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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Dynamics Explorer 1, retarding ion mass spectrometer summary spectrograms: 82/001 to 82/109 spin-time spectrograms for H(+), He(+), O(+), N(+), O(++), M/Z=2, and molecular ions

The Retarding Ion Mass Spectrometer (RIMS) experiment onboard the Dynamics Explorer 1 (DE 1) satellite was designed to perform energy and mass-per-change analysis on low-energy ions (less than 50 eV) with mass/charge ratios ranging from 1 to 40 amu/Z. The DE 1 satellite, carrying the RIMS experiment, was launched into an elliptical polar orbit on August 3, 1981. The approximate 7.5 hour orbit has perigee of 675 km altitude and apogee of 24,875 km altitude. This document, and those that follow in this series, contains summary RIMS data spectrograms for each orbit for which RIMS data are available. The RIMS instrument began returning science data on day 280 of 1981 and continued to return usable data until the end of the DE mission in March 1991. It should be noted that studies of the RIMS data set should be conducted only with a thorough awareness of the material described in the introduction section presented here, or in collaboration with a scientist familiar with RIMS data analysis.

Source record↗
NASA NTRS1995

Dynamics Explorer 1, retarding ion mass spectrometer summary spectrograms-82/110 to 82/229 spin-time spectrograms for H(+), He(+), O(+), N(+), O(++), M/Z = 2, and molecular ions

The retarding ion mass spectrometer (RIMS) experiment onboard the Dynamics Explorer 1 (DE 1) satellite was designed to perform energy and mass-per-charge analysis on low-energy ions (less than 50 eV) with mass/charge ratios ranging from 1 to 40 amu/Z. The DE 1 satellite, carrying the RIMS experiment, was launched into an elliptical polar orbit on August 3, 1981. The approximately 7.5 hour orbit has perigee of 675 km altitude and apogee of 24,875 km altitude. this document and those that following in this series, contains summary RIMS data spectrograms for each orbit for which RIMS data are available. The RIMS instrument began returning science data on day 280 of 1981 and continued to return usable data until the end of the DE mission in March 1991. It should be noted that studies of the RIMS data set should be conducted only with a thorough awareness of the material described in the introduction section presented here, or in collaboration with a scientist familiar with RIMS data analysis.

Source record↗
NASA NTRS1995

Dynamics Explorer 1, retarding ion mass spectrometer summary spectrograms-82/230 to 82/265 spin-time spectrograms for H(+), He(+), O(+), N(+), O(++), M/Z = 2, and molecular ions

The retarding ion mass spectrometer (RIMS) experiment onboard the Dynamics Explorer 1 (DE 1) satellite was designed to perform energy and mass-per-charge analysis on low-energy ions (less than 50 eV) with mass/charge ratios ranging from 1 to 40 amu/Z. the DE 1 satellite, carrying the RIMS experiment, was launched into an elliptical polar orbit on August 3, 1981. The approximately 7.5 hour orbit has perigee of 675 km altitude and apogee of 24,875 km altitude. This document and those that follow in this series, contain summary RIMS data spectrograms for each orbit for which RIMS data are available. The RIMS instrument began returning science data on day 280 of 1981 and continued to return usable data until the end of the DE mission in March 1991. It should be noted that studies of the RIMS data set should be conducted only with a thorough awareness of the material described in the introduction section presented here, or in collaboration with a scientist familiar with RIMS data analysis.

Source record↗
NASA NTRS1994

The conductive propagation of nuclear flames. 2: Convectively bounded flames in C + O and O + Ne + Mg cores

We determine the speeds, and many other physical properties, of flame fronts that propagate inward into degenerate and semidegenerate cores of carbon and oxygen (CO) and neon and oxygen (NeOMg) white dwarfs when such flames are bounded on their exterior by a convective region. Combustion in such fronts, per se, is incomplete, with only a small part of the initial mass function burned. A condition of balanced power is set up in the star where the rate of energy emitted as neutrinos from the convective region equals the power available from the unburned fuel that crosses the burning front. The propagation of the burning front itself is in turn limited by the temperature at the base of the convective shell, while cannot greatly exceed the adiabatic value. Solving for consistency between these two conditions gives a unique speed for the flame. Typical values for CO white dwarfs are a few hundredths of a centimeter per second. Flames in NeOMg mixtures are slower. Tables are presented in a form that can easily be implemented in stellar evolution codes and yield the rate at which the convective shell advances into the interior. Combining these velocities with the local equations for stellar structure, we find a minimum density for each gravitational potential below with the local equations for stellar structure, we find a minimum density for each gravitational potential below which the flame cannot propagate, and must die. Although detailed stellar models will have to be constructed to reslove some issues conclusively, our results that a CO white dwarf inginted at its edge will not burn carbon all the way to its center unless the mass of the white dwarf exceeds 0.8 solar mass. On the other hand, it is difficult to ignite carbon burning by compression alone anywhere in a white dwarf whose mass does not exceed 1.0 solar mass. Thus, compressionally ignited shell carbon burning in an accerting CO dwarf almost certainly propagates all the way to the center of the star. Implications for neutron star formation, and Type Ia supernova models, are briefly discussed. These are also applicable to massive stars in the about 10-12 solar mass range which ignite neon burning off center.

Timmes, F. X.↗
NASA NTRS1994

O(+)-O collision frequency in high-speed flows

Throughout much of the terrestrial thermosphere and ionosphere, the motions of the neutral and ionized constituents are closely coupled and relative velocities are small, of the order of 100 m/s or less. This is particularly true at midlatitudes to low latitudes where typical velocities in the neutral gas due to tidal forcing are only 20-50 m/s. However, the solar wind-magnetosphere interaction drives a large-scale convection pattern in the polar ionosphere. When the rapid adjustment of the plasma to changes in the solar wind is combined with the slower response of the more massive neutral gas, large relative velocities on the order of 1 km/s can exist for substantial lengths of time. This will be more common during periods of high geomagnetic activity, as a result of the greater number of magnetic substorms and other particle precipitation events. When a significant relative velocity is present, the calculation of interaction parameters of the two gases passing through each other, such as collision frequency, must include that velocity. These effects are usually neglected when interpreting wind and ion drift observations. We show how the collision frequency is affected by a directed velocity between any two gases interacting with a power law or exponential potential energy curved. The directed velocity increases the collision frequency at all temperatures for most ion-neutral interactions. For certain power law potentials, such as the charge quadrupole, the collision frequency is decreased. We present an analytic solution for the high-speed collision integral using the resonance charge exchange cross section.

Pesnell, William Dean↗
NASA NTRS1999

Recent Development on O(+)-O Collision Frequency and Ionosphere-Middle Atmosphere Coupling

The collision frequency between an oxygen atom and its singly charged ion controls the transfer of energy between the solar radiation and the thermosphere. There were a long standing discrepancy, extending over a decade, between the theoretical and empirical determination of this frequency, and the empirical value of this frequency exceeded the theoretical value by a factor of 1.7. Recent improvements in theory were obtained by using accurate oxygen ion-oxygen atom potential energy curves, and partial wave quantum mechanical calculations. Similarly, recently three independent statistical methods were applied to the empirical determination of this frequency. These methods give results consistent with each other, and together with the recent theoretical improvements, bring the ratio close to unity, as it should be. It will be shown that the old statistical method for this determination contained accumulative errors, leading to a larger value for this ratio. The recent improvements lead to an average value of the empirical to the theoretical ratio equal to 0.98, with an uncertainty of +/- 8%, resolving the old discrepancy between theory and observations. The main source of uncertainties are errors in the profile of the oxygen atom density, which is of the order of 11 %. An alternative method to find the oxygen atom density is being suggested.

Omidvar, K.↗
NASA NTRS1999

Recent Development on O(+) - O Collision Frequency and Ionosphere-Thermosphere Coupling

The collision frequency between an oxygen atom and its singly charged ion controls the momentum transfer between the ionosphere and the thermosphere. There has been a long standing discrepancy, extending over a decade, between the theoretical and empirical determination of this frequency: the empirical value of this frequency exceeded the theoretical value by a factor of 1.7. Recent improvements in theory were obtained by using accurate oxygen ion-oxygen atom potential energy curves, and partial wave quantum mechanical calculations. We now have applied three independent statistical methods to the observational data, obtained at the MIT/Millstone Hill Observatory, consisting of two sets A and B. These methods give results consistent with each other, and together with the recent theoretical improvements, bring the ratio close to unity, as it should be. The three statistical methods lead to an average for the ratio of the empirical to the theoretical values equal to 0.98, with an uncertainty of +/-8%, resolving the old discrepancy between theory and observation. The Hines statistics, and the lognormal distribution statistics, both give lower and upper bounds for the Set A equal to 0.89 and 1.02, respectively. The related bounds for the Set B are 1.06 and 1.17. The average values of these bounds thus bracket the ideal value of the ratio which should be equal to unity. The main source of uncertainties are errors in the profile of the oxygen atom density, which is of the order of 11%. An alternative method to find the oxygen atom density is being suggested.

Omidvar, K.↗
NASA NTRS2000

Impact of atmospheric water vapor on the thermal infrared remote sensing of volcanic sufur dioxide emmisions: A case study from Pu'u 'O'o vent of Kilauea volcano, Hawaii

The December 18, 1999, launch of NASA's Terra satellite put two multispectral thermal infrared imaging instruments into Earth orbit. Experiments with airborne instruments have demonstrated that the data from such instruments can be used to detect volcanic SO2 plumes and clouds.

Mount Etna eruptions imaging plumes SO2↗