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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 1,189 records · Page 66
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Structural and compositional characterization of RF magnetron cosputtered lithium silicate films: From Li2Si2O5 to lithium-rich Li8SiO6

In this study, the structure and composition of lithium silicate thin films deposited by radio-frequency magnetron cosputtering are investigated. Five compositions ranging from Li2Si2O5 to Li8SiO6 were confirmed by inductively coupled plasma-optical emission spectroscopy, and structural analysis on the evolution of nonbridging oxygens in the thin films was conducted using Fourier transform infrared spectroscopy. It was found that nonbridging oxygens increased as the silicate network breaks apart with the increasing lithium content, which agrees with previous studies on lithium silicates. Thin film impurities were examined using x-ray photoelectron spectroscopy and time of flight secondary ion mass spectroscopy and traced back to target synthesis. This study utilizes a unique synthesis technique for lithium silicate thin films that can be used to model the lithium silicates formed on the surface of silicon anodes in lithium ion batteries and can bridge the understanding between this layer and the influence of silicates on ionic conductivity of the silicon interphase layer.

Coyle, Jaclyn↗
DOE OSTI2016

WE-DE-206-02: MRI Hardware - Magnet, Gradient, RF Coils

Magnetic resonance imaging (MRI) has become an essential part of clinical imaging due to its ability to render high soft tissue contrast. Instead of ionizing radiation, MRI use strong magnetic field, radio frequency waves and field gradients to create diagnostic useful images. It can be used to image the anatomy and also functional and physiological activities within the human body. Knowledge of the basic physical principles underlying MRI acquisition is vitally important to successful image production and proper image interpretation. This lecture will give an overview of the spin physics, imaging principle of MRI, the hardware of the MRI scanner, and various pulse sequences and their applications. It aims to provide a conceptual foundation to understand the image formation process of a clinical MRI scanner. Learning Objectives: Understand the origin of the MR signal and contrast from the spin physics level. Understand the main hardware components of a MRI scanner and their purposes Understand steps for MR image formation including spatial encoding and image reconstruction Understand the main kinds of MR pulse sequences and their characteristics.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Coherent scattering of monochromatic RF radiation by ionization electrons of an extensive air shower

The possibility of detecting extensive air showers by recording and analyzing the radio pulse produced by the reradiation of a wave moving toward the cascade disk is considered. The coherent amplification of the scattered radiation in the direction of motion of the shower is shown to be due to a relativistic effect. An example of a real facility and its peculiarities are discussed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Influence of substrate temperature on structural and optical properties of RF sputtered ZnMnO thin films

The ZnMnO thin films were deposited on glass substrates by radio frequency magnetron sputtering method. The properties of ZnMnO thin films were investigated by high-resolution x-ray diffractometer (HRXRD),atomic force microscopy (AFM), UV-Vis spectrometer and room temperature photoluminescence (PL), under the influence of substrate temperature. The substrate temperature was varied from 300, 400 and 500°C. With increasing the substrate temperature, the structure of the films changed from cubic to hexagonal. The cubic ZnMnO thin films grown along [210] direction, while the hexagonal ones grown along [002] direction. The changes in surface morphology provided a proof on the structural transition. Also, decrease and increase of optical band gap is associated with cubic or hexagonal structure of the films.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Ion-Beam Processing during RF Magnetron Sputtering on the properties of ZnO Films

The effect of ion-beam processing alternating with magnetron sputtering on the properties of zinc-oxide thin films is investigated. It is shown that ion-beam processing reduces the growth rate, coherent-scattering-region sizes, and the resistivity. The stoichiometric index, band gap, and refractive index increase. The transparency of the films in the weak absorption region remains unchanged.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Properties of ZnSe/Al{sub 2}O{sub 3} Nanostructures Obtained by RF Magnetron Sputtering

Experimental data for the synthesis of ZnSe/Al{sub 2}O{sub 3} nanostructures utilizing a technology widely used in integrated circuit (IC) production are reported. It has been shown that the refractive index and size of the coherent scattering domains grow, whereas the energy bandgap decreases, with an increase in ZnSe width. It has been supposed that samples with a ZnSe width of 9 Å contain a ZnSeO{sub 3} compound and/or ZnSe ⋅ Al{sub 2}O{sub 3} complex compound. Multilayer heterostructures with a ZnSe width more than 9 Å contain cubic ZnSe nanocrystallites.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

RF Design of a High Average Beam-Power SRF Electron Source

There is a significant interest in developing high-average power electron sources, particularly in the area of electron sources integrated with Superconducting Radio Frequency (SRF) systems. For these systems, the electron gun and cathode parts are critical components for stable intensity and high-average powers. In this initial design study, we will present the design of a 9-cell accelerator cavity having a frequency of 1.3 GHz and the corresponding field optimization studies.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

RF Controls for High-Q Cavities for the LCLS-II

The SLAC National Accelerator Laboratory is building LCLS-II, a new 4 GeV CW superconducting (SCRF) Linac as a major upgrade of the existing LCLS. The LCLS-II Low-Level Radio Frequency (LLRF) collaboration is a multi-lab effort within the Department of Energy (DOE) accelerator complex. The necessity of high longitudinal beam stability of LCLS-II imposes tight amplitude and phase stability requirements on the LLRF system (up to 0.01% in amplitude and 0.01° in phase RMS). This is the first time such requirements are expected of superconducting cavities operating in continuous-wave (CW) mode. Initial measurements on the Cryomodule test stands at partner labs have shown that the early production units are able to meet the extrapolated hardware requirements to achieve such levels of performance. A large effort is currently underway for system integration, Experimental Physics and Industrial Control System (EPICS) controls, transfer of knowledge from the partner labs to SLAC and the production and testing of 76 racks of LLRF equipment.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Magnetron R&D for high efficiency CW RF sources for industrial accelerators

The scheme of using high-efficiency magnetrons to drive radiofrequency accelerators has been demonstrated at 2450 MHz in CW mode *. Magnetron test stands at JLab and GA have been set up to further test the noise figure and the locking speed of the injection phase-lock method. For higher power applications, power combining experiments using a TM010 cavity-type combiner and a magic tee for the binary combiner while using a single clean injection signal has been carried out at 2450 MHz. The frequency pulling effect between the magnetron and a low-Q cavity has been shown to enhance the frequency locking bandwidth compared to the injection phase-lock alone. The principle has been studied by the equivalent circuit simulation, analytical model, and finally confirmed experimentally on the magnetrons. Due to the pandemic delay in 2020, the equivalent high power tests using a 75kW, 915MHz industrial magnetron will be done in 2021 and will be reported in a future paper.

Wang, H.↗