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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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Rotational inelastic transitions in atom-diatomic collisions, discussing restricted distorted-wave approximation, transition probabilities, impact parameters, inelastic and glory quenching, etc
Direct interaction between hydrogen atom and positive ion with one electron, using Born and two and four state impact parameter treatments
Electron and proton impact excitations of He using Born two and four state versions of impact parameter treatment
Calculating spin exchange cross section for collision between two positive He ions in impact parameter approximation
Correction factors for small values of logarithm of Debye length ratio to mean impact parameter in electrical conductivity of fully ionized plasma
The influence of multipole interactions on exchanges of rotational energy in molecular collisions was investigated by means of a simple two-state impact parameter approximation. The calculations are restricted to linear molecules and to dipole and quadrupole fields. The effects of such exchanges on the thermal conductivity of gases and of gaseous mixtures was investigated, after correcting the kinetic theory of mixtures to include exchanges between unlike molecules. It was found that dipole-quadrupole and quadrupole-quadrupole interactions may have a significant effect for molecules with low moments of inertia. In particular, quadrupole interactions are important in the hydrogen isotopes, and the calculated corrections for H2 are consistent with recent experimental work by Harris. The theory seems capable of accounting for the anomalies observed in HF + DF and HCl + DCl mixtures in terms of multipolar accidental resonances.
An impact parameter method using Coulomb trajectories is applied to the calculation of cross sections for two electron detachment processes. The asymptotic behavior of the cross sections at high energies is investigated in detail. Energy distributions of ejected electrons at three different incident energies are also calculated. Some of the results obtained are compared with available experimental data.
Investigation of the influence of resonant multipole interactions on exchanges of rotational energy in molecular collisions, by means of a simple two-state impact-parameter approximation. It is found that dipole-quadrupole and quadrupole-quadrupole interactions can have a significant effect for molecules with low moments of inertia.
Results of an occultation experiment carried out on June 14-15, 1969, when the Crab Nebula pulsar passed within 80 min of arc from the center of the sun. For a time interval of two months around this event comparisons are made of the reception times of pulses at frequencies of 111.5, 196.5, and 430 MHz for the purpose of determining the contribution of the solar corona to the integrated electron density along the total path length to the pulsar. For impact parameters between 5 and 12 solar radii the measured integrated densities are not incompatible with those that can be derived from a spherically symmetric Baumbach-Allen model. The systematic differences in density obtained at each observation frequency can be explained in terms of refraction effects.
Potential surfaces for the system K+IR were considered, taking into account a covalent surface, an ionic surface, the overall potential, and a comparison of a modified Bunker-Blais and a hybrid covalent-ionic potential of the electron-jump type. The Lagrange equations were solved as a system of second-order differential equations. The impact parameter, angular, and energy dependences of the product distributions for the nonreactive, reactive, and dissociative scattering were studied.
Light curves of occultations of Europa by Io were used to generate a crude map of albedo features on Europa. Impact parameters and magnitude ratios for each event were imposed on a model. Residuals between the observed and computed light curves were interpreted as albedo features on Europa. In order to improve the fit between the observations and the model a general polar brightening was employed. The effects of additional albedo features and alternate models are discussed.
Analysis of three occultations of JII (Europa) by JI (Io) has resulted in a preliminary reflectivity map of JII for the hemisphere centered on longitude 324 deg, a measurement of 1483 plus or minus 20 km for the radius of JII, estimates of the event impact parameters, determination of the midevent times, and a visual geometric albedo of 0.74, for JII. A fourth occultation light curve was used after derivation of the results to confirm their validity.
A three-axis cosmic dust experiment placed on the lunar surface by the Apollo 17 crew is registering impact parameters of cosmic dust and lunar ejecta. A total of 1117 events have been recorded in eight months of data. Preliminary conclusions on the nature of the data include possible evidence of lunar soil transport associated with the terminators. Particle fluxes have been derived for two of the three sensor systems and for specified conditions of exposure.
Regional hydrologic planning models built upon remote sensing capabilities and suited for ungaged watersheds are developed. The effectiveness of such models is determined along with which parameters impact most the minimization of errors associated with the prediction of peak flow events (floods). Emphasis is placed on peak flood prediction because of its significance to users for the purpose of planning, sizing, and designing waterworks.
A theoretical model of charge exchange utilizing reasonable potential energy curves and coupling matrix elements in a two state impact parameter calculation is presented.
The paper presents a detailed parameterization of the transverse momentum in hadronic collisions on multiplicity and on beam momentum. Hadronic collisions are considered at energies below the ultra-high energy domain, on the basis of an uncertainty relation and a naive eikonal model with an impact-parameter-dependent multiplicity.
Light curves of occultations of Europa by Io have been used to generate a crude map of albedo features on Europa. The best values currently available for the impact parameters and magnitude ratios for each event have been imposed on our model. Residuals between the observed and computed light curves are interpreted as albedo features on Europa. In order to improve the fit between the observations and the model, it became necessary to impose a general polar brightening. The effects of additional albedo features and alternate models are discussed.
An important difference between the radio and stellar occultation techniques for probing planetary atmospheres is that a crucial equation relating refraction angle with ray impact parameter is solved in opposite directions in the two techniques. The solution is tolerant of small geometrical errors for stellar occultations but, unfortunately, not for radio occultations.