Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “hot plasma”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Solar reflection of dark matter with dark-photon mediators

Abstract We consider the scattering of low-mass halo dark-matter particles in the hot plasma of the Sun, focusing on dark matter that interact with ordinary matter through a dark-photon mediator. The resulting “solar-reflected” dark matter (SRDM) component contains high-velocity particles, which significantly extend the sensitivity of terrestrial direct-detection experiments to sub-MeV dark-matter masses. We use a detailed Monte Carlo simulation to model the propagation and scattering of dark-matter particles in the Sun, including thermal effects, with special emphasis on ultralight dark-photon mediators. We study the properties of the SRDM flux, obtain exclusion limits from various direct-detection experiments, and provide projections for future experiments, focusing especially on those with silicon and xenon targets. We find that proposed future experiments with xenon and silicon targets can probe the entire “freeze-in benchmark”, in which dark matter is coupled to an ultralight dark photon, including dark-matter masses as low as 𝒪(keV). Our simulations and SRDM fluxes are publicly available.

Astronomy & Astrophysics↗
DOE OSTI2023

Near-threshold resonances in C 11 and the B 10 ( p , α ) Be 7 aneutronic reaction

The nucleus 11 C plays an important role in the boron-proton fusion reactor environment as a catalyzer of the 10 B(p,α) 7 Be reaction which, by producing a long-lived isotope of 7 Be, poisons the aneutronic fusion process 11 B(p,2α) 4 He. The low-energy cross section of 10 B(p,α) 7 Be depends on the near-threshold states 7/2$^{+}_{1}$, 5/2$^{+}_{2}$, 5/2$^{+}_{3}$ in 11 C whose properties are primarily known from the indirect measurements. Here we investigate the continuum-coupling induced collectivization of these resonances in the shell model embedded in the continuum. We predict a significant enhancement of the 10 B(p,α) 7 Be cross section at energies accessible to the laser-driven hot plasma facilities.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2022

Shock revival in core-collapse supernovae assisted by heavy axionlike particles

We report axionlike particles (ALPs) are a class of hypothetical pseudoscalar particles which feebly interact with ordinary matter. The hot plasma of core-collapse supernovae is a possible laboratory to explore physics beyond the standard model including ALPs. Once produced, some of the ALPs can be absorbed by the supernova matter and affect energy transfer. In this study, we calculate the ALP emission in core-collapse supernovae and the backreaction on supernova dynamics consistently. It is found that the stalled bounce shock can be revived if the coupling between ALPs and photons is as high as $g_{aγ}$ ~ 10 -9 GeV -1 and the ALP mass is 40–400 MeV. Most of the models result in more energetic explosions than the average observed supernova. While this can be used to place constraints on those ALPs, long-term simulations across multiple progenitors need to be further investigated to place robust limits.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Principal Challenges in Toroidal Magnetic Confinement Fusion Systems

Research efforts toward a practical and economical magnetically confined fusion power source have made steady progress over the years. Today, the principal approaches to confining a hot plasma of Deuterium and Tritium ions long enough for a significant frac/on to undergo thermonuclear burn employ toroidal geometries. Such geometries are attractive because charged particles are tightly bound around the field lines, undergoing locally helical orbits as they travel along those lines. In the core regions of the plasma, the field lines have no connection to the material surfaces making up the interior of the vacuum vessel, so that plasma confinement times can be long enough for significant thermonuclear burnup via fusion reactions to take place. For good confinement, the geometry of the field lines must be such that nested field lines (which lie on nested flux surfaces) twist around the toroidal axis (a quasi-circular line that approximately lies in the center of the confined plasma) at rates that vary based on their distance from that axis. The rotational transform (or field line pitch), iota/2π , is defined as the number of poloidal transits per single toroidal transit of a field line on a toroidal flux surface.

42 ENGINEERING↗
DOE OSTI2025

NewLife Nuclear - An Environmentally and Economically Minded Solution for Fusion Energy Waste Handling

Energy demand is rising as a result of innovative and increasingly more energy intensive processes coming to fruition, particularly through the recent interest in the development of AI data centers as well as manufacturing with the push towards increasing domestic manufacturing interest. Fusion energy can provide virtually limitless energy to support this increase in energy demand. Fusion energy concepts, largely classified as magnetic fusion energy (MFE) and inertial fusion energy (IFE) are being pursued, each having unique challenges to overcome before the successful deployment of electricity to the grid. Achieving fusion ignition on the National Ignition Facility, first in December 2022, and eight times since, has demonstrated the scientific viability of the IFE approach. Meanwhile, MFE test stands continue to improve confinement times, making meaningful strides in progressing towards experimental scientific viability. In each of these approaches, an emphasis is placed on generating more power out of the system than what is required to power the system. An under-researched area applicable to both IFE and MFE is handling activated waste coming out of fusion energy systems, both in the course of normal daily operations, as well as in intermittent periods as structural materials may need to be replaced. In the context of an IFE plant system, commonly discussed plant designs suggest targets are ignited within a chamber at a rate of up to one million targets per day. Between each shot, the chamber housing the ignition event will clear a portion of the chamber – resulting in a mixture of vaporized target gas, target debris, and other materials being expelled from the chamber [source]. Additionally, IFE system concepts typically discuss the modularization of plant designs, which are expected to be replaced periodically as the components degrade over time. This would result in the irradiated chamber structure materials, likely metals and alloys, needing to be removed and safely stored. In MFE plant systems, while targets are not ignited at a repetition rate with the frequent chamber clearing as is expected in IFE plant systems, it is anticipated that portions of the confinement area interfacing with the hot plasma will need to be replaced periodically. In each system, without additional investment and research into alternative processing and recycling methods, the result is storing irradiated materials, and other elements in a safe containment area until they are no longer activated. – resulting in significant waste both economic and environmental.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Evolution of the Thermodynamic Properties of Clusters of Galaxies out to Redshift of 1.8

The thermodynamic properties of the hot plasma in galaxy clusters retains information on the processes leading to the formation and evolution of the gas in their deep, dark matter potential wells. These processes are dictated not only by gravity but also by gas physics, e.g. AGN feedback and turbulence. Here, we study the thermodynamic properties, e.g. density, temperature, pressure, and entropy, of the most massive and the most distant (z > 1.2) SPT-selected clusters, and compare them with those of the nearby clusters (z < 0.1) to constrain their evolution as a function of time and radius. We find that thermodynamic properties in the outskirts of high redshift clusters are remarkably similar to the low redshift clusters, and their evolution follows the prediction of the self-similar model. Their intrinsic scatter is larger, indicating that the physical properties that lead to the formation and virialization of cluster outskirts show evolving variance. On the other hand, thermodynamic properties in the cluster cores deviates significantly from self-similarity indicating that the processes that regulate the core are already in place in these very high redshift clusters. This result is supported by the unevolving physical scatter of all thermodynamic quantities in cluster cores.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

SZ–X-Ray Surface Brightness Fluctuations in the SPT-XMM Clusters

The hot plasma in galaxy clusters, the intracluster medium, is expected to be shaped by subsonic turbulent motions, which are key for heating, cooling, and transport mechanisms. The turbulent motions contribute to the nonthermal pressure, which, if not accounted for, consequently imparts a hydrostatic mass bias. Accessing information about turbulent motions is thus of major astrophysical and cosmological interest. Characteristics of turbulent motions can be indirectly accessed through surface brightness fluctuations. This study expands on our pilot investigations of surface brightness fluctuations in the Sunyaev–Zel’dovich and in X-ray data by examining, for the first time, a large sample of 60 clusters using both SPT-SZ and XMM-Newton data and spans the redshift range 0.2 < z < 1.5, thus constraining the respective pressure and density fluctuations within 0.6 R $_{500}$. We deem density fluctuations to be of sufficient quality for 32 clusters, finding mild correlations between the peak of the amplitude spectra of density fluctuations and various dynamical parameters. We infer turbulent velocities from density fluctuations with an average Mach number $\mathcal{M}$ 3D = 0.52 ± 0.14, in agreement with numerical simulations. For clusters with inferred turbulent Mach numbers from fluctuations in both pressure, $\mathcal{M}$ P , and density, $\mathcal{M}$ ρ , we find broad agreement between $\mathcal{M}$ P and $\mathcal{M}$ ρ . Our results suggest either a bimodal or a skewed unimodal Mach number distribution, with the majority of clusters being turbulence-dominated (subsonic) while the remainder are shock-dominated (supersonic).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Magnetically Arrested Circumbinary Accretion Flows

Abstract Binary systems with comparable masses and a surrounding accretion disk can accrete gas through spiral accretion streams penetrating the central cavity formed by tidal interactions. Using three-dimensional Newtonian magnetohydrodynamics simulations, we investigate the possibility of a magnetically arrested accretion flow through the cavity. Rather than solely continuously feeding the binary through spiral accretion streams, the accretion is regulated by the strong magnetic field inside the cavity. Transport of mass and angular momentum onto the binary then proceeds largely periodically in magnetic flux eruption episodes. The ejected flux tubes carry angular momentum outward and away from the binary, inject hot plasma into the disk, and can launch flares. This likely intermittent scenario could have potential implications for the emission signatures of supermassive black hole binaries and shed light onto the role magnetic fields play in the binary’s orbital evolution.

Astronomy & Astrophysics↗
DOE OSTI2025

Comparing XRISM Cluster Velocity Dispersions with Predictions from Cosmological Simulations: Are Feedback Models Too Ejective?

The dynamics of the intracluster medium (ICM), the hot plasma that fills galaxy clusters, are shaped by gravity-driven cluster mergers and feedback from supermassive black holes (SMBHs) in the cluster cores. XRISM measurements of ICM velocities in several clusters offer insights into these processes. We compare XRISM measurements for nine galaxy clusters (Virgo, Perseus, Centaurus, Hydra-A, PKS 0745–19, A2029, Coma, A2319, and Ophiuchus) with predictions from three state-of-the-art cosmological simulation suites, TNG-Cluster, the Three Hundred Project GADGET-X, and GIZMO-SIMBA, that employ different models of feedback. In cool cores, XRISM reveals systematically lower velocity dispersions than the simulations predict, with all 10 measurements below the median simulated values by a factor of 1.5–1.7 on average and all falling within the bottom 10% of the predicted distributions. The observed kinetic-to-total pressure ratio is also lower, with a median value of 2.2%, compared to the predicted 5.0%–6.5% for the three simulations. Outside the cool cores and in non-cool-core (NCC) clusters, simulations show better agreement with XRISM measurements, except for the outskirts of the relaxed, cool-core cluster A2029, which exhibits an exceptionally low kinetic pressure support (<1%), with none of the simulated systems in either of the three suites reaching such low levels. The NCC Coma and A2319 exhibit dispersions at the lower end but within the simulated spread. Our comparison suggests that the three numerical models may overestimate the kinetic effects of SMBH feedback in cluster cores. Additional XRISM observations of NCC clusters will clarify if there is a systematic tension in the gravity-dominated regime as well.

galaxy clusters↗
NASA NTRS1966

X-ray and gamma-ray astronomy

Sources of X-rays and high-energy gamma rays, including inverse Compton effect, synchrotron radiation, brehmsstrahlung from hot plasma, and decay of neutral pions

X-RAY ASTRONOMY↗
NASA NTRS1969

Discrete extrasolar X-ray sources.

Galactic X ray sources observed in EM spectrum high energy region, discussing hot plasma cloud thermal radiation and electrons synchrotron radiation as emission sources

Rossi, B. B.↗
NASA NTRS1964

Injection and distribution of liquids in the flow fields of blunt shapes at hypersonic speeds

A possible method for reducing the attenuation of radio transmission from hypersonic vehicles is by injection of a liquid into the flow field. The hot plasma layer surrounding the vehicle could presumably be quenched if the latent heat of the liquid and the heat capacity of the vapor could be utilized efficiently. In the case of stagnation-point injection, the momentum of the liquid could be utilized to modify the bow shock and possibly reduce the initial ionization. To attain these objectives of efficient coolant utilization or modification of the bow shock a knowledge of the liquid injection, atomization, spray penetration, and evaporation processes is required. This report presents the results of a study of liquid injection into hypersonic flow fields. A simplified theory for evaporation distances is derived and is shown to be in qualitative agreement with experimental data. Correlation of experimental data for maximum cross-current penetration of the liquid spray for injection near the shoulder pf a hemisphere cylinder, a sphere 9° cone, and a Mercury model are given. These data were obtained in the Langley Mach 8 variable density tunnel with both liquid nitrogen and water injection to provide a large range of liquid parameters. Flow-field disturbances, as indicated by schlieren photographs and surface pressures, increased with the ratio of coolant mass flux to airstream mass flux. For stagnation-point injection, the maximum shock standoff distance was correlated by the ratio of the liquid jet momentum flux to the airstream momentum flux.

Ivan E. Beckwith↗
NASA NTRS1972

Spacecraft charging at synchronous orbit.

Observation that ATS 5 can charge to potentials as high as 10,000 volts during eclipse, and as high as 200 volts in sunlight. This charging has been used to infer the presence of the plasmasphere at synchronous altitude in the midnight region, and its prompt disappearance when hot plasma is injected in association with substorms. Although injected plasma has a density of 1.0 per cu cm the remaining cold plasma (less than 50 eV) has a density of 0.01 per cu cm. A mathematical model of ATS 5 has been constructed that can be used to predict spacecraft potentials. In addition, parts of ATS 5 can charge to several hundred volts without affecting the overall spacecraft potential appreciably.

Deforest, S. E.↗