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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 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1983

A thermal oscillating two-stream instability

A theory for the oscillating two-stream instability, in which the Ohmic heating of the electrons constitutes the nonlinearity, is developed for an inhomogeneous and magnetized plasma. Its possible role in explaining short-scale, field-aligned irregularities observed in ionospheric heating experiments is emphasized. The theory predicts that the initial growth of such irregularities is centered around the level of upper hybrid resonance. Furthermore, plane disturbances nearly parallel to the magnetic meridian plane have the largest growth rates. Expressions for threshold, growth rate, and transverse scale of maximum growth are obtained. Special attention is paid to the transport theory, since the physical picture depends heavily on the kind of electron collisions which dominate. This is due to the velocity dependence of collision frequencies, which gives rise to the thermal forces

Dysthe, K. B.↗
NASA NTRS1992

On the thermal structure of Triton's thermosphere

The analysis of the Voyager 2 Ultraviolet Spectrometer solar occultation data obtained at Triton is consistent with a spherically symmetric, isothermal thermosphere above 400 km at T(infinity) = 96 K. A detailed calculation of energy loss processes in a pure N2 atmosphere indicates that solar heating, with calculated T(infinity) = 70 K, is insufficient to account for the inferred T(infinity) = 96 K. The magnetosphere must deposit twice as much power as the sun to heat the thermosphere to 96 K and generate the observed N2 tangential column densities above 450 km. The thermal escape of H and N atoms and the downward diffusion of N atoms to recombine below 130 km results in local ionospheric heating efficiency of 24 percent. An upper limit on the tropopause CO mixing ratio of 2 x 10 exp -4 is inferred in the absence of aerosol heating to balance its efficient cooling by LTE rotational line emission.

Stevens, Michael H.↗
NASA NTRS1978

Ionosphere/microwave beam interaction study

The microwave beam of the Solar Power Satellite (SPS) is predicted to interact with the ionosphere producing thermal runaway up to an altitude of about 100 kilometers at a power density threshold of 12 mW/cm sq (within a factor of two). The operation of the SPS at two frequencies, 2450 and 5800 MHz, is compared. The ionosphere interaction is less at the higher frequency, but the tropospheric problem scattering from heavy rain and hail is worse at the higher frequency. Microwave signals from communication satellites were observed to scintillate, but there is some concern that the uplink pilot signal may be distorted by the SPS heated ionosphere. The microwave scintillations are only observed in the tropics in the early evenings near the equinoxes. Results indicate that large phase errors in the uplink pilot signal can be reduced.

Gordon, W. E.↗
NASA NTRS2022

Stormtime Ring Current Heating of the Ionosphere and Plasmasphere

The energy deposition from ring current ions into the high density “cold” plasma of the ionosphere and plasmasphere is analyzed, based on a Comprehensive Inner Magnetosphere-Ionosphere simulation of the 2015 October 7 storm. In addition, the Naval Research Laboratory Sami3 is Also a Model of the Ionosphere ionosphere/plasmasphere code is used to simulate the effect of Coulomb-collision heating of plasmasphere and ionosphere electrons by ring current ions. We find that, during stormtime peaks in the Dst index, energy is deposited at altitudes as low as 100 km. Heating along the entirety of any given field line, both in the ionosphere and plasmasphere, contributes to increased temperatures in the ionosphere F layer and inner magnetosphere and to subsequent cold O + outflows. However, relative to the heating of the plasmasphere, the direct heating of the ionosphere by ring current ions produces only small effects. Qualitative model-data agreement on the N + /O + density ratio is consistent with the hypothesis that these outflows are driven by thermal forcing.

J. Krall↗
NASA NTRS1990

Observations on the DE 1 spacecraft of ELF/VLF waves generated by an ionospheric heater

DE 1 satellite radio observations were conducted in the 1525-5925 Hz range during a pass over an ionospheric heating facility; the waves were detected during a 2-min period, and the measurements indicated pulse-stretching by a few hundred msec, in conjunction with spectral broadening of about 10 Hz. The observed signal delays and pulse distortion are not consistent with expectations assuming propagation in a smooth magnetosphere between the assumed 'polar electrojet antenna' in the ionospheric D/E region and the 11,000-km altitude of the satellite. Scattering by density irregularities is judged the likely sources of the spectral broadening and delays.

James, H. G.↗
NASA NTRS1974

The saturation spectrum of parametric instabilities

Recent calculations on the nonlinear saturation spectrum of the parametric decay instability are described. The initial calculations did not use the correct expression for the spontaneous emission term and were aimed at obtaining the distribution of spectral energy in the unstable part of wave vector space. Results of those initial calculations are combined here with the correct expression for the spontaneous emission term to obtain the distribution of spectral energy in the stable part of wave vector space. These latter calculations are believed to be relevant to the interpretation of the so called plasma line spectra obtained in ionospheric heating experiments at Arecibo, Puerto Rico.

Fejer, J. A.↗
NASA NTRS1975

Theoretical and experimental studies of space-related plasma wave propagation and resonance phenomena

A ten year summary was given of university research on the nature and characteristics of space related plasma resonance phenomena, whistler propagation in laboratory plasmas, and theoretical and experimental studies of plasma wave propagation. Data are also given on long delayed echoes, low frequency instabilities, ionospheric heating, and backscatter, and pulse propagation. A list is included of all conference papers, publications, and reports resulting from the study.

Crawford, F. W.↗
NASA NTRS1978

An empirical model of the interrelationship of electron temperature and density in the daytime thermosphere at solar minimum

The AE-C satellite measurements of electron temperature and ion concentration are used to construct a model of the relationship between these parameters and its variation with altitude in the daytime, nonauroral ionosphere. The major features of the model are that electron temperature is independent of ion concentration at altitudes below 200 km and that electron temperature varies inversely with ion concentration above perhaps 250 km. This behavior is qualitatively consistent with current theoretical models of ionospheric heating and cooling.

Brace, L. H.↗
NASA NTRS1984

The production of ion conics by oblique double layers

Magnetized test ions are subjected to acceleration through a numerically simulated oblique double layer in order to determine whether they emerge with velocity vectors aligned with or oblique to the ambient magnetic field. A criterion for oblique alignment, depending on the double-layer parameters and on the external magnetization, is obtained. When it is applied to observed and theoretical auroral double layers, this criterion predicts that accelerated heavy ions will be substantially less magnetic field aligned than will accelerated hydrogen ions, thus suggesting auroral double layers as a source of high-energy ion conics. Test particle simulations are also used to investigate the perpendicular heating of ions at low altitudes by the electric fields associated with moving auroral arcs. The rapid motion of small-scale structures in the arcs is suggested as a source of low-energy conical ion distributions, and the slow drifts of the entire arc forms are inferred to heat ionospheric ions.

Borovsky, J. E.↗
NASA NTRS1992

A source mechanism producing HF-induced plasma lines (HFPLS) with up-shifted frequencies

Attention is given to a nonlinear scattering process analyzed as a source mechanism producing the frequency up-shifted HFPLs observed in the Arecibo ionospheric heating experiments. A physical picture is offered to explain how Langmuir waves with frequencies greater than the HF heater wave frequency can be produced in the heating experiments and be detected by incoherent radars as frequency up-shifted HFPLs. Since the considered scattering process occurs in a region near the reflection height, it explains why the frequency up-shifted HFPLs should originate from the altitude near the reflection height as observed. The theory also shows that the amount of frequency up-shift is inversely proportional to the frequency of the HF heater and increases linearly with the electron temperature. The quantitative analysis of the theory shows a good agreement with the experimental results.

Kuo, S. P.↗
NASA NTRS1995

Active Experiments in Space Plasmas; Symposium D4.1 of Commission D, COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

Papers from the conference are presented and cover the following topics: ion and electron beams; ionospheric modification; spacecraft interactions; chemical releases; and plasma waves. Auroras and plasma emissions are reported from electron beam injection experiments on the EXCEDE 3 rocket and APEX satellite respectively. The important parameters affecting the charging of spacecraft during the operation of electron guns is covered. The Active Magnetospheric Particle Acceleration Satellite (AMPAS) mission utilizing dual-payload tethered satellites and both up and downward directed electron beams is proposed to study the magnetosphere. Recent results and associated theories from the Sura, Arecibo and Troms ionospheric heating facitlites are presented. The effects of neutral gases on spacecraft charging are examined in a series of rocket flights. Many results from the Combined Release and Radiation Effects Satellite chemical release experiments are presented.

Rietveld, M. T.↗
NASA NTRS2010

FASTSAT-HSV01 Synergistic Observations of the Magnetospheric Response During Active Periods: MINI-ME, PISA and TTI

Understanding the complex processes within the inner magnetosphere of Earth particularly during storm periods requires coordinated observations of the particle and field environment using both in-situ and remote sensing techniques. In fact in order to gain a better understanding of our Heliophysics and potentially improve our space weather forecasting capabilities, new observation mission approaches and new instrument technologies which can provide both cost effective and robust regular observations of magnetospheric activity and other space weather related phenomenon are necessary. As part of the effort to demonstrate new instrument techniques and achieve necessary coordinated observation missions, NASA's Fast Affordable Science and Technology Satellite Huntsville 01 mission (FASTSAT-HSVOI) scheduled for launch in 2010 will afford a highly synergistic solution which satisfies payload mission opportunities and launch requirements as well as contributing iri the near term to our improved understanding of Heliophysics. NASA's FASTSAT-HSV01 spacecraft on the DoD Space Test Program-S26 (STP-S26) Mission is a multi-payload mission executed by the DoD Space Test Program (STP) at the Space Development and Test Wing (SDTW), Kirtland AFB, NM. and is an example of a responsive and economical breakthrough in providing new possibilities for small space technology-driven and research missions. FASTSAT-HSV is a unique spacecraft platform that can carry multiple small instruments or experiments to low-Earth orbit on a wide range of expendable launch vehicles for a fraction of the cost traditionally required for such missions. The FASTSAT-HSV01 mission allows NASA to mature and transition a technical capability to industry while increasing low-cost access to space for small science and technology (ST) payloads. The FASTSAT-HSV01 payload includes three NASA Goddard Space Flight Center (GSFC) new technology built instruments that will study the terrestrial space environment and potentially contribute to space weather research in a synergistic manner. MINI-ME, a neutral atom imager, will observe the neutral atom inputs to ionospheric heating which can be important during high levels of magnetospheric activity. PISA, a plasma impedance spectrometer, will measure simultaneously the local electron densities and temperatures as well as measure small scale density structure (500 m spatial scale) during these active periods. TTI, a thermospheric imager, will remotely determine the thermospheric temperature response to this magnetospheric activity. Together, these observations will contribute significantly to a comprehensive understanding of the flow of energy through and the response of the storm-time terrestrial magnetosphere.

Casas, Joseph C.↗
NASA NTRS1975

Coulomb collisions of ring current particles: Indirect source of heat for the ionosphere

The additional energy requirements of the topside ionosphere during a magnetic storm are less than one quarter of the ring current energy. This energy is supplied largely by Coulomb collisions of ring current protons of energy less than about 20 keV with background thermal electrons which conduct the heat to the ionosphere. Past criticisms are discussed of this mechanism for the supply of energy to the SAR-arc and neighboring regions of the ionosphere.

Cole, K. D.↗
NASA NTRS1980

Microwave heating of the lower ionosphere

Changes in the properties of the lower ionosphere due to ohmic heating of the plasma by the solar power satellite (SPS) microwave power beam are considered. The development of a predictive model of the underdense interaction of an electromagnetic beam and the lower ionosphere is described. The extent to which the Platteville and Arecibo experiments simulate SPS conditions is considered.

Meltz, G.↗
NASA NTRS1990

Temperatures of individual ion species and heating due to charge exchange in the ionosphere of Venus

The coupled electron and multispecies ion energy equations were solved for daytime conditions in the Venus ionosphere. The heating rates due to charge exchange between hot oxygen atoms and thermal oxygen ions were calculated and incorporated into the energy equations. The combination of the traditional EUV heating and this hot oxygen energy source leads to calculated electron and individual ion temperatures significantly lower than the measured values during solar cycle maximum conditions. Calculations were also carried out for solar cycle minimum conditions, which led to considerably lower temperatures; no data are available which would allow direct comparisons of these results with measurements. In order to obtain calculated temperature values consistent with the observed ones, for solar cycle maximum conditions, topside heat inflows into the ion and electron gases have to be introduced or the thermal conductivity must be reduced by considering the effect of steady and fluctuating magnetic fields, as was done in previous studies. The addition of hot oxygen heating leads to minor increases in the calculated ion temperatures except for the case of reduced thermal conductivities. Separate temperatures were calculated for each ion species for a number of different conditions and in general the differences were found to be relatively small.

Kim, Jhoon↗
NASA NTRS1972

Dissipation of electric fields in the ionosphere

The heating and movement of the upper atmosphere at ionospheric levels in response to electric currents are discussed. Joule dissipation, generation of winds, and pressure gradients are significant factors in the energetics of the ionospheric electric currents flowing during magnetic storms and also of the Sq current system.

Cole, K. D.↗