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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 271 records · Page 15
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NASA NTRS1982

Plasma wave levels and IMF orientations preceding observations of interplanetary shocks by ISEE-3

Some interplanetary shocks detected by ISEE-3 are preceded by many hours of strongly enhanced plasma wave noise at a few kHz, while others have essentially no wave precursors above background. It has been shown that these extremes correspond to quasi-parallel and quasi-perpendicular shocks, respectively, based on the instantaneous orientation angle of the interplanetary magnetic field (IMF) to the shock normal at the time the shocks cross the spacecraft. It is shown that precursor wave noise level is correlated with field orientation and an extrapolated instantaneous orientation angle throughout the preshock observation interval for two contrasting active and quiet cases, and that intermediate, variable noise levels correspond to intermediate, variable IMF orientations. It is inferred that foreshocks are an intrinsic part of the structure of quasiparallel interplanetary shocks.

Greenstadt, E. W.↗
NASA NTRS2000

Plasma Densities in the Vicinity of Callisto from Galileo Plasma Wave Observations

The Galileo spacecraft has made seven close flybys of Jupiter's moon Callisto. During the closest of these (C22), which approached to within 535 km of the surface, the plasma wave instrument detected a very clear upper hybrid emission as the spacecraft passed near the moon. The peak electron density indicated by the upper hybrid resonance emission was 400/cc, almost one-thousand times the, electron density in the magnetosphere of Jupiter at the orbit of Callisto. These observations indicate that Callisto is probably surrounded by a dense ionospheric-like plasma.

Gurnett, D. A.↗
NASA NTRS1988

Plasma wave turbulence around the shuttle - Results from the Spacelab-2 flight

During the Spacelab-2 flight, which occurred from July 29, to August 6, 1985, a spacecraft called the Plasma Diagnostics Package (PDP) was released from the shuttle to explore the plasma environment around the shuttle. The plasma wave instrument on the PDP detected a region of intense broadband turbulence around the shuttle at frequencies extending from a few Hz to about 10 kHz. The noise has broadband intensities ranging from 1 to 5 mV/m and was observed at distances of up to 400 m from the shuttle. The highest intensities occurred in the region downstream of the shuttle and along magnetic field lines passing near the shuttle. The intensities also tended to increase during periods of high thruster activity, which provides strong evidence that the noise is caused by an interaction of the ionosphere with gaseous emissions from the shuttle, similar in many respects to the interaction of a comet with the solar wind. Antenna interference patterns observed in the wideband data show that the wavelength of the turbulence is very short, a few meters or less.

Gurnett, D. A.↗
NASA NTRS1981

Plasma waves excited in the upstream region by density gradient of energetic-particle streams associated with the earth's bow shock

The present study is concerned with the excitation of plasma waves at the boundaries of the streams of energetic particles which are associated with the earth's bow shock. The analysis was motivated by observational results acquired with the ISEE spacecraft (Parks et al., 1981). It is shown theoretically that the density gradient of energetic ions can only excite ion waves, whereas that of energetic electrons can excite both ion waves and Langmuir waves. This conclusion appears to be consistent with observations.

Wu, C. S.↗
NASA NTRS2004

Cluster II Wideband (WBD) Plasma Wave Investigation Mission Operations and Data Analysis

This Summary of Research is being submitted to NASA Goddard Space Flight Center. A summary of the significant accomplishments of the Cluster Wideband (WBD) Plasma Wave Investigation team achieved during the period of the grant, October 1,2000 through January 14, 2004, and a listing of all of the publications that resulted from work carried out under the grant is presented. Also included is a listing of the numerous public outreach activities that took place during the period of the grant in which the Cluster mission and Cluster WBD science were discussed.

Gurnett, Donald A.↗
NASA NTRS1992

Plasma wave profiles of earth's bow shock at low Mach numbers - ISEE 3 observations on the far flank

A survey of selected crossings far downstream from the subsolar shock is presented in which the overall plasma wave (PW) behavior of a selected set of nearly perpendicular crossings and another set of limited Mach number but broad geometry are delinated. The result is a generalizable PW signature, or signatures, of low Mach number shocks and some likely implications of those signatures for the weak shock's plasma physical processes on the flank. The data are found to be consistent with the presence of ion beam interactions producing noise ahead of the shock in the ion acoustic frequency range. The presence or absence, and the amplitudes, of PW activity are explainable by the presence or absence of a population of upstream ions controlled by the component of the interplanetary magnetic field normal to the solar wind flow.

Greenstadt, E. W.↗
NASA NTRS1994

Geotail MCA plasma wave data analysis

NASA Grant NAG 5-2346 supports the data analysis effort at The University of Iowa for the GEOTAIL Multi-Channel Analyzer (MCA) which is a part of the GEOTAIL Plasma Wave Instrument (PWI). At the beginning of this reporting period we had just begun to receive our GEOTAIL Sirius data on CD-ROMs. Much programming effort went into adapting and refining the data analysis programs to include the CD-ROM inputs. Programs were also developed to display the high-frequency-resolution PWI Sweep Frequency Analyzer (SFA) data and to include in all the various plot products the electron cyclotron frequency derived from the magnitude of the magnetic field extracted from the GEOTAIL Magnetic Field (MGF) data included in the GEOTAIL Sirius data. We also developed programs to use the MGF data residing in the Institute of Space and Astronautical Science (ISAS) GEOTAIL Scientific Data Base (SDB). Our programmers also developed programs and provided technical support for the GEOTAIL data analysis efforts of Co-lnvestigator William W. L. Taylor at Nichols Research Corporation (NRC). At the end of this report we have included brief summaries of the NRC effort and the progress being made.

Anderson, Roger R.↗
NASA NTRS2001

A Minimal Radio and Plasma Wave Investigation For a Mercury Orbiter Mission

The primary thrust of the effort at The University of Iowa for the definition of an orbiter mission to Mercury is a minimum viable radio and plasma wave investigation. While it is simple to add sensors and capability to any payload, the challenge is to do reasonable science within limited resources; and viable missions to Mercury are especially limited in payload mass. For a wave investigation, this is a serious concern, as the sensor mass often makes up a significant fraction of the instrumentation mass.

Kurth, W. S.↗
NASA NTRS1990

Plasma waves associated with the space shuttle

Water molecules outgassed from the Space Shuttle suffer collisional charge-exchange with ionospheric oxygen ions, thereby forming unstable distributions of pick-up water ions and leading to high levels of plasma waves near the Shuttle. Liouville's equation with a charge-exchange source term is solved for the water ion distribution function as a function of position relative to the Shuttle. The observational characteristics of the near zone Shuttle waves are summarized. A linear theory in which beam like distributions of water ions drive Doppler shifted lower hybrid waves via the modified two stream instability is developed. This theory explains many characteristics of the near zone waves. Further work on the effects of wave nonlinearities and spatial inhomogeneity is required to explain the detailed frequency spectrum of the waves. The observed wave levels apparently satisfy the threshold condition for modulational instability of lower hybrid waves.

Cairns, I. H.↗
NASA NTRS1989

ISEE/ICE plasma wave data analysis

The work performed for the period 1 Jan. 1985 to 30 Oct. 1989 is presented. The objective was to provide reduction and analysis of data from a scientific instrument designed to study solar wind and plasma wave phenomena on the International Sun Earth Explorer 3 (ISEE-3)/International Cometary Explorer (ICE) missions.

Greenstadt, E. W.↗
NASA NTRS1979

Plasma wave turbulence at Jupiter's bow shock

Voyager 1 measurements of wave-particle interactions of Jupiter's bow shock are reported. Some of the wave phenomena detected during the spacecraft's third inbound passage are discussed. The results indicate that the Jovian magnetosheath was characterized by a virtual absence of detectable plasma wave turbulence after passage through the bow shock and that there were impulsive wave structures within the shock with durations as small as 1, 2, or 3 sec.

Scarf, F. L.↗
NASA NTRS2021

ARTEMIS Observations of Plasma Waves in Laminar and Perturbed Interplanetary Shocks

The ‘Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon's Interaction with the Sun’ (ARTEMIS) mission provides a unique opportunity to study the structure of interplanetary shocks and the associated generation of plasma waves with frequencies between ~50-8000 Hz due to its long duration electric and magnetic field burst waveform captures. We compare wave properties and occurrence rates at 11 quasi-perpendicular interplanetary shocks with burst data within 10 minutes (~3200 proton gyroradii upstream, ~1900 downstream) of the shock ramp. A perturbed shock is defined as possessing a large amplitude whistler precursor in the quasi-static magnetic field with an amplitude greater than ⅓ the difference between the upstream and downstream average magnetic field magnitudes; laminar shocks lack these large precursors and have a smooth, step function-like transition. In addition to wave modes previously observed, including ion acoustic, whistler, and electrostatic solitary waves, waves in the ion acoustic frequency range that show rapid temporal frequency change are common. Three shocks had burst captures in the ramp; of these, the two laminar shocks with burst data in the ramp contained a wide range of large amplitude wave modes in the ramp whereas the one perturbed shock contained no such waves. Thus, energy dissipation through wave-particle interactions is more prominent in these two laminar shocks than in the perturbed shock. Based on observations from all 11 shocks, the The wave occurrence rates for laminar shocks are higher in the transition region, especially the ramp, than downstream. In contrast, perturbed shocks have approximately 2-3 times the wave occurrence rate downstream than laminar shocks.

L. A. Davis↗
NASA NTRS1988

Transverse ion energization and low-frequency plasma waves in the mid-altitude auroral zone - A case study

Evidence of transverse ion energization at altitudes of several earth radii in the auroral zone was reexamined using several hundred hours of high-sensitivity and high-resolution plasma data obtained by the Dynamics Explorer 1 satellite. The data on particle environment encountered at midaltitudes in the auroral zone disclosed rapid variations in the values of total density, thermal structure, and composition of the plasma in the interval measured; the modes of low-frequency plasma waves also varied rapidly. It was not possible to unambiguously identify in these data particle and wave signature of local transverse ion energization; however, many intervals were found where local transverse ion heating was consistent with the observations.

Peterson, W. K.↗
NASA NTRS1990

The excitation of plasma waves by a current source moving in a magnetized plasma - Two-dimensional propagation

The steady motion of a large conducting body in a magnetized plasma has been shown to create a spatial structure of charges and currents in the plasma which propagate without attenuation along the magnetic field direction (the label 'Alfven wings' has been given to this structure because of its resemblance to the wings of a biplane). It has been found that the Alfven wing structure breaks up into individual Fourier components which propagate away from the source at an angle slightly greater with respect to the magnetic field than the alignment of the original structure. This process depends on wave frequency. A given frequency is lost from the Alfven wing structure at a distance which varies as 1/omega-cubed. The amplitude of these traveling waves decreases at a rate which is inversely proportional to the square root of the distance from the source.

Rasmussen, Craig E.↗
NASA NTRS2002

Polar Plasma Wave Investigation Data Analysis in the Extended Mission

This Summary of Research is being submitted to NASA Goddard Space Flight Center in fulfillment of the final reporting requirement under Grant NAG5-7943, which terminated on March 31, 2002. The following contains a summary of the significant accomplishments of the Polar Plasma Wave Investigation (PWI) team during the period of the grant, April 1, 1999 through March 31, 2002, and a listing of all of the publications that resulted from work carried out under the grant. Also included below is a listing of the numerous public outreach activities that took place during the period of the grant in which the Polar mission and Polar PWI science were discussed.

Gurnett, Donald A.↗
NASA NTRS1993

Plasma waves downstream of weak collisionless shocks

In September 1983 the International Sun Earth Explorer 3 (ISEE 3) International Cometary Explorer (ICE) spacecraft made a long traversal of the distant dawnside flank region of the Earth's magnetosphere and had many encounters with the low Mach number bow shock. These weak shocks excite plasma wave electric field turbulence with amplitudes comparable to those detected in the much stronger bow shock near the nose region. Downstream of quasi-perpendicular (quasi-parallel) shocks, the E field spectra exhibit a strong peak (plateau) at midfrequencies (1 - 3 kHz); the plateau shape is produced by a low-frequency (100 - 300 Hz) emission which is more intense behind downstream of two quasi-perpendicular shocks show that the low frequency signals are polarized parallel to the magnetic field, whereas the midfrequency emissions are unpolarized or only weakly polarized. A new high frequency (10 - 30 kHz) emission which is above the maximum Doppler shift exhibit a distinct peak at high frequencies; this peak is often blurred by the large amplitude fluctuations of the midfrequency waves. The high-frequency component is strongly polarized along the magnetic field and varies independently of the lower-frequency waves.

Coroniti, F. V.↗
NASA NTRS2016

The FIELDS Instrument Suite for Solar Probe Plus Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients

NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

Solar Probe Plus↗
NASA NTRS1988

A comparison of the plasma wave spectra for the eight AMPTE chemical releases

The Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM spacecraft performed a series of eight chemical releases in essentially comparable pairs. There were two lithium releases in the solar wind, two lithium and two barium releases in the near-Earth magnetotail, and two barium releases to simulate artificial comets, one in the solar wind and the other in the magnetosheath. A variety of plasma waves were observed in conjunction with each of the releases. Although there were unique features associated with some of the individual releases, the comparable releases generally produced similar wave emissions. This paper discusses the similarities and differences among the releases.

Koons, H. C.↗