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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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At least 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

ESRA Mission Overview for MMO [Slides]

The Experiment for Space Radiation Analysis (ESRA) is a pathfinder for rapid Demonstration and Validation (DemVal) missions that the Los Alamos National Laboratory will fly on a 4-year cadence. The primary goal is to provide TRL maturation and risk reduction for next generation systems.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Resolution of a few problems in the application of quasilinear theory to calculating diffusion coefficients in heliophysics [Slides]

Three problems with the historical literature were discussed. Kennel and Engelmann (1966): ‘notational error’ that implies that diffusion coefficients depend on the distribution of wave power with respect to ψ. This dependence is unphysical and is not present in Lyons+ 1971. Kennel and Engelmann (1966) assume that only a single frequency can be associated with each wave vector: not necessarily true for EMIC, e.g. Lyons (1974a, 1974b) incorrectly used the Jacobian to relate the power spectral density in (ω,χ) space to that into (κ ⊥ , κ ∥ space. The correct use of the Jacobian: (1) Eliminates undesirable properties associated with N(ω) : lack of integrability, lack of superposition; and (2) Can produce orders of magnitude changes to the diffusion coefficients, but depends on the wave distribution: bigger effect for more oblique waves, and depends on the plasma parameter: bigger effect for smaller $ω_{pe}/ω_{ce}$.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Magnetic Reconnection in Solar Flares [Slides]

Magnetic reconnection is the underlying mechanism in solar flares. Magnetic reconnection is an astrophysical process in an electrically conducting plasma where neighboring magnetic field lines running anti-parallel break and reconnection therefore exchanging the direction of their paths. The result of this process is the magnetic field energy converting to kinetic and thermal energy which is explosively released. The scale of a solar is extremely large compared to Earth so kinetic simulations are unable to portray an accurate model. In this project, we are using an astrophysical magnetohydrodynamic (MHD) simulation code known as Athena++ with the reconnection problem generator file created by Li et al. 2018. To further study this simulation, we began testing a heating/cooling term. The results of the original file will be compared with the modified file with an implemented heating/cooling term to better understand how solar flares function.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Algorithm Theoretical Basis Document For PreMevE 2.0 Model

Man-made satellites operating in medium- and high-altitude Earth orbits are continuously exposed to hazardous space radiation originated from different sources. Among them, one major contributor is the relativistic electron population—with kinetic energies comparable to or larger than their rest energy of 0.511 Megaelectron-volt (MeV)—trapped inside Earth’s outer Van Allen belt. Owing to their high penetration capability, these MeV electrons are difficult to be fully stopped by normal shielding. Particularly, during MeV electron events when electron intensities across the outer belt are greatly elevated to sustaining high levels—up to 10 3 - 10 4 times as observed in the geosynchronous (GEO) orbit and low-Earth-orbits (LEOs), space-borne electronic systems with inadequate hardening are susceptible to deep-dielectric charging and discharging phenomenon caused by those electrons, and thus may suffer severe damages or even stop functioning. Therefore, protecting critical space infrastructures from harsh space weather conditions– including MeV electron events – has high priority for many space sectors, such as the aerospace industry, service providers and government agencies.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Simulating of magnetic reconnection in solar flares

Magnetic reconnection is an astrophysical process where neighboring magnetic field lines running anti-parallel are reconfigured. Observations of solar flares are what pushed for serious research regarding magnetic reconnection as it seemed to be the underlying mechanism. The reconfiguration of the field lines results in an explosive release of energy as magnetic field energy is converted into plasma kinetic and thermal energies. Our work begins with Athena++, an astrophysical magnetohydrodynamic (MHD) simulation code, and an existing magnetic reconnection setup.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Simulating ‘Two Ribbon’ Type Solar Flares [Slides]

The underlying mechanism in solar flares in a process known as magnetic reconnection. This astrophysical process is when magnetic field lines, running anti-parallel, break and reconnect. The change in configuration of field lines results in an explosive release of energy as the leftover magnetic energy is converted to kinetic and thermal energies. In this project, we are using an astrophysical magnetohydrodynamic (MHD) simulation code known as Athena++ with a reconnection problem generator file created by Li et al. 2018. Our current research is to successfully implement a radiative cooling term into the MHD equations as it could have important physical effects on the plasma. We use Klimchuk et al. 2008 and SPEX_DM as our chosen cooling functions. The results from the SPEX_DM function show there is a condensation forming that we had predicted but had not seen before with our simulation code. We will continue to analyze the SPEX_DM function and potentially implement thermal conduction.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Fall SULI Report

This fall, I interned under Fan Guo and Xiaocan Li in T-2 at Los Alamos National Laboratory through the SULI program. I investigated how shock thickness is impacted by collisions between particles in plasmas and how particle acceleration in shocks is impacted by the mass ratio for protons and electrons used in simulations. Both investigations were carried out using the VPIC simulation code. I found that collisions do not meaningfully impact shock width and that higher mass ratios lead to somewhat more electron acceleration in shocks. This write-up is in three parts, the first discussing a description of what I was up to personally throughout the fall, the second discussing the results of the collisional shock study, and the third discussing the results of the high mass ratio shock study.

79 ASTRONOMY AND ASTROPHYSICS↗