNC) Naval Products site on three separate occasions during the months of October and November 2011. The purpose of these visits was to conduct confirmatory surveys of soils associated with the Argyle Street sewer line that was being removed. Soil samples were collected from six different, judgmentally determined locations in the Argyle Street sewer trench. In addition to the six soil samples collected by ORISE, four replicate soil samples were collected by Cabrera Services, Inc. (CSI) for analysis by the ORISE laboratory. Replicate samples S0010 and S0011 were final status survey (FSS) bias samples; S0012 was an FSS systematic sample; and S0015 was a waste characterization sample. Six soil samples were also collected for background determination. Uranium-235 and uranium-238 concentrations were determined via gamma spectroscopy; the spectra were also reviewed for other identifiable photopeaks. Radionuclide concentrations for these soil samples are provided. In addition to the replicate samples and the samples collected by ORISE, CSI submitted three soil samples for inter-laboratory comparison analyses. One sample was from the background reference area, one was from waste characterization efforts (material inside the sewer line), and one was a FSS sample. The inter-laboratory comparison analyses results between ORISE and CSI were in agreement, except for one sample collected in the reference area. Smear results For Argyle Street sewer pipes are tabulated.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Independent Verification Survey of the SPRU Lower Level Hillside Area at the Knolls Atomic Power Laboratory, Niskayuna, New York (Final Report)

During August 10, 2011 through August 19, 2011, and October 23, 2011 through November 4, 2011, ORAU/ORISE conducted verification survey activities at the Separations Process Research Unit (SPRU) site that included in-process inspections, surface scans, and soil sampling of the Lower Level Hillside Area. According to the Type-B Investigation Report, Sr-90 was the primary contributor to the majority of the activity (60 times greater than the Cs-137 activity). The evaluation of the scan data and sample results obtained during verification activities determined that the primary radionuclide of concern, Sr-90, was well below the agreed upon soil cleanup objective (SCO) of 30 pCi/g for the site. However, the concentration of Cs-137 in the four judgmental samples collected in final status survey (FSS) Units A and B was greater than the SCO. Both ORAU and aRc surveys identified higher Cs-137 concentrations in FSS Units A and B; the greatest concentrations were identified in FSS Unit A.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2013

Project X: Accelerator Reference Design

Project X is a high-intensity proton facility being developed to support a world-leading program of Intensity Frontier physics over the next two decades at Fermilab. Project X is an integral part of the U.S. Intensity Frontier Roadmap as described in the P5 report of May 2008 [1] and within the Fermilab Strategic Plan of November 2011 [2]. This document represents Part I of the “Project X Book” describing the Project X accelerator facility and the broad range of physics research opportunities enabled by Project X. Parts II and III provide in-depth descriptions of the physics research program, both within and beyond particle physics [3]. The primary elements of the U.S. program to be supported by Project X include: Neutrino Experiments: Experimental studies of neutrino oscillations and neutrino interaction physics with ultra-intense neutrino beams provided by a high-power proton source with energies up to 120 GeV, utilizing near detectors at the Fermilab site and massive detectors at distant underground laboratories. Goal: At least 2 MW of proton beam power at any energy between 60 to 120 GeV; several hundred kW of proton beam power on target at 8 GeV. Kaon, Muon, Nucleon, and Neutron Precision Experiments: World-leading experiments studying ultra-rare kaon decays, searching for muon-to-electron conversion and nuclear electron dipole moments (EDMs), and exploring neutron properties at very high precision. Goal: MW-class proton beams supporting multiple experiments at 1 and 3 GeV, with flexible capability for providing distinct beam formats to concurrent users while allowing simultaneous operations with the neutrino program. Material Science and Nuclear Energy Applications: High-intensity accelerator, spallation, target and transmutation technology demonstrations will provide critical input into the design of future energy systems, including next generation fission reactors, nuclear waste transmutation systems and future thorium fuel-cycle power systems. Possible applications of muon spin rotation techniques provide sensitive probes of the magnetic structure of materials. Goal: Provide MW-class proton beams at 1 GeV, coupled with novel targets required to support a broad range of materials science and energy applications. Platform for Evolution to Future Frontier Facilities: A high-intensity proton source will strengthen and modernize the Fermilab injector complex, providing a robust platform upon which to build future frontier facilities. The Neutrino Factory and Muon Collider are examples that would provide world-leading capabilities at the Intensity and Energy Frontiers for many decades to come. Goal: Provide a straightforward upgrade path for a 4 MW, low-duty-factor source of protons at energies between 5 and 15 GeV. These four elements are expected to form the basis of the Mission Need statement required for the Department of Energy (DOE) Critical Decision 0 (CD-0), and represent the fundamental design criteria for Project X. The following chapters present the Reference Design for the Project X accelerator facility. The Reference Design is based on a continuous wave (CW) superconducting (SC) linac providing up to 1 and 3 MW of beam power at 1 and 3 GeV respectively. A pulsed linac provides acceleration of roughly 4% of the beam delivered from the CW linac to the 8 GeV injection energy of the existing Recycler/Main Injector complex. Upgrades to the Recycler and Main Injector support a factor of three increase, beyond current capabilities, in proton beam power at 60 to 120 GeV. The Reference Design represents a facility that will be unique in the world with unmatched capabilities for the delivery of very high beam power, with flexible beam formats, to multiple users at multiple energies. The utilization of linacs within the Project X facility enables capabilities beyond what is achievable with circular accelerators. It is anticipated that the final configuration and operating parameters of the complex will be further refined through the R&D program in advance of CD-2.

Holmes, Stephen D.↗
DOE OSTI2012

Impact of Natural Gas Appliances on Pollutant Levels in California Homes

This report presents results from the first year of a 2-year study, investigating associations of five air pollutants (CO, NO 2 , NO X , formaldehyde and acetaldehyde) with the presence of natural gas appliances in California homes. From November 2011 to March 2012, pollutant concentration and occupant activity data were collected in 155 homes for 6-day periods. The sample population included both single-family (68%) and multi-family (32%) dwellings, with 87% having at least one gas appliance and 77% having an unvented gas cooking appliance. The geometric mean (GM) NO 2 levels measured in the kitchen, bedroom and outside of homes were similar at values of 15, 12 and 11 ppb, respectively. In contrast, the GM NO X levels measured in the kitchen and bedroom of homes were much higher than levels measured outdoors, at levels of 42 and 41 ppb, compared to 19 ppb, respectively. Roughly 10% of sampled homes had 6-day average NO2 levels that exceeded the outdoor annual average limit set by the California Ambient Air Quality Standards (CAAQS) (30 ppb). The GMs of the highest 1-h and 8-h CO level measured in homes were 2.5 and 1.1 ppm, respectively. Four homes had a 1-h or 8-h concentration that exceeded the outdoor limits set by the CAAQS. The GM formaldehyde and acetaldehyde concentrations measured in homes were 15 and 7 ppb, respectively. Roughly 95% of homes had average formaldehyde levels indoors that exceeded the Chronic Reference Exposure Level set by the California EPA (7 ppb). Concentrations of NO 2 and NO X , and to a lesser extent CO were associated with use of gas appliances, particularly unvented gas cooking appliances. Based on first principles, it is expected that effective venting of cooking pollutant emissions at the source will lead to a reduction of pollutant concentrations. However, no statistical association was detected between kitchen exhaust fan use and pollutant concentrations in homes in this study where gas cooking occurred frequently. The lack of statistical

03 NATURAL GAS↗
DOE OSTI2016

IEA Task 32: Wind Lidar Systems for Wind Energy Deployment (LIDAR)

Under the International Energy Agency Wind Implementing Agreement (IEA Wind) Task 11, researchers started examining novel applications for remote sensing and the issues around them during the 51st topical expert meeting about remote sensing in January 2007. The 59th topical expert meeting organized by Task 11 in October 2009 was also dedicated to remote sensing, and the first draft of the Task's recommended practices on remote sensing was published in January 2013. The results of the Task 11 topical expert meetings provided solid groundwork for a new IEA Wind Task 32 on wind lidar technologies. Members of the wind community identified the need to consolidate the knowledge about wind lidar systems to facilitate their use, and to investigate how to exploit the advantages offered by this technology. This was the motivation that led to the start of IEA Wind Task 32 'Lidar Application for Wind Energy Deployment' in November 2011. The kick-off was meeting was held in May 2012.

17 WIND ENERGY↗
DOE OSTI2016

Multiscale Variability of the Tropopause Transition Layer During AMIE

An investigation has been carried out of the influence of the Madden-Julian Oscillation on the tropical tropopause layer (TTL) using data from the ARM MJO Investigation Experiment (AMIE) during the period October-November 2011. A variety of data from the ARM Mobile Facility deployed during AMIE on Gan Island have been used in the study: 3-hourly atmospheric soundings, the Ka-band ARM Zenith Radar (KAZR) radar reflectivity fields, and the ARM PI-Product CombRet (Combined Retrieval, Microphysical Retrievals, and Heating Rates) produced by PNNL. Additional data used in the study are from CALIPSO, ERAi reanalyses, DYNAMO (Dynamics of the MJO) sounding network observations, the S-PolKa radar on Gan Island, and the DOE ARM sites at Manus and Nauru.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Slipstream pilot-scale demonstration of a novel amine-based post-combustion technology for carbon dioxide capture from coal-fired power plant flue gas

Post-combustion CO 2 capture (PCC) technology offers flexibility to treat the flue gas from both existing and new coal-fired power plants and can be applied to treat all or a portion of the flue gas. Solvent-based technologies are today the leading option for PCC from commercial coal-fired power plants as they have been applied in large-scale in other applications. Linde and BASF have been working together to develop and further improve a PCC process incorporating BASF’s novel aqueous amine-based solvent technology. This technology offers significant benefits compared to other solvent-based processes as it aims to reduce the regeneration energy requirements using novel solvents that are very stable under the coal-fired power plant feed gas conditions. BASF has developed the desired solvent based on the evaluation of a large number of candidates. In addition, long-term small pilot-scale testing of the BASF solvent has been performed on a lignite-fired flue gas. In coordination with BASF, Linde has evaluated a number of options for capital cost reduction in large engineered systems for solvent-based PCC technology. This report provides a summary of the work performed and results from a project supported by the US DOE (DE-FE0007453) for the pilot-scale demonstration of a Linde-BASF PCC technology using coal-fired power plant flue gas at a 1-1.5 MWe scale in Wilsonville, AL at the National Carbon Capture Center (NCCC). Following a project kick-off meeting in November 2011 and the conclusion of pilot plant design and engineering in February 2013, mechanical completion of the pilot plant was achieved in July 2014, and final commissioning activities were completed to enable start-up of operations in January 2015. Parametric tests were performed from January to December 2015 to determine optimal test conditions and evaluate process performance over a variety of operation parameters. A long-duration 1500-hour continuous test campaign was performed from May to August 2016 at a selected process condition to evaluate process performance and solvent stability over a longer period similar to how the process would operate as a continuously running large-scale PCC plant. The pilot plant integrated a number of unique features of the Linde-BASF technology aimed at lowering overall energy consumption and capital costs. During the overall test period including startup, parametric testing and long-duration testing, the pilot plant was operated for a total of 6,764 hours out of which testing with flue gas was performed for 4,109 hours. The pilot plant testing demonstrated all of the performance targets including CO 2 capture rate exceeding 90%, CO 2 purity exceeding 99.9 mol% (dry), flue gas processing capacity up to 15,500 lbs/hr (equivalent to 1.5 MWe capacity slipstream), regeneration energy as low as 2.7 GJ/tonne CO 2 , and regenerator operating pressure up to 3.4 bara. Excellent solvent stability performance data was measured and verified by Linde and BASF during both test campaigns. In addition to process data, significant operational learnings were gained from pilot tests that will contribute greatly to the commercial success of PCC. Based on a thorough techno-economic assessment (TEA) of the Linde-BASF PCC process integrated with a 550 MWe supercritical coal-fired power plant, the net efficiency of the integrated power plant with CO 2 capture is increased from 28.4% with the DOE/NETL Case 12 reference to 30.9% with the Linde-BASF PCC plant previously presented utilizing the BASF OASE® blue solvent [Ref. 4], and is further increased to 31.4% using a Linde-BASF PCC plant with BASF OASE® blue solvent and an advanced stripper interstage heater (SIH) configuration. The Linde-BASF PCC plant incorporating the BASF OASE® blue solvent also results in significantly lower overall capital costs, thereby reducing the cost of electricity (COE) and cost of CO 2 captured from $147.25/MWh and $56.49/MT CO 2 , respectively, for the reference DOE/NETL Case 12 plant, to $128.49/MWh and $41.85/MT CO2 for process case LB1, respectively, and $126.65/MWh and $40.66/MT CO 2 for process case SIH, respectively. With additional innovative Linde-BASF PCC process configuration improvements, the COE and cost of CO 2 captured can be further reduced to $125.51/MWh and $39.90/MT CO 2 for a further optimized PCC process defined as LB1-CREB. Most notably, the Linde-BASF process options assessed have already demonstrated the potential to lower the cost of CO 2 captured below the DOE target of $40/MT CO 2 at the 550 MWe scale for second generation PCC technologies. Project organization, structure, goals, tasks, accomplishments, process criteria and milestones will be presented in this report along with highlights and key results from parametric and long-duration testing of the Linde-BASF PCC pilot. The parametric and long-duration testing campaigns were aimed at validating the performance of the PCC technology against targets determined from a preliminary techno-economic assessment. The stability of the solvent with extended operation in a realistic power plant setting was measured with performance verified. Additionally, general solvent classification information, process operating conditions, normalized solvent performance data, solvent stability test results, flue gas conditions data, CO 2 purity data in the gaseous product stream, steam requirements and process flow diagrams, and updated process economic data for a scaled-up 550 MWe supercritical power plant with CO 2 capture are presented and discussed in this report.

20 FOSSIL-FUELED POWER PLANTS↗
DOE OSTI2017

American Fuel Cell Bus Project Evaluation: Third Report

This report presents results of the American Fuel Cell Bus (AFCB) Project, a demonstration of fuel cell electric buses operating in the Coachella Valley area of California. The prototype AFCB, which was developed as part of the Federal Transit Administration's (FTA) National Fuel Cell Bus Program, was delivered to SunLine in November 2011 and was put in revenue service in mid-December 2011. Two new AFCBs with an upgraded design were delivered in June/July of 2014 and a third new AFCB was delivered in February 2015. FTA and the AFCB project team are collaborating with the U.S. Department of Energy (DOE) and DOE's National Renewable Energy Laboratory to evaluate the buses in revenue service. This report covers the performance of the AFCBs from July 2015 through December 2016.

33 ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2020

A Systems Biology Approach to Energy Flow in H 2 Producing Microbial Communities: Microbial Mats

This report describes the results of work conducted at NASA Ames Research Center, in collaboration with investigators at Lawrence Livermore National Laboratory, during the time period 12/15/2014 to 12/15/2017. The work was an extension of a collaboration with LLNL that began in 2008. Work this reporting period focused primarily on tasks related to microbial mats from both the Elkhorn Slough and Baja California field sites, including the analysis and publication of data produced prior to 12/15/2014. During this reporting period, in addition to the microbial mat work, we also conducted a series of experiments with a particular algal-bacterial association (C. sorokiniana and A. brasilense). A number of aspects of this well-characterized algal-bacterial association enabled us not only to further our understanding of interactions between these particular organisms, but to apply that knowledge and techniques to our collection of microorganisms isolated from microbial mats. Microbial mat experiments focused both on intact mat communities and on cultures of organisms isolated from the mats (the Microbial Mat Living Library). In a series of co-culture experiments, we documented both positive and negative interactions amongst heterotrophic and autotrophic isolates of microbial mat microorganisms. One particularly important and novel mat cyanobacterium (ESFC-1) was studied in detail. We developed techniques to pursue an investigation of functional redundancy (the idea that closely related organisms perform identical roles in a community) in cyanobacterial autotrophs in the Elkhorn Slough microbial mat. In those experiments, we documented numerous instances of increases in growth rate between co-cultures of two organisms (relative to their growth rate in isolation) performing what would seem to be identical functional roles. Simplified microbial mat communities consisting of organisms from the Microbial Mat Living Library were constructed and studied in laboratory experiments. The “constructed mats” were grown in standard laboratory glassware and plasticware, but cultures were also combined with artificial materials in an effort to re-create the three-dimensional structure of naturally occurring microbial mats. These constructed mats re-created a number of functions attributable to natural microbial mats (N-fixation, H2-production) and simplified their study using molecular ecological techniques due to the smaller number of microbial “species” present. Cyanobacteria which migrated in response to vertical variations in light intensity (irradiance) obtained characteristic positions in constructed mats that were similar to their positions in natural mats. A detailed investigation of nitrogen cycling in both the Baja California and Elkhorn Slough microbial mats was initiated during this reporting period. The nitrogen cycle in the microbial mats has not been studied in depth, despite the fact that nitrogen usually limits growth in marine environments. The organisms conducting nitrogen cycling in both microbial mats were studied using the genomes available from earlier work on these mats, as well as with a targeted approach using molecular ecological methods developed here. Quantitative measurements of rates of nitrogen transformations were made using stable isotopically labeled nitrogen. The processes quantified and examined using molecular ecological methods included: nitrogen fixation, ammonification, ammonium and nitrate assimilation, denitrification, anaerobic oxidation of ammonium, and dissimilatory nitrate reduction to ammonium. In a series of experiments designed to examine a potential application for microbial mats, we demonstrated that both Elkhorn Slough and Baja California microbial mats were very effective in removing large quantities of both nitrate and ammonium from waste streams containing these compounds at levels where they would be considered to be pollutants. Considerable effort was expended during this reporting period to analyze, and prepare for publication, metagenomes and metatranscriptomes collected from two experimental manipulations of microbial mats. The first, a diel study, was conducted in November 2011, while the second, an investigation of the effects of sulfate on community composition, was conducted during this reporting period. For the earlier study, reference-based and reference-free methods were used to assess microbial ecology and genetic partitioning in these complex microbial systems, and that work is available as a pre-print. Four metagenomes from the same experiment were published. In the second, longer (nearly 200 day) manipulation, rRNA iTag libraries for cDNA and DNA were analyzed to determine the effects of sulfate concentration on microbial mat community composition over the course of the experiment. Work on the algal-bacterial association (Chlorella sorokiniana and Azospirillum brasilense) focused initially on demonstrating the transfer of carbon and nitrogen between the partners, using stable isotopic labeling and the LLNL NanoSIMS. Subsequently, the potential role of diazotrophy (nitrogen fixation) by the bacterial partner in supporting the growth of the association was assessed in a series of experiments. It appears to be the case that, although the bacterial partner demonstrably increases the fitness of the algae under nitrogen limitation, and cells of C. sorokiniana receive nitrogen originally fixed from atmospheric nitrogen by A. brasilense, the amount of nitrogen obtained by diazotrophy is too small to explain the increase in fitness.

08 HYDROGEN↗
DOE OSTI2022

Quantitative Ceilometer-Radar Studies of Clouds Field Campaign Report

The Long Island Solar Farm (LISF) is a 32-megawatt solar photovoltaic power plant built through a collaboration including BP Solar, the Long Island Power Authority (LIPA), and the U.S. Department of Energy (DOE). The LISF, located on the Brookhaven National Laboratory site, began delivering power to the LIPA grid in November 2011, and is currently one of the largest solar photovoltaic power plants in the eastern United States. It is generating enough renewable energy to power approximately 4,500 homes and is helping New York State meet its clean energy and carbon reduction goals. Brookhaven National Laboratory (BN)L has the LISF instrumented and is capturing solar insolation and power data that can be used for research purposes. Additional information on LISF is available here: https://www.bnl.gov/lisf/. A network of nine high-definition (HD cameras) and 32 pyranometers are deployed within the LISF for the purpose of monitoring the location and characteristics of clouds and available global horizontal irradiance at the surface across the region. Information collected by this network every 30 s is currently used in BNL’s solar NowCasting algorithm, which forecasts near-term solar energy availability accounting for the behavior of clouds. The most important parameters for forecasting the near-term solar energy availability are accurate estimations of their horizontal extend, horizontal motion, and cloud base height. Currently, images from nearly located cameras are used to estimate the cloud base height. In order to evaluate the potential of this method for estimating the cloud base height, we decided to deploy a Vaisala ceilometer at the LISF.

14 SOLAR ENERGY↗
DOE OSTI2022

Scoping Analysis of MACCS Modeling Improvements for the Study of Protective Action Recommendations

In late 2004, the U.S. Nuclear Regulatory Commission (NRC) initiated a project to analyze the relative efficacy of alternative protective action strategies in reducing consequences to the public from a spectrum of nuclear power plant core melt accidents. The study is documented in NUREG/CR-6953, “Review of NUREG-0654, Supplement 3, ‘Criteria for Protective Action Recommendations for Severe Accidents,’” Volumes 1, 2, and 3. The Protective Action Recommendations (PAR) study provided a technical basis for enhancing the protective action guidance contained in Supplement 3, “Guidance for Protective Action Strategies,” to NUREG-0654/FEMA-REP-1, Rev. 1, “Criteria for Preparation and Evaluation of Radiological Emergency Response Plans and Preparedness in Support of Nuclear Power Plants, ” dated November 2011. In the time since, a number of important changes and additions have been made to the MACCS code suite, the nuclear accident consequence analysis code used to perform the study. The purpose of this analysis is to determine whether the MACCS results used in the PAR study would be different given recent changes to the MACCS code suite and input parameter guidance. Updated parameters that were analyzed include cohorts, keyhole evacuation, shielding and exposure parameters, compass sector resolution, and a range of source terms from rapidly progressing accidents. Results indicate that using updated modeling assumptions and capabilities may lead to a decrease in predicted health consequences for those within the emergency planning zone compared to the original PAR study.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2022

Similarity of the turbulent kinetic energy dissipation rate distribution in the upper mixed layer of the tropical Indian Ocean

Turbulence within the upper ocean mixed layer plays a key role in various physical, biological, and chemical processes. Between September and November 2011, a dataset of 570 vertical profiles of the turbulent kinetic energy (TKE) dissipation rate, as well as conventional hydrological and meteorological data, were collected in the upper layer of the tropical Indian Ocean. These data were used to statistically analyze the vertical distribution of the TKE dissipation rate in the mixed layer. The arithmetic-mean method made the statistical TKE dissipation rate profile more scattered than the median and geometric-mean methods. The statistical TKE dissipation rate were respectively scaled by the surface buoyancy flux and the TKE dissipation rate at the mixed-layer base. It was found that the TKE dissipation rate scaled by that at the mixed-layer base exhibited better similarity characteristics than that scaled by the surface buoyancy flux, whether the stability parameter D/|L MO | was greater or less than 10, indicating that the TKE dissipation rate at the mixed-layer base is a better characteristic scaling parameter for reflecting the intrinsic structure of the TKE dissipation rate in the mixed layer, where D and L MO are respectively the mixed-layer thickness and the Monin-Obukhov length scale. The parameterization of the TKE dissipation rate at the mixed-layer base on the shear-driven dissipation rate and the surface buoyancy flux was further explored. It was found that the TKE dissipation rate at the mixed-layer base could be well fitted by a linear combination of three terms: the wind-shear-driven dissipation rate, the surface buoyancy flux, and a simple nonlinear coupling term of these two.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Spin-down Evolution and Radio Disappearance of the Magnetar PSR J1622–4950

We report on 2.4 yr of radio timing measurements of the magnetar PSR J1622−4950 using the Parkes Observatory, between 2011 November and 2014 March. During this period the torque on the neutron star (inferred from the rotational frequency derivative) varied greatly, though much less erratically than during the 2 yr following its discovery in 2009. During the last year of our measurements the frequency derivative decreased in magnitude monotonically by 20%, to a value of −1.3 × 10{sup −13} s{sup −2}, a factor of 8 smaller than when it was discovered. The flux density continued to vary greatly during our monitoring through 2014 March, reaching a relatively steady low level after late 2012. The pulse profile varied secularly on a similar timescale as the flux density and torque. A relatively rapid transition in all three properties was evident in early 2013. After PSR J1622−4950 was detected in all of our 87 observations up to 2014 March, we did not detect the magnetar in our resumed monitoring starting in 2015 January and have not detected it in any of the 30 observations conducted through 2016 September.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Pseudo-automatic Determination of Coronal Mass Ejections’ Kinematics in 3D

Coronal mass ejection (CME) events are among the main drivers of geomagnetic disturbances, and hence play a central role in the Sun–Earth system. Their monitoring and, in particular, the determination of their speed and direction of propagation are key issues for the forecasting of space weather near to Earth. We have implemented a method to track CME events in three dimensions by combining triangulation and tie-pointing analysis with a supervised computer vision algorithm. This novel approach does not rely on any geometric constraint, and eliminates the need for visual identification of the CME boundaries. We applied our method to 17 CME events observed simultaneously by the twin Solar Terrestrial Relations Observatory ( STEREO ) COR2 coronagraph imagers from 2008 December to 2011 November in order to obtain their 3D kinematical characterization (i.e., the velocity vector) along with their morphological properties. About ten of these events have already been analyzed using other methodologies. In these cases, we carried out a thorough comparison with our results and found that, in spite of the different nature and spatial coverage range of the other methods with respect to CORSET3D, the majority of the results agree. We found, however, that three events exhibited discrepancies in the magnitude of the velocity vector, four in the longitudinal direction of propagation, and in only one case was there a discrepancy in latitude. The discrepancies appeared in those cases where quasi-simultaneous, quasi-co-located events were observed in the coronagraphs’ fields of view.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

On the Link between the Release of Solar Energetic Particles Measured at Widespread Heliolongitudes and the Properties of the Associated Coronal Shocks

Under the paradigm that the main agents in the acceleration of solar energetic particles (SEPs) are shocks initially driven by coronal mass ejections, we analyze whether the properties of the shocks in the corona inferred from combining extreme-ultraviolet (EUV) and white-light (WL) observations from multiple vantage points together with magnetohydrodynamic (MHD) simulations of the corona can be used to determine the release of SEPs into different regions of the heliosphere and hence determine the longitudinal extent of the SEP events. We analyze the SEP events observed on 2011 November 3, 2013 April 11, and 2014 February 25 over a wide range of heliolongitudes. MHD simulations provide the characteristics of the background medium where shocks propagate, in particular the Alfvén and sound speed profiles that allow us to determine both the extent of the EUV waves in the low corona and the fast magnetosonic Mach number ( M {sub FM}) of the shocks. The extent of the EUV waves in the low corona is controlled by this background medium and does not coincide with the extent of the SEP events in the heliosphere. Within the uncertainties of (i) the extent and speed of the shock inferred from EUV and WL images and (ii) the assumptions made in the MHD models, we follow the evolution of M {sub FM} at the region of the shock magnetically connected to each spacecraft. The estimated release times of the first SEPs measured by each spacecraft does not coincide with the time when the M {sub FM} at this region exceeds a given threshold.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2017

Simultaneous Observations of H{sub 2}O and SiO Masers toward OH/IR Stars

We performed simultaneous observations of SiO v = 1, 2, {sup 29}SiO v = 0, J = 1–0, and H{sub 2}O 6{sub 12}→5{sub 23} maser lines toward 252 OH/IR stars using the individual 21 m telescopes of the Korean VLBI Network (KVN). The observations for studying SiO and H{sub 2}O maser properties associated with the different evolutionary stages of OH/IR stars were carried out from 2011 November to 2012 July. Both H{sub 2}O and SiO masers were detected from 50 sources with a detection rate of 20% in one epoch of observation. One-sided SiO maser emissions without H{sub 2}O were detected from 108 sources and H{sub 2}O maser emission was detected from 11 sources, of which the detection rates were 43% and 4%, respectively. The overall detection rate of the SiO maser was 63%, and that of the H{sub 2}O maser was 24%. There were 65 new detections in the SiO maser lines, 22 new detections in the H{sub 2}O maser line, and 4 new detections in the {sup 29}SiO maser line. For the H{sub 2}O and/or SiO maser- detected sources, mutual relations between SiO and H{sub 2}O maser properties (including peak and integrated antenna temperatures, and full widths at zero power, etc.) are investigated based on a statistical analysis. We also investigate these maser properties on an IRAS two-color diagram related to stellar evolutionary sequences. In particular, a large number of SiO v = 2-only detected sources appear among the SiO-only detected sources compared to those of both H{sub 2}O and SiO maser detected sources and also appear in the later evolutionary stages of asymptotic giant branch AGB stars in the IRAS two-color diagram. These results may be associated with the development of a hot and thick dust envelope at later stages of AGB evolution and the different excitation conditions of SiO v = 1 and v = 2 masers. Our observational results will be useful for statistical studies of circumstellar envelopes of OH/IR stars related to their late evolution and future very long baseline interferometry (VLBI) observations.

79 ASTRONOMY AND ASTROPHYSICS↗