Magnetic flux flow in a Type 2 superconductor
Flow measurement of magnetic flux in Nb-Zr superconductor to infer magnetic induction and currents in material
Urban, E. W.↗
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Results for “MAGNETIC INDUCTION”
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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Very high-temperature permeameter
High temperature permeameter for measuring magnetizing force or magnetic induction in vacuum or inert atmosphere
Barranger, J. P.↗
Electrical conductivity and velocity of highly ionized plasma flows - Theory and experiment.
Use of an immersible, three-coil, magnetic-induction probe, previously tested in a low-density supersonic argon jet, to measure electrical conductivity and velocity profiles of a highly ionized high-density nitrogen jet in the continuum flow regime where effects due to probe bow shocks and boundary layers might not be negligible. Measured centerline values of electrical conductivity and velocity were compared with predictions based on a theoretical analysis previously developed to study the gas as it expanded adiabatically and inviscidly from an equilibrium sonic state to the nozzle exit. The resulting numerical exit plane values for electron density and electron temperature were then substituted into the Spitzer-Haerm conductivity formula to compute a theoretical conductivity which agreed within 40% of the measured conductivity, while the calculated and experimental velocity values differed by as much as 50%. The lack of agreement was attributed to the possible use of invalid assumptions and boundary conditions in the computer analysis or to the unknown effects of shocks on the probe data.
Vendell, E. W.↗
Electromagnetic connector
Connector pair consists of two iron cores brought together a short distance from each other. Each core is wound with insulated wire. Ac signal is connected through the pair across the gap by magnetic induction. Device can be used underwater or in flammable atmosphere.
Gardner, W. C.↗
Thermal structure of the moon.
Numerical calculations for the structure of convection cells within a self-gravitating, fluid sphere are used to determine the temperature distribution within the moon. The distribution of surface heat flux is also given. The results are compared with the temperatures deduced from magnetic induction within the moon and with the surface heat flow measurement carried out on Apollo 15.
Turcotte, D. L.↗
Magnetic torque on a rotating superconducting sphere
The London theory of superconductivity is used to calculate the torque on a superconducting sphere rotating in a uniform applied magnetic field. The London theory is combined with classical electrodynamics for a calculation of the direct effect of excess charge on a rotating superconducting sphere. Classical electrodynamics, with the assumption of a perfect Meissner effect, is used to calculate the torque on a superconducting sphere rotating in an arbitrary magnetic induction; this macroscopic approach yields results which are correct to first order. Using the same approach, the torque due to a current loop encircling the rotating sphere is calculated.
Holdeman, L. B.↗
Lunar electromagnetic scattering. IV - Transfer functions in the long-wavelength limit
The theory for asymmetric lunar magnetic induction in the long-wavelength limit, applicable to induction in the solar wind and magnetosheath plasmas at frequencies no higher than about 0.01 Hz, is presented. The lunar response to arbitrary ambient field orientations can be synthesized from the responses to field fluctuations parallel and perpendicular to the cavity axis. Radial and tangential transfer functions for a particular lunar electrical conductivity model are shown as functions of frequency and angular distance from the cavity axis for parallel and perpendicular field directions. Transfer functions based on asymmetric theory are significantly different from those based on symmetric approximations. Conductivity profiles from inversions of a given data set are strongly dependent on the theory incorporated in the inversions, the nature of the driving field, and the assumed location of the observer. Thus lunar conductivity models from surface and orbital magnetometer data, obtained either on the dayside or the nightside of the moon, must be determined using asymmetric theory.
Schwartz, K.↗
Electromagnetic heating of minor planets in the early solar system
Electromagnetic processes occurring in the primordial solar system are likely to have significantly affected planetary evolution. In particular, electrical coupling of the kinetic energy of a dense T-Tauri-like solar wind into the interior of the smaller planets could have been a major driver of thermal metamorphism. Accordingly a grid of asteroid models of various sizes and solar distances was constructed using dc transverse magnetic induction theory. Plausible parameterizations with no requirement for a high environmental temperature led to complete melting for Vesta with no melting for Pallas and Ceres. High temperatures were reached in the Pallas model, perhaps implying nonmelting thermal metamorphosis as a cause of its anomalous spectrum. A reversal of this temperature sequence seems implausible, suggesting that the Ceres-Pallas-Vesta dichotomy is a natural outcome of the induction mechanism. Highly localized heating is expected to arise due to an instability in the temperature-controlled current distribution. Localized metamorphosis resulting from this effect may be relevant to the production and evolution of pallasites, the large presumed metal component of S object spectra, and the formation of the lunar magma ocean.
Herbert, F.↗
Transformer induced instability of the series resonant converter
It is shown that the common series resonant power converter is subject to a low frequency oscillation that can lead to the loss of cyclic stability. This oscillation is caused by a low frequency resonant circuit formed by the normal L and C components in series with the magnetizing inductance of the output transformer. Three methods for eliminating this oscillation are presented and analyzed. One of these methods requires a change in the circuit topology during the resonance cycle. This requires a new set of steady state equations which are derived and presented in a normalized form. Experimental results are included which demonstrate the nature of the low frequency oscillation before cyclic stability is lost.
King, R. J.↗
A study of the high frequency limitations of series resonant converters
A transformer induced oscillation in series resonant (SR) converters is studied. It may occur in the discontinuous current mode. The source of the oscillation is an unexpected resonant circuit formed by normal resonance components in series with the magnetizing inductance of the output transformers. The methods for achieving cyclic stability are: to use a half bridge SR converter where q0.5. Q should be as close to 1.0 as possible. If 0.5q1.0, the instability will be avoided if psi2/3q-1/3. The second objective was to investigate a power field effect transistor (FET) version of the SR converter capable of operating at frequencies above 100 KHz, to study component stress and losses at various frequencies.
Stuart, T. A.↗
Numerical study of two-dimensional non-plane MHD wave propagation in a supersonic, superalfvenic magnetohydrodynamic flow
The features of a 2.5-dimensional time-dependent MHD numerical code used to simulate the propagation of finite amplitude MHD waves through an inhomogeneous, supersonic superalfvenic medium are described. Basic equations for conservation of mass, momentum, and free energy in a unit volume plasma gas and for magnetic induction are defined. Initial conditions are functions of the radial coordinates and disturbances are introduced at the lower boundary. A set of finite difference equations based on a Lax-Wendroff scheme is used for the simulation. The model is applied to analyzing a solar flare shock wave in steady-state and global transient conditions while propagating at 1 AU heliolongitude.
Han, S. M.↗
A heterodyne receiver for the submillimeter wavelength region based on cyclotron resonance in InSb at low temperatures
A heterodyne receiver has been developed for observation of interstellar atomic and molecular lines in the submillimeter wavelength region. The main detection mechanism of the device is cyclotron resonance in bulk n-InSb due to a quantized magnetic field. Measurements were carried out between 492 and 812 GHz in order to determine the sensitivity of the device for astrophysical applications. Double sideband receiver noise temperatures of 250 K at 492 GHz; 350 K at 625 GHz; and 510 K at 812 GHz were obtained. The magnetic induction for the laboratory tests was about 2.5 KG and the mixer operating temperature was about 1.6 K. It is shown that the receiver is sensitive enough to identify the narrow rotation lines of diatomic hydrides in dark-cloud regions of the interstellar medium.
Brown, E. R.↗
New cellular automaton model for magnetohydrodynamics
A new type of two-dimensional cellular automation method is introduced for computation of magnetohydrodynamic fluid systems. Particle population is described by a 36-component tensor referred to a hexagonal lattice. By appropriate choice of the coefficients that control the modified streaming algorithm and the definition of the macroscopic fields, it is possible to compute both Lorentz-force and magnetic-induction effects. The method is local in the microscopic space and therefore suited to massively parallel computations.
Chen, Hudong↗
The ingestible thermal monitoring system
A thermal monitoring system for measuring body core temperatures was developed that contains an ingestible pill which is both commandable and rechargeable, and which uses magnetic induction for command and telemetry as well as for recharging. The pill electronics consist of a battery power source, a crystal-controlled oscillator that drives a small air coil, and a command detection circuit. The resulting 262-kHz magnetilc field can be easily detected from a distance of 1 m. The pill oscillator functions at voltages less than 1 V, supplied by a single Ni-Cd battery, which must be recharged after 72 h of continuous transmission. The pill can be recalibrated periodically to compensate for long-term drift.
Cutchis, Protagoras N.↗
Electric currents in E-like planetary ionospheres
In this paper an MHD approach is used to consider the conduction of electric current in a lightly ionized gas, taking into account the gradients of pressure in the ion and electron gases, in addition to the electric field. The coefficients of electrical conductivity are found for each driver of current. New expressions for the components of heat dissipation associated with each driver of current are developed, which are fully consistent with kinetic theory. The relationship of the results to those obtained by kinetic theory is discussed. New components of currents associated with planetary equatorial electrojets are found. A new diffusion equation for magnetic induction is found, applicable in E-like regions of planetary ionospheres, and stellar photospheres.
Cole, K. D.↗
Makeup and uses of a basic magnet laboratory for characterizing high-temperature permanent magnets
A set of instrumentation for making basic magnetic measurements was assembled in order to characterize high intrinsic coercivity, rare earth permanent magnets with respect to short term demagnetization resistance and long term aging at temperatures up to 300 C. The major specialized components of this set consist of a 13 T peak field, capacitor discharge pulse magnetizer; a 10 in. pole size, variable gap electromagnet; a temperature controlled oven equipped with iron cobalt pole piece extensions and a removable paddle that carries the magnetization and field sensing coils; associated electronic integrators; and sensor standards for field intensity H and magnetic moment M calibration. A 1 cm cubic magnet sample, carried by the paddle, fits snugly between the pole piece extensions within the electrically heated aluminum oven, where fields up to 3.2 T can be applied by the electromagnet at temperatures up to 300 C. A sample set of demagnetization data for the high energy Sm2Co17 type of magnet is given for temperatures up to 300 C. These data are reduced to the temperature dependence of the M-H knee field and of the field for a given magnetic induction swing, and they are interpreted to show the limits of safe operation.
Niedra, Janis M.↗
Toroid Joining Gun For Fittings And Couplings
Hand-held gun used to join metal heat-to-shrink couplings. Uses magnetic induction (eddy currents) to produce heat in metal coupling, and thermocouple to measure temperature and signals end of process. Gun, called "toroid joining gun" concentrates high levels of heat in localized areas. Reconfigured for use on metal heat-to-shrink fitting and coupling applications. Provides rapid heating, operates on low power, lightweight and portable. Safe for use around aircraft fuel and has no detrimental effects on surrounding surfaces or objects. Reliable in any environment and under all weather conditions. Gun logical device for taking full advantage of capabilities of new metal heat-to-shrink couplings and fittings.
Fox, Robert L.↗
Paramagnetic-Salt Thermometer With Flux Pump And SQUID's
Paramagnetic-salt low-temperature thermometer incorporates improved superconducting magnetic-flux pump, multiple superconducting quantum interference devices as magnetometers, and feedback stabilization of magnetic flux. Requires much smaller initial magnetizing currents and provides improved temperature resolution via suppression of drift in magnetic induction.
Strayer, Donald M.↗