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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Error field measurements with rotating RMP fields for DIII-D H-mode

3D magnetic sensors are employed to identify the amplitude and toroidal phase of error fields (EF) by analyzing the torque balance for magnetic islands entrained by rotating resonant magnetic perturbations (RMPs) in DIII-D H-mode plasmas. This technique of torque balance allows for efficient error field identification, offering a valuable tool for scenario-specific and optimized error field compensation (EFC) and requires only magnetic diagnostics. The torque balance used in this work includes the contribution from electromagnetic torque due to error fields, wall response, RMP fields, and viscous. Results show that viscous torque plays a crucial role, particularly during locked modes and H-mode plasmas, ensuring accurate data fits with lower residuals. The torque balance technique reveals that the L- and H-mode plasmas have distinct EF configurations, and consistent with a model-based EF analysis including MHD response in IPEC and the SURFMN EF simulation. This technique shows great robustness in measuring the intrinsic EF amplitude regardless of its amplitude or toroidal phase. Repeated discharges with EFC disparities exhibit consistent results of intrinsic error field within a reasonable range near the “standard” error field compensation. Additionally, the use of a rotating n = 1 resonant magnetic perturbation offers the advantage of reducing disruption risks by entraining saturated magnetic islands. These findings are instrumental for optimizing EF correction in fusion devices, thereby enhancing tearing mode suppression and overall plasma stability.

3D magnetic sensors↗
NASA NTRS2011

Fiber-Optic Magnetic-Field-Strength Measurement System for Lightning Detection

A fiber-optic sensor system is designed to measure magnetic fields associated with a lightning stroke. Field vector magnitudes are detected and processed for multiple locations. Since physical limitations prevent the sensor elements from being located in close proximity to highly conductive materials such as aluminum, the copper wire sensor elements (3) are located inside a 4-cubic-in. (.66-cubic-cm) plastic housing sensor head and connected to a fiber-optic conversion module by shielded cabling, which is limited to the shortest length feasible. The signal path between the conversion module and the avionics unit which processes the signals are fiber optic, providing enhanced immunity from electromagnetic radiation incident in the vicinity of the measurements. The sensors are passive, lightweight, and much smaller than commercial B-dot sensors in the configuration which measures a three-dimensional magnetic field. The system is expandable, and provides a standard-format output signal for downstream processing. Inside of the sensor head, three small search coils, each having a few turns on a circular form, are mounted orthogonally inside the non-metallic housing. The fiber-optic conversion module comprises three interferometers, one for each search coil. Each interferometer has a high bandwidth optical phase modulator that impresses the signal received from its search coil onto its output. The output of each interferometer travels by fiber optic cable to the avionics unit, and the search coil signal is recovered by an optical phase demodulator. The output of each demodulator is fed to an analog-to-digital converter, whose sampling rate is determined by the maximum expected rate of rise and peak signal magnitude. The output of the digital processor is a faithful reproduction of the coil response to the incident magnetic field. This information is provided in a standard output format on a 50-ohm port that can be connected to any number of data collection and processing instruments and/or systems. The measurement of magnetic fields using fiber-optic signal processing is novel because it eliminates limitations of a traditional B-dot system. These limitations include the distance from the sensor to the measurement device, the potential for the signal to degrade or be corrupted by EMI from lightning, and the size and weight of the sensor and associated plate.

Gurecki, Jay↗
DOE OSTI2025

A simple and highly efficient protocol for 13 C-labeling of plant cell wall for structural and quantitative analyses via solid-state nuclear magnetic resonance

Plant cell walls are made of a complex network of interacting polymers that play a critical role in plant development and responses to environmental changes. Thus, improving plant biomass and fitness requires the elucidation of the structural organization of plant cell walls in their native environment. The 13 C-based multi-dimensional solid-state nuclear magnetic resonance (ssNMR) has been instrumental in revealing the structural information of plant cell walls through 2D and 3D correlation spectral analyses. However, the requirement of enriching plants with 13 C limits the applicability of this method. To our knowledge, there is only a very limited set of methods currently available that achieve high levels of 13 C-labeling of plant materials using 13 CO 2 , and most of them require large amounts of 13 CO 2 in larger growth chambers. In this study, a simplified protocol for 13C-labeling of plant materials is introduced that allows ca 60% labeling of the cell walls, as quantified by comparison with commercially labeled samples. This level of 13 C-enrichment is sufficient for all conventional 2D and 3D correlation ssNMR experiments for detailed analysis of plant cell wall structure. The protocol is based on a convenient and easy setup to supply both 13 C-labeled glucose and 13 CO 2 using a vacuum-desiccator. The protocol does not require large amounts of 13 CO 2 . This study shows that our 13 C-labeling of plant materials can make the accessibility to ssNMR technique easy and affordable. The derived high-resolution 2D and 3D correlation spectra are used to extract structural information of plant cell walls. This helps to better understand the influence of polysaccharide-polysaccharide interaction on plant performance and allows for a more precise parametrization of plant cell wall models.

09 BIOMASS FUELS↗
DOE OSTI2025

Electron-Ion Collider (EIC) Hadron Storage Ring (HSR) Injection Transport Beamline (Y-Line Ext.) Lattice Design and Magnet Parameters

The preliminary design of the Electron-Ion Collider (EIC) Hadron Storage Ring (HSR) Normal Conducting Injection Beamline ( Y-Line Ext. ) lattice is discussed. The preliminary design includes the periodic cells, matching sections, state of the art Twiss parameters at the HSR injection, the magnet parameters and first order instrumentation placement. Furthermore, the beamline parameters, element coordinates, and other information are discussed. The names of the HSR Injection Beamline elements used in this technical report ( i.e. HD1, HQ1 ) are preliminary and not the official site wide names.

43 PARTICLE ACCELERATORS↗
NASA NTRS1968

Analysis of flutter in tape transport systems

Effect of flutter on digital data is recorded by magnetic tape recorders used with instrumentation systems. Major effect for both FM and direct recording techniques is shown to be a perturbation of the signal time base.

Davis, R. C.↗
NASA NTRS1972

Search for antimatter in primary cosmic rays.

Data from two flights of a new superconducting magnetic spectrometer are reported. This instrument was capable of a direct matter-antimatter separation in the cosmic rays. Antimatter events would appear in the spectrometer as trajectories which curve in the opposite direction to common matter, because of their negative charge. A brief description of the equipment and of the characteristics of the instrument is presented, along with the data processing techniques used. A new upper limit on the amount of antimatter in primary cosmic rays has been established. The limits are considerably lower than those for any previous experiment.

Buffington, A.↗
NASA NTRS1973

The Pioneer 11 high-field fluxgate magnetometer

The High Field Fluxgate Magnetometer Experiment flow aboard the Pioneer 11 spacecraft to investigate Jupiter's magnetic field is described. The instrument extends the spacecraft's upper limit measurement capability by more than an order of magnitude to 17.3 gauss with minimum power and volume requirements.

Acuna, M. H.↗
NASA NTRS1975

Optimization of multimagnetometer systems on a spacecraft

The problem of optimizing the position of magnetometers along a boom of given length to yield a minimized total error is investigated. The discussion is limited to at most four magnetometers, which seems to be a practical limit due to weight, power, and financial considerations. The outlined error analysis is applied to some illustrative cases. The optimal magnetometer locations, for which the total error is minimum, are computed for given boom length, instrument errors, and very conservative magnetic field models characteristic for spacecraft with only a restricted or ineffective magnetic cleanliness program. It is shown that the error contribution by the magnetometer inaccuracy is increased as the number of magnetometers is increased, whereas the spacecraft field uncertainty is diminished by an appreciably larger amount.

Neubauer, F. M.↗
NASA NTRS1985

Theoretical and Experimental Beam Plasma Physics (TEBPP)

The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is deployed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations in the near field ( 10 m) and mid field (10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

Roberts, W. T.↗
NASA NTRS1985

Plasma-depleted holes, waves, and energized particles from high-altitude explosive plasma perturbation experiments

The results of high-explosive shaped charge experiments King Crab and Bubble Machines I and II, intended to perturb the ambient plasma and magnetic field, are discussed. The instrumentation was flown above an altitude of 460 km in March 1980 and 1981 and comprised a single-axis dipole electric field detector, a fixed bias cylindrical Langmuir probe, a three-axis attitude magnetometer, and curved plated energetic ion and electron electrostatic analyzer. Among the effects of the explosion which are detailed, emphasis is placed on the creation of an ion-depleted dark hole during the Bubble Machine II experiment; mechanisms explaining the phenomenon are outlined. The auroral intensity ion beams with energies of up to 6.8 keV, observed following the explosion in the field-aligned ion electrostatic analyzer, are suggested to represent an existing ion conic population pitch angle scattered by the released barium into the view of the detector.

Wescott, E. M.↗
NASA NTRS1986

Theoretical and Experimental Beam Plasma Physics (TEBPP)

The theoretical and experimental beam plasma physics (TEBPP) consists of a package of five instruments to measure electric and magnetic fields, plasma density and temperature, neutral density, photometric emissions, and energetic particle spectra during firings of the particle injector (SEPAC) electron beam. The package is developed on a maneuverable boom (or RMS) and is used to measure beam characteristics and induced perturbations field ( 10 m) and mid field ( 10 m to 100 m) along the electron beam. The TEBPP package will be designed to investigate induced oscillations and induced electromagnetic mode waves, neutral and ion density and temperature effects, and beam characteristics as a function of axial distance.

Roberts, B.↗
NASA NTRS1988

Three-meter balloon-borne telescope

The Three-Meter Balloon-Borne Telescope is planned as a general purpose facility for making far-infrared and submillimeter astronomical observations from the stratosphere. It will operate throughout the spectral range 30 microns to 1 millimeter which is largely obscurred from the ground. The design is an f/13.5 Cassegrain telescope with an f/1.33 3-meter primary mirror supported with a 3-axis gimbal and stabilization system. The overall structure is 8.0 m high by 5.5 m in width by 4.0 m in depth and weighs 2000 kg. This low weight is achieved through the use of an ultra lightweight primary mirror of composite construction. Pointing and stabilization are achieved with television monitoring of the star field, flex-pivot bearing supports, gyroscopes, and magnetically levitated reaction wheels. Two instruments will be carried on each flight; generally a photometric camera and a spectrometer. A 64-element bolometer array photometric camera operating from 30 to 300 microns is planned as part of the facility. Additional instruments will be derived from KAO and other development programs.

Hoffmann, William F.↗
NASA NTRS1995

Simultaneous prenoon and postnoon observations of three field-aligned current systems from Viking and DMSP-F7

The spatial structure of dayside large-scale field-aligned current (FAC) systems is examined by using Viking and Defense Meteorological Satellite Program-F7 (DMSP-F7) data. We focus on four events in which the satellites simultaneously observed postnoon and prenoon three FAC systems: the region 2, the region 1, and the mantle (referred to as midday region O) systems, from equatorward to poleward. These events provide the most solid evidence to date that the midday region O system is a separate and unique FAC system, and is not an extension of the region 1 system from other local times. The events are examined comprehensively by making use of a mulit-instrumental data set, which includes magnetic field, particle flux, electric field, auroral UV image data from the satellites, and the Sondrestrom convection data. The results are summarized as follows: (1) Region 2 currents flow mostly in the central plasma sheet (CPS) precipitation region, often overlapping with the boundary plasma sheet (BPD) at their poleward edge. (2) The region 1 system is located in the core part of the auroral oval and is confined in a relatively narrow range in latitude which includes the convection reversal. The low-latitude boundary layer, possibly including the outer part of the plasma sheet, and the external cusp are the major source regions of dayside region 1 currents. (2) Midday region O currents flow on open field lines and are collocated with the shear of antisunward convection flows with velocites decreasing poleward. On the basis of these results we support the view that both prenoon and postnoon current systems consist of the three-sheet structure when the disctortion ofthe convection pattern associated with interplanetary magnetic field (IMF) B(sub Y) is small and both morningside and eveningside convection cells are crescent-shaped. We also propose that the midday region O and a part of the region 1 systems are closely coupled to the same source.

Ohtani, S.↗
NASA NTRS1993

Ionospheric convection response to slow, strong variations in a Northward interplanetary magnetic field: A case study for January 14, 1988

We analyze ionospheric convection patterns over the polar regions during the passage of an interplanetary magnetic cloud on January 14, 1988, when the interplanetary magnetic field (IMF) rotated slowly in direction and had a large amplitude. Using the assimilative mapping of ionospheric electrodynamics (AMIE) procedure, we combine simultaneous observations of ionspheric drifts and magnetic perturbations from many different instruments into consistent patterns of high-latitude electrodynamics, focusing on the period of northward IMF. By combining satellite data with ground-based observations, we have generated one of the most comprehensive data sets yet assembled and used it to produce convection maps for both hemispheres. We present evidence that a lobe convection cell was embedded within normal merging convection during a period when the IMF B(sub y) and B(sub z) components were large and positive. As the IMF became predominantly northward, a strong reversed convection pattern (afternoon-to-morning potential drop of around 100 kV) appeared in the southern (summer) polar cap, while convection in the northern (winter) hemisphere became weak and disordered with a dawn-to-dust potential drop of the order of 30 kV. These patterns persisted for about 3 hours, until the IMF rotated significantly toward the west. We interpret this behavior in terms of a recently proposed merging model for northward IMF under solstice conditions, for which lobe field lines from the hemisphere tilted toward the Sun (summer hemisphere) drape over the dayside magnetosphere, producing reverse convection in the summer hemisphere and impeding direct contact between the solar wind and field lines connected to the winter polar cap. The positive IMF B(sub x) component present at this time could have contributed to the observed hemispheric asymmetry. Reverse convection in the summer hemisphere broke down rapidly after the ratio absolute value of B(sub y)/B(sub z) exceeded unity, while convection in the winter hemisphere strengthened. A dominant dawn-to-dusk potential drop was established in both hemispheres when the magnitude of B(sub y) exceeded that of B(sub z) with potential drops of the order of 100 kV, even while B(sub z) remained northward. The latter transition to southward B(sub z) produced a gradual intensification of the convection, but a greater qualitative change occurred at the transition through absolute value of B(sub y)/B(sub z) = 1 than at at the transition through B(sub z) = 0. The various convection patterns we derive under northward IMF conditions illustrate all possibilities previously discussed in the literature: nearly single-cell and multicell, distorted and symmetric, ordered and unordered, and sunward and antisunward.

Knipp, D. J.↗
NASA NTRS1998

Low-field MRI of laser polarized noble gas

NMR images of laser polarized 3He gas were obtained at 21 G using a simple, homebuilt instrument. At such low fields magnetic resonance imaging (MRI) of thermally polarized samples (e.g., water) is not practical. Low-field noble gas MRI has novel scientific, engineering, and medical applications. Examples include portable systems for diagnosis of lung disease, as well as imaging of voids in porous media and within metallic systems.

Non-NASA Center↗
NASA NTRS2010

AXTAR: Mission Design Concept

The Advanced X-ray Timing Array (AXTAR) is a mission concept for X-ray timing of compact objects that combines very large collecting area, broadband spectral coverage, high time resolution, highly flexible scheduling, and an ability to respond promptly to time-critical targets of opportunity. It is optimized for sub-millisecond timing of bright Galactic X-ray sources in order to study phenomena at the natural time scales of neutron star surfaces and black hole event horizons, thus probing the physics of ultra-dense matter, strongly curved spacetimes, and intense magnetic fields. AXTAR s main instrument, the Large Area Timing Array (LATA) is a collimated instrument with 2 50 keV coverage and over 3 square meters effective area. The LATA is made up of an array of super-modules that house 2-mm thick silicon pixel detectors. AXTAR will provide a significant improvement in effective area (a factor of 7 at 4 keV and a factor of 36 at 30 keV) over the RXTE PCA. AXTAR will also carry a sensitive Sky Monitor (SM) that acts as a trigger for pointed observations of X-ray transients in addition to providing high duty cycle monitoring of the X-ray sky. We review the science goals and technical concept for AXTAR and present results from a preliminary mission design study

Ray, Paul S.↗