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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

A search for space energy alternatives

This paper takes a look at a number of schemes for converting radiant energy in space to useful energy for man. These schemes are possible alternatives to the currently most studied solar power satellite concept. Possible primary collection and conversion devices discussed include the space particle flux devices, solar windmills, photovoltaic devices, photochemical cells, photoemissive converters, heat engines, dielectric energy conversion, electrostatic generators, plasma solar collectors, and thermionic schemes. Transmission devices reviewed include lasers and masers.

Gilbreath, W. P.↗
NASA NTRS1982

Multi-ion resonances in finite temperature plasma

Dispersion properties of electrostatic waves in a multi-ion plasma are examined, with an analysis that incorporates the effects of finite temperature, finite parallel wavenumber, and wave growth/damping in a systematic development of equations. Numerical solutions and analytic formulas are given for an ion plasma consisting of H(+), O(+), and S(+) for application to Jupiter's magnetosphere. It is demonstrated how observations of plasma resonance lines may be used as a diagnostic of ion composition in magnetospheric plasma. This potential use of high-sensitivity/high-resolution plasma wave instrumentation may provide information necessary to resolve issues concerning the origin of plasmas in the earth's neighborhood.

Barbosa, D. D.↗
NASA NTRS1985

Electrostatic ion cyclotron waves in a plasma with an ion beam and counterstreaming bulk electrons - Waves in the zero-frequency band

A common feature of the auroral plasma in the region above field-aligned (parallel) potential drops are electrostatic hydrogen cyclotron (EHC) waves. The present paper has the objective to show that wave excitation in the zero-frequency band can occur when the ion beams and the current-carrying bulk electrons counterstream. The instability mechanism involves the Landau interaction of the slow (negative energy) ion-beam-cyclotron waves with the drifting electrons and also with the target (background) ions. Only the latter resonant interaction between the beam and the target ions was considered by Okuda and Nishikawa (1984). In this study, it is shown that an electron drift makes an additional unstable contribution to the waves in the zero-frequency band, including those discussed by Okuda and Nishikawa.

Singh, N.↗
NASA NTRS1986

Parallel electric fields in extragalactic jets - Double layers and anomalous resistivity in symbiotic relationships

After examining the properties of Coulomb-collision resistivity, anomalous (collective) resistivity, and double layers, a hybrid anomalous-resistivity/double-layer model is introduced. In this model, beam-driven waves on both sides of a double layer provide electrostatic plasma-wave turbulence that greatly reduces the mobility of charged particles. These regions then act to hold open a density cavity within which the double layer resides. In the double layer, electrical energy is dissipated with 100 percent efficiency into high-energy particles, creating conditions optimal for the collective emission of polarized radio waves.

Borovsky, J. E.↗
NASA NTRS1987

Evolution of the axial electron cyclotron maser instability, with applications to solar microwave spikes

The nonlinear evolution of cyclotron radiation from streaming and gyrating electrons in an external magnetic field is analyzed. The nonlinear dynamics of both the fields and the particles are treated fully relativistically and self-consistently. The model includes a background plasma and electrostatic effects. The analytical and numerical results show that a substantial portion of the beam particle energy can be converted to electromagnetic wave energy at frequencies far above the electron cyclotron frequency. In general, the excited radiation can propagate parallel to the magnetic field and, hence, escape gyrothermal absorption at higher cyclotron harmonics. The high-frequency Doppler-shifted cyclotron instability can have saturation efficiencies far higher than those associated with well-known instabilities of the electron cyclotron maser type. Although the analysis is general, the possibility of using this model to explain the intense radio emission observed from the sun is explored in detail.

Vlahos, Loukas↗
NASA NTRS1991

Assessment of environmental effects on Space Station Freedom Electrical Power System

Analyses of EPS (electrical power system) interactions with the LEO (low earth orbit) environment are described. The results of these analyses will support EPS design so as to be compatible with the natural and induced environments and to meet power, lifetime, and performance requirements. The environmental impacts to the Space Station Freedom EPS include aerodynamic drag, atomic oxygen erosion, ultraviolet degradation, VXB effect, ionizing radiation dose and single event effects, electromagnetic interference, electrostatic discharge, plasma interactions (ion sputtering, arcing, and leakage current), meteoroid and orbital debris threats, thermal cycling effects, induced current and voltage potential differences in the SSF due to induced electric field, and contamination degradation.

Lu, Cheng-Yi↗
NASA NTRS1995

Mechanism for generation of 2-3 kHz radiation in the outer heliosphere

The question of how low-frequency non-thermal radio emissions at the boundary of the heliosphere might be generated is considered. The mechanism consists of two steps. First, the beam of energetic electrons generates a high level of electrostatic Langmuir plasma waves. Second, electromagnetic radiation results from the non-linear interaction between Langmuir waves. Intensity of radio emissions at 2 to 3 kHz detected by the Voyager plasma wave instrument in the outer heliosphere can be explained provided that the electron beams generating Langmuir waves exist also in the postshock plasma due to secondary shocks in the compressed solar wind beyond the termination shock. Modification of the heliospheric shocks by the cosmic ray pressure is also taken into account. The field strengths of Langmuir waves required to generate the second harmonic emissions are of 50 to 100 microvolts per meter. These waves may be observed in situ by Voyager 1 and 2 in the near future.

Macek, W. M.↗
NASA NTRS2001

Observational and theoretical analyses of polar cap/auroral region f(sub p) and 2 f(sub p) emissions using the polar and DE 1 satellites

The objective of this proposal was to conduct a comprehensive observational and theoretical investigation, including 2-D numerical simulations of emissions that occur near f(sub p) and 2 f(sub p) as observed by the Dynamics Explorer 1 (DE 1) spacecraft in the mid-altitude polar magnetosphere. Electrostatic electron plasma waves (or Langmuir waves) and associated electromagnetic (ETD) radiation near f(sub p) and 2 f(sub p) have previously been observed associated with the Earth's foreshock and in coronal/solar wind type II and III solar radio bursts. The observations of similar emissions in the terrestrial polar magnetosphere have not been previously reported and are important for a better understanding of the range of generation processes. We have been cataloging the location, electric and magnetic intensity, polarization, bandwidth, etc. of the emissions. The theoretical analysis included linear and nonlinear plasma theory. The goal was to fully describe the generation processes for both the f(sub p) (PF component) and 2 f(sub p) (H component) emissions. Although this goal was not completely accomplished, we have made significant advances in our understanding of these emissions.

Menietti, J. D.↗
NASA NTRSDate not supplied

Characterizing Electrical Arc Behavior in Ion Engines

Gridded ion engines represent a class of electric thrusters characterized by high propulsive efficiency and high total impulse capabilities. These engines operate by applying high voltage to multi-aperture electrodes, thereby electrostatically accelerating plasma to generate thrust. Within the course of normal operations, periodic occurrences of high voltage breakdowns manifest within the thruster. These breakdowns constitute an inherent aspect of operation, with observations indicating a diminishing frequency and total count over the thruster's operational lifespan. To safeguard the propulsion system during such occurrences, the power processing unit (PPU) employs an automated arc extinction sequence, termed "recycle," which is triggered upon detection of an over-current condition. The initial phase of this sequence involves momentarily deactivating the high voltage and reducing the discharge current to a predetermined level, minimizing plasma impingement as the ion beam is defocused. The high voltage is subsequently reapplied, and the discharge current is returned to its nominal value. The entire sequence typically spans approximately 800 milliseconds. Throughout a recycle event, the propulsion system experiences various current and voltage transients as the arc current traverses the system and different power supplies are toggled on and off.

electric propulsion↗
NASA NTRS1971

Verification of theory on weak turbulence relating to the sequence of diffuse plasma resonances in space.

An interpretation of the sequence of diffuse plasma resonances observed by space probes (Alouette 2 and ISIS-1 satellites) is developed in terms of wave-particle nonlinear interaction in a weakly turbulent plasma including the electrostatic electron cyclotron harmonic wave instability. The longest time duration of the center frequency of the diffuse plasma resonance is found to coincide with the most favorable condition for the electrostatic electron cyclotron harmonic wave instability which is obtained by solving the dispersion equation obtained for a linear approximation of the kinetic wave equation for the warm magnetoactive plasma. The electrostatic field due to the transmission of the intense rf pulse produces plasma turbulence involving nonlinear wave-wave interaction and temperature anisotropy which leads to instability. This instability supplies energy to the turbulence. The process can be thought of as a feedback system.

Oya, H.↗
NASA NTRS1992

Electrostatic turbulence in the earth's central plasma sheet produced by multiple-ring ion distributions

Attention is given to a mechanism to generate a broad spectrum of electrostatic turbulence in the quiet time central plasma sheet (CPS) plasma. It is shown theoretically that multiple-ring ion distributions can generate short-wavelength (less than about 1), electrostatic turbulence with frequencies less than about kVj, where Vj is the velocity of the jth ring. On the basis of a set of parameters from measurements made in the CPS, it is found that electrostatic turbulence can be generated with wavenumbers in the range of 0.02 and 1.0, with real frequencies in the range of 0 and 10, and with linear growth rates greater than 0.01 over a broad range of angles relative to the magnetic field (5-90 deg). These theoretical results are compared with wave data from ISEE 1 using an ion distribution function exhibiting multiple-ring structures observed at the same time. The theoretical results in the linear regime are found to be consistent with the wave data.

Huba, J. D.↗
NASA NTRS1984

Electrostatic ion-cyclotron waves in magnetospheric plasmas Nonlocal aspects

The importance of the effect of the magnetic shear and the finite size of current channel on the electrostatic ion-cyclotron instability for the space plasmas is illustrated. A non-local treatment is used. When the channel width Lc, is larger than the shear length Ls, there is a large reduction in the growth rate along with a noteworthy reduction of the band of the unstable perpendicular wavelengths. For Lc less than or = Ls/10 the growth rate is not much altered from its local value, however for Lc/pi i less than or = 10 to the second power the growth rate starts falling below the local value and vanishes for Lc pi i. The non-local effects lead to enhanced coherence in the ion cyclotron waves. Previously announced in STAR as N84-14917

Ganguli, G.↗