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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2004

Shock Heating: Effects on Chondritic Material

At the 1994 Conference on Chondrules and the Protoplanetary Disk, shock waves were discussed as mechanisms that may have been responsible for forming chondrules, millimeter-sized igneous spheres which are significant components of chondritic meteorites, and references therein]. At the time, shock waves were appealing because they were thought to be brief, repetitive events that were quantitatively shown to be able to rapidly heat silicates to the appropriate temperatures for chondrule formation. Since that meeting, more detailed models for the thermal processing of material in shock waves have been developed. These models have tracked the thermal evolution of the silicates for longer periods of time and found that their cooling rates are also consistent with what has been inferred for chondrules. In addition to the thermal histories of these particles, shock waves may be able to explain a number of other features observed in primitive meteorites. Here, we review the recent work that has been done in studying the interaction of solids with shock waves in the solar nebula.

Desch, S. J.↗
NASA NTRS1981

Optical absorption of carbon and hydrocarbon species from shock heated acetylene and methane in the 135-220 nm wavelength range

Absorption spectroscopy of carbon and hydrocarbon species has been performed in a shock tube at an incident shock condition for a wavelength range of 135-220 nm, in order to obtain information needed for calculating radiation blockage ahead of a planetary probe. Instrumentation consisted of high frequency response pressure transducers, thin-film heat transfer gages, or photomultipliers coupled by light pipes. Two test-gas mixtures, one with acetylene and the other with methane, both diluted with argon, were used to provide a reliable variation of C3 and C2H concentration ratio. Comparison of tests results of the two mixtures, in the temperature range of 3750 + or - 100 K, showed the main absorbing species to be C3. The wavelength for maximum absorption agrees well with the theoretical values of 7.68 eV and 8.03 eV for the vertical excitation energy, and a value of 0.90 for the electronic oscillator strength, obtained from the measured absorption band, is also in good agreement with the predicted value of 0.92.

Shinn, J. L.↗
NASA NTRS1972

Vacuum ultraviolet line radiation measurements of a shock-heated nitrogen plasma

Line radiation, in the wavelength region from 1040 to 2500 A from nitrogen plasmas, was measured at conditions typical of those produced in the shock layer in front of vehicles entering the earth's atmosphere at superorbital velocities. The radiation was also predicted with a typical radiation transport computer program to determine whether such calculations adequately model plasmas for the conditions tested. The results of the comparison show that the radiant intensities of the lines between 1040 and 1700 A are actually lower than are predicted by such computer models.

Mcclenahan, J. O.↗
NASA NTRS1973

The dissociation of shock-heated carbon monoxide

Investigation of the dissociation kinetics of undiluted carbon monoxide over the 5,600 to 12,000 K temperature range. Data are presented that have been obtained as time-resolved pressure measurements on the end wall of a shock tube and radiation emission of a C2 Swan system (0-0 band) behind incident shock waves. The decomposition of CO is complex and includes a chain with C2 as an intermediate species. The dissociation rate for the overall process has been found to be independent of the proportions of the collision partners M = CO, C, and O. The rate constant found is on the average about 10 times that previously measured with argon as the collision partner.

Hanson, R. K.↗
NASA NTRS1976

Equilibrium and nonequilibrium electron density measurements in transient shock-heated hydrogen-helium plasmas

In the NASA planetary program, atmospheric entry probe missions to Jupiter, Saturn, and Uranus are potential programs now being planned for the 1980's. The work reported in this paper is concerned with predicting the electron density, and resulting radiative emission from the shock layer which must be accommodated by the entry probe heatshield. Within the hydrogen-helium plasma surrounding the forward heatshield, there are regions of near thermochemical equilibrium whose properties are predictable - however, there are uncertainties in these electron density calculations necessitating further measurements by H-beta line broadening and holographic interferometer fringe shift as reported here. There is good agreement between the results obtained from the holographic measurements and the spectroscopic measurements which lends confidence to each of the two completely independent diagnostic techniques. The equilibrium electron density determined from the experimental measurements is somewhat higher than that predicted.

Livingston, F. R.↗
NASA NTRS2010

Detection of Shock-Heated Gas Using the Sz Effect in Rxj 1347-1145

Using the MUSTANG 3.3 mm bolometer array on the GBT we have measured the Sunyaev-Zel'dovich Effect (SZE) in the most x-ray luminous cluster known, RXJ 1 347-1145 (z=0.45) at a resolution of 10" (fwhm). This is the highest resolution image of the SZE to date and confirms previous indications of a localized departure from pressure equilibrium in the form of a small, very hot (>0 keV) parcel of gas, presumably resulting from a merger shock. We discuss the measurements, their interpretation, and future work.

Mason, Brian S.↗