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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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Computer graphics of vibrational effects in ion molecule collisions including electron tunneling oscillations, nuclear capture, and molecular oscillations and relaxation
Interferometric technique for measuring atomic or molecular oscillator strengths in vacuum UV
Fluidic oscillator use as molecular weight sensor for gas mixtures
Sensing molecular weights of gases with fluidic oscillator
Fluidic oscillator molecular weight of flowing mono- and polyatomic gases, discussing frequency dependence on pressure drop and temperature
Evaluation of fluidic oscillator as molecular weight sensor of gases
Optical determination of molecular hydrogen Lyman band oscillator strength from individual rotational lines
The observation of relaxation oscillations in both the (C-13)H3F and (C-12)H3F optically pumped lasers is reported. Expressions are derived for the oscillation frequency and its temperature and pressure dependences using a four-level rate equation model. Excellent agreement between measured frequencies and the theory presented is observed. Models are considered for using this phenomenon to determine the rotational and vibrational relaxation mechanisms of the laser gases.
Mean oscillation amplitudes, thermodynamic functions and molecular polarizabilities of mixed phosphorus halides
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By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).
Millimeter wave oscillator AFC system utilizing inherent stability of molecular rotational transition applied to reflex klystron stabilization
Oscillator strengths and autoionization lifetime of aluminum I doublet measured in shock tube
Eigenvalues and eigenvectors calculated for several low-lying autoionizing levels in helium
Electronic oscillator strengths for nitrogen second positive and nitrogen first negative systems from observations of shock layers about hypersonic projectiles
Thermal energy transfer between free electrons and molecular vibration
Transition probabilities of nitrogen-nitrogen collision obtained with time-dependent wave functions of forced harmonic oscillator and by numerical methods
Auroral excitation rates and molecular vibrational tempratures in nitrogen 2PG from Franck-Condon factors obtained from intensity measurements and high resolution absorption spectral data