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Results for “CONFINEMENT”

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 109 records · Page 6

All sources NASA NTRS DOE OSTI

NASA NTRS2003

Exercise load index and changes in body weight during long-duration confinement in an isolated environment

PURPOSE: The objectives of this project were to investigate exercise load and body weight related to long-duration confinement in a closed environment simulating ISS flight conditions, and to evaluate subjects' motivation to continue the experiment and their adaptation to isolation. METHODS: Four Russian male subjects participated in a 240-d experiment (Group I), and four subjects (three male subjects and one female subject) from Austria, Canada, Japan, and Russia participated in a 110-d experiment (Group II). Exercise load was estimated during confinement using a modified Rating of Perceived Exertion scale. Free reports were used to determine subjects' motivation. Body weight was measured before, during, and after confinement. RESULTS: Group I achieved their lowest exercise loads during their first month of isolation; problems with adaptation to the isolation environment were also reported during this first month. Group II exercise load was significantly lower in the second month due to crewmember problems; loss of motivation could be noted from their free reports. The subject with the lowest exercise load retired from the isolation experiment earlier than scheduled. Exercise load was not correlated with prior exercise habits. Significant differences in body weight was observed between group I and II and between Russian and non-Russian subjects. One subject in Group I experienced a significant increase in his body weight. CONCLUSION: Exercise load may be a good indicator for adaptation problems and motivation changes in closed environments. Immobility, lack of space, and smoking cessation in general did not induce significant body weight changes.

Exercise/physiology↗

NASA NTRS2000

Efficient Multi-Dimensional Simulation of Quantum Confinement Effects in Advanced MOS Devices

We investigate the density-gradient (DG) transport model for efficient multi-dimensional simulation of quantum confinement effects in advanced MOS devices. The formulation of the DG model is described as a quantum correction ot the classical drift-diffusion model. Quantum confinement effects are shown to be significant in sub-100nm MOSFETs. In thin-oxide MOS capacitors, quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion of quantum effects may reduce gate capacitance by 25% or more. As a result, the inclusion of quantum effects in simulations dramatically improves the match between C-V simulations and measurements for oxide thickness down to 2 nm. Significant quantum corrections also occur in the I-V characteristics of short-channel (30 to 100 nm) n-MOSFETs, with current drive reduced by up to 70%. This effect is shown to result from reduced inversion charge due to quantum confinement of electrons in the channel. Also, subthreshold slope is degraded by 15 to 20 mV/decade with the inclusion of quantum effects via the density-gradient model, and short channel effects (in particular, drain-induced barrier lowering) are noticeably increased.

Biegel, Bryan A.↗

NASA NTRS2005

A Spreadsheet for the Mixing of a Row of Jets with a Confined Crossflow

An interactive computer code, written with a readily available software program, Microsoft Excel (Microsoft Corporation, Redmond, WA) is presented which displays 3 D oblique plots of a conserved scalar distribution downstream of jets mixing with a confined crossflow, for a single row, double rows, or opposed rows of jets with or without flow area convergence and/or a non-uniform crossflow scalar distribution. This project used a previously developed empirical model of jets mixing in a confined crossflow to create an Microsoft Excel spreadsheet that can output the profiles of a conserved scalar for jets injected into a confined crossflow given several input variables. The program uses multiple spreadsheets in a single Microsoft Excel notebook to carry out the modeling. The first sheet contains the main program, controls for the type of problem to be solved, and convergence criteria. The first sheet also provides for input of the specific geometry and flow conditions. The second sheet presents the results calculated with this routine to show the effects on the mixing of varying flow and geometric parameters. Comparisons are also made between results from the version of the empirical correlations implemented in the spreadsheet and the versions originally written in Applesoft BASIC (Apple Computer, Cupertino, CA) in the 1980's.

J D Holderman↗

NASA NTRS2005

A Spreadsheet for the Mixing of a Row of Jets with a Confined Crossflow

J D Holderman↗

NASA NTRS2003

Tool for Bending a Metal Tube Precisely in a Confined Space

A relatively simple, manually operated tool enables precise bending (typically, within 1/2 of the specified bend angle) of a metal tube located in a confined space, with a minimum of flattening of the tube and without significant gouging of the tube surface. The tool is designed for use in a situation in which the tube cannot be removed from the confined space for placement in a conventional benchmounted tube bender. The tool is also designed for use in a situation in which previously available hand-held tube benders do not afford the required precision, do not support the tube wall sufficiently to prevent flattening or gouging, and/or do not fit within the confined space. The tool is designed and fabricated for the specific outer diameter and bend radius of the tube to be bent. The tool (see figure) includes a clamping/radius block and a top clamping block that contain mating straight channels of semicircular cross section that fit snugly around the tube. The mating portions of the clamping/radius block and the top clamping block are clamped around a length of the tube that is adjacent to the bend and that is intended to remain straight. The clamping/radius block is so named because beyond the straight clamping section, its semicircular channel extends to a non-clamping section that is curved at the specified bend radius. A pivot hole is located in the clamping/radius block at the center of the bend circle. The tool includes a bending block that, like the other blocks, contains a straight semicircular channel that fits around the outside of the tube. The bending block contains a pivot hole to be aligned with the pivot hole in the clamping/radius block. Once the tube has been clamped between the clamping/ radius and top clamping blocks, the bending block is placed around the tube, the pivot holes are aligned, and a pivot pin is inserted through the pivot holes.

Davis, Gary T.↗

NASA NTRSDate not supplied

Thinking Big and Broad About Isolation and Confinement Analogs: A Community Panel Discussion

As crewed spaceflight missions are set to explore greater distances from Earth and fly longer durations than ever before, we must expand our understanding of the impacts of prolonged isolation and confinement on the health, performance, and well-being of astronauts. In combination with flight research, ground-based analogs that simulate key mission conditions like the social and physical isolation associated with distance from Earth are essential research platforms for characterizing risk and developing validated and feasible countermeasures that support future crews and ground support teams. With several isolation and confinement analogs currently operating, and even more in development, there is great opportunity for a collaborative global analog environment to complement and optimize research efforts. The Research Operations and Integration team will moderate a panel discussion among analog operators and scientists who utilize isolation and confinement analogs. The focus of discussion will be the potential for strategic coordination, portability, and harmonization of science across different platforms; and identifying the valuable similarities and differences among isolation analogs as well as existing gaps within the analog community. A Q&A session will follow with attendees encouraged to ask questions and join in the discussion.

Reanna Elise Whiting↗

DOE OSTI2024

Lateral Confinement in 2D Nanoplatelets: A Strategy to Expand the Colloidal Quantum Engineering Toolbox

Among colloidal nanocrystals, 2D nanoplatelets offer a unique set of properties with exceptionally narrow luminescence and low lasing thresholds. Furthermore, their anisotropic shape expands the playground for the complex design of heterostructures where spectra but also scattering rates can be engineered. A challenge that still remains is to combine shell growth which makes NPLs stable, with spectral tunability. Indeed, most reported shelled nanoplatelets end up being red emitters due to a loss of quantum confinement. Here, the combination of both lateral and in-plane confinements within a single heterostructure is explored. A CdS/CdSe/CdS/CdZnS core–crown–crown shell structure that enables yellow emission is grown and that is responsive to a large range of excitation including visible photons, X-ray photons, electron beams, and electrical excitations. k.p simulations predict that emission tunability of up to several 100 s of meV can be obtained in ideal structures. This material also displays stimulated emission resulting from bi-exciton emission with a low threshold. Once integrated into an LED stack, this material is compatible with sub-bandgap excitation and exhibits high luminance. Scaling of the electroluminescence properties by downsizing the pixel size is also investigated.

2D materials↗

DOE OSTI2025

Confinement performance predictions for a high field axisymmetric tandem mirror

This paper presents a Hammir tandem mirror confinement performance analysis based on Realta Fusion’s first-of-a-kind model for axisymmetric magnetic mirror fusion performance. This model uses an integrated end plug simulation model including, heating, equilibrium and transport combined with a new formulation of the plasma operation contours (POPCONs) technique for the tandem mirror central cell. Using this model in concert with machine learning optimization techniques, it is shown that an end plug utilizing high temperature superconducting magnets and modern neutral beams enables a classical tandem mirror pilot plant producing a fusion gain Q > 5. The approach here represents an important advance in tandem mirror design. The high-fidelity end plug model enables calculations of heating and transport in the highly non-Maxwellian end plug to be made more accurately. The detailed end plug modelling performed in this work has highlighted the importance of classical radial transport and neutral beam absorption efficiency on end plug viability. The central cell POPCON technique allows consideration of a wide range of parameters in the relatively simple near-Maxwellian central cell, facilitating the selection of more optimal central cell plasmas. These advances make it possible to find more conservative classical tandem mirror fusion pilot plant operating points with lower temperatures, neutral beam energies and end plug performance requirements than designs in the literature. Despite being more conservative, it is shown that these operating points have sufficient confinement performance to serve as the basis of a viable fusion pilot plant provided that they can be stabilized against magnetohydrodynamic and trapped particle modes.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗

DOE OSTI2026

Non-dimensional confinement scaling in similar negative triangularity plasmas on the DIII-D and TCV tokamaks

Similarity experiments were performed on the DIII-D and TCV tokamaks to explore the scaling of energy confinement in negative triangularity (NT) plasmas using non-dimensional variables. Near up-down symmetric plasmas with large top-bottom averaged NT were created in a lower single null configuration, with the shape of the separatrix being closely matched between the two devices. The normalized energy confinement is found to weakly improve at increasing collisionality and, between the two devices, shows a machine size scaling behavior between Bohm and gyro-Bohm. Engineering scaling on a large DIII-D dataset is in agreement with the non-dimensional experiment.

confinement scaling↗

DOE OSTI2025

Inertial Confinement Fusion: Status and Challenges

While a variety of laboratory-based fusion schemes have been studied for decades, the only fusion scheme yet to demonstrate fusion ignition and significant energy gain has been X-ray-driven inertially confined fusion. Ignition was demonstrated to occur at the thermodynamic conditions where it had long been expected, but the energy required for the implosion system to reach these conditions was more than projected years ago. This short review gives a status update on the three principal inertial confinement fusion schemes and research challenges going forward.

gain↗

DOE OSTI2025

Confinement Exploiting Arrays of Cross-Flow Turbines (ConExT) (Final Scientific/Technical Report)

Final technical report for the ARPA-E SHARKS project: Confinement Exploiting Arrays of Cross-Flow Turbines (ConExT). This involved collaboration by the University of Washington, University of Wisconsin, National Renewable Energy Laboratory, and Oberon Insights. Cost-effective, large-scale utilization of tidal and river current resources requires turbine arrays. Most array concepts involve multiple, staggered rows of turbines analogous to wind farms. However, in water, turbines that have an appreciable projected area (i.e., the projected area over a full revolution) relative to a channel’s cross-sectional area can theoretically extract far more energy than when operating in isolation. This suggests substantial benefits to a confinement-exploiting approach to array layout, in which turbines are more densely clustered in a single row spanning a channel. The objective of this project was to move this concept from theory to practice, as well as establishing environmental and economic trade-offs. This objective was accomplished through scale-model experimentation, high-fidelity computational fluid dynamic simulation, and integrated techno-economic modeling.

16 TIDAL AND WAVE POWER↗

NASA NTRSDate not supplied

Behavioral Medicine Risks and Mitigations in Isolated, Confined, and Extreme Environments

Human spaceflight beyond low Earth orbit will present unique environmental challenges to astronauts’ operational performance and well-being. Crews will need to work and live in confined and hazardous environments for prolonged missions that involve variable workloads and limitations to privacy, food options, exercise capabilities, leisure outlets, and communication with ground support personnel and loved ones. Currently, behavioral and cognitive risks of spaceflight are mitigated by selecting exceptionally resilient crews and providing extensive individual and team skills training pre-mission, as well as in-mission crew support via a suite of countermeasures targeting sleep and performance optimization, stress management, family support, and team cohesion. However, current countermeasures are difficult or impossible to implement in long-distance exploration as they require real-time communication with Earth and routine resupply. New countermeasure approaches are needed to adapt and enhance the current complement for the new challenges ahead. NASA therefore conducts research at ground-based spaceflight analogs to aid in characterizing the behavioral and cognitive risks of living and working in isolated, confined, and extreme (ICE) operational environments. Antarctic research stations are among the few long-duration ICE analogs in existence and are therefore uniquely positioned to support behavioral medicine research to enable human exploration beyond Earth. In this review, we will discuss previous and ongoing efforts to better understand spaceflight behavioral medicine risks, as well as validate new countermeasure approaches for future missions to the moon and Mars.

Behavioral Health↗

DOE OSTI2024

Line operators, vortex statistics, and Higgs versus confinement dynamics

We study a 2+1D lattice gauge theory with fundamental representation scalar fields which has both Higgs and confining regimes with a spontaneously-broken U(1) 0-form symmetry. We show that the Higgs and confining regimes may be distinguished by a natural gauge invariant observable: the phase Ω of a correlation function of a vortex line operator linking with an electric Wilson line. We employ dualities and strong coupling expansions to analytically explore parameter regimes which were inaccessible in previous continuum calculations, and discuss possible implications for the phase diagram.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Pore confinement enhances but surface adhesion reduces bacterial cell-to-cell conjugation

As the habitats of bacteria, soil pore network and surface properties control the distribution, adhesion, and motility of bacteria in soils. These physical processes in turn influence bacterial accesses to nutrients and bacterial interactions. Our understanding on the pore- and surface-mediated bacterial interactions is currently limited. In this research, we evaluated the effects of soil pore confinement and surface adhesion on conjugation-based bacterial interactions. The interaction was measured by plasmid transfer between donor and recipient cells within the population of soil bacterium Pseudomonas putida. We found that the presence of porous sand media led to a net increase in conjugation frequency compared to sand-free liquid control. The increase is attributed to the facilitated effect of pore confinement on the collision of bacteria within pores. In contrast, bacterial adhesion to sand surfaces under elevated ionic strength conditions decreased the conjugation frequency as a result of mobility reduction on the surface. Such collision and adhesion mechanisms jointly drive the conjugation as a function of pore and surface properties of porous media. Finally, these results provide valuable insights into the roles of soil pores and surfaces in regulating horizontal gene transfer, an essential cell-to-cell interaction sustaining key processes of soil ecology and health.

59 BASIC BIOLOGICAL SCIENCES↗

DOE OSTI2026

Adsorption-based direct air capture using hierarchical porous composites prepared via confined-space crystallization

Capturing CO₂ at trace concentration remains a critical challenge in sustainable carbon management via adsorption, as conventional adsorbents suffer from low CO₂ selectivity, poor moisture tolerance, and energy-intensive regeneration requirements. Here, we report a hierarchical Ba²⁺-exchanged silicoaluminophosphate (Ba²⁺-CSAPO-34) composite synthesized via confined-space crystallization within an activated carbon matrix. Comprehensive characterization revealed a confined nucleation mechanism and the successful incorporation of Ba²⁺ active sites within the SAPO-34 framework, achieved via a two-step liquid ion-exchange protocol. The core-shell architecture combines the selective CO₂ binding of Ba²⁺-functionalized SAPO-34 with the hydrophobic protection of the carbon shell. Fixed-bed adsorption tests demonstrated strong CO₂ binding (at 500-2500 ppm), no roll-up, and effective suppression of water affinity, while maintaining high selectivity even at 90% relative humidity. A phenomenological adsorption model, validated against dynamic breakthrough data, accurately predicted dynamic adsorption behavior under real-world operating conditions, enabling rational process design for direct air capture (DAC) and closed-loop life support systems. Furthermore, these results establish Ba²⁺-CSAPO-34 as a scalable, moisture-resistant adsorbent that addresses key limitations in trace CO₂ capture, advancing practical implementation of carbon removal technologies.

77 NANOSCIENCE AND NANOTECHNOLOGY↗

DOE OSTI2025

Cascading from $\mathscr{N}$ = 2 supersymmetric Yang–Mills theory to confinement and chiral symmetry breaking in adjoint QCD

We argue that adjoint QCD in 3 + 1 dimensions, with any SU(N) gauge group and two Weyl fermion flavors (i.e. one adjoint Dirac fermion), confines and spontaneously breaks its chiral symmetries via the condensation of a fermion bilinear. We flow to this theory from pure $\mathscr{N}$ = 2 SUSY Yang–Mills theory with the same gauge group, by giving a SUSY-breaking mass M to the scalars in the $\mathscr{N}$ = 2 vector multiplet. This flow can be analyzed rigorously at small M, where it leads to a deconfined vacuum at the origin of the $\mathscr{N}$ = 2 Coulomb branch. The analysis can be extended to all M using an Abelian dual description that arises from the N multi-monopole points of the $\mathscr{N}$ = 2 theory. At each such point, there are N −1 hypermultiplet Higgs fields h$^{i=1,2}_m$, which are SU(2) R doublets. We provide a detailed study of the phase diagram as a function of M, by analyzing the semi-classical phases of the dual using a combination of analytic and numerical techniques. The result is a cascade of first-order phase transitions, along which the Higgs fields h i m successively turn on, and which interpolates between the Coulomb branch at small M, where all h$^{i}_m$ = 0, and a maximal Higgs branch, where all h$^{i}_m$ ≠ 0, at sufficiently large M. We show that this maximal Higgs branch precisely matches the confining and chiral symmetry breaking phase of two-flavor adjoint QCD, including its broken and unbroken symmetries, its massless spectrum, and the expected large-N scaling of various observables. The spontaneous breaking pattern SU(2) R → U(1) R , consistent with the Vafa–Witten theorem, is ensured by an intricate alignment mechanism for the h$^{i}_m$ in the dual, and leads to a CP 1 sigma model of increasing radius along the cascade.

D’Hoker, Eric [Univ. of California, Los Angeles, C↗

DOE OSTI2024

Does Confinement Mediate Cerium Exchange and Its Impact on Ionomer Properties?

Thin-film ionomers, pivotal in the function of fuel-cell catalyst layers (CLs), are undercharacterized compared to their bulk membrane counterparts, especially with respect to cation effects. Cerium cations, used as an additive in fuel-cell membranes, tend to migrate from the membrane into the CL ionomer during operation. Further, this study investigates whether cerium doping of perfluorinated sulfonic acid ionomer changes under confinement (to a nanometer thin film) and affects the hydration behavior. Confinement has a negligible effect on the ionomer’s cerium partitioning, yet it reduces the ionomer water uptake. Thus, cerium replaces protons similarly in a membrane or CL ionomer; however, its presence affects the thermodynamics of hydration differently.

36 MATERIALS SCIENCE↗

DOE OSTI2026

Confined Room-Temperature Ferromagnetism in Kagome (Fe 3 Sn 2 /CoSn) Superlattices

We reveal the presence of robust ferromagnetism in topological kagome (Fe 3 Sn 2 /CoSn) ×n superlattices via polarized neutron reflectivity (PNR) and magnetization measurements. Using molecular beam epitaxy, we have synthesized superlattices of alternating ferromagnetic Fe 3 Sn 2 and paramagnetic CoSn layers, the interfacial integrity of which is confirmed using scanning transmission electron microscopy. Magnetization depth profiles, obtained by fitting the PNR data, confirm the presence of ferromagnetism in the confined Fe 3 Sn 2 layers at room temperature, with minimal thickness dependence down to 2 nm. A net magnetization is found in the near-surface region of CoSn, which we attribute to surface oxidation. Our results demonstrate that superlattice engineering is a means to confine ferromagnetism in kagome metals, enabling future studies of thickness-dependent anomalous Hall and Nernst effects as well as spin-dependent transport and tunneling in device structures.

kagome metals↗