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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Temporal Evolution of the Plasma Sheath Surrounding Solar Cells in Low Earth Orbit

High voltage solar array interactions with the space environment can have a significant impact on array performance and spacecraft charging. Over the past 10 years, data from the International Space Station has allowed for detailed observations of these interactions over long periods of time. Some of the surprising observations have been floating potential transients, which were not expected and are not reproduced by existing models. In order to understand the underlying processes producing these transients, the temporal evolution of the plasma sheath surrounding the solar cells in low Earth orbit is being investigated. This study includes lumped element modeling and particle-in-cell simulation methods. This presentation will focus on recent results from the on-going investigations.

Willis, Emily M.↗
NASA NTRS2017

Temporal Evolution of the Plasma Sheath Surrounding Solar Cells in Low Earth Orbit

High voltage solar array interactions with the space environment can have a significant impact on array performance and spacecraft charging. Over the past 10 years, data from the International Space Station has allowed for detailed observations of these interactions over long periods of time. Some of the surprising observations have been floating potential transients, which were not expected and are not reproduced by existing models. In order to understand the underlying processes producing these transients, the temporal evolution of the plasma sheath surrounding the solar cells in low Earth orbit is being investigated. This study includes lumped element modeling and particle-in-cell simulation methods. This presentation will focus on recent results from the on-going investigations.

Willis, Emily M.↗
NASA NTRS2020

Quantitative Magnetic Resonance Image Assessment of the Optic Nerve and Surrounding Sheath after Spaceflight

A subset of long-duration spaceflight astronauts have experienced ophthalmic abnormalities, collectively termed spaceflight-associated neuro-ocular syndrome (SANS). Little is understood about the pathophysiology of SANS; however, microgravity-induced alterations in intracranial pressure (ICP) due to headward fluid shifts is the primary hypothesized contributor. In particular, potential changes in optic nerve (ON) tortuosity and ON sheath (ONS) distension may indicate altered cerebrospinal fluid dynamics during weightlessness. The present longitudinal study aims to provide a quantitative analysis of ON and ONS cross-sectional areas, and ON deviation, an indication of tortuosity, before and after spaceflight. Ten astronauts undergoing ~6-month missions on the International Space Station (ISS) underwent high-resolution magnetic resonance imaging (MRI) preflight and at five recovery timepoints extending to 1 year after return from the ISS. The mean changes in ON deviation, ON cross-sectional area, and ONS cross-sectional area immediately post flight were−0.14 mm (95% CI:−0.36 to 0.08, Bonferroni-adjusted P=1.00), 0.13 mm2(95% CI−0.66 to 0.91, Bonferroni-adjusted P=1.00), and−0.22 mm2(95% CI:−1.78 to 1.34, Bonferroni-adjusted P=1.00), respectively, and remained consistent during the recovery period. Terrestrially, ONS distension is associated with increased ICP; therefore, these results suggest that, on average, ICP was not pathologically elevated immediately after spaceflight. However, a subject diagnosed with optic disc edema (Frisen Grade 1, right eye) displayed increased ONS area post flight, although this increase is relatively small compared to clinical populations with increased ICP. Advanced quantitative MRI-based assessment of the ON and ONS could help our understanding of SANS and the role of ICP.

Jesse Rohr↗
NASA NTRS1971

Improved high-temperature metal-sheathed cables

Process prevents moist air degradation of cables insulated with magnesium oxide. Electrical-grade silicone oil is polymerized by heat application to produce water repellant surface coating. Insulation treated with this oil repels moisture.

Fox, H. A., Jr.↗
NASA NTRS1974

Report of the Plasma Physics and Environmental Perturbation Laboratory (PPEPL) working groups. Volume 1: Plasma probes, wakes, and sheaths working group

It is shown in this report that comprehensive in-situ study of all aspects of the entire zone disturbance caused by a body in a flowing plasma resulted in a large number if requirements on the shuttle-PPEPL facility. A large amount of necessary in-situ observation can be obtained by adopting appropriate modes of performing the experiments. Requirements are indicated for worthwhile studies, of some aspects of the problems, which can be carried out effectively while imposing relatively few constraints on the early missions. Considerations for the desired growth and improvement of the PPEPL to facilitate more complete studies in later missions are also discussed. For Vol. 2, see N74-28170; for Vol# 3, see N74-28171.

Source record↗
NASA NTRS1981

The plasma wake of mesosonic conducting bodies. I - An experimental parametric study of ion focusing by the plasma sheath

The experimental investigation considered is concerned with the deflection of ion streams resulting from the interaction of conducting test bodies with an unmagnetized, mesosonic (supersonic with respect to ions but subsonic with respect to electrons) plasma stream. The investigation is, therefore, limited to plasma-electrostatic interactions. The experimental conditions are similar to those of the spacecraft-ionospheric interaction in that the ionic mass and number density, the electron temperature, and the plasma drift velocity ranges include values appropriate for small satellites or diagnostic probes at 200 to 400 km altitude. The study provides direct observations of deflected ion streams for cylindrical test bodies and gives a detailed description of the effects of the governing, dimensionless parameter ratios obtained from the steady-state, nonmagnetic Maxwell-Vlasov system of equations.

Stone, N. H.↗