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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
NASA NTRS1994

Large angle magnetic suspension test fixture

Over the past few decades, research has proven the feasibility of the concept of noncontacting magnetic bearing systems which operate with no wear or vibration. As a result, magnetic bearing systems are beginning to emerge as integral parts of modern industrial and aerospace systems. Further applications research is still required. NASA has loaned an existing magnetic bearing device, the Annular Suspension and Pointing System (ASPS), to ODU to permit student design teams the opportunity to pursue some of these studies. The ASPS is a protoype for a high-accuracy space payload pointing and vibration isolation system. The project objectives are to carry out modifications and improvements to the ASPS hardware to permit recommissioning in a 1-g (ground-based) environment. Following recommissioning, new applications will be studied and demonstrated, including a rotary joint for solar panels. The first teams designed and manufactured pole shims to reduce the air-gaps and raise the vertical force capability as well as on control system studies. The most recent team concentrated on the operation of a single bearing station, which was successfully accomplished with a PC-based digital controller. The paper will review the history and technical background of the ASPS hardware, followed by presentation of the progress made and the current status of the project.

Britcher, Colin P.↗
DOE OSTI2023

Relaxation measurements of an MRI system phantom at low magnetic field strengths

Abstract Objective Temperature controlled T 1 and T 2 relaxation times are measured on NiCl 2 and MnCl 2 solutions from the ISMRM/NIST system phantom at low magnetic field strengths of 6.5 mT, 64 mT and 550 mT. Materials and methods The T 1 and T 2 were measured of five samples with increasing concentrations of NiCl 2 and five samples with increasing concentrations of MnCl 2 . All samples were scanned at 6.5 mT, 64 mT and 550 mT, at sample temperatures ranging from 10 °C to 37 °C. Results The NiCl 2 solutions showed little change in T 1 and T 2 with magnetic field strength, and both relaxation times decreased with increasing temperature. The MnCl 2 solutions showed an increase in T 1 and a decrease in T 2 with increasing magnetic field strength, and both T 1 and T 2 increased with increasing temperature. Discussion The low field relaxation rates of the NiCl 2 and MnCl 2 arrays in the ISMRM/NIST system phantom are investigated and compared to results from clinical field strengths of 1.5 T and 3.0 T. The measurements can be used as a benchmark for MRI system functionality and stability, especially when MRI systems are taken out of the radiology suite or laboratory and into less traditional environments.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2023

High-energy synchrotron flares powered by strongly radiative relativistic magnetic reconnection: 2D and 3D PIC simulations

ABSTRACT The time evolution of high-energy synchrotron radiation generated in a relativistic pair plasma energized by reconnection of strong magnetic fields is investigated with 2D and 3D particle-in-cell (PIC) simulations. The simulations in this 2D/3D comparison study are conducted with the radiative PIC code OSIRIS, which self-consistently accounts for the synchrotron radiation reaction on the emitting particles, and enables us to explore the effects of synchrotron cooling. Magnetic reconnection causes compression of the plasma and magnetic field deep inside magnetic islands (plasmoids), leading to an enhancement of the flaring emission, which may help explain some astrophysical gamma-ray flare observations. Although radiative cooling weakens the emission from plasmoid cores, it facilitates additional compression there, further amplifying the magnetic field B and plasma density n, and thus partially mitigating this effect. Novel simulation diagnostics utilizing 2D histograms in the n-B space are developed and used to visualize and quantify the effects of compression. The n-B histograms are observed to be bounded by relatively sharp power-law boundaries marking clear limits on compression. Theoretical explanations for some of these compression limits are developed, rooted in radiative resistivity or 3D kinking instabilities. Systematic parameter-space studies with respect to guide magnetic field, system size, and upstream magnetization are conducted and suggest that stronger compression, brighter high-energy radiation, and perhaps significant quantum electrodynamic effects such as pair production, may occur in environments with larger reconnection-region sizes and higher magnetization, particularly when magnetic field strengths approach the critical (Schwinger) field, as found in magnetar magnetospheres.

Schoeffler, K. M. (ORCID:0000000276447381)↗
NASA NTRS1993

Magnetic suspension actuator concepts and applications

The fundamental aspect which makes magnetic suspension systems possible is the magnetic phenomena by which significant forces can be generated. Each of these force-producing phenomena has unique characteristics and is implementable in a unique fashion, such that each performs the magnetic suspension task differently than the others. A practical overview of the force-producing concepts, their unique characteristics, and their typical methods of application is provided.

Kroeger, John↗
NASA NTRS1994

Concept verification of three dimensional free motion simulator for space robot

In the development of automatic assembling technologies for space structures, it is an indispensable matter to investigate and simulate the movements of robot satellites concerned with mission operation. The movement investigation and simulation on the ground will be effectively realized by a free motion simulator. Various types of ground systems for simulating free motion have been proposed and utilized. Some of these methods are a neutral buoyancy system, an air or magnetic suspension system, a passive suspension balance system, and a free flying aircraft or drop tower system. In addition, systems can be simulated by computers using an analytical model. Each free motion simulation method has limitations and well known problems, specifically, disturbance by water viscosity, limited number of degrees-of-freedom, complex dynamics induced by the attachment of the simulation system, short experiment time, and the lack of high speed super-computer simulation systems, respectively. The basic idea presented here is to realize 3-dimensional free motion. This is achieved by combining a spherical air bearing, a cylindrical air bearing, and a flat air bearing. A conventional air bearing system has difficulty realizing free vertical motion suspension. The idea of free vertical suspension is that a cylindrical air bearing and counter balance weight realize vertical free motion. This paper presents a design concept, configuration, and basic performance characteristics of an innovative free motion simulator. A prototype simulator verifies the feasibility of 3-dimensional free motion simulation.

Okamoto, Osamu↗
NASA NTRSDate not supplied

Dynamic Stability Test Technique for Blunt Bodies in a Magnetic Suspension and Balance System

Techniques for the measurement of subsonic dynamic stability derivatives of blunt-body re-entry capsules are being developed using a Magnetic Suspension and Balance System at NASA Langley Research Center. The measured aerodynamics of a 45-degree sphere-cone similar to configurations being considered for Mars Sample Return Earth Entry Vehicle are reported. A novel test method has been developed where forced oscillatory translation of a test article is used to excite yaw attitude oscillations. The forced motion is then halted to observe free-to-oscillate behavior of the test article. Parameter identification methods are used to extract drag as well as static and dynamic yawing moment stability characteristics from the measured forces and observed attitude histories. This combination of forced excitation followed by free-to-oscillate dynamics is a repeatable method to produce test article attitude histories that can be used to measure aerodynamic characteristics.

Entry Systems Modeling↗
NASA NTRSDate not supplied

Dynamic Stability Test Technique for Blunt Bodies in a Magnetic Suspension and Balance System

Techniques for the measurement of subsonic dynamic stability derivatives of blunt-body re-entry capsules are being developed using a Magnetic Suspension and Balance System at NASA Langley Research Center. The measured aerodynamics of a 45-degree sphere-cone similar to configurations being considered for Mars Sample Return Earth Entry Vehicle are reported. A novel test method has been developed where forced oscillatory translation of a test article is used to excite yaw attitude oscillations. The forced motion is then halted to observe free-to-oscillate behavior of the test article. Parameter identification methods are used to extract drag as well as static and dynamic yawing moment stability characteristics from the measured forces and observed attitude histories. This combination of forced excitation followed by free-to-oscillate dynamics is a repeatable method to produce test article attitude histories that can be used to measure aerodynamic characteristics.

Entry Systems Modeling↗
NASA NTRS1990

Magnetic suspension and balance system advanced study, phase 2

The design improvements for the system encompass 14 or 18 external superconductive coils mounted on a 8 x 8 foot wind tunnel, a superconductive model core magnet on a holmium mandrel to fit an F-16 model, model wings of permanent magnet material Nd2Fe14B, and fiber glass epoxy structure. The Magnetic Suspension and Balance System (MSBS) advanced design is confirmed by the successful construction and test of a full size superconductive model core solenoid with holmium mandrel. The solenoid is 75 cm long and 12.6 cm in diameter and produces 6.1 tesla for a hold time of 47 minutes. An integrated coil system design of a new compact configuration without specific coils for roll or pitch shows promise of simplicity; magnet reductions of 30 percent compared to the most recent 1985 design are possible.

Boom, R. W.↗
NASA NTRS1992

Solar full-disk magnetic field image receiving system and observation software

The paper introduces terminal hardware system of 10 cm high resolution full-disk magnetic field telescope among solar multi-channel telescope produced by Beijing Astronomical Observatory, and its software procedure by using imaging processing as well real time data collecting. These data were processed by Sun Workstation 470/4, including doing some spectrum analysis, the system is unique in the world now. It uses a set of CCD (1320 pixels plus 1035 pixels) of high resolution image explosion, also it has a set of fast and high resolution (1024 pixel plus 1024 pixel) image processor. Moreover, we can obtain higher time and space resolution about solar full-disk magnetic field and velocity field. This will provide excellent means in observation and studies of full-disk solar large-scale magnetic field and velocity field.

Xu, Yan↗
DOE OSTI2018

Visualization of Multi-Dimensional Imaging Data for the DIII-D National Fusion Facility

With funding provided from the Office of Fusion Energy Science’s program on Diagnostic Systems for Magnetic Fusion Energy Sciences, the PI and his team have pioneered the development of microwave imaging systems for magnetic fusion plasma diagnostics. Specifically, electron cyclotron emission (ECE) imaging [1], a passive radiometric technique, measures electron temperature fluctuations; and microwave imaging reflectometry (MIR) [2], an active radar imaging technique, measures electron density fluctuations. These microwave imaging diagnostic instruments developed by UC Davis have made important contributions to fusion science in a relatively short period of time from their original installation on DIII-D. The microwave imaging diagnostic technique has matured considerably since the beginning of a fruitful collaboration with DIII-D and PPPL, and has also been adopted at preeminent tokamak facilities worldwide. As discussed in detail in the following, this has continued with the development of revolutionary microwave diagnostic instruments employing monolithic millimeter wave integrated circuit (MMIC) system-on-chip (SoC) technology. Specifically, “chip” receivers mounted in liquid crystal polymer (LCP) modules have been demonstrated to dramatically improve the performance of the electron cyclotron emission imaging (ECEI) system including: 30x improvement in noise temperature thereby permitting absolute 2-D electron temperature images, outstanding shielding against out-of-band interference including microwave bursting which had plagued previous ELM studies using the old quasi-optical mini-lens ECEI system, and independent modules facilitating flexible repair and replacement. Under the “Visualization of multi-dimensional imaging data for the DIII-D National Fusion Facility” program, funding was provided for a research scientist postdoc and a Ph.D. student to support physics studies at DIII-D employing these instruments. This endeavor is synergistic with our current grant under the DOE Fusion Energy Sciences (FES) program on Diagnostic Systems for Magnetic Fusion Energy Sciences. This support considerably increased the scientific output of the diagnostics. The activities were strongly focused in the areas of pedestal and ELM stability, energetic particle confinement, and the early detection and avoidance of tokamak disruptions employing the microwave imaging diagnostic instruments developed under the advanced diagnostics program where imaging of the ELM crash was made possible by the elimination of the interference from the associated microwave “bursts”

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1984

Development of high frequency low weight power magnetics for aerospace power systems

A dominant design consideration in the development of space type power magnetic devices is the application of reliable thermal control methods to prevent device failure which is due to excessive temperature rises and hot temperatures in critical areas. The resultant design must also yield low weight, high efficiency, high reliability and maintainability, and long life. The weight savings and high efficiency that results by going to high frequency and unique thermal control techniques is demonstrated by the development of a 25 kVA, 20 kHz space type transformer under the power magnetics technology program. Work in the area of power rotary transformer is also discussed.

Schwarze, G. E.↗
DOE OSTI2026

Magnetic resonance control of spin-correlated radical pair dynamics in vivo

Magnetic fields can influence reactions involving spin-correlated radical pairs (SCRPs). This provides a mechanism by which both static and time-varying magnetic fields can affect living systems at the biomolecular level. However, an engineered SCRP system conferring magnetic sensitivity to a non-native biochemical process in a multicellular organism has not yet been demonstrated. Here, in this study, we demonstrate control of SCRP dynamics using magnetic resonance in a live transgenic animal. We show that the emission of various red fluorescent proteins (RFPs), in the presence of a flavin cofactor, can be modified by a combination of static and radiofrequency magnetic fields applied near the electron spin resonance frequency. This effect was measured at room temperature both in vitro and in the nematode Caenorhabditis elegans, genetically modified to express the RFP mScarlet. These observations suggest that the magnetic field effects measured in RFP-flavin systems are due to quantum-correlated radical pairs with a coherence time larger than 4 ns. Our experiments demonstrate that radiofrequency magnetic fields can influence dynamics of reactions involving SCRPs in vivo, potentially enabling new methods for remotely controlling biomolecular processes, such as gene expression, and suggest broader potential for quantum tools in biology.

Burd, Shaun C. [Stanford Univ., CA (United States)↗
NASA NTRS1996

H Infinity Control of Magnetic Bearings to Ensure Both System and External Periodic Disturbance Robustness

Both self-excited and forced disturbances often lead to severe rotor vibrations in a magnetic bearing systems with long slender shafts. This problem has been studied using the H-infinity method, and stability with good robustness can be achieved for the linearized model of a magnetic bearing when small transient disturbances are applied. In this paper, the H-infinity control method for self-excited and forced disturbances is first reviewed. It is then applied to the control of a magnetic bearing rotor system. In modelling the system, the shaft is first discretized into 18 finite elements and then three levels of condensation are applied. This leads to a system with three masses and three compliant elements which can be described by six state variable coordinates. Simulation of the resultant system design has been performed at speeds up to 10,000 rpm. Disturbances in terms of different initial displacements, initial impulses, and external periodic inputs have been imposed. The simulation results show that good stability can be achieved under these different transient disturbances using the proposed controller while at the same time reducing the sensitivity to external periodic disturbances.

Jiang, Yuhong↗
DOE OSTI2010

Low field magnetic resonance imaging

A method and system of magnetic resonance imaging does not need a large homogenous field to truncate a gradient field. Spatial information is encoded into the spin magnetization by allowing the magnetization to evolve in a non-truncated gradient field and inducing a set of 180 degree rotations prior to signal acquisition.

Pines, Alexander↗
NASA NTRS1992

Overview of magnetic suspension research at Langley Research Center

An overview of research in small- and large-gap magnetic suspension systems at LaRC is presented. The overview is limited to systems which have been built as laboratory models or engineering models. Small-gap systems applications include the Annular Momentum Control Device (AMCD), which is a momentum storage device for the stabilization and control of spacecraft, and the Annular Suspension and Pointing System (ASPS), which is a general purpose pointing mount designed to provide orientation, mechanical isolation, and fine pointing space experiments. These devices are described and control and linearization approaches for the magnetic suspension systems for these devices are discussed. Large-gap systems applications at LaRC have been almost exclusively wind tunnel magnetic suspension systems. A brief description of these efforts is also presented.

Groom, Nelson J.↗