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At least 937 records · Page 52

Supernova-Explosion Mechanism Involving Neutrinos

A major part of the energy released upon the gravitational collapse of massive-star cores is carried away by neutrinos. Neutrinos play a crucial role in collapsing supernovae (SNe). At the present time, mathematical models of core-collapse SNe are based on multidimensional gas dynamics and thermonuclear reactions, whereas the neutrino transport is frequently treated in simplified way. An accurate analysis of neutrinos in a spherically symmetric gravitational collapse is performed on the basis of Boltzmann kinetic equations including all weak-interaction reactions with exact quantum-mechanical matrix elements. The role of multidimensional effects is studied bymeans of multidimensional gas dynamics allowing for the neutrino transport via diffusion treated by employing flux limiters. The possibility of largescale convection, which is of interest both from the point of view of explaining a type II supernova (SN) and from the point of view of implementing an experiment aimed at detecting possible energetic (≳10 MeV) neutrinos from an SN, is discussed. Thermonuclear burning leads to the explosion of a type I SN. A hot central region and the subsequent large-scale convection may also play an important role in the SN mechanism. If neutrinos and convection play a key role for a type II SN, then, in order to explain gamma radiation from product radioactive elements, convection is of importance in the case of SNe belonging to both types. In addition, convection may be important for bright type I SNe. Original methods are presented for multidimensional gas dynamics involving thermonuclear burning and for multitemperature gas dynamics involving radiative transfer.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Experimental Detection of the Signs of a Coulomb Explosion in Micropinch Plasma

A flow of ions with energies of about 3 MeV propagating in the direction perpendicular to the symmetry axis of discharge has been detected in high-current low inductance vacuum spark. Estimations show that the measured ion energies quite well correspond to the value that can be achieved as a result of “Coulomb explosion” of the waist of a plasma channel of discharge current at the stage preceding its radiation compression.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Explosive Ice Multiplication Induced by Multiplicative-Noise Fluctuation of Mechanical Breakup in Ice–Ice Collisions

The number of ice fragments generated by breakup of large graupel in collisions with small graupel fluctuates randomly owing to fluctuations in relative sizes and densities of colliding graupel particles and the stochastic nature of fracture propagation. This paper investigates the impact of the stochasticity of breakup on ice multiplication. When both the rate of generation of primary ice and the initial number concentration of ice crystals are low, the system most likely loses all the initial ice and graupel owing to a lack of sustaining sources. Even randomness does not change this mean evolution of the system in its phase space. However, a fluctuation of ice breakup number gives a small but finite chance that substantial ice crystal fragments are generated by breakup of large graupel. That, in turn, generates more large graupel. This multiplicative process due to fluctuations potentially leads to a small but finite chance of explosive growth of ice number.A rigorous stochastic analysis demonstrates this point quantitatively. The randomness considered here belongs to a particular category called ‘‘multiplicative’’ noise, because the noise amplitude is proportional to a given physical state. To contrast the multiplicative-noise nature of ice breakup with a standard ‘‘additive’’ noise process, fluctuation of the primary ice generation rate is also considered as an example of the latter. These processes are examined by taking the Fokker–Planck equation that explicitly describes the evolution of the probability distribution with time. As an important conclusion, stability in the phase space of the cloud microphysical system of breakup in ice–ice collisions is substantially altered by the multiplicative noise.

54 ENVIRONMENTAL SCIENCES↗

Growing Pacific Linkage with Western North Atlantic Explosive Cyclogenesis

Abstract Explosive cyclones (ECs), defined as extratropical cyclones that experience normalized pressure drops of at least 24 hPa in 24 h, are impactful weather events in the North Atlantic sector, but year-to-year changes in the frequency and impacts of these storms are sizeable. To analyze the sources of this interannual variability, we track cases of ECs and dissect them into two spatial groups: those that formed near the east coast of North America (coastal) and those in the north central Atlantic (high latitude). The frequency of high-latitude ECs is strongly correlated with the North Atlantic Oscillation, a well-known feature, whereas coastal EC frequency is statistically linked with an atmospheric wave train emanating from the North Pacific in the last 30 years. This wave train pattern of alternating high and low pressure is associated with heightened upper-level divergence and Eady growth rates along the east coast of North America, likely resulting in a stronger correspondence between the atmospheric wave train and coastal EC frequency. Using coupled model experiments, we show that the tropical and North Pacific oceans are an important factor for this atmospheric wave train and the subsequent enhancement of seasonal baroclinicity in the North Atlantic.

58 GEOSCIENCES↗

Polymorphic Phase Control of RDX-Based Explosives

The polymorphic phase of 1,3,5-trinitro-1,3,5-triazine (RDX) was examined as a function of mass loading, solvent, and sample deposition technique. When RDX was deposited at a high mass loading, the vibrational modes in the obtained Raman spectra were indicative of concomitant polymorphism as both the α-RDX and β-RDX phases were present. At low mass loadings, only β-RDX was observed regardless of solvent when using the drop cast crystallization method. However, α-RDX (the thermodynamically stable polymorphic phase observed with visible quantities of the explosive) was observed when RDX deposits were dry transferred. Observation of α-RDX was independent of the initial mass loading or the initial deposition solvent when using the dry transfer methodology. These data indicate that the use of the dry transfer preparation method can be used to successfully prepare RDX-based test articles with the α-RDX phase regardless of the solvent used to initially dissolve the RDX, the initial deposition technique, or the mass loading.

Brady, John J.↗

Exascale models of stellar explosions: Quintessential multi-physics simulation

The ExaStar project aims to deliver an efficient, versatile, and portable software ecosystem for multi-physics astrophysics simulations run on exascale machines. The code suite is a component-based multi-physics toolkit, built on the capabilities of current simulation codes (in particular Flash-X and Castro), and based on the massively parallel adaptive mesh refinement framework AMReX. It includes modules for hydrodynamics, advanced radiation transport, thermonuclear kinetics, and nuclear microphysics. The code will reach exascale efficiency by building upon current multi- and many-core packages integrated into an orchestration system that uses a combination of configuration tools, code translators, and a domain-specific asynchronous runtime to manage performance across a range of platform architectures. The target science includes multi-physics simulations of astrophysical explosions (such as supernovae and neutron star mergers) to understand the cosmic origin of the elements and the fundamental physics of matter and neutrinos under extreme conditions.

79 ASTRONOMY AND ASTROPHYSICS↗

PoroTomo: Horizontal Distributed Acoustic Sensing (DAS) Measurements During an M 2.3 Explosion

Included here are Distributed Acoustic Sensing (DAS) data collected by the horizontal DAS array at Brady's Hot Springs Geothermal Field. The system recorded this data during an M 2.3 explosion at the Nevada Test Site (NTS), which is located approximately 400km southeast of the field. On December 19, 2018, a Silixa iDAS interrogator continuously acquired data on single-mode fibers, starting approximately two hours prior to the detonation and extending until 15 minutes after the event. This dataset comprises separate SEG-Y files that span the entire recording interval. The measurement fiber was part of the PoroTomo experiment and is horizontally emplaced in alluvial fan gravels at a depth of approximately one meter for a distance of more than 2.5 km in a zig-zag pattern. Exact coordinates of this DAS surface array are provided in the attached GDR dataset below. The iDAS interrogator channel spacing is 1.021 m and gauge length is 10 m. Concurrent Distributed Temperature Sensing (DTS) measurements made with a Silixa XT on the multi-mode fibers aided in calibrating the DAS measurements.

15 GEOTHERMAL ENERGY↗

Nonlinearities in Magnetic Confinement, Ionospheric Physics, and Population Explosion Leading to Profile Resilience Нелінійності в магнетному утриманні, фізиці іоносфери та процесі демографічного вибуху, які приводять до стійкості профілю

Nonlinearities play an important role in many fields. In the field of thermonuclear fusion, they are involved in questions such as profile resilience and fluid closure. A nonlinear phenomenon common to both fusion and astrophysical planets is the generation of zonal flows. These flows play a significant role in determining the level of turbulence and fluid closure in fusion. The effects of resonance broadening and nonlinearities are investigated, specifically focusing on the case of nonlinear instability that has appeared in drift waves. Similarities and differences between our systems are discussed, with population explosion and the dynamics of nonlinear systems for drift waves by different states in profile resilience described with great precision. The aim of our study is to put our fluid model for drift waves in tokamaks within the wider framework of statistical physics principles. This reinforces our belief in the broad application of our drift wave model, which encompasses current tokamaks, ITER, and the fusion pilot plant.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

Explosion Discrimination Using Seismic Gradiometry and Spectral Filtering of Data

Here, we present a new method to discriminate between earthquakes and buried explosions using observed seismic data. The method is different from previous seismic discrimination algorithms in two main ways. First, we use seismic spatial gradients, as well as the wave attributes estimated from them (referred to as gradiometric attributes), rather than the conventional three-component seismograms recorded on a distributed array. The primary advantage of this is that a gradiometer is only a fraction of a wavelength in aperture compared with a conventional seismic array or network. Second, we use the gradiometric attributes as input data into a machine learning algorithm. The resulting discrimination algorithm uses the norms of truncated principal components obtained from the gradiometric data to distinguish the two classes of seismic events. Using high-fidelity synthetic data, we show that the data and gradiometric attributes recorded by a single seismic gradiometer performs as well as a conventional distributed array at the event type discrimination task.

58 GEOSCIENCES↗

Joint Inversion of Regional Waveform, First-Motion Polarity, and Synthetic Aperture Radar Surface Displacement for the Fourth and Sixth North Korean Declared Nuclear Explosions

Here, this study analyzed the Democratic People’s Republic of Korea’s (DPRK) fourth (DPRK4, 6 January 2016 M w 4.49) and sixth (DPRK6, 7 September 2017 M w 5.2) declared nuclear tests, employing a joint seismic and Interferometric Synthetic Aperture Radar (InSAR) inversion to improve understanding of these events and enhance moment tensor (MT) inversion capabilities. The recent efforts have focused on employing seismic waveform and InSAR geodetic deformation data separately to analyze these and the previous nuclear tests (e.g., Chiang et al., 2018; Myers et al., 2018; Wang et al., 2018). Building upon our previous work (Chi-Durán et al., 2021), we performed a joint regional waveform, first-motion (FM) polarity, and surface displacement inversion, which demonstrated improved source-type discrimination, a revised MT solution with reduced scalar moment uncertainty, and an independently constrained location. In this article, we build on the previous results for DPRK6 by including an analysis using a four-layered velocity model with free-surface topography to compute the near-source static deformation Green’s functions. The model consists of a 50 m basalt layer (⁠V P = 2.07 km/s, V S = 1.2 km/s⁠), a 250 m stratified volcanic deposit layer (⁠V P = 1.73 km/s, V S = 1.0 km/s⁠), a 700 m weathered granodiorite layer (⁠V P = 2.5 km/s, V S = 1.3 km/s⁠⁠), and a granodiorite half-space (⁠V P = 5.35 km/s, V S = 3.09 km/s⁠⁠). The half-space shares the velocity of the regional MDJ2 velocity model (Ford et al., 2010), which has proven effective for waveform inversion in the region. This model considers the range of reported values for various lithologies and weathering effects. Our findings show that using the layered velocity model enhances the recovery of source location and depth for both the explosions by improving fits and reducing uncertainties. The joint inversion also improves source-type discrimination and better constrains the scalar seismic moment necessary for downstream yield estimation.

58 GEOSCIENCES↗

Moment Tensor Source-Type Analysis for the Democratic People's Republic of Korea-Declared Nuclear Explosions (2006-2017) and 3 September 2017 Collapse Event

The Democratic People's Republic of Korea (DPRK) conducted its sixth announced nuclear test on 3 September 2017 03:30 UTC (mb 6.1). There was an aftershock 8.5 min later (mb 4.1). Such aftershocks were noteworthy and often associated with post–nuclear explosion collapses. We performed moment tensor (MT) and network sensitivity solution (NSS) analysis using regional long-period surface-wave and first-motion (FM) polarities. We also extended this analysis to the previous five DPRK nuclear tests. The NSS results, which include MT solution uncertainties, show large isotropic components for the events and are within the population of other U.S. nuclear and collapse events on the fundamental lune. The FM data improved the NNS source-type resolution. The agreement between MT seismic moments and independent coda-envelope amplitudes indicated no biases with the Earth model error or poorly constrained seismic moment for shallow seismic sources. The MT for the collapse is not a pure implosion and consistent with an equivalent tensional closing crack mechanism and two-sided vertical point force.

58 GEOSCIENCES↗

Data supporting the article titled "Heterogeneous Multiphase Flow Properties of Volcanic Rocks and Implications for Noble Gas Transport from Underground Nuclear Explosions"

The submission is a Reproducible Research (RR) data archive that contains the supporting multiphase fluid flow and curve fitting results of the Vadose Zone Journal article titled: "Heterogeneous Multiphase Flow Properties of Volcanic Rocks and Implications for Noble Gas Transport from Underground Nuclear Explosions." The article's DOI number is the following: https://doi.org/10.1002/vzj2.20123. Please see the "Methods and Materials" section of the journal article and the ReadMe.txt in the RR_ARCHIVE folder for further details. Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND Number: SAND2021-3407 O.

mercury injection capillary pressure↗

A Study of China s Explosive Growth in the Plug-in Electric Vehicle Market

The year 2015 marks a turning point in China s plug-in electric vehicle (PEV) or new energy vehicle (NEV) industry, with an explosive growth in both productions and sales, following the gloomy period of 2009-2012. The PEV production in 2015 reached a record level of nearly 380,000 units, a 352 % increase from 2014, making China the largest PEV market in the world. For the potential implications on energy and the environment, it is worth studying the driving forces of China s PEV market and understanding its future trajectory and dynamics. The key findings of this report are listed in the following. Though controversial, the government monetary incentives have played a significant role to impel China to be the largest light PEV (191,100 units) market in the world. Chinese vehicle buyers appear more price sensitive on PEVs. Inexpensive low-cost micro electric vehicles are the most popular vehicle model in China s PEV market (38.9 % of the PEV market in 2015). In contrast, the premium or luxury vehicles are more popular in the gasoline vehicle segment. In fact, China is expected to be the largest premium car market in 2016. The PEV sales growth is primarily possible because of the young domestic private-owned auto manufacturers, which are mostly located in south China. Top-tier conventional vehicle automakers in China appear to be less proactive in the PEV market, based on market shares. This is in clear contrast to the U.S. market, where major automakers are generally the primary players in the PEV market. The PEVs produced by the domestic automakers are concentrated in the low-end market segment, while the high-end vehicle segment is dominated by the foreign brands. At present, the substantial market growth and government subsidies afford the domestic entrants to quickly gain profits in the low-end segment. The PEV consumers in China are very sensitive to the vehicle price, thus prefer the PEVs with cheaper prices after government subsidies, and care less about the driving quality and comfort. In contrast, most PEV consumers in the United States (U.S.) have higher incomes, view the PEVs as a high-status symbol, and care less about the vehicle prices, and therefore welcome the premium PEVs more in the U.S. The PEV financial subsidies by the Chinese government are divided into three stages based on the strategic directions and policies. In 2009 2012, government incentives concentrated on the public fleet vehicles, while excluding the individual consumers from the subsidies in most cities. In 2013 2015, comprehensive central/local government incentives were extended to all vehicle purchasers including the individual buyers in most cities, which was conducive to the phenomenal growth of the PEV sales. For years 2016 to 2020, monetary incentives are being phased out and will be substituted by other non-monetary incentives (such as the standards for Chinese Cooperate Average Fuel Consumption and New Energy Vehicle Credits) for the sustainable development of the PEV market. The PEV subsidy fraud has drawn attention by the central government, which prompts the government to be more prudent about monetary incentives. With the advantage of high acceptance in the PEV market and integrated EV charging infrastructure, the region with better economic development brings a more aggressive PEV roll-out plan to the municipalities who are more willing to solve the local urban pollution while keeping the automotive market in sustainable growth. On the one hand, the local automakers are offered abundant subsidies from the Chinese government to those who intend to help the Chinese automotive industry seize the industrial upgrading opportunity to transform its manufacturing sector, and they have taken most shares of the PEV market. On the other hand, facing the trade barriers, the foreign automakers have dominated the premium PEV sales in China, although their total market shares in the PEV market are much less than the domestic automakers. In diverse selectable alternative fuel vehicle technologies, China has put its focus on the PEV technologies for the technological modernization in the automotive industry; the research and development in fuel cell vehicle technologies in China is less competitive compared with other countries such as Japan and the U.S. With the demand of batteries from the PEV automakers, the Chinese EV battery industry is aggressively expanding. It has risks in excessive production capacity, and faces the challenges from the competitors from Japan and South Korea.

33 ADVANCED PROPULSION SYSTEMS↗

Explosive Infrasonic Events: Sensor Comparison Experiment (SCE)

SCE (sensor comparison experiment) 1 through 4 consists of a series of four controlled above-ground explosions designed to provide new data for overpressure propagation. Infrasound data were collected by LLNL iPhones and other sensors. Origin times, locations HOB, and yields are not being released at this time and are therefore not included in this report. This preliminary report will be updated as access to additional data changes, or instrument responses are determined.

47 OTHER INSTRUMENTATION↗