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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Water-cooled Helmholtz coil for Ultra-low Magnetic Field Testing

Ultra-low magnetic field testing requires precise and finely calibrated instrumentation interacting with very marginal magnetic fields in highly controlled environments. We designed a large Helmholtz coil system for implementation around a 17.825-inch outer diameter Helium-3 Cryogenic fridge, to serve as both a field-zeroing device and to enable higher resolution on magnetic field sweeps during experiments. We present finite volume modeling and finite element analysis results which indicate the device could safely run at 20 [A] in perpetuity, producing a magnetic field of 65 [mT], without the surface facing the Cryogenic fridge exceeding 50°C. The overall system parts expense is $\$$4,882.76.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS2011

Miniature Laser Magnetometer

A conceptual design has been developed for a miniature laser magnetometer (MLM) that will measure the scalar magnitude and vector components of near-Earth magnetic fields. The MLM incorporates a number of technical innovations to achieve high-accuracy and high-resolution performance while significantly reducing the size of the laser-pumped helium magnetometer for use on small satellites and unmanned aerial vehicles (UAVs). and electronics sections that has the capability of measuring both the scalar magnetic field magnitude and the vector magnetic field components. Further more, the high-accuracy scalar measurements are used to calibrate and correct the vector component measurements in order to achieve superior vector accuracy and stability. The correction algorithm applied to the vector components for calibration and the same cell for vector and scalar measurements are major innovations. The separate sensor and electronics section of the MLM instrument allow the sensor to be installed on a boom or otherwise located away from electronics and other noisy magnetic components. The MLM s miniaturization will be accomplished through the use of advanced miniaturized components and packaging methods for the MLM sensor and electronics. The MLM conceptual design includes three key innovations. The first is a new non-magnetic laser package that will allow the placement of the laser pump source near the helium cell sensing elements. The second innovation is the design of compact, nested, triaxial Braunbek coils used in the vector measurements that reduce the coil size by a factor of two compared to existing Helmholtz coils with similar field-generation performance. The third innovation is a compact sensor design that reduces the sensor volume by a factor of eight compared to MLM s predecessor.

Slocum, Robert↗
NASA NTRS2004

Magnetic and Langmuir Probe Measurements on the Plasmoid Thruster Experiment (PTX)

The Plasmoid Thruster Experiment (PTX) operates by inductively producing plasmoids in a conical theta-pinch coil and subsequently ejecting them at high velocity. An overview of PTX is described in a companion paper. The shape and magnetic field structure of the translating plasmoids will be measured with of an array of inductive magnetic field probes. Six sets of two B-dot probes (for a total of twelve probes) have been constructed for measuring B(sub z) and B(sub theta), the axial and azimuthal components of the magnetic field. The probes were calibrated with a Helmholtz coil, driven alternately by a high-voltage pulser or a signal generator. The probes are wound on a G-10 form, and have an average (calibrated) NA of 9.37 x 10(exp -5) square meters, where N is the number of turns and A is cross-sectional area. The frequency response of the probes was measured over the range from 1 kHz to 10 MHZ. The electron number density n(sub e), electron temperature T(sub e) and velocity v will be determined from measurements taken with a quadruple Langmuir probe, situated in the exhaust chamber. Three of the four probes on the quadruple probe sample the current-voltage characteristic, and from this yield measurements of T(sub e) and n(sub e). The fourth probe provides a measurement of plasma flow velocity. A 6-inch long alumina rod, hollowed with four holes to house the probe wires, is being used to construct the quadruple probe. A variety of propellants will be used, including hydrogen, nitrogen and argon. From the measurements of the plasmoid mass, density, temperature, and velocity, the basic propulsion characteristics of PTX will be evaluated.

Koelfgen, Syri J.↗
NASA NTRS2004

Magnetic and Langmuir Probe Measurements on the Plasmoid Thruster Experiment (PTX)

The Plasmoid Thruster Experiment (PTX) operates by inductively producing plasmoids in a conical theta-pinch coil and ejecting them at high velocity. A plasmoid is a plasma with an imbedded closed magnetic field structure. The shape and magnetic field structure of the translating plasmoids have been measured with of an array of magnetic field probes. Six sets of two B-dot probes were constructed for measuring B(sub z) and B(sub theta), the axial and azimuthal components of the magnetic field. The probes are wound on a square G10 form, and have an average (calibrated) NA of 9.37 x l0(exp -5) square meters, where N is the number of turns and A is the cross-sectional area. The probes were calibrated with a Helmholtz coil, driven by a high-voltage pulser to measure NA, and by a signal generator to determine the probe's frequency response. The plasmoid electron number density n(sub e) electron temperature T(sub e), and velocity ratio v/c(sub m), (where v is the bulk plasma flow velocity and c(sub m), is the ion thermal speed) have also been measured with a quadruple Langmuir probe. The Langmuir probe tips are 10 mm long, 20-mil diameter stainless steel wire, housed in a 6-inch long 4-bore aluminum rod. Measurements on PTX with argon and hydrogen from the magnetic field probes and quadruple Langmuir probe will be presented in this paper.

Koelfgen, Syri J.↗
DOE OSTI2021

Bioinspired aligned magnetic features in aerogels for humidity sensing

Many natural plant tissues, such as pinecones, utilize structures to transduce changes in humidity into movement or strain. These often employ layered structures with aligned features in order to create differential stress across the material as different portions swell at different rates. Here, by replicating these types of structures in synthetic materials we can create structures that respond to humidity in a similar manner. Taking these aligned features as inspiration, silica aerogels with tailored humidity reactive properties were created. This behavior was achieved by creating aligned features in these aerogels using a Helmholtz coil to produce a uniform magnetic field that aligned ferrofluid droplets into chains and needle like features. These magnetite-based structures were shown to retain their superparamagnetic properties, allowing them to easily be removed from the aerogels, leaving a large number of aligned channels. Aerogels with the removed needles experienced significantly different strains than both unmodified aerogels and aerogels with the aligned features still in place. Aerogels with these tunable aligned features could be used in humidity sensors that can transduce changes in humidity into strain and could be used in applications such as volatile organic compound capture.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

AC Magnetometry Using Nano-ferrofluid Cladded Multimode Interferometric Fiber Optic Sensors for Power Grid Monitoring Applications

The AC magnetic field response of the superparamagnetic nano-ferrofluid is an interplay between the Neel and Brownian relaxation processes and is generally quantified via the susceptibility measurements at high frequencies. The high frequency limit is dictated by these relaxation times which need to be shorter than the time scale of the time varying magnetic field for the nano-ferrofluid to be considered in an equilibrium state at each time instant. Even though the high frequency response of ferrofluid has been extensively investigated for frequencies up to GHz range by non-optical methods, harnessing dynamic response by optical means for AC magnetic field sensing in fiber-optic-based sensors-field remains unexplored. Instead, the incorporation of nano-ferrofluid as sensing materials has been only limited to DC magnetic field sensing, often citing their long response time as a limiting factor to AC field sensing. This work reports the finding of high frequency (up to 15 kHz) AC magnetic field sensing capability of nanomagnetic fluid as the cladding material of a fiber-optic multimode interferometry (MMI) structure optimized for the fourth self-imaging spectral response. The key parameter enabling high frequency response is the short response time (<1 ms) achieved by optimizing both the sensing structure and nano-ferrofluid solution. Focus has been imparted on 60 Hz line-frequency profiles of various current/magnetic fields to test the efficacy of these sensors in metering and monitoring current and current-induced magnetic fields in the electrical power grid systems. The magnetic field sensitivity of 240 mV/Gauss per dBm of transmitted power was achieved for 60 Hz field applied via Helmholtz coil, whereas the 60 Hz AC current sensitivity of 2.83 mV/A was measured due to magnetic field induced by current in a straight conducting wire.

42 ENGINEERING↗
DOE OSTI2025

In-Field Testing of Components for Feedback and Control of the ITER Disruption Mitigation System

Here, the shattered pellet injection (SPI) method has been chosen as the disruption mitigation system (DMS) for ITER. To protect the device from plasma disruptions that cause damaging heat and electromagnetic loads, SPI is used to inject high-Z material into the plasma. The process of SPI utilizes cryogenic cooling to form solid pellets. Pellets are accelerated down a barrel and into an angled surface, causing the pellet to shatter prior to entering the tokamak chamber. For the DMS to function reliably, the 27 separate shattered pellet injectors planned for ITER must rely on many components to provide accurate feedback data and for control functions. Each component in the DMS is exposed to an elevated background magnetic field depending on its placement and proximity to the plasma chamber. A Helmholtz coil test stand that is operated at Oak Ridge National Laboratory was utilized to test the components in relevant background field levels to assess component performance. This paper details the test design and results for in-field component operation for a variety of components. This list includes the following components: two different network switches for camera connectivity, a VAT fast shutter valve intended to reduce the flow of SPI propellant gas into the torus, a solenoid control valve intended for use in the pellet formation process, pressure/vacuum switches to be used for feedback and control, a printed circuit board piezo pressure sensor to be used to measure breech pressure, and various relays for the high-voltage pulsed power supply used to drive the SPI propellant valve.

Disruption mitigation↗
DOE OSTI2024

Understanding the impact of an applied axial magnetic field on efficient current coupling on the Z machine

Magnetized liner inertial fusion (MagLIF) is an attractive concept for producing thermonuclear fusion reactions. The MagLIF platform involves the operation of Helmholtz coils to apply a 15 Tesla axial magnetic field to the load region, where a cylindrical, fuel-filled metal liner is imploded by a ∼ 2 0 MA current pulse. The fringe field from these coils extends into the transmission line that delivers the current to the target. We investigated the extent to which this applied field disturbs the nominal power flow within that transmission line. A simplified model of the geometry shows that adding the applied magnetic field results in magnetic field lines that connect the cathode to the anode, suggesting electrons may not be magnetically insulated in this region. Particle-in-cell simulations indicated the addition of the applied magnetic field would not significantly impact the current delivery to the load. Velocimetry was used to experimentally assess the current delivery with and without the applied magnetic field. We find no measurable effects of the applied field on current delivery in the configuration investigated in this study. Published by the American Physical Society 2024

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

The Radiative Magneto-Hydrodynamics of Colliding Flow: Instabilities, Reconnection and Exoplanet Atmosphere Connections

Hypersonic flows of magnetized plasmas naturally produce strong shocks when obstructions or self‐interactions (flow collisions) occur. Such complex flows occur in a wide variety of HEDP settings such as Z‐pinches and laser driven implosion experiments that include magnetic fields via explosive Helmholtz coils (MIFEDS) When thermal energy behind the shocks can be lost to optically thin radiation, the flow dynamics becomes even more complex, admitting a range of new instabilities such as the Nonlinear Thin Shell Instability (NTSI). Because of their inherent non‐ linearity, multi‐dimensionality and time‐dependence (i.e. turbulence), the ability to articulate the underlying physics of colliding hypersonic magnetized flows represents a significant frontier in HEDP studies. The addition of radiative cooling to these flows propels the study even further into the domain of extreme plasma physics. Exploration of these forms of HED plasmas is of interest to basic plasma physics as well as of interest for their application to Inertial Confinement Fusion.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Evolution of the electrothermal instability from thick rod z pinches subject to dynamically and statically applied axial magnetic field

LDRD Project 229427 aimed to determine how electrothermal instability (ETI) driven heating on a z-pinch rod pulsed with intense current evolves under mixed magnetic field (azimuthal + axial) conditions, which is pertinent to pulsed-power-driven magnetically-insulated transmission lines and physics targets. Experiments focused on diagnosing ETI-driven heating from deliberately-machined and well-characterized micron-scale surface defects (referred to as engineered defects or ED). Prior to the start of this project, understanding of how unmagnetized (B z =0) ED evolve had been obtained—simulations largely reproduce the experimentally observed high temperature spots which develop at the poles of bare/uncoated ED. Project 229427 extended the Mykonos Facility ED experimental platform to include axial field. In the first class of experiments, axial field was provided “dynamically” via a helical return can (HRC). In this case, B z and B θ rise at the same rate. Generally, the HRC generated magnetic field at a fixed polarization angle Φ B =arctan(B z /B θ )=15° on the rod's surface. In the second class of experiments, axial field was provided “statically” via a slow-rising (millisecond) external Helmholtz coil pair. In this case, B z was effectively constant/static throughout the 100 ns rise of the Mykonos current. For either case, a primary goal was to determine whether ETI provides a helical seed perturbation for the subsequent growth of the helical magneto Rayleigh-Taylor modes observed in MagLIF (static B z ) and dynamic screw pinch (DSP, dynamic B z ) experiments. When dynamic field was applied using an HRC, emissions from individual ED aligned toward Φ B , while emissions from ED within pairs elongated and preferentially merged along Φ B . These data strongly support that for a randomized defect distribution, heating from nearby current-density perturbations will favorably merge about Φ B to generate an extended seed perturbation that aligns toward the surface-field polarization, and this may impact the orientation of subsequent MRT growth on imploding liners. The results from the static field experiments were largely inconclusive, as any ETI heating rotation, if present, was obscured/overwhelmed by local/random heating from ED rim imperfections.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2025

Demonstrating magnetic field robustness and reducing temporal T1 noise in transmon qubits through magnetic field engineering

The coherence of superconducting transmon qubits is often disrupted by fluctuations in the energy relaxation time (T1), limiting their performance for quantum computing. While background magnetic fields can be harmful to superconducting devices, we demonstrate that both trapped magnetic flux and externally applied static magnetic fields can suppress temporal fluctuations in T1 without significantly degrading its average value or qubit frequency. Using a three-axis Helmholtz coil system, we applied calibrated magnetic fields perpendicular to the qubit plane during cooldown and operation. Remarkably, transmon qubits based on tantalum-capped niobium (Nb/Ta) capacitive pads and aluminum-based Josephson junctions (JJs) maintained T1 lifetimes near 300 μs even when cooled in fields as high as 600 mG. Both trapped flux up to 600 mG and applied fields up to 400 mG reduced T1 fluctuations by more than a factor of two, while higher field strengths caused rapid coherence degradation. We attribute this stabilization to the polarization of paramagnetic impurities, the role of trapped flux as a sink for non-equilibrium quasiparticles (QPs), and partial saturation of fluctuating two-level systems (TLSs). These findings challenge the conventional view that magnetic fields are inherently detrimental and introduce a strategy for mitigating noise in superconducting qubits, offering a practical path toward more stable and scalable quantum systems.

Abdisatarov, Bektur [Fermilab; Jefferson Lab]↗
NASA NTRS1972

Design and testing of a magnetic suspension and damping system for a space telescope

The basic equations of motion are derived for a two dimensional, three degree of freedom simulation of a space telescope coupled to a spacecraft by means of a magnetic suspension and isolation system. The system consists of paramagnetic or ferromagnetic discs confined to the magnetic field between two Helmholtz coils. Damping is introduced by varying the magnetic field in proportion to a velocity signal derived from the telescope. The equations of motion are nonlinear, similar in behavior to the one-dimensional Van der Pol equation. The computer simulation was verified by testing a 264-kilogram air bearing platform which simulates the telescope in a frictionless environment. The simulation demonstrated effective isolation capabilities for disturbance frequencies above resonance. Damping in the system improved the response near resonance and prevented the build-up of large oscillatory amplitudes.

Ockman, N. J.↗
NASA NTRS1971

The null magnetic field as reference for the study of geomagnetic directional effects in animals and man.

Techniques for producing very low and zero magnetic fields are considered, giving attention to the compensation of the geomagnetic field by a Helmholtz coil system, approaches utilizing the shielding power of highly permeable alloys, and the complete exclusion of the geomagnetic field with the aid of a superconductive shield. Animal experiments in low magnetic fields are discussed, together with the exposure of man to 'null' magnetic fields and the Josephson junction as a possible biosensor of magnetic fields. It is found that neither the functions nor the behavior of man changes significantly during a two-week exposure to magnetic fields below 50 gammas.

Beischer, D. E.↗
NASA NTRS1992

Characterization of radiation-induced damage in high performance polymers by electron paramagnetic resonance imaging spectroscopy

The potential for long-term human activity beyond the Earth's protective magnetosphere is limited in part by the lack of detailed information on the effectiveness and performance of existing structural materials to shield the crew and spacecraft from highly penetrating space radiations. The two radiations of greatest concern are high energy protons emitted during solar flares and galactic cosmic rays which are energetic ions ranging from protons to highly oxidized iron. Although the interactions of such high-energy radiations with matter are not completely understood at this time, the effects of the incident radiation are clearly expected to include the formation of paramagnetic spin centers via ionization and bond-scission reactions in the molecular matrices of structural materials. Since this type of radiation damage is readily characterized by Electron Paramagnetic Resonance (EPR) spectroscopy, the NASA Langley Research Center EPR system was repaired and brought on-line during the 1991 ASEE term. A major goal of the 1992 ASEE term was to adapt the existing core of the LaRC EPR system to meet the requirements for EPR Imaging--a powerful new technique which provides detailed information on the internal structure of materials by mapping the spatial distribution of unpaired spin density in bulk media. Major impetus for this adaptation arises from the fact that information derived from EPRI complements other methods such as scanning electron microscopy which primarily characterize surface phenomena. The modification of the EPR system has been initiated by the construction of specially designed, counterwound Helmholtz coils which will be mounted on the main EPR electromagnet. The specifications of the coils have been set to achieve a static linear magnetic field gradient of 10 gauss/mm/amp along the principal (Z) axis of the Zeeman field. Construction is also in progress of a paramagnetic standard in which the spin distribution is known in all three dimensions. This sample will be used to assess the linearity of the magnetic field gradient and to ensure authentic image reconstruction. A second major task was to secure the computer capability to enable image reconstruction from projection data generated by the magnetic field gradients. To this end, commercially available and public domain software packages which perform inverse Fourier Transform and convoluted (filtered) back projection functions are being integrated into the existing EPR data processing system.

Suleman, Naushadalli K.↗
NASA NTRS1994

Plasma heating for containerless and microgravity materials processing

A method for plasma heating of levitated samples to be used in containerless microgravity processing is disclosed. A sample is levitated by electrostatic, electromagnetic, aerodynamic, or acoustic systems, as is appropriate for the physical properties of the particular sample. The sample is heated by a plasma torch at atmospheric pressure. A ground plate is provided to help direct the plasma towards the sample. In addition, Helmholtz coils are provided to produce a magnetic field that can be used to spiral the plasma around the sample. The plasma heating system is oriented such that it does not interfere with the levitation system.

Leung, Emily W.↗