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Results for “trapped field magnets”

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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

The magnitude of the magnetic field near the surface of a high-T(sub c) superconductor with a trapped flux

In 1986, much excitement was caused by the discovery of a class of materials that conducted electricity with zero resistance at temperatures above the boiling temperature of liquid nitrogen. This excitement was checked by the difficulties of manufacturing ceramics and the usefulness of high temperature superconductors that were restricted by their becoming high resistive conductors at small current densities. A lack of pinning of the magnetic field flux caused the return of high resistance as the current was increased in these materials. A study of the magnetic field near the surface of a high temperature superconductor is the first step in the search for a means of pinning the flux lines and increasing their critical current densities. The author found that a comparison between the defects in the surface of the superconductor and the magnetic field showed only a change in the field near the notch and the edge. No correlation was found between the surface grain or structure and the oscillations in the magnetic field. The observed changes in the magnetic field show resonances which may give an indication of the non-flux pinning in these superconductors. A flux pinning mechanism will increase the critical current densities; therefore, other methods of determining this field should be tried. The author proposes using a flux gate magnetometer with a detector wound on a ferrite core to measure the magnitude and direction of the magnetic field.

Overcash, Dan R.↗
NASA NTRS1982

Effects of Titan on trapped particles in Saturn's magnetosphere

Magnetic field data from Voyager 1 magnetometer experiment are used with angular distribution data from the same spacecraft's low energy charged particle experiment to investigate the influences of Titan on the magnetosphere energetic particle distributions, with attention to the pitch angle distributions of ions and electrons. Titan appears to disrupt the corotation motion of the ions, since, while the fluxes of the ions in the corotation direction are of diminished intensity, those observed in the equatorial plane perpendicular to this direction are almost unaffected. The resulting distribution and trajectory modeling conclusions suggest that the convection electric field is absent in the wake of Titan, and that the presence of Titan produces a reduction in the fluxes of the electrons and flatter distributions with pitch angle.

Maclennan, C. G.↗
DOE OSTI2021

Using cyclotron radiation emission for ultra-high resolution x-ray spectroscopy

Abstract Cyclotron radiation emission spectroscopy (CRES) is an approach to measuring the energy of an electron trapped in an externally applied magnetic field. The bare electron can come from different interactions, including photoelectric absorption, Compton scatters, beta decay, and pair production. CRES relies on measuring the frequency of the electron’s cyclotron motion, and because the measurement times extend over 10 6 –10 7 cycles, the energy resolution is on the order of a single electronvolt. To date, CRES has only been performed on internal beta-emitting radioisotopes, but the technology can be applied to x-ray spectrometery through appropriate selection of a target gas and sufficient intensity of the distinct x-ray source. The applications of this technology range from high-precision measurements of atomic energy levels to calibrations of basic science experiments, to trace element identification. In this work we explore the use of CRES for x-ray spectroscopy within the rubric of measuring the energy levels of argon. Though the energy levels of argon are well established, we adopt this motivation as an example question around which a detector may be designed. The issues we explore include target material, density, electron trapping depth, noise levels, and overall efficiency. We also discuss spectral deconvolution and how the multiple peaks obtained from a single target/source pair can be used to enhance the robustness of the measurement.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2023

Design and performance of a novel low energy multispecies beamline for an antihydrogen experiment

The ALPHA Collaboration, based at the CERN Antiproton Decelerator, has recently implemented a novel beamline for low energy (≲100 eV) positron and antiproton transport between cylindrical Penning traps that have strong axial magnetic fields. Here, we describe how a combination of semianalytical and numerical calculations was used to optimize the layout and design of this beamline. Using experimental measurements taken during the initial commissioning of the instrument, we evaluate its performance and validate the models used for its development. By combining data from a range of sources, we show that the beamline has a high transfer efficiency and estimate that the percentage of particles captured in the experiments from each bunch is (78 ± 3)% for up to 10 5 antiprotons and (71 ± 5)% for bunches of up to 10 7 positrons.

43 PARTICLE ACCELERATORS↗
DOE OSTI2025

Omnigenous stellarators with improved ideal and kinetic ballooning stability

Omnigenity is a property of a magnetic field which ensures confinement of trapped particles. It is a necessary requirement for any high-performance stellarator. After creating an omnigenous equilibrium, one must also ensure reduced transport resulting from kinetic and magnetohydrodynamic (MHD) instabilities. To this end, we leverage the GPU-accelerated DESC optimization suite, which is used to design stable, finite-β omnigenous equilibria with poloidal, toroidal, and helical symmetry, achieving Mercier, ideal ballooning, and as a consequence, improved kinetic ballooning stability. We discover stellarators with second stability, a regime of large pressure gradient where an equilibrium becomes ideal ballooning stable, and demonstrate and explore both using theory and gyrokinetic simulations the connection between ideal and kinetic ballooning stability.

optimization↗
DOE OSTI2024

Exactly solvable model of light-scattering errors in quantum simulations with metastable trapped-ion qubits

Here, we analytically solve a model for light scattering in Ising dynamics of metastable atomic qubits, generalizing the approach of Foss-Feig et al. to include leakage outside the qubit manifold. We analyze the influence of these fundamental errors in simulations of proposed experiments with metastable levels of 40 Ca + ions in a Penning trap. We find that “effective magnetic fields” generated by leaked qubits have significant impacts on spin-spin correlation functions for Greenberger-Horne-Zeilinger state preparation or for quantum simulations with strong coupling, while spin squeezing uses a much weaker coupling and is largely insensitive to the simulated leakage errors, even with a few hundred ions. Our theory and results are expected to be useful in modeling a variety of metastable qubit experiments in the future.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2023

Josephson Traveling Wave Parametric Amplifiers to Enable Future Neutrino Mass Measurements

Technologies for “quantum sensing" have the promise of dramatically improved sensitivity in some experiments that explore nuclear physics at the boundaries of our current knowledge. In particular, the Josephson Traveling Wave Parametric Amplifier (JTWPA) could enable future experiments such as Project 8 that use Cyclotron Radiation Emission Spectroscopy (CRES) to measure the absolute neutrino mass scale in tritium beta decays. CRES consists of detecting a signal of approximately one femtowatt of power radiated by electrons trapped in a 1-T magnetic field. The frequency of that radiation, around 27 GHz for a tritium endpoint electron, is inversely proportional to the electron energy. One of the significant challenges of a CRES experiment is the detection of minimal signal power levels. State-of-the-art transistor-based technologies will not likely achieve sufficient signal-to-noise ratio (SNR) in a competitive neutrino mass experiment. However, emerging quantum technologies have been demonstrated to operate at the fundamental lower limits of noise permitted by the laws of quantum mechanics. Of those technologies, JTWPAs appear to satisfy future performance needs with speed gain, bandwidth, and very low noise. We propose to bring together a group of neutrino physicists, experts in the needs of future neutrino mass measurements, with leaders in the field of quantum information science and JTWPA technology to develop JTWPAs appropriate for neutrino mass measurements.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
NASA NTRS1971

A study of environmental effects caused by cesium from ion thrusters

The ATS-F satellite will carry two cesium ion thrusters. Cesium is a material that is not present in the upper atmosphere, and there is concern that the introduction of this material may result in some unexpected behavior. A study has been conducted to assess the magnitude of the effects that are to be expected. No observable effects were found as a result of the study. Consideration was given to the origin and destination of the material and the various reactions that could occur. The origin was considered to be anywhere in space from altitudes of about 100 km upward. The probable short term destination is in the form of cesium ions trapped in the earth's magnetic field or as ions and atoms in the heterosphere. The maximum possible number of cesium atoms in the field of view of an earth based observer is of the order of one million per square centimeter, far too few to be observable by visible, near-visible, or radio-frequency means. Further, no phenomena could be found that would result in the occurance of an observable event.

Source record↗
NASA NTRS1973

The greenhouse of Titan.

Analysis of non-gray radiative equilibrium and gray convective equilibrium on Titan suggests that a massive molecular-hydrogen greenhouse effect may be responsible for the disagreement between the observed IR temperatures and the equilibrium temperature of an atmosphereless Titan. Calculations of convection indicate a probable minimum optical depth of 14 which corresponds to a molecular hydrogen shell of substantial thickness with total pressures of about 0.1 bar. It is suggested that there is an equilibrium between outgassing and blow-off on the one hand and accretion from the protons trapped in a hypothetical Saturnian magnetic field on the other, in the present atmosphere of Titan. It is believed that an outgassing equivalent to the volatilization of a few kilometers of subsurface ice is required to maintain the present blow-off rate without compensation for all geological time. The presence of an extensive hydrogen corona around Titan is postulated, with surface temperatures up to 200 K.

Sagan, C.↗
NASA NTRS1972

Diffusion models for Jupiter's radiation belt

Solutions are given for the diffusion of trapped particles in a planetary magnetic field in which the first and second adiabatic invariants are preserved but the third is not, using as boundary conditions a fixed density at the outer boundary (the magnetopause) and a zero density at an inner boundary (the planetary surface). Losses to an orbiting natural satellite are included and an approximate evaluation is made of the effects of the synchrotron radiation on the energy of relativistic electrons. Choosing parameters appropriate to Jupiter, the electrons required to produce the observed synchrotron radiation are explained. If a speculative mechanism in which the diffusion is driven by ionospheric wind is the true explanation of the electrons producing the synchrotron emission it can be concluded that Jupiter's inner magnetosphere is occupied by an energetic proton flux that would be a serious hazard to spacecraft.

Jacques, S. A.↗
NASA NTRS1976

High-latitude troughs and the polar cap boundary

OGO 6 observations of troughs in the thermal plasma densities in the topside ionosphere are discussed. Ion mass spectrometer measurements were correlated with energetic electron detector and electric field measurements. It is shown that the variation of ion composition at high latitudes is complex and frequently characterized by mid-latitude and high-latitude density depression. Prominent high-latitude troughs in the atomic ion (H, He, O) distributions were seen to lie frequently near the polar cap boundary. This indicates that these troughs are unrelated to the plasmapause which is found on closed magnetic field lines away from the trapping boundary. The production of the high-latitude troughs is shown to be related to enhancements in the soft electron flux and/or to the convection electric field.

Grebowsky, J. M.↗
NASA NTRS1977

A high accuracy all-angle gyroscope readout using quantized flux

Means are described to use SQUID magnetometer flux counting and the London moment of a spherical superconducting gyroscope to read out the gyroscope spin axis direction to an accuracy of at least 23 bits per quadrant. The system is discussed in analogy to optical fringe counting as applied to distance measurement. Several methods of applying both analog and digital SQUID magnetometers to the readout problem are given, as well as limitations on each. Described are two methods of increasing the flux available for measurement: magnetizing the gyroscope with a trapped field, and optimizing readout circuit inductances. Finally, the same principle on which the gyroscope readout is based is applied to a description of a high accuracy, flux counting, digital angle encoder.

Anderson, J. T.↗
NASA NTRS1982

Findings on rings and inner satellites of Saturn of Pioneer 11

The introductory part of this paper gives a short account of the theory of absorption by planetary rings and satellites of energetic charged particles that are trapped in a planet's magnetic field and describes the observable consequences of such absorption processes. The previously published University of Iowa observations of absorption features during Pioneer 11's passage through Saturn's inner radiation belt on 1 September 1979 are critically reanalyzed and related to other evidence on rings and satellites inside 2.9 Saturn radii, especially that from the imaging system on Voyagers 1 and 2. It is found (a) that satellites 1979 S1, 1979 S2, and 1980 S3 are almost certainly identical; (b) that the evidence for 1979 S4 is weak to nonexistent; (c) that 1979 S5 and two other nearby absorption features and 1979 S6 and one other nearby absorption feature are probably caused by longitudinal and radial structure of Ring F and not by satellites; and (d) that absorption feature 1979 S3 at 169,200 + or - 600 km is identified with the optically observed Ring G.

Van Allen, J. A.↗
NASA NTRS1984

Trapped-proton energy spectrum determination (M0002-1)

The objective of this experiment is to measure the flux and energy spectrum of protons with energies of 1 to MeV. These protons are trapped on the Earth's magnetic field lines as part of the inner radiation belt, or Van Allen zone. The proton will be encountered predominantly in the South Atlantic anomaly at a 90 deg pitch angle.

Frederick J Rich↗
NASA NTRS1990

Numerical solution of the time-dependent kinetic equation for electrons in magnetized plasma

A numerical solution is developed for the time-dependent kinetic equation describing the evolution of arbitrary distributions of electrons injected into a magnetized plasma. Included in the equation are pitch-angle scattering and energy loss because of Coulomb collisions and magnetic mirroring. The numerical code can be easily modified to include other scattering or radiation terms. The numerical results are shown to agree well with known analytic solutions for various simplified configurations such as homogeneous injection in a homogeneous plasma, electron beams moving with small pitch angle with respect to the magnetic field, and injection into a magnetic trap.

Hamilton, Russell J.↗
NASA NTRS1991

Preliminary results from the heavy ions in space experiment

The Heavy Ions In Space (HIIS) experiment is intended to provide a deep survey of intensely ionizing particles in low earth orbit. Intensely ionizing particles produce single event effects in microelectronic components and are now recognized as the principal cause of spacecraft anomalies. These particles also make an important contribution to radiation doses. Besides the practical applications, HIIS data will be used to study several important scientific questions. By measuring heavy ions that stop in HIIS, the anomalous component of cosmic rays can be studied, evidence can be searched for of heavy ions trapped in the earth's magnetic field and by comparing HISS data with observations from outside the magnetosphere, the mean ionic charge state can be determined of solar energetic particles. HIIS will also record relativistic ultraheavy galactic cosmic rays. Their elemental composition will be measured from tin to uranium. Results are presented on the elemental resolution for stopping heavy ions and relativistic heavy ions.

Adams, J. H., Jr.↗
NASA NTRS1991

Magnetic levitation of condensed hydrogen

Liquid and solid molecular hydrogen has been levitated using a pair of small superconducting solenoids. The hydrogen samples, up to 3 mm in dimension, were trapped in a magnetic potential having either a discrete minimum or a minimum in the form of a ring 1 cm in diameter. The hydrogen could be moved about in the magnetic trap by applying an electric field.

Paine, C. G.↗
NASA NTRS1992

Radiation Monitoring Equipment Dosimeter Experiment

Spacecraft crews risk exposure to relatively high levels of ionizing radiation. This radiation may come from charged particles trapped in the Earth's magnetic fields, charged particles released by solar flare activity, galactic cosmic radiation, energetic photons and neutrons generated by interaction of these primary radiations with spacecraft and crew, and man-made sources (e.g., nuclear power generators). As missions are directed to higher radiation level orbits, viz., higher altitudes and inclinations, longer durations, and increased flight frequency, radiation exposure could well become a major factor for crew stay time and career lengths. To more accurately define the radiological exposure and risk to the crew, real-time radiation monitoring instrumentation, which is capable of identifying and measuring the various radiation components, must be flown. This presentation describes a radiation dosimeter instrument which was successfully flown on the Space Shuttle, the RME-3.

Hardy, Kenneth A.↗