Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “PLASMA WAVES”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Simple scalings for various regimes of electron acceleration in surface plasma waves

Different electron acceleration regimes in the evanescent field of a surface plasma wave are studied by considering the interaction of a test electron with the high-frequency electromagnetic field of a surface wave. The non-relativistic and relativistic limits are investigated. Simple scalings are found demonstrating the possibility to achieve an efficient conversion of the surface wave field energy into electron kinetic energy. This mechanism of electron acceleration can provide a high-frequency pulsed source of relativistic electrons with a well defined energy. In the relativistic limit, the most energetic electrons are obtained in the so-called electromagnetic regime for surface waves. In this regime, the particles are accelerated to velocities larger than the wave phase velocity, mainly in the direction parallel to the plasma-vacuum interface.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1981

Plasma waves near Saturn: Initial results from Voyager 1

The Voyager 1 encounter with Saturn provided the first opportunity to investigate plasma wave interactions in the magnetosphere of Saturn. An overview of the principal results from the Voyager 1 plasma wave instrument is presented starting with the initial detection of Saturn and ending about four weeks after closest approach. A survey plot of the electric field intensities detected during the Saturn encounter is shown starting shortly before the inbound shock crossing and ending shortly after the outbound magnetopause crossing. Many intense waves were observed in the vicinity of Saturn. To provide a framework for presenting the observations, the results are discussed more or less according to the sequence in which the data were obtained.

Gurnett, D. A.↗
NASA NTRS1993

Cassini radio and plasma wave investigation - Data compression and scientific applications

The Radio and Plasma Wave Science (RPWS) experiment being built for the Cassini spacecraft will study a wide range of plasma and radio wave phenomena in the magnetosphere of Saturn and will also make valuable measurements during the cruise phase and at other encounters. A feature of data from wave receivers is the capability of producing vastly more data than the spacecraft telemetry link is capable of transmitting back to the Earth. Thus, techniques of on-board data compression and data reduction are important. The RPWS instrument has one processor dedicated to data compression tasks.

Woolliscroft, L. J. C.↗
NASA NTRS1993

Cassini radio and plasma wave investigation: Data compression and scientific applications

The Radio and Plasma Wave Science (RPWS) experiment being built for the Cassini spacecraft will study a wide range of plasma and radio wave phenomena in the magnetosphere of Saturn and will also make valuable measurements during the cruise phase and at other encounters. A feature of data from wave receivers is the capability of producing vastly more data than the spacecraft telemetry link is capable of transmitting back to the Earth. Thus, techniques of on-board data compression and data reduction are important. The RPWS instrument has one processor dedicated to data compression tasks.

Woolliscroft, L. J. C.↗
DOE OSTI2015

Nonlinear surface plasma wave induced target normal sheath acceleration of protons

The mode structure of a large amplitude surface plasma wave (SPW) over a vacuum–plasma interface, including relativistic and ponderomotive nonlinearities, is deduced. It is shown that the SPW excited by a p-polarized laser on a rippled thin foil target can have larger amplitude than the transmitted laser amplitude and cause stronger target normal sheath acceleration of protons as reported in a recent experiment. Substantial enhancement in proton number also occurs due to the larger surface area covered by the SPW.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2013

Negative-mass Instability in Nonlinear Plasma Waves

The negative-mass instability (NMI), previously found in ion traps, appears as a distinct regime of the sideband instability in nonlinear plasma waves with trapped particles. As the bounce frequency of these particles decreases with the bounce action, bunching can occur if the action distribution is inverted in trapping islands. In contrast to existing theories that also infer instabilities from the anharmonicity of bounce oscillations, spatial periodicity of the islands turns out to be unimportant, and the particle distribution can be unstable even if it is flat at the resonance. An analytical model is proposed which describes both single traps and periodic nonlinear waves and concisely generalizes the conventional description of the sideband instability in plasma waves. The theoretical results are supported by particle-in-cell simulations carried out for a regime accentuating the NMI effect.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

Plasma wave instability in a quantum field effect transistor with magnetic field effect

The current-carrying state of a nanometer Field Effect Transistor (FET) may become unstable against the generation of high-frequency plasma waves and lead to generation of terahertz radiation. In this paper, the influences of magnetic field, quantum effects, electron exchange-correlation, and thermal motion of electrons on the instability of the plasma waves in a nanometer FET are reported. We find that, while the electron exchange-correlation suppresses the radiation power, the magnetic field, the quantum effects, and the thermal motion of electrons can enhance the radiation power. The radiation frequency increases with quantum effects and thermal motion of electrons, but decreases with electron exchange-correlation effect. Interestingly, we find that magnetic field can suppress the quantum effects and the thermal motion of electrons and the radiation frequency changes non-monotonely with the magnetic field. These properties could make the nanometer FET advantageous for realization of practical terahertz oscillations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1992

Observations of plasma waves in the solar wind interaction region of Comet Giacobini-Zinner at high time resolution

High-time-resolution spectra of plasma wave emissions detected in the interaction region of Comet Giacobini-Zinner with the solar wind reveal a wave phenomenology much more complicated than first reported. Spectra often exhibit three or more independent peaks, which become more prominent the deeper into the interaction region the spacecraft traversed. The main peaks correspond to whistler emissions below the electron cyclotron frequency, a midfrequency peak near the maximum Doppler shift frequency for waves with k lambda(D) = 1, a high-frequency peak above the Doppler shift maximum frequency, and electron plasma oscillations at the plasma frequency. Similar multipeaked spectra are also observed downstream from weak shocks at Earth, which suggests that the plasma wave generation mechanisms responsible need not require particle populations created by photoionization.

Moses, S. L.↗
NASA NTRS1982

Plasma wave experiment for the ISEE-3 mission

Results of analyses of data received from a scientific instrument designed to study solar wind and plasma wave phenomena on the ISEE-3 mission are discussed in two papers prepared for publication. A study of plasma wave levels in and interplanetary magnetic field orientation preceding observations of interplanetary shocks by the satellite infers that quasi-parallel, interplanetary shocks are preceded by foreshocks whose presence is not obviously attributable to scattering of ion beams generated at quasi-perpendicular zones of these interplanetary shocks. Investigations of whistler mode turbulence in the disturbed solar wind resulted in various indirect lines of evidence indicating that these whistler waves are generated propagating at large angles to the local interplanetary field, a fact which helps identify possible free energy sources for their growth.

Scarf, F. L.↗
DOE OSTI2018

Trapped Particle Effects in the Parametric Instability of Near-Acoustic Plasma Waves

Quantitative experiments on the parametric decay instability of near-acoustic plasma waves provide strong evidence that trapped particles reduce the instability threshold below fluid models. At low temperatures, the broad characteristics of the parametric instability are determined by the frequency detuning of the pump and daughter wave, and the wave-wave coupling strength, surprisingly consistent with cold fluid, three-wave theories. Furthermore, at higher temperatures, trapped particle effects dominate, and the pump wave becomes unstable at half the threshold pump wave amplitude with similar exponential growth rates as for a cold plasma.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1985

Plasma waves associated with the AMPTE artificial comet

Numerous plasma wave effects were detected by the AMPTE/IRM spacecraft during the artificial comet experiment on December 27, 1984. As the barium ion cloud produced by the explosion expanded over the spacecraft, emissions at the electron plasma frequency and ion plasma frequency provided a determination of the local electron density. The electron density in the diamagnetic cavity produced by the ion cloud reached a peak of more than 5 x 10 to the 5th per cu cm, then decayed smoothly as the cloud expanded, varying approximately as t exp-2. As the cloud began to move due to interactions with the solar wind, a region of compressed plasma was encountered on the upstream side of the diamagnetic cavity. The peak electron density in the compression region was about 1.5 x 10 to the 4th per cu cm. Later, a very intense (140 mVolt/m) broadband burst of electrostatic noise was encountered on the sunward side of the compression region. This noise has characteristics very similar to noise observed in the earth's bow shock, and is believed to be a shocklike interaction produced by an ion beam-plasma instability between the nearly stationary barium ions and the streaming solar wind protons.

Gurnett, D. A.↗
DOE OSTI2025

Theoretical investigation of plasma wave generation by pulsed electron beams in space

Here, we report theoretical calculations of plasma wave generation in the whistler modes and in the extraordinary modes, by pulsed electron beams in a magnetized plasma. The numerical simulations of the wave generation take into account the longitudinal expansion of the electron beam due to the space charge force and the energy spread. The work presented in this article provides predictions for the wave generation performance of the beam plasma interactions experiment (Beam PIE), where pulsed electron beams were produced by a spaceborne radio frequency (RF) linear accelerator. We also theoretically explore the desirable properties of the pulsed electron beam for future space experiments, which will be the next step toward eventually demonstrating the radiation-belt remediation (RBR).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2004

Observations of Plasma Waves near Mars and Their Implications for Atmospheric Loss

We use data from over 500 premapping orbits of Mars Global Surveyor magnetometer data to present statistical results on the characteristics of the plasma waves in the near Mars space. We find that plasma waves in the dayside Martian magnetosheath are primarily compressional waves (i.e. magnetosonic or mirror mode waves) and in the nightside magnetosheath and tail regions that the waves are primarily associated with ion gyromotion. Some of these waves are produced by gyrating oxygen ions and as such represent observations of the ongoing erosion of the Martian atmosphere by the solar wind.

Espley, J. R.↗
NASA NTRS1993

Plasma Waves Observed at Low Altitudes in the Tenuous Venus Nightside Ionosphere

The Pioneer Venus Orbiter Electric Field Detector (OEFD) measured many plasma wave bursts throughout the low altitude ionosphere during the final entry phase of the spacecraft. Apart from 100 Hz bursts observed at very low altitudes (approx. 130 km), the bursts fall into two classes. The first of these is a wideband signal that is observed in regions of low magnetic field, but average densities, in comparison to the prevailing ionospheric condition. This wideband signal is not observed in the 30 kHz channel of the OEFD, but is restricted to the 5.4 kHz channel and lower. Since these bursts are observed with roughly constant burst rate above 160 km altitude, we attribute them to ion acoustic mode waves generated by precipitating solar wind electrons. The second type of signal is restricted to 100 Hz only, and is observed in regions of low electron beta, consistent with whistler-mode waves. These waves could be generated by lightning in the Venus atmosphere if the vertical component of the magnetic field greater than 3.6 nT. Unfortunately, the spacecraft spin axis is mainly horizontal, and only that component of magnetic field can be measured. Alternatively, the 100 Hz bursts could be generated locally through gradient drift instabilities, provided the ambient magnetic field is horizontal. Because the ionosphere is very different during the entry phase, compared to the ionosphere as observed early in the Pioneer Venus mission, any conclusions regarding the source of the plasma waves detected during entry phase cannot be applied directly to the earlier observations.

Strangeway, R. J.↗
NASA NTRS1982

The structure of Titan's wake from plasma wave observations

The electron density profile inferred from plasma wave emissions detected during the Voyager 1 flyby of Titan exhibits three distinct peaks with densities of about 40/cu cm, the first peak corresponding to the entry into the magnetic tail, the second corresponding to the neutral sheet crossing from the northern to the southern tail lobe, and the third corresponding to the outbound exit from the tail. Large depressions in the magnetic field strength are observed coincident with each of the density peaks, indicating that a dense plume of plasma is being carried downstream of Titan by the interaction with the rapidly rotating magnetosphere of Saturn. The 8600 K plasma temperature estimated suggests that the plasma originates from the ionosphere of Titan, probably forming a plasma plume with a theta or H cross section extending downstream from Titan.

Gurnett, D. A.↗
NASA NTRS1993

Plasma waves observed at low altitudes in the tenuous Venus nightside ionosphere

The Pioneer Venus (PV) Orbiter Electric Field Detector (OEFD) measured many plasma wave bursts throughout the low altitude ionosphere during the final entry phase of the spacecraft. Apart from 100 Hz bursts observed at very low altitudes (approx. 130 km), the bursts fall into two classes. The first of these is a wideband signal that is observed in regions of low magnetic field, but average densities, in comparison to the prevailing ionospheric condition. This wideband signal is not observed in the 30 kHz channel of the OEFD, but is resricted to the 5.4 kHz channel and lower. Since these bursts are observed with roughly constant burst rate above 160 km altitude, we attribute them to ion acoustic mode waves generated by precipitating solar wind electrons. The second type of signal is restricted to 100 Hz only, and is observed in the regions of low electron beta, consistent with whistler-mode waves. These waves could be generated by lightning in the Venus atmosphere if the vertical component of the magnetic field greater than 3.6 nT. Because the ionosphere is very different during the entry phase, compared to the ionosphere as observed early in the Pioneer Venus mission, any conclusions regarding the source of the plasma waves detected during entry phase cannot be applied directly to the earlier observations.

Strangeway, R. J.↗