Larmor and Helmholtz theorems for relativistic charged fluid flow.
Larmor theorem within relativity for inviscid charged fluid under electromagnetic and gravitational fields, deriving Helmholtz equation
Schmid, L. A.↗
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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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Correlations in light from a laser at threshold
Statistics of photoelectron count distribution of electromagnetic laser radiation field in threshold region of oscillation
Alley, C. O.↗
The OGO-V plasma wave detector - Instrumentation and in-flight operation.
OGO 5 spacecraft detector instrumentation for measuring electrostatic and electromagnetic waves electric fields with coupled antennas, describing in-flight operation
Crook, G. M.↗
Lunar Explorer 35.
Lunar Explorer 35 measurements of lunar surface electromagnetic properties, magnetic fields and solar wind-moon interactions
Ness, N. F.↗
Method of fabricating a twisted composite superconductor
A method of producing a twisted, stabilized wire or tube superconductor which can be used to wind electromagnets, armatures, rotors, field windings for motors and generators, and other magnetic devices which use a solenoid, toroidal, or other type winding is reported. At least one groove is formed along the length of a wire substrate which is then twisted into a helix and a layer of intermetallic superconducting material is formed in the groove. This layer can be formed by depositing the desired intermetallic compound into the groove or by diffusing one component of the superconductor into the groove formed in a substrate composed of the other component. The superconductor prepared by this method comprises a non-superconductor wire twisted into the shape of a helix, having at least one groove containing a layer of superconductor material along the length of the wire.
Brown, G. V.↗
Theory of electron-positron showers in double radio sources
A black hole of mass of about 300 million solar masses is assumed to be present in the nucleus of an active galaxy or quasar. With an axial magnetic field near 1000 gauss, a potential drop 10 to the 19th volts is generated by the unipolar induction of a rotating accretion disk surrounding the black hole. The possibility that the acceleration of electrons or positrons in the unipolar fields initiates an electromagnetic cascade shower at distances at least 10 to the 16th cm from the black hole is investigated. The scattering medium for the shower is considered to be the spectrum of low energy photons originating from the inner region of the disk. It is found that at completion of the cascade, power-law energy spectra of relativistic electrons and positrons and of gamma-rays emerge under appropriate conditions. If the cascade-initiating particles are collimated, the electrons and positrons emerge in a collimated beam. Such beams may power extragalactic double radio sources.
Burns, M. L.↗
Volume integrals of ellipsoids associated with the inhomogeneous Helmholtz equation
Problems of wave phenomena in the fields of acoustics, electromagnetics and elasticity are often reduced to an integration of the inhomogeneous Helmholtz equation. Results are presented for volume integrals associated with the inhomogeneous Helmholtz equation, for an ellipsoidal region. By using appropriate Taylor series expansions and the multinomial theorem, these volume integrals are obtained in series form for regions r greater than r-prime and r less than r-prime, where r and r-prime are the distances from the origin to the point of observation and the source. Derivatives of these integrals are easily evaluated. When the wavenumber approaches zero the results reduce directly to the potentials of ellipsoids of variable densities.
Fu, L. S.↗
Overview of containerless processing technologies
Many of the experiments to be carried out in the Space Shuttle will require containerless processing techniques that will provide manipulation and control of weightless (molten) materials without physical contact with container walls or other holding devices. The variety of containerless processing technologies now being developed for space- and ground-based materials processing facilities is surveyed. It is shown how the utilization of air jets or high-intensity acoustic, electromagnetic, or electrostatic fields can produce forces that support and manipulate materials. Most of the present containerless research seeks to develop high-temperature systems capable of melting and resolidifying materials. An introduction to available NASA test facilities is provided.
Barmatz, M.↗
Volume integrals associated with the inhomogeneous Helmholtz equation. Part 1: Ellipsoidal region
Problems of wave phenomena in fields of acoustics, electromagnetics and elasticity are often reduced to an integration of the inhomogeneous Helmholtz equation. Results are presented for volume integrals associated with the Helmholtz operator, nabla(2) to alpha(2), for the case of an ellipsoidal region. By using appropriate Taylor series expansions and multinomial theorem, these volume integrals are obtained in series form for regions r 4' and r r', where r and r' are distances from the origin to the point of observation and source, respectively. Derivatives of these integrals are easily evaluated. When the wave number approaches zero, the results reduce directly to the potentials of variable densities.
Fu, L. S.↗
Magnetic probing of the solar interior
The magnetic field patterns in the region beneath the solar photosphere is determined. An approximate method for downward extrapolation of line of sight magnetic field measurements taken at the solar photosphere was developed. It utilizes the mean field theory of electromagnetism in a form thought to be appropriate for the solar convection zone. A way to test that theory is proposed. The straightforward application of the lowest order theory with the complete model fit to these data does not indicate the existence of any reasonable depth at which flux conservation is achieved.
Benton, E. R.↗
An electromagnetic/electrostatic dual cathode system for electron beam instruments
A method of providing cathode redundancy which consists of two fixed cathodes and uses electromagnetic and/or electrostatic fields to direct the electron beam to the electron optical axis is presented, with application to the cathode system of the Scanning Electron Microscope and Particle Analyzer proposed for NASA's Mariner Mark II Comet Rendezvous/Asteroid Flyby projected for the 1990s. The symmetric double deflection system chosen has the optical property that the image of the effective electron source is formed above the magnet assembly near the apparent position of the effective source, and it makes the transverse positions of the electron sources independent of the electron beam energy. Good performance of the system is found, with the sample imaging resolution being the same as for the single-axis cathode.
Bradley, J. G.↗
Large-gap magnetic suspension systems
The classification of magnetic suspension devices into small-gap and large-gap categories is addressed. The relative problems of position sensing, control systems, power supplies, electromagnets, and magnetic field or force analysis are discussed. The similarity of all systems from a controls standpoint is qualified. Some applications where large-gap technology is being applied to systems with a physically small air-gap are mentioned. Finally, the applicability of some other suspension approaches, such as electrodynamic or superconducting are briefly addressed.
Britcher, Colin P.↗
Sounding rocket measurements of suprathermal ion acceleration
Transverse ion acceleration has been observed at rocket altitudes between 500 and 1000 km due to (1) the injection of 100-200 eV argon plasma; (2) auroral electron precipitation; and (3) the injection of electromagnetic waves. Field-aligned currents necessary to neutralize the plasma injection payloads and naturally occurring in the aurora could be responsible for the ions observed in (1) and (2) above. Associated with the aurora, both bulk heating and tail heating are observed, sometimes simultaneously. In this case, either different masses are accelerated or different mechanisms are responsible. The bulk heating is closely correlated with the aurora structure while tail heating is not so well correlated. Recent high-time-resolution rocket ion data have revealed that the transverse acceleration process is of very short duration (about 100 ms) and occurs in a very limited volume (a few hundred kilometers along B and on the order of the ion gyrodiameter across B). Such impulse acceleration events are correlated with waves near the lower hybrid resonance.
Arnoldy, Roger L.↗
Technical Challenges in Reliable Microelectronics Packaging of Microelectromechanical Systems (MEMS) for Space Applications
MEMS have shown a significant promise in the last decade for a variety of applications such as air-bag, pressure sensors, accelerometer, microgyro, chemical sensors, artificial nose, etc. Standard semiconductor microelectronics packaging needs the integrated circuits (IC) to be protected from the harsh environment, and provide electrical communication with the other parts of the circuit, facilitate thermal dissipation efficiently, and impart mechanical strength to the silicon die. Microelectronics packaging involves wafer dicing, bonding, lead attachment, encapsulation to protect from the environment, electrical integrity, and package leak tests to assure the reliable IC packaging technology. Active elements or microstructures in MEMS devices often interfaces with the hostile environment where packaging leak tests and testing of such devices using chemical and mechanical parameters will be very difficult and expensive. Packaging of MEMS is significantly complex as they serve to protect from the environment and microstructures interact with the same environment to measure or affect the desired physical or chemical parameters. The most of the silicon circuitry is sensitive to temperature, moisture, magnetic field, light, and electromagnetic interference. The package must then protect the on-board silicon circuitry while simultaneously exposing the microsensor to the effect it measures to assure the packaging technology of MEMS. MEMS technology has a major application in developing a microspacecraft for space systems provided reliability of MEMS packaging technology is sufficiently addressed. This MEMS technology would eventually miniaturize many of the components of the spacecraft to reach the NASA's goal by building faster, cheaper, better, smaller spacecraft to explore the space more effectively. This paper discusses the latest developments in the MEMS technology and challenging technical issues in the packaging of hermetically sealed and non-hermetically sealed MEMS sensor devices for microspacecraft applications.
Ramesham, Rajeshuni↗
Assessment and Assurance of Microelectronics Packaging Technology of Microelectromechanical Systems (MEMS)
Microelectromechanical systems (MEMS) have shown a significant promise in the last decade for a variety of applications such as air-bag, pressure sensors, accelerometer, microgyro, etc. Standard semiconductor microelectronics packaging needs the integrated circuits to be protected from the harsh environment, and provide electrical communication with the other parts of the circuit, facilitate thermal dissipation efficiently, and impart mechanical strength to the silicon die. Microelectronics packaging involves wafer dicing, bonding, lead attachment, encapsulation to protect from the environment, electrical integrity, and package leak tests to assure the packaging technology. In the case of MEMS the microstructures (active elements) often interfaces with the hostile environment where packaging leak tests and testing of such devices using chemical and mechanical parameters will be very difficult and expensive. Packaging of MEMS is significantly complex as they serve to protect from the environment and microstructures interact with the same environment to measure or affect the desired physical or chemical parameters. The most of the silicon circuitry is sensitive to temperature, moisture, magnetic field, light, and electromagnetic interference. The package must then protect the on-board silicon circuitry while simultaneously exposing the microsensor to the effect it 'measures to assure the MEMS technology by lowering the risk to zero. MEMS technology has a major application in developing a microspacecraft for space systems provided assurance of MEMS technology is sufficiently addressed nondestructively. This technology would eventually miniaturize many of the components of the spacecraft to reach the NASA's safety and mission assurance goal by building faster, cheaper, better, smaller spacecraft to explore the space more effectively by teaming-up with the other NASA centers using the limited resources available. This paper discusses the latest developments in the MEMS technology and challenging issues in the packaging of hermetically sealed and non-hermetically sealed MEMS sensor devices based on silicon, poly-silicon, and other materials for microspacecraft applications considering the space environment and reliability assurance qualification guidelines in perspective. Acknowledgments: The above research work is supported by the NASA Electronics Parts and Packaging Program (NEPP) and performed by the Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA under a contract with the NASA - Code Q for the Office of Safety and Mission Assurance Program 323-79.
Ramesham, Rajeshuni↗
Geometrical Effects on the Electromagnetic Radiation from Lightning Return Strokes
The morphological difference between the electromagnetic radiation-field waveforms of "first" and "subsequent" return strokes in cloud-to-ground lightning flashes is well known and can be used to identify the formation of new channels to ground. This difference is generally believed due to the existence of branches on first-stroke channels, whereas subsequent strokes re-illuminate only the main channel of a previous stroke; but experimental evidence for this hypothesis is relatively weak. It has been argued for the influence of channel geometry on the fine structure of radiation from subsequent return strokes by comparing the field-change waveforms recorded at the same station from strokes within the same flash and between different flashes of both natural and triggered lightning. The present paper introduces new evidence for both of these hypotheses from a comparison of waveforms between sensors in different directions from the same stroke.
Willett, J. C.↗
The Consequences of Alfven Waves and Parallel Potential Drops in the Auroral Zone
The goal of this research is to examine the causes of field-aligned plasma acceleration in the auroral zone using satellite data and numerical simulations. A primary question to be addressed is what causes the field-aligned acceleration of electrons (leading to precipitation) and ions (leading to upwelling ions) in the auroral zone. Data from the Fast Auroral SnapshoT (FAST) and Polar satellites is used when the two satellites are in approximate magnetic conjunction and are in the auroral region. FAST is at relatively low altitudes and samples plasma in the midst of the auroral acceleration region while Polar is at much higher altitudes and can measure plasmas and waves propagating towards the Earth. Polar can determine the sources of energy streaming earthward from the magnetotail, either in the form of field-aligned currents, electromagnetic waves or kinetic particle energy, that ultimately leads to the acceleration of plasma in the auroral zone. After identifying and examining several events, numerical simulations are run that bridges the spatial region between the two satellites. The code is a one-dimensional, long system length particle in cell simulation that has been developed to model the auroral region. A main goal of this research project is to include Alfven waves in the simulation to examine how these waves can accelerate plasma in the auroral zone.
Schriver, David↗
Massive Black Hole Mergers: Can We "See" what LISA will "Hear"?
The final merger of massive black holes produces strong gravitational radiation that can be detected by the space-borne LISA. If the black hole merger takes place in the presence of gas and magnetic fields, various types of electromagnetic signals may also be produced. Modeling such electromagnetic counterparts of the final merger requires evolving the behavior of both gas and fields in the strong-field regions around the black holes. We will review current efforts to simulate these systems, and discuss possibilities for observing the electromagnetic signals they produce.
Centrella, Joan↗