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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 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

A state of the art current-septum dipole magnet

Here, the acceleration process of charged particle beams often requires the use of few acceleration stages to provide the beam with the desired energy. The extraction of the beam from one acceleration stage and the injection to the next, both require a special type of magnet which comes under the name septum magnet. Such a magnet generates a strong field in one region and a very low field in another region with the two regions separated by a very thin material (septum). The septum thickness of such a magnet should be as thin as possible to reduce the strength of other devices, like kickers, which are involved in the extraction or injection processes. A thin septum is also advantageous during the slow beam extraction process to reduce the beam losses at the septum. One of the methods which in theory can generate very large differences in field strength in adjacent field regions separated by a thin septum, is the use of two thin parallel current sheets of infinite dimensions. In practice we use other devices that can approximate such an abrupt change of the magnetic field within the septum thickness. In this paper we describe such a device, the DC current septum, we present results from the study of its electromagnetic properties, and we discuss a method to minimize the magnetic field in the region which requires a very small magnetic field. We also provide some results from the experimental measurements of the magnetic field generated by the D6 current septum magnet which is installed in the experimental beam line of the NASA’s Space Radiation Laboratory (NSRL) facility [1],[2] at Brookhaven National Laboratory (BNL). This septum magnet is part of the beam’s extraction system from the AGS-Booster into the NSRL beam line for material and biological studies.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Expanding Configurational Complexity through Dipole Dilution in Pseudohalide Argyrodite Ion Conductors

The advantageous properties of (pseudo)halide argyrodite ion conductors of the formula Li 6 PS 5 X (X = Cl – , Br – , I – , CN – ) have motivated extensive studies of their structure-transport relationships, particularly as they pertain to the role of atomic site disorder. The argyrodite structure can accommodate additional configurational complexity to promote ion transport via extended three-anion site mixing and the potential for orientational disorder of molecular anions. In this work, we explore a ternary anion system including the cyanide anion, expanding site disorder and introducing dipolar orientations as an additional degree of freedom. We prepared the series Li 6 PS 5 (CN) 1–x Br x , in which the dipolar cyanide anions are systematically diluted with bromide. We find that anion disorder, as determined by synchrotron and neutron diffraction and quantified by configurational entropy (S config ), is correlated with lowered activation barriers and increased lithium ion conductivity. We propose that S config describes the electrostatic heterogeneity of the Li environments, flattening the energetic landscape for ion transport. While anion substitution strongly impacts the activation barrier for transport, the temperature-independent Arrhenius prefactor does not follow the same trend. Through heat-capacity measurements of attempt frequency and deconvolution of terms within the prefactor, we rationalize the apparent decoupling of activation energy and prefactor to strong cyanide-lithium interactions that increase the entropy of migration. Together, these results expand the structure–property relationships in the argyrodite family to encompass multiple facets of disorder and the subsequent impact on lithium ion transport.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗