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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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NASA NTRS1991

LEO spacecraft leakage current and discharging phenomena - TRW LDEF SP-HVDE (space plasma-high voltage drainage experiment)

Two identical SP-HVDE trays were flown in the NASA 5.75-year LDEF (Long Duration Exposure Facility), one near the leading edge and the other near the trailing edge, in the LEO (low earth orbit) environment. Each experiment tray consisted of six assemblies with each made of Kapton dielectric samples of varying thicknesses (i.e., 2 mils, 3 mils, and 5 mils) biased under +/- 300 V, +/- 500 V, and +/- 1000 V. The objectives have been successfully achieved by measuring the first post-flight long-term (i.e. roughly 8-month experiment) average leakage current through 95 percent measurable coulombmeters and surface materials.

Yaung, J. Y.↗
NASA NTRS1992

Effect of hemorrhage on cardiac output, vasopressin, aldosterone, and diuresis during immersion in men

The purpose of this research was to test the hypotesis that a reduction in blood volume would attenuate or eliminate immersion-induced increases in cardiac output (Q(sub co)) and urine excretion, and to investigate accompanying vasoactive and fluid-electrolyte hormonal responses. Eight men (19-23 yr) were supine during a 2-hr control period in air, and then sat for 5-hr test periods in air at 20 C (dry control, DC); water at 34.5 C (wet control, WC); and water (34.5 C) after hemorrhage (WH) of 14.8 plus or minus 0.3 percent of their blood volume. Blood volume was -11.6 plus or minus 0.6 percent at immersion (time 0). Mean (bar-X hrs 1-5) Q(sub co) was unchanged in WC (5.3 plus or minus 0.01 l/min) and in WH (4.5 plus or minus 0.1 l/min), but decreased (P less than 0.05) in DC to 3.6 plus or minus 0.1 l/min. Mean urine excretion rates were 1.0 plus or minus 0.2 ml/min for DC and 1.1 plus or minus 0.2 ml/min for WH; both were lower (P less than 0.05) than that for WC of 2.0 plus or minus 0.4 ml/min. Plasma (Na+) and (Osm) were unchanged in all experiments. Mean plasma vasopressin (PVP) (bar-X hrs 1-5) was 1.1 plus or minus 0.1 pg/ml in WC, and higher (P less than 0.05) in DC (2.1 plus or minus 0.2 pg/ml)and WH (2.1 plus or minus 0.1 pg/ml); it was unchanged during air and water test periods. Thus, hemorrhage attenuated the immersion-induced increase in Q(sub co), eliminated the WC diuresis, maintained plasma renin activity and PVP at DC levels and did not change immersion-induced aldosterone suppression; the osmotic diuresis during control immersion is apparently not due to either aldosterone suppression or vasopressin suppression.

Greenleaf, J. E.↗
NASA NTRS1972

Electrostatic-probe measurements of plasma parameters for two reentry flight experiments at 25000 feet per second

Unique plasma diagnostic measurements at high altitudes from two geometrically similar blunt body reentry spacecraft using electrostatic probe rakes are presented. The probes measured the positive ion density profiles (shape and magnitude) during the two flights. The probe measurements were made at eight discrete points (1 cm to 7 cm) from the vehicle surface in the aft flow field of the spacecraft over the altitude range of 85.3 to 53.3 km (280,000 to 175,000 ft) with measured densities of 10 to the 8th power to 10 to the 12th power electrons/cu cm, respectively. Maximum reentry velocity for each spacecraft was approximately 7620 meters/second (25,000 ft/sec). In the first flight experiment, water was periodically injected into a flow field which was contaminated by ablation products from the spacecraft nose region. The nonablative nose of the second spacecraft thereby minimized flow field contamination. Comparisons of the probe measured density profiles with theoretical calculations are presented with discussion as to the probable cause of significant disagreement. Also discussed are the correlation of probe measurements with vehicle angle of attack motions and the good high altitude agreement between electron densities inferred from the probe measurements, VHF antenna measurements, and microwave reflectometer diagnostic measurements.

Jones, W. L., Jr.↗
NASA NTRS1974

Observations of moon-plasma interactions by orbital and surface experiments

Extensive magnetic field observations together with crucial plasma measurements by the Explorer 35 lunar orbiter and Apollo surface and orbital experiments have established the basic nature of the moon's interaction with the solar wind and interplanetary magnetic field. The effective absorption of the incident solar wind by the moon creates a plasma void or cavity behind the moon. The cavity-associated magnetic signature is characterized by an enhancement in magnetic field magnitude B within the cavity as compared with the mean level of B in the surrounding interplanetary plasma and dips or decreases in B near the cavity boundaries with the solar wind. Apollo particle and field measurements on the lunar surface have provided evidence of a regional interaction of the highly conducting solar wind with lunar remanent magnetic fields. Simultaneous plasma and magnetic field data, from the spectrometer and the lunar surface magnetometer at the Apollo 12 location, show the compression of the local remanent field by large solar wind and magnetosheath plasma dynamic pressures.

Schubert, G.↗
NASA NTRS1985

An enhancement of plasma density by neutral gas injection observed in SEPAC Spacelab-1 experiment

An enhancement of plasma density observed during a neutral gas injection in Space Experiments with Particle Accelerators by the Space Shuttle/Spacelab-1 is presented. When a plume of nitrogen gas was injected from the orbiter into space, a large amount of plasma was detected by an onboard plasma probe. The observed density often increased beyond the background plasma density and was strongly dependent on the attitude of the orbiter with respect to the velocity vector. This effect has been explained by a collisional interaction between the injected gas molecules and the ionospheric ions relatively drifting at the orbital speed.

Sasaki, S.↗
NASA NTRS2014

Concerning the Charging of an Exploration Craft on and near a Small Asteroid

Introduction: An object immersed in an airless plasma environment will experience a natural process of surface charging in order to acheieve current balance, or zero net electric current to the object. It has been shown in recent computer simulations that the small-body plasma environment is very complex [1], considering effects of photoemission, topography, and formation of a plasma wake. For this work we consider an exploration craft (or astronaut) immersed within a plasma environment near an asteroid, which exhibits widely varying solar wind and photoelectric particle fluxes and continuously evolving illumination conditions. Objective: We aim to determine how an explo-ration craft or astronaut suit accumulates charge while located in the "nightside" asteroid wake where the particle fluxes are reduced, and in the dayside near-surface photoelectron sheath, by combining an object charging model [2] with kinetic simulations of a near-asteroid plasma environment [1]. We consider an astronaut floating near the asteroid while not in contact with the surface, as well as an astronaut moving along the surface using their hands/gloves to crawl along. Results: The modeling results suggest that remediation of triboelectric charge via accumulation of plasma currents is an important factor to consider when designing future NEA mission infrastructure, especially if repeated and frequent contact with the surface is planned. In shadowed regions such as the location shown in Fig. 1a, the plasma currents are so low (and the effective charge-remediation timescale so long, e.g. minutes to hours) that repeated contact with the surface tribocharges the glove in an uncontrollable fashion, as shown for two representative electron temperatures in Fig. 2a. The resulting buildup of significant negative charge would eventually initiate some other "current of last resort" [4] such as transport of positively-charged dust, field-emission from the glove, or significant alteration of environmental ion currents within the wake. In contrast, the few-meters-thick dayside photoelectron sheath in which the astronaut of Fig. 1b is immersed in is so rich in electrons (and hence so electrically conductive) that accumulated tribocharge dissipates almost instantaneously (e.g. in less than a ms) as shown in Fig. 2b. As our model astronaut orbits the NEA they would experience plasma currents and associated charge re-mediation times spanning many orders of magnitude, and the fusion between our numerical models provides a detailed understanding of the charging hazards possibly associated with contact-based NEA exploration.

Asteroid↗
NASA NTRS1992

NASCAP/LEO simulations of Shuttle Orbiter charging during the SAMPIE experiment

The electrostatic charging of the Space Shuttle Orbiter during the operation of the Solar Array Module Plasma Interaction Experiment (SAMPIE) was modeled using the NASA Charging Analyzer Program/ low Earth orbit (NASCAP/LEO) computer code. The SAMPIE experiment consists of an array of various solar cells representing the present technologies. The objectives of the experiment are to investigate the arcing and current collection characteristics of these cells when biased to high potentials in a LEO plasma. NASCAP/LEO is a 3-D code designed to simulate the electrostatic charging of a spacecraft exposed to a plasma at LEO or ground test conditions. At its most extreme configuration, with the largest array segment of the SAMPIE experiment biased + 600 V with respect to the orbiter and facing the ram direction, the computer simulations predict that the orbiter's potential will be approximately -20 V with respect to the plasma.

Chock, Ricaurte↗
NASA NTRS1994

A Study of High Altitude Hypersonic Flow-Field Radiation

This paper presents the results of the works carried out jointly at Stanford University and Ames Research Center under a grant from the Ballistic Missile Defense Organization (BMDO) (formerly the Strategic Defense Initiative Organization) to explain and understand the results of the two flight experiments, Bow Shock Ultra-Violet 1 and Bow Shock Ultra-Violet 2, carried out by the Organization. A portion of the material contained in this paper has been reported elsewhere in open literature. However, this paper provides (1) the details of scientific contents not available in those literature, (2) the links among those and the logical order of the efforts involved, and (3) some materials not contained in any open literature. The first author is responsible for execution of the work; the second author directed the work of the first author. In the two flight experiments mentioned above, the spectra of radiation in the ultraviolet wavelength range incident on the stagnation point of a blunt body were measured at the flight speeds of 3.8 and 5.2 km/sec over a wide range of altitudes. The results were compared first with the calculations made using the original version of the NEQAIR/STRAP codes written earlier by the second author. At low altitudes, the calculations agreed with the measurement. However, at high altitudes, the calculations underestimated the intensity of the radiation by several orders of magnitudes. A shock tube experiment was carried out at CALSPAN and a plasma-torch experiment was carried out at Stanford University to produce experimental data to help explain the discrepancy. In addition, the shock tube experiment at Ames Research Center carried out independently of the BMDO was also found to be relevant to this question. In this paper, several theoretical models are developed and calculations using the models were carried out to explain the results not only of the flight experiments but also of the CALSPAN, Stanford, and Ames experiments. The are: (1) the diffusion model for the rotational mode to explain the slowness of rotational excitation, (2) assignment of different vibrational temperatures and different relaxation rates for different molecules, and (3) the modification of the NEQAIR code to accommodate the new experimental data. This paper shows that the discrepancy between the flight data and calculation is smaller with the present model, but is still substantial.

Moreau, Stephane↗
NASA NTRS1995

Electromagnetic Radiation in the Plasma Environment Around the Shuttle

As part of the SAMPIE (The Solar Array Module Plasma Interaction Experiment) program, the Langmuir probe (LP) was employed to measure plasma characteristics during the flight STS-62. The whole set of data could be divided into two parts: (1) low frequency sweeps to determine voltage-current characteristics and to find electron temperature and number density; (2) high frequency turbulence (HFT dwells) data caused by electromagnetic noise around the shuttle. The broadband noise was observed at frequencies 250-20,000 Hz. Measurements were performed in ram conditions; thus, it seems reasonable to believe that the influence of spacecraft operations on plasma parameters was minimized. The average spectrum of fluctuations is in agreement with theoretical predictions. According to purposes of SAMPIE, the samples of solar cells were placed in the cargo bay of the shuttle, and high negative bias voltages were applied to them to initiate arcing between these cells and surrounding plasma. The arcing onset was registered by special counters, and data were obtained that included the amplitudes of current, duration of each arc, and the number of arcs per one experiment. The LP data were analyzed for two different situations: with arcing and without arcing. Electrostatic noise spectra for both situations and theoretical explanation of the observed features are presented in this report.

Vayner, Boris V.↗
NASA NTRS1996

Low Frequency Waves in the Plasma Environment Around the Shuttle

As a part of the SAMPIE (The Solar Array Module Plasma Interaction Experiment) program, the Langmuir probe (LP) was employed to measure plasma characteristics during the flight of STS-62. The whole set of data could be divided into two parts: (1) low frequency sweeps to determine voltage-current characteristics and to find the electron temperature and number density; (2) high frequency turbulence (HFT) data caused by electromagnetic noise around the Shuttle. Broadband noise was observed at 250-20,000 Hz frequencies. Measurements were performed in ram conditions; thus, it seems reasonable to believe that the influence of spacecraft operations on plasma parameters was minimized. It is shown that ion acoustic waves were observed, and two kinds of instabilities are suggested for explanation of the origin of these waves. According to the purposes of SAMPIE, samples of solar cells were placed in the cargo bay of the Shuttle, and high negative bias voltages were applied to them to initiate arcing between these cells and the surrounding plasma. The arcing onset was registered by special counters, and data were obtained that included the amplitudes of current, duration of each arc, and the number of arcs per one experiment. The LP data were analyzed for two different situations: with arcing and without arcing. Electrostatic noise spectra for both situations and a theoretical explanation of the observed features are presented in this paper.

Vayner, Boris V.↗
NASA NTRS1993

The SAMPIE flight experimental final technical requirements document

The Solar Array Module Plasma Interactions Experiment (SAMPIE) is a shuttle based flight experiment scheduled for launch in early 1994. SAMPIE will investigate plasma interactions of high voltage space power systems in low earth orbit. Solar cell modules, representing several technologies, will be biased through a series of high voltages to characterize both arcing and plasma current collection. Other solar modules, specially modified in accordance with current theories of arcing and breakdown, will demonstrate the possibility of arc suppression. Finally, several test modules will be included to study the basic nature of these interactions. The science and technology goals for the project are defined in the Technical Requirements Document (TRD) which is presented here in its final form. The experiment is being developed at NASA LeRC in Cleveland, Ohio, and is sponsored by the NASA Office of Aeronautics and Space Technology (OAST).

Hillard, G. Barry↗
NASA NTRS1994

Whistler mode waves in the Jovian magnetosheath

During the Ulysses flyby of Jupiter in February 1992, the spacecraft traversed the Jovian magnetosheath for a few hours during the inbound pass and for aa few days during the outbound pass. Burstlike electomagnetic waves at frequencies of approximately 0.1-0.4 of the local electron cyclotron frequency have been observed by the Unified Radio and Plasma Wave (URAP) experiement. The waves were more often observed in the regions which were probably the outer or the middle magnetosheath, especially near the bow shock, and rarely seen in the magnetosphere/magnetosheath boundary layer. The propagation angles of the waves are estimated by comparing the measurements of the wave electric and magnetic fields in the spacecraft spin plane with the corresponding values calculated using the cold plasma dispersion relation under local field and plasma conditions. It is found that the waves propagate obliquely with wave angles between approximately 30 deg and 50 deg. These waves are likely to be the whistler mode waves which are excited by suprathermal electrons with a few hundred eV and a slight anisotropy (T(sub perp)/T(sub parallel) approximately 1.1-1.5). They are probably similar in nature to the lion roars observed in the Earth's magnetosheath. Signature of coupling between the mirror and the whistler mode have also been observed. The plasma conditions which favor the excitation of the whistler mode instability during the wave events exists as observed by the plasma experiement of Ulysses.

Lin, Naiguo↗
NASA NTRS1988

Ionospheric holes - A review of theory and recent experiments

Artificially induced ionospheric holes result from in situ injections of highly reactive molecules, which greatly enhance the chemical recombination rates between the ions and electrons found in the upper atmosphere. During the past decade, experiment-of-opportunity observations, theory and computer simulations have succeeded in establishing plasma-depletion experiments as a useful tool for probing the normal and disturbed behavior of the ionosphere. Ionospheric-hole experiments now focus on applications of the technique to laboratory-in-space investigations of various space plasma processes.

Mendillo, Michael↗
NASA NTRS1975

Electrostatic and electromagnetic turbulence associated with the earth's bow shock

Simultaneous measurements were made of the electric and magnetic field spectral densities in the earth's bow shock by a plasma wave experiment on the Imp 6 spacecraft. The frequency range of the plasma wave detector was 20 Hz to 200 kHz. Electric fields were measured with high-sensitivity 100-m long dipole antennas and magnetic fields were measured with single-turn loop antennas. Two components are distinguished in the electric field spectrum in the bow shock: one component has a broad peak centered in the region 200-800 Hz, while the other component increases monotonically with decreasing frequency. The magnetic field spectrum has only one component that increases monotonically with decreasing frequency and has an upper cutoff frequency near the local electron gyrofrequency. This magnetic field turbulence is judged to be caused by whistler mode waves. The monotonic component of the electric field spectrum is thought to be the electric field spectrum of these whistler mode waves.

Rodriguez, P.↗
NASA NTRS1987

The low energy plasma in the Uranian magnetosphere

The Plasma Science experiment on Voyager 2 detected a magnetosphere filled with a tenuous plasma, rotating with the planet. Temperatures of the plasma, composed of protons and electrons, ranged from 10 eV to about 1 keV. The sources of these protons and electrons are probably the ionosphere of Uranus or the extended neutral hydrogen cloud surrounding the planet. As at earth, Jupiter, and Saturn, there is an extended magnetotail with a central plasma sheet. Although similar in global structure to the magnetospheres of these planets, the large angle between the rotation and magnetic axes of the planet and the orientation of the rotation axis with respect to the solar wind flow make the Uranian magnetosphere unique.

Mcnutt, R. L., Jr.↗
NASA NTRSDate not supplied

Voyager 1 and 2 Preliminary Observations Within Interplanetary Space of Upstream Suprathermal < 6 KeV Electrons Evidently Connected to Jupiter’s Bow Shock

We present for the first time the Voyager 1 and 2 plasma instrument observations within the interplanetary space of upstream suprathermal E < 6 keV electrons during times when close < 100 RJ from Jupiter’s bow shock. These measurements are a biproduct of our recovery of the Voyager Jupiter flyby measurements of the plasma electrons made by the Plasma Science Experiment (PLS) (Bridge et al., 1977). The initial ion and electron plasma observations were first reported by Bridge et al. (1979a, b). The periods were chosen to follow those reported by Zwickl et al. (1981) using energetic particle data with E ≥ 30 keV from the Low Energy Charged Particle (LECP) instrument (Krimigis et al., 1977). For this study we also use Voyager magnetic field data (Ness et al., 1979a, b) which is critical for this study. Basically, whenever the interplanetary magnetic field is nearly radially aligned relative to the spacecraft sun line, connection to the Jovian bow shock is believed to occur and one would expect those times when the keV suprathermal electron would be observed, but we also see them when the field is not radial but close to Jupiter’s bow shock. Whenever the magnetic field is radial the plasma instrument’s D cup or side sensor, which makes the electron observations (10 eV ≤ E ≤ 6 keV), is viewing ∼ 90 degree pitch angle electrons but evidently its wide field-of-view (FOV) allows one to see the keV electrons assumed to be field aligned. So, we will be looking into FOV alignment issues relative to the local magnetic field vector and any evidence for pitch angle scattering by plasma waves (see Scarf et al., 1981) that might broaden their width in pitch angle and allow their detection.

E C Sittler, Jr↗
NASA NTRS1990

Theory of plasma contactors in ground-based experiments and low Earth orbit

Previous theoretical work on plasma contactors as current collectors has fallen into two categories: collisionless double layer theory (describing space charge limited contactor clouds) and collisional quasineutral theory. Ground based experiments at low current are well explained by double layer theory, but this theory does not scale well to power generation by electrodynamic tethers in space, since very high anode potentials are needed to draw a substantial ambient electron current across the magnetic field in the absence of collisions (or effective collisions due to turbulence). Isotropic quasineutral models of contactor clouds, extending over a region where the effective collision frequency upsilon sub e exceeds the electron cyclotron frequency omega sub ce, have low anode potentials, but would collect very little ambient electron current, much less than the emitted ion current. A new model is presented, for an anisotropic contactor cloud oriented along the magnetic field, with upsilon sub e less than omega sub ce. The electron motion along the magnetic field is nearly collisionless, forming double layers in that direction, while across the magnetic field the electrons diffuse collisionally and the potential profile is determined by quasineutrality. Using a simplified expression for upsilon sub e due to ion acoustic turbulence, an analytic solution has been found for this model, which should be applicable to current collection in space. The anode potential is low and the collected ambient electron current can be several times the emitted ion current.

Gerver, M. J.↗