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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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1,493 records · Page 83
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

The Berkeley Sample of Stripped-Envelope Supernovae

We present the complete sample of stripped-envelope supernova (SN) spectra observed by the Lick Observatory Supernova Search (LOSS) collaboration over the last three decades: 888 spectra of 302 SNe, 652 published here for the first time, with 384 spectra (of 92 SNe) having photometrically determined phases. After correcting for redshift and Milky Way dust reddening and reevaluating the spectroscopic classifications for each SN, we construct mean spectra of the three major spectral subtypes (Types IIb, Ib, and Ic) binned by phase. We compare measures of line strengths and widths made from this sample to the results of previous efforts, confirming that OI λ7774 absorption is stronger and found at higher velocity in Type Ic SNe than in Types Ib or IIb SNe in the first ∼30 days after peak brightness, though the widths of nebular emission lines are consistent across subtypes. We also highlight newly available observations for a few rare subpopulations of interest.

spectroscopic↗
NASA NTRS2022

The Endurance Rocket Mission

NASA’s Endurance sounding rocket (yard No. 47.001) will launch from Ny Ålesund, Svalbard in May 2022 on a solid fueled Oriole III-A launch vehicle. Its ∼19 minute flight will carry it to an altitude of ∼780 km above Earth’s sunlit polar cap. Its objective is to make the first measurement of the weak “ambipolar” electric field generated by Earth’s ionosphere. This field is thought to play a critical role in the upwelling and escape of ionospheric ions, and thus potentially in the evolution of Earth’s atmosphere. The results will enable us to determine the importance to ion escape of this previously unmeasured fundamental property of our planet, which will aid in a better understanding of what makes Earth habitable. Endurance will carry six science instruments (with 16 sensors) that will measure the total electrical potential drop below the spacecraft, and the physical parameters required to understand the physics of what generates the ambipolar field. The mission will be supported by simultaneous observations of solar and geomagnetic activity.

Glyn Collinson↗
DOE OSTI2020

Safeguards Technical Objectives for Thorium Molten Salt Reactor Fuel Cycles

China, Denmark, France, India, Indonesia, the United Kingdom, and the United States, among others, are exploring commercial thorium fuel cycles for domestic power production and/or international export. For any thorium fuel cycle facilities built and/or operated in a non-nuclear weapon State with a comprehensive safeguards agreement, those facilities and any associated nuclear material would be subject to international nuclear safeguards by the International Atomic Energy Agency (IAEA). Thorium fuel cycle facilities offered for the application of safeguards under a voluntary offer agreement by a nuclear weapon State would also be subject to safeguards, if selected by the IAEA. Compared to uranium/plutonium fuel cycle facilities, thorium fuel cycle facilities are comparatively diverse from an inspection and accounting perspective, differing greatly in material type, form, and design from uranium/plutonium fuel cycle facilities and also from each other. Of these, the most complex thorium fuel cycles – and therefore likely the most challenging to the implementation of international nuclear safeguards – are those that include thorium molten salt reactors. With thorium fuel cycles approaching near-term commercial deployment timelines, it is imperative that the international nuclear safeguards community begins to think about how to adapt existing international nuclear safeguards concepts and approaches to thorium fuel cycles, as well as mitigate any gaps that may exist. This paper focuses on the development of recommended safeguards technical objectives for efficient and effective application of international nuclear safeguards measures (e.g., containment / surveillance, non-destructive assay, destructive assay, environmental sampling) to thorium molten salt reactors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2021

Design Considerations for the Field Use of International Nuclear Safeguards Technology

The process of developing and deploying safeguards technology should be carried out in such a way that it supports the International Atomic Energy Agency’s (IAEA’s) international safeguards verification mission, while also being efficient in terms of both cost and time. This process, however, may be hindered by a general lack of nuclear facility operating experience among the scientists or engineers designing safeguards technology, or the inability to interact with the IAEA inspector end user. As a result, equipment designers may have difficulty understanding inspector needs and the limitations of using safeguards technology in the field, often leading to inefficiencies (in the form of increased cost and time spent) in the safeguards technology design process. Here, to mitigate this knowledge gap, the Y-12 National Security Complex in Oak Ridge, Tennessee, has developed design considerations that should be incorporated into safeguards technologies, focusing on non-destructive assay equipment. Timelines for integration of these considerations into the design process are also discussed.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗
DOE OSTI2024

Time resolved X-ray diffraction using the FIDDLE diagnostic at NIF: Preliminary assessment of diffraction precision

The Flexible Imaging Diffraction Diagnostic for Laser Experiments (FIDDLE) is a new diagnostic at the National Ignition Facility (NIF) designed to observe in situ solid-solid phase changes at high pressures using time resolved X-ray diffraction. FIDDLE currently incorporates five Icarus Ultrafast X-ray Imager sensors that take 2 ns snapshots and can be tuned to collect X-rays for tens of ns. The platform utilizes the laser power at NIF for both the laser drive and the generation of 10 keV X-rays for ~10 ns using a Ge backlighter foil. We aim to use FIDDLE to observe diffraction at different times during compression to probe the kinetics of phase changes. Pb undergoes two solid-solid phase transitions during ramp compression: from FCC to HCP and HCP to BCC. Results will be reported on some of the first shots using the FIDDLE diagnostic at NIF on ramp compressed Pb to a peak pressure of ~110 GPa and a single undriven CeO2 calibration shot. A discussion of the uncertainties in the observed diffraction is included.

Vennari, C. E.↗