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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 703 records · Page 39
All sourcesNASA NTRSDOE OSTI
NASA NTRS2020

The Role of Solar Wind Hydrogen in Space Weathering: Insights from Laboratory-Irradiated Northwest Africa 12008

Micrometeoroid impacts, solar wind plasma interactions, and regolith gardening drive the complicated and nuanced mechanism of space weathering (or optical maturation); a process by which a material’s optical properties are changed as a result of chemical and physical alterations at the surface of grains on airless bodies. Reddened slopes, attenuated absorption bands, and an overall reduction in albedo in the visible and near-IR wavelength ranges are primarily the result of native iron nanoparticle (npFe0) production within glassy rims that form from sputtering and vaporization. The sizes and abundance of these particles provide information about the relative surface exposure age of a particular grain. In addition, many studies have indicated that composition greatly affects the rate at which optical maturation occurs. Despite our understanding of how npFe0 affects optical signatures, the relative roles of micrometeoroid bombardment and solar wind interactions remains undetermined. To simulate the early effects of weathering by the solar wind and to determine thresholds for optical change with respect to a given mineral phase, we irradiated a fine-grained lunar basalt with 1 keV H+ to a fluence of 6.4 x 1016 H+ per sq.cm. Surface alterations within four phases have been evaluated using transmission electron microscopy (TEM). We found that for a given fluence of H+, the extent of damage acquired by each grain was dependent on its composition. No npFe(0) was produced in any of the phases evaluated in this study. These results are consistent with many previous studies conducted using ions of similar energy, but they also provide valuable information about the onset of space weathering and the role of the solar wind during the early stages of optical maturation.

Shusterman, M. L.↗
NASA NTRS1996

Spacecraft Charging, An Update

Spacecraft charging and its associated plasma interactions continue to be major issues for Earth-orbiting spacecraft. Although typically thought of as a surface effect on geosynchronous spacecraft, internal charging and low-altitude phenomena are increasingly causing concern. This review will concentrate on the problems introduced by penetrating electrons and related processes, and on issues tied to plasma/aurora.

Spacecraft↗
NASA NTRSDate not supplied

A Notional Artemis Lunar Surface Exploration Package (ArLSEP) based on the Gandalf Staff Platform

Introduction: The Artemis program is planning to deliver crew and cargo to the lunar surface, but there is no current package for supporting lunar in-struments and experiments similar to the Apollo Lunar Surface Exploration Package (ALSEP). This abstract provides a possible concept for such a package using the Gandalf Staff Platform as a common core. Gandalf Staff: The Gandalf Staff is an early prototype system developed over FY’21/FY’22 using NASA Science Technology Mission Directorate (STMD) Center Information Fund (CIF) grants to de-sign, build and test “proof-of-concept” components. These components include a 24v battery powered monopole that powers a suite of subsystems, including a Graphical User Interface (GUI) for crew, surface voice and data communications, Lunar Search and Rescue (LunaSAR) navigation and communications, LiDAR, field site external lighting, 360-degree camera, and a geothermal instrument for measuring sub-surface temperature gradient. The staff can be carried independently by an Extra-Vehicular Activity (EVA) astronaut, or can be mounted into a tripod for “hands free” support at a surface site being investigated. The staff can be attached to an external solar array and power storage system for long-duration operations. [1,2] ALSEP: An ASLEP flew on each mission Apollo 12 to Apollo 17. For Apollo 11, a simplified packaged called the Early Apollo Scientific Experiments Pack-age (EASEP) was flown. Each package included a “Central Station” that provided the power and communications connected to a variety of instruments and sensors. The power was provided by a Radioisotope Thermoelectric Generator (RTG) fueled by Plutoni-um-238 generating 70 watts of power (initially, decayed over time) [3]. The communications system provide for direct to Earth data transfer from the lunar surface. Each pack-age was stowed externally in the Lunar Module (LM) Scientific Equipment (SEQ) bay with a mass up to 163 kg (Apollo 17). The crew unloaded the ALSEP from the LM and deployed the instruments on the lunar surface. Although designed to operate for only 1 year, many sites operated for up to 8 years successfully [4]. The Active Seismic Experiment (ASE) included 3 geophones for detecting seismic waves created by mortars and thumpers deployed by the crew. Other active experiments measured the lunar atmosphere, the heat flow in the subsurface, the lunar gravity and potential gravity waves, the lunar magnetic field, the solar wind and plasma interactions in cislunar space. Passive experiments included collectors for dust and cosmic rays, and retroreflectors for precise measurements of distance using a laser from Earth. The ALSEP program continues to generate insights into lunar formation and evolution. ArLSEP Concepts: The lunar surface science package for the Artemis program will hopefully exceed the capability of the ALSEP. There are multiple issues for discussion leading to the design of a new ArLSEP, needing requirements definition from the science community, NASA mission architecture, and NASA budget planners. 1. Delivery Mechanism Two possible projects currently provide capability to deliver scientific cargo to the lunar surface: 1) the Commercial Lunar Payload Services (CLPS) [5] and the Human Landing System (HLS) [6, 7]. Each project is controlled by a different organization within NASA and budgeted with different criteria although both support lunar exploration. The HLS system delivers crew (and potentially cargo) to human landing sites. If an ArLSEP is “predeployed” to such a site, the design must include power (either from the vehicle or independently) to keep the electronics functioning until deployed by the crew. If an ArLSEP is delivered on a vehicle after the crew is present on the lunar surface, safety protocols require adequate distance from the humans for impact from descent propelled sur-face regolith ejecta. This distance can not exceed the capability of the crew to walk (if no rover) to the vehicle for ArLSEP deployment. 2. Overall Guidelines The general design of ArLSEP will likely follow the ALSEP with a common system for communications and power; however, significant architecture differences between Apollo and Artemis exist. Power: The RTG will not be available for early Artemis missions nor likely follow-on Lunar Exploration Transportation Services (LETS) missions [8]. Thus, ArLSEP power must be supplied by solar arrays with sufficient battery capability to “keep alive” necessary electronics during any lunar surface eclipse period. Communication: The Artemis program is developing a series of communications satellites for lunar orbit to provide surface transmission of data and voice to Earth. Called “LunaNET”, this network is component useful for ArLSEP since south polar locations may not always have direct “line-of-sight” to Earth [9]. 3. Concept of Operations (ConOps) The general ConOps for ArLSEP is to deliver the package to lunar surface before the crew arrives, and then have the crew deploy the package after some period of time. This requires coordinated design (for power systems) and launch window (for schedule) on both the cargo and crew missions. Once the ArLSEP is deployed, it will operate autonomously for a number of years. It should be designed to be EVA compatible for crew maintenance and upgrade. 4. Notional Design (for discussion purpose only) The landing site near the South Pole is expected to have no eclipse cycle exceeding 5 days, so the “keep alive” power is 144 hours (6 days to include margin). A 12v ArLSEP will use rechargeable LiFePO4 cells, which are common in the Electric Vehicle (EV) industry. With a current of 5 amps and a 125 watt system, the mass is about 90kg. The comm. system and structure adds another 10kg, thus the “Central Station” is approximately 100kg. The solar power is collected on four arrays (each 2m above the surface), and the entire ArLSEP is designed to stow in a 2m x 1m x 1m volume. The experiment and instrument design will vary for each installation and add mass to the total (although they are expected to fit within the 2m3 volume). Seismic wave generation will likely not be provided with mortars, thus an electric “thumper” will be required. Active instruments such as imaging systems and sensing instruments will benefit from the additional power and communication capability provided by ArLSEP. Passive systems such as retroreflectors, witness plates, and cosmic dust collectors can be added to either the landing vehicle and/or the ArLSEP. With repeated HLS missions to the same human site, the ArLSEP can be expanded and easily maintained for long duration science collection on the lunar surface.

ALSEP↗
NASA NTRS2014

Science Enhancements by the MAVEN Participating Scientists

NASA implemented a Participating Scientist Program and released a solicitation for the Mars Atmosphere and Volatile EvolutioN mission (MAVEN) proposals on February 14, 2013. After a NASA peer review panel evaluated the proposals, NASA Headquarters selected nine on June 12, 2013. The program’s intent is to enhance the science return from the mission by including new investigations that broaden and/or complement the base-line investigations, while still addressing key science goals. The selections cover a broad range of science investigations. Included are: a patching of a 3D exosphere model to an improved global ionosphere-thermosphere model to study the generation of the exosphere and calculate the escape rates; the addition of a focused study of upper atmosphere variability and waves; improvement of a multi-fluid magnetohydrodynamic model that will be adjusted according to MAVEN observations to enhance the understanding of the solar-wind plasma interaction; a global study of the state of the ionosphere; folding MAVEN measurements into the Mars International Reference Ionosphere under development; quantification of atmospheric loss by pick-up using ion cyclotron wave observations; the reconciliation of remote and in situ observations of the upper atmosphere; the application of precise orbit determination of the spacecraft to measure upper atmospheric density and in conjunction with other Mars missions improve the static gravity field model of Mars; and an integrated ion/neutral study of ionospheric flows and resultant heavy ion escape. Descriptions of each of these investigations are given showing how each adds to and fits seamlessly into MAVEN mission science design.

Mars↗
NASA NTRS2020

Collisional-Radiative Models of Neutral and Singly-Ionized Xenon in Hall Thrusters: Experimental Validation and Model Investigations

The recently developed collisional radiative (CR) models for neutral xenon (Xe I) and singly charged xenon ion (Xe II) described by Chaplin et al. in the paper "Insights from Collisional-Radiative Models of Neutral and Singly-Ionized Xenon in Hall Thrusters" also submitted to the 2021 AIAA Propulsion and Energy Forum are more thoroughly investigated. Comparisons between the existing and recently developed JPL Xe I CR models are done and reasons for discrepancies between the two models are explored. An experiment to validate the Xe II CR model is carried out in the anode region of the UCLA Plasma interactions facility. The Xe II CR model is applied to measured xenon ion emission line intensities to determine electron temperature and density. Spatial resolution of these optical measurements is obtained through an Abel inversion for direct comparison to Langmuir probe results. Although the measured electron densities were on the order of $10^{17}$ m$^{-3}$ and the Xe II CR model is most suitable for use with densities above $10^{18}$ m$^{-3}$ due to the strong dependence of the line ratios on electron temperature in that regime, initial results from the validation experiment show reasonable agreements between the optical and Langmuir probe results. The 441 nm to 605 nm line ratio appears to have the most promise for non-intrusive electron temperature measurements with the Xe II CR model. Shortcomings of the Xe II CR model revealed in the validation experiment are to be explored further.

Lobbia, Robert B.↗
NASA NTRSDate not supplied

Quantifying Primary Arc-Induced Degradation of Perovskite Solar Cells

Primary arcing induced by spacecraft charging presents a significant hazard to thin film solar cells if left unchecked. Here, we present the results of a preliminary effort to quantify the impacts of primary arcing to perovskite solar cells. Solar cells operating in a charged environment are susceptible to electrostatic discharges known as arcing. While primary arcs are not generally considered a major concern for traditional space PV, for thin film cells, these can induce significant heating and subsequent damage. We conducted ESD testing in a LEO-like plasma in the National Plasma Interaction Facility at NASA Glenn Research Center to quantify impacts to cell performance by arcing. The perovskites tested saw a decrease of short circuit current with an increased number of arcs, averaging a relative change of 73.89 ± 15.90% after 60 total arcs supplied a cumulative energy dose of 76.12 mJ to the string. Ongoing work entails testing with larger perovskite data sets and expanding to include additional thin film cell technologies to demonstrate the risk unmitigated primary arcing presents.

primary arcing↗
DOE OSTI2023

Plasma surface ionization wave interactions with single channels

Abstract The study of plasma surface ionization waves (SIWs) in recent years has primarily focused on planar surfaces and periodic two dimensional structures. In application, substrates are likely to have non-planar morphology such as cracks, pores, and steps. Additionally, targets for the applications of medicine or catalysis may have targets with heterogeneous composition. This classification of targets are brought under the umbrella of complex interfaces. In this work, plasma SIWs were incident on a complex target consisting of a single channel cut into glass slides. The SIW velocities for the in-channel portion of the wave and radially propagating portion of the wave were tracked. It was found that surface wave velocities are not significantly affected by channel geometry, but primarily increase with pulse energy. A third propagation direction for the SIW is characterized in the azimuthal direction relative to the radial portion of the wave. Channel geometry is found to greatly effect the area treated by the plasma but not the propagation velocity of the surface wave. Surface wave morphology and the impact on application is also discussed. A simple model was introduced to understand the mechanisms behind SIW escape from a channel. It was found that the ratio of pulse energy to a geometry dependent minimum energy can predict the escape angle of a SIW from single channels.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1990

Particle-in-cell simulations of sheath formation around biased interconnectors in a low-earth-orbit plasma

The interaction between satellite solar arrays and the LEO plasma is presently studied with particle-in-cell simulations in which an electrical potential was suddenly applied to the solar cell interconnector. The consequent temporal response was followed for the real O(+)-electron mass ratio in the cases of 100- and 250-V solar cells, various solar cell thicknesses, and solar cells with secondary electron emission. Larger applied potentials and thinner solar cells lead to greater initial polarization surface charges, and therefore longer discharging and shielding times. When secondary electron emission from the cover glass is brought to bear, however, the potential structure is nearly planar, allowing constant interaction between plasma electrons and cover glass; a large fraction of the resulting secondary electrons is collected by the interconnector, constituting an order-of-magnitude increase in collected current.

Thiemann, H.↗
NASA NTRS2004

Development of a Computationally Efficient, High Fidelity, Finite Element Based Hall Thruster Model

This report documents the development of a two dimensional finite element based numerical model for efficient characterization of the Hall thruster plasma dynamics in the framework of multi-fluid model. Effect of the ionization and the recombination has been included in the present model. Based on the experimental data, a third order polynomial in electron temperature is used to calculate the ionization rate. The neutral dynamics is included only through the neutral continuity equation in the presence of a uniform neutral flow. The electrons are modeled as magnetized and hot, whereas ions are assumed magnetized and cold. The dynamics of Hall thruster is also investigated in the presence of plasma-wall interaction. The plasma-wall interaction is a function of wall potential, which in turn is determined by the secondary electron emission and sputtering yield. The effect of secondary electron emission and sputter yield has been considered simultaneously, Simulation results are interpreted in the light of experimental observations and available numerical solutions in the literature.

Jacobson, David↗
DOE OSTI2023

Resonant instabilities mediated by drag and electrostatic interactions in laboratory and astrophysical dusty plasmas

Dusty plasmas are known to support a diverse range of instabilities, including both generalizations of standard plasma instabilities and ones caused by effects specific to dusty systems. It has been recently demonstrated that a novel broad class of streaming instabilities, termed resonant drag instabilities (RDIs), can be attributed to a particular resonance phenomenon, manifested by defective eigenvalues of the linearized dust/fluid system. In this work, it is demonstrated that this resonance phenomenon is not unique to RDIs and can be used as a framework to understand a wider range of instabilities, termed resonant instabilities. Particular attention is given to the filamentary ionization instability seen in laboratory dusty plasmas and to the two-stream instability. It is shown that, due to the commonalities in underlying physics between the dust-ion-acoustic two-stream instability and the acoustic RDI, these instabilities should be relevant in strongly overlapping regimes in astrophysical dusty plasmas. Further, it is proposed that a similar overlap in the experimental accessibility of these modes (and of the filamentary instability) allows for the possibility of experimental investigation in the laboratory of complex and astrophysically relevant instability dynamics.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Experimental evaluation of the vapor box divertor concept with an open vapor box module in Magnum-PSI

A promising approach to handle the intense plasma heat flux in the divertor region of a tokamak is the Vapor Box Divertor (VBD). Here plasma-lithium interaction creates a dense lithium vapor cloud which interacts with the incoming plasma, effectively shielding the tungsten surface beneath, therefore preventing overheating and sputtering of the tungsten and increasing the component’s lifetime. Two key steps must be addressed to validate this concept: investigating plasma-Li interactions and the transport mechanism of the latter in the presence of plasma. To explore this, a Vapor Box Module (VBM) has been designed for use with the linear plasma generator Magnum-PSI. The VBM consists of a series of three cylindrical boxes, with Li being evaporated at a controlled temperature in the central box (CB). Divertor-like plasma enters the VBM from an upstream aperture, interacts with the Li vapor cloud and exits through a downstream aperture ultimately impacting a target equipped with a calorimetry system. Optical diagnostics Thomson scattering, Filtered fast camera Imaging and optical emission spectroscopy provided information on plasma parameters in terms of electron density n e , temperature T e and plasma composition before and after this interaction. A significant reduction in plasma power was observed upon the establishment of lithium vaporization determined via cooling water calorimetry and embedded thermocouples at the downstream target. This resulted in a drop of the target temperature from ∼800 °C to ∼350 °C (57%) at the highest applied power (11.1 MW m −2 ) and CB temperature (∼700 °C). Lithium condensation at the side boxes of the VBM in combination with strong plasma momentum transfer effectively prevented upstream migration of lithium, while enhancing Li transport toward the target. The achievement of the two main goals of reducing plasma power and confining the Li in the VBM, are consistent with earlier published preliminary SOLPS-ITER simulations. This study shows that the presence of lithium in a VBD-like configuration can result in a strong reduction of power to the target surface, while at the same time the lithium vapor is effectively confined by the VBM, aided by the incoming plasma, preventing its escape from the VBM geometry. This represents a valuable step toward validating the feasibility of the VBD configuration in future fusion reactors.

Magnum-PSI↗
DOE OSTI2022

The influence of particle size on the fluid dynamics of a laser-induced plasma

The interaction of a laser-induced shock wave with nanoparticles and microparticles of aluminum oxide is investigated through experiments and modeling. The chemistry and physics of the interaction between the particles and plasma generated from laser ablation shows similarities and discrete differences for the two particle sizes. For both particle sizes, early stage (< 10 μs) ionization was dominant and evidenced by higher concentrations of Al II. While both sizes exhibit ionization over the same duration, the intensity of emission was greater for nanoparticles indicating greater concentrations of ionized species. Moreover, the dispersion of species was notably more elongated for microparticles while radial dispersion was more pronounced for nanoparticles with elevated drag forces. At later stages (i.e., > 10 μs), oxidation reactions were dominant for both particle sizes, but the same distinctions in flow field were observed and attributed to particle drag. In all stages of interaction, microparticles expand axially with less drag that suppresses their radial expansion. As a result, the dispersion of reactive species was mapped over an up to 80% larger area for nanoparticles relative to microparticles. Results shown here can be applied toward advancing experimental diagnostics and particle-shock wave modeling and simulation efforts for energetic materials.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗