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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Intercepting Grids Made of Anisotropic Pyrolytic Graphite in Electron Guns with a Dispenser Cathode

The results of experimental studies into the application of anisotropic pyrolytic graphite (APG) as grid structures in power microwave devices with a dispenser cathode are detailed. The dependences of emission characteristics of molybdenum, hafnium, and APG in diodes and electron guns on the electron-flow power dissipated at the studied samples and on cathode temperature are presented. It is demonstrated that the power dissipation capacity of APG grid structures (without parasitic thermionic emission) is up to 20 and 9 times higher than that of molybdenum and hafnium grids, respectively.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
NASA NTRS1974

Ephemeris data and error analysis in support of a Comet Encke intercept mission

Utilizing an orbit determination based upon 65 observations over the 1961 - 1973 interval, ephemeris data were generated for the 1976-77, 1980-81 and 1983-84 apparitions of short period comet Encke. For the 1980-81 apparition, results from a statistical error analysis are outlined. All ephemeris and error analysis computations include the effects of planetary perturbations as well as the nongravitational accelerations introduced by the outgassing cometary nucleus. In 1980, excellent observing conditions and a close approach of comet Encke to the earth permit relatively small uncertainties in the cometary position errors and provide an excellent opportunity for a close flyby of a physically interesting comet.

Yeomans, D. K.↗
NASA NTRS1974

Origin of fifteen cosmic dust particles intercepted by Pioneer 8 and 9

Consistent data for more than 8 years have been obtained from two identical cosmic dust particle experiments on board the space probes Pioneer 8 and 9. The two spacecraft are in direct heliocentric orbits with perihelia between 0.75 AU and 1.00 AU. On the basis of the data it is concluded that the majority of dust particles having elliptical orbits detected by the two space probes show orbital characteristics of Apollo group asteroids which originated from residual nuclei of short-period comets.

Rhee, J. W.↗
NASA NTRS1976

Orbital elements of dust particles intercepted by Pioneers 8 and 9

Results of analysis of the orbital elements of interplanetary dust particles collected by Pioneers 8 and 9 are presented in tabular form. The following conclusions are drawn from the analysis: (1) statistical analysis confirms that the nature of the nominal trajectories is essentially correct, with the most probable elements close to the nominal ones, (2) the elliptic or hyperbolic nature of most orbits is not affected by reasonable density assumptions, and (3) the incoming asymptote of the hyperbolic orbits is consistent with the particles arriving from the apex of the solar motion.

Wolf, H.↗
NASA NTRS1981

Decision Aids for Airborne Intercept Operations in Advanced Aircrafts

A tactical decision aid (TDA) for the F-14 aircrew, i.e., the naval flight officer and pilot, in conducting a multitarget attack during the performance of a Combat Air Patrol (CAP) role is presented. The TDA employs hierarchical multiattribute utility models for characterizing mission objectives in operationally measurable terms, rule based AI-models for tactical posture selection, and fast time simulation for maneuver consequence prediction. The TDA makes aspect maneuver recommendations, selects and displays the optimum mission posture, evaluates attackable and potentially attackable subsets, and recommends the 'best' attackable subset along with the required course perturbation.

Madni, A.↗
NASA NTRS1984

Deployment of a Secondary Concentrator to Increase the Intercept Factor of a Dish with Large Slope Errors

The testing of a hyperbolic trumpet non-imaging secondary concentrator with a parabolic dish having slope errors of about 10 mrad is reported. The trumpet, which has a concentration ratio of 2.1, increased the flux through a 141-mm focal aperture by 72%, with an efficiency of 96%, thus demonstrating its potential for use in tandem with cheap dishes having relatively large slope errors.

Ortabasi, U.↗
NASA NTRS1985

A study of severe storm electricity via storm intercept

Storm electricity data, radar data, and visual observations were used both to present a case study for a supercell thunderstorm that occurred in the Texas Panhandle on 19 June 1980 and to search for insight into how lightning to ground might be related to storm dynamics in the updraft/downdraft couplet in supercell storms. It was observed that two-thirds of the lightning ground-strike points in the developing and maturing stages of a supercell thunderstorm occurred within the region surrounding the wall cloud (a cloud feature often characteristic of a supercell updraft) and on the southern flank of the precipitation. Electrical activity in the 19 June 1980 storm was atypical in that it was a right-mover. Lightning to ground reached a peak rate of 18/min and intracloud flashes were as frequent as 176/min in the final stages of the storm's life.

Arnold, Roy T.↗