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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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Pole erosion measurements for the development model of the Magnetically Shielded Miniature Hall Thruster (MaSMi-DM)
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Mars Mission Scenarios Suggesting Requirements for GCR Shielding, Surface Excavation & Construction
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Time Domain Boundary Element Method Prediction of Noise Shielding by a NACA 0012 Airfoil
As aircraft noise constraints become more stringent and the number/mixture of aircraft configurations grows, it becomes more important to understand the interaction of individual aircraft noise sources with nearby aircraft structures. Understanding these interactions and exploring possible approaches to mitigate or exploit their acoustic impact is essential for overcoming key noise barriers. This paper describes the further validation of a time domain boundary element approach for the prediction of the interactions between incident noise sources and nearby aircraft structures. Predictions were completed for multiple source locations and comparisons of these results with measured data are presented. Overall, very good agreement between the predicted and measured quantities was obtained in both the pressure time histories and pressure spectra. The effects of surface mesh resolution and source waveform are also presented. The very promising results demonstrate the capabilities of the time domain methodology employed in this study and provide further confidence in its continued development and application in future studies.
Crystal Shielding for Space Radiation - CIF First Year Report
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Electrodynamic Dust Shield Technology (Helmet and Stereo Camera) NextSTEP
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Anomalous Ion Heating and Pole Erosion in the 12.5-kW Hall Effect Rocket with Magnetic Shielding (HERMeS)
Wear measurements of the inner pole cover in HERMeS have shown as much as ten times higher erosion rates than past numerical simulations predicted. Also, measurements of ion velocity distribution functions (IVDF) suggest that ion heating occurs near the chamfered regions of the acceleration channel and around the inner pole surface. In our companion paper we present theoretical evidence that the plasma conditions in this region can excite instabilities in the lower hybrid frequency. Here, we provide further evidence of their presence through comparisons between numerical simulations and measurements. After including in the 2-D axisymmetric hydrodynamic-PIC code Hall2De an idealized model of the ion temperature based on a scaling with the lower hybrid frequency, we find the agreement between the computed and measured IVDF is significantly improved. In addition, the computed erosion rates at the inner pole surface are now in close agreement with wear test measurements.
SHIELD: a Small, High Impact Energy Landing Device for Low-Cost Access to the Martian Surface
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Nuclear Data Needs for Human Space Radiation Shielding
Protecting astronauts from the harmful effects of space radiation is a high priority for NASA. Space radiation transport codes utilize particle production cross sections describing the interactions of incident radiation with matter. The availability of measured nuclear cross section data needed for these studies will be reviewed. The energy range of interest for space radiation protection is approximately 100 MeV/n to 10 GeV/n. The majority of data are for projectile fragmentation partial and total cross sections, including both charge changing and isotopic cross sections. Cross section data are organized into categories which include charge changing, elemental, isotopic for total, single and double differential with respect to momentum, energy and angle. This plenary talk will discuss gaps in the data relevant to space radiation protection and recommendations for future experiments will be made. Double differential cross section data for light ion production will be emphasized.