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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
NASA NTRS1974

Lagrangian methods in plasma dynamics. II - Construction of Lagrangians for plasmas

Consideration of the construction of suitable Lagrangian functions for the dynamics of a cold plasma in such a way as to retain the relativistically covariant formalism. In one method, this is achieved by the introduction of a set of three variables which label the world lines of the particles. A second method results in a Clebsch-type representation. Sturrock's relativistic Lagrangian and Low's hot plasma Lagrangian are also briefly discussed in the context of the present work. The behavior of the canonical stress tensor is considered. The applicability of many of the general results in part I (Dougherty, 1970) is ensured by establishing the existence of the Lagrangian function.

Dougherty, J. P.↗
NASA NTRS1986

The plasma dynamics of hypersonic spacecraft: Applications of laboratory simulations and active in situ experiments

Attempts to gain an understanding of spacecraft plasma dynamics via experimental investigation of the interaction between artificially synthesized, collisionless, flowing plasmas and laboratory test bodies date back to the early 1960's. In the past 25 years, a number of researchers have succeeded in simulating certain limited aspects of the complex spacecraft-space plasma interaction reasonably well. Theoretical treatments have also provided limited models of the phenomena. Several active experiments were recently conducted from the space shuttle that specifically attempted to observe the Orbiter-ionospheric interaction. These experiments have contributed greatly to an appreciation for the complexity of spacecraft-space plasma interaction but, so far, have answered few questions. Therefore, even though the plasma dynamics of hypersonic spacecraft is fundamental to space technology, it remains largely an open issue. A brief overview is provided of the primary results from previous ground-based experimental investigations and the preliminary results of investigations conducted on the STS-3 and Spacelab 2 missions. In addition, several, as yet unexplained, aspects of the spacecraft-space plasma interaction are suggested for future research.

Stone, N. H.↗
NASA NTRS1998

Dusty Plasma Dynamics Near Surfaces in Space

The investigation 'Dusty Plasma Dynamics Near Surfaces in Space' is an experimental and theoretical study of the dynamics of dust particles on airless bodies in the solar system in the presence of a photoelectron sheath generated by solar ultraviolet light impinging on the surface. Solar UV illumination of natural and manmade surfaces in space produces photoelectrons which form a plasma sheath near the surface. Dust particles on the surface acquire a charge and may be transported by electric fields in the photoelectron sheath generated by inhomogeneities in the surface or the illumination (such as shadows). The sheath itself has a finite vertical extent leading to (at least) an electric field normal to the illuminated surface. If dust particles are launched from the surface by some other process, such as meteoroid impact, or spacecraft activity on the surface, these grains become charged and move under the influence of gravity and the electric field. This can give rise to suspension of the particles above the surface, loss from the parent body entirely (if accelerated beyond escape velocity), and a different distribution of dust ejecta from what would be expected with purely gravitational dynamics.

Colwell, Joshua E.↗
NASA NTRS1998

A Coupled Plasma Dynamics and Gas Flow Model for Semiconductor Processing

A continuum modeling approach by self-consistently coupling plasma dynamics and gas flow will be presented for the analysis of high density plasma reactors. Experimental data shows that gas flow distribution affects the etch rate uniformity even at low pressures (6-20 mTorr) and flow rates (20-70 sccm). This study will investigate the effects of gas flow and gas energy on bulk plasma densities and temperatures using a continuum model. The model solves multidimensional equations of mass balance for neutrals and ions, gas momentum, separate energy equations for electrons and neutrals and Maxwell's equations for power coupling. A test case of N2 plasma in a 300mm TCP etch reactor, for which hybrid model and Langmuir probe data are available, is chosen for this analysis. Our preliminary results show that modeling gas flow and energy improves the predictions of electron density and its spatial variation in the reactor when compared with the experimental data. The aim of this study is to identify the operating conditions for the TCP reactor when a self-consistent modeling of gas flow is important.

Bose, Deepak↗
NASA NTRS1993

Plasma dynamics driven by finite-width current filament and KV potential drops in ionosphere-magnetosphere coupling

We have simulated the plasma dynamics of a quasi-two-dimensional current filament in ionosphere-magnetosphere coupling. The simulation consists of a set of one-dimensional flux tube simulations with different imposed time-dependent, field-aligned currents. The dynamical interactions of the individual current filaments with the ionospheric and magnetospheric plasma generate kV field-aligned potential drops along the field lines, and the side-by-side display exhibits the evolution of the implied potential structure in the horizontal direction. The primary cross-field motion produced by the horizontal E-field (ExB drift) is perpendicular to both of the significant spatial directions, and is thus ignorable in this geometry. The effects of other cross-field drict processes are discussed. The simulation thus provides insight into the dynamical evolution of 2D potential structures driven by an imposed finite-width field-aligned current profile. Spatial and temporal variation of other plasma parameters (temperatures, density, etc.) that are determined primarily by parallel transport effects are also displayed.

Ganguli, Supriya B.↗
NASA NTRS1992

Observations of plasma dynamics in the coma of P/Halley by the Giotto ion mass spectrometer

The paper reports observations of plasma dynamics in the coma of P/Halley by the Giotto ion mass spectrometer. Measurements of protons and alpha particles from the far upstream region to the near ionopause region and of ions of mass 12-32 at distances of about 250,000 to 40,000 km from the nucleus are presented. The discontinuity known as the magnetic pileup boundary (MPB) is apparent only in proton, alpha particle, and magnetometer data, indicating that it is a tangential discontinuity of solar wind origin. No significant change is found in the properties of the heavy ions across the MPB. The issue of whether a cometopause was unambiguously observed at Comet Halley is discussed; it is concluded that the observations do not convincingly support the idea of a boundary due to internal cometary processes. A comparison of the observations to MHD models is made. The plasma flow directions at all distances greater than 30,000 km from the nucleus are in agreement with MHD calculations.

Goldstein, B. E.↗
NASA NTRS1975

Corruption of radio metric Doppler due to solar plasma dynamics: S/X dual-frequency Doppler calibration for these effects

Doppler data from Mariner 6, 7, 9, and 10 and Pioneer 10 and 11 were discussed and the rms noise level for various sun-earth-probe angles were shown. The noise levels of both S- and X-band Doppler data for sun-earth-probe angles smaller than 20 deg were observed to be orders of magnitude greater than nominal. Such solar plasma-related Doppler degradation reduced the Mariner 10-Mercury 11 encounter navigation accuracy by nearly a factor of 10. Furthermore, this degradation was shown to be indirectly related to plasma dynamics and not a direct measure of the dynamics.

Winn, F. B.↗
NASA NTRS2018

MAVEN Case Studies of Plasma Dynamics in Low‐Altitude Crustal Magnetic Field at Mars 1: Dayside Ion Spikes Associated With Radial Crustal Magnetic Fields

We report for the first time, simultaneous ion, electron, magnetic field vector and electric field wave measurements made possible by Mars Atmosphere and Volatile EvolutioN, during ion energy flux spikes in low‐altitude radial crustal magnetic fields on the Mars dayside. Observations show energetic electrons and ions (E > 25 eV) precipitating on magnetic field lines assumed as closed. Ions (E < 1.4 keV) display broad velocity distributions toward Mars, showing ions flowing from higher altitude possibly after magnetic reconnection or loss cone filling from pitch angle scattering effects. Precipitating ions (E < 1.4 keV) show nonadiabatic features depending on ion mass and energy and returning ions (E < 1.4 keV) show evidence of conserving the first adiabatic invariant in a mirror field. We observe magnetic field perturbations up to 60 nT, electric field wave amplitudes up to 38 mV/m, and brief periods of peaked electron spectra. At ∼175 km and at times Mars Atmosphere and Volatile EvolutioN is below the mirroring altitude of electrons, we observe mirroring and transverse heating of H+ ions alongside increased electric field wave amplitude fluctuations. It suggests field aligned potential drops result from different mirror altitudes of ions and electrons. Ions E > 1.4 keV (O+) occur as injected accelerated ion beams and ions heated after energization or deceleration. Energy dispersed kilo‐electron‐volt ions suggest a selection effect in radial magnetic fields for lower‐energy Marsward ions, compared to reflection of higher‐energy anti‐Sunward ions. Precipitating kilo‐electron‐volt ions show energy deposition rates of 3.6 ×10(exp -6) W/sq m and sputtering escape rates from precipitating O+ ions of 1.5 ×10(exp 5)/(sq cm.s) and 2.1 ×10(exp 6)/(sq cm.s) are calculated.

Plasma Dynamics↗
NASA NTRS1993

Thermosphere and F-region plasma dynamics in the equatorial region

The dynamics of the equatorial thermosphere and the F-region plasma are reviewed, highlighting some features observed with the San Marco satellite, the AE-E, and the DE-2, as well as with ground-based facilities at Arecibo and Jicamarca. Particular attention is given to the midnight temperature maximum and related phenomena, and to results on zonal neutral and plasma flows at F-region heights.

Herrero, F. A.↗
NASA NTRS1992

Plasma dynamics on current-carrying magnetic flux tubes. II - Low potential simulation

The evolution of plasma in a current-carrying magnetic flux tube of variable cross section is investigated using a one-dimensional numerical simulation. The flux tube is narrow at the two ends and broad in the middle. The middle part of the flux tube is loaded with a hot, magnetically trapped population, and the two ends have a more dense, gravitationally bound population. A potential difference larger than the gravitational potential but less than the energy of the hot population is applied across the domain. The general result is that the potential change becomes distributed along the anode half of the domain, with negligible potential change on the cathode half. The potential is supported by the mirror force of magnetically trapped particles. The simulations show a steady depletion of plasma on the anode side of the flux tube. The current steadily decreases on a time scale of an ion transit time. The results may provide an explanation for the observed plasma depletions on auroral field lines carrying upward currents.

Swift, Daniel W.↗