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Results for “Saha-Boltzmann”

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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Pulsed electromagnetic gas acceleration

Terminal voltage measurements with long cathodes in a high power, quasi-steady MPD discharge show that the critical current for the onset of voltage fluctuations, which was previously shown to be a function of cathode area, approaches an asymptote for cathodes of very large surface area. Floating potential measurements and photographs of the discharge luminosity indicate that the fluctuations are confined to the vicinity of the cathode and hence reflect a cathode emission process rather than a fundamental limit on MPD performance. Photoelectric measurements of particular argon neutral and ion transitions show that the higher electronic states are populated more heavily than would be calculated on the basis of Saha-Boltzmann equilibrium at the local electron temperature and number density. Preliminary optical depth measurements show that for a current of 4 kA and an argon mass flow of 12 g/sec, a population inversion exists between the upper and lower states of the 4880 A argon ion transition.

Jahn, R. G.↗
NASA NTRS1975

Laser processes in plasmadynamic flows

Radiation emitted from the exhaust flow of a multi-megawatt, quasi-steady magnetoplasmadynamic accelerator has been examined photoelectrically for argon mass flows from 6 to 32 g/sec and arc currents up to 25 kA. Vacuum ultraviolet radiation, indicative of resonance transitions, has been detected photoelectrically at various axial locations downstream of the arc chamber, consistent with a relaxation length calculated using a collisional-radiative recombination model. Photoelectric measurements of particular transitions in the neutral and first ionic state of argon show that populations of excited electronic states of AII are in excess of that which would be expected on the basis of Saha-Boltzmann equilibrium at the local electron temperature and number density. Optical depth measurements indicate that for a current of 4 kA and argon mass flow of 12 g/sec, a population inversion exists between the upper and lower states of the 0.4880 micron argon ion transition.

Campbell, E. M.↗
NASA NTRSDate not supplied

Including Radiative Heating for the Design of the Orion Backshell for Artemis-1: A Narrative

The backshell radiative heating for Earth entry was ignored primarily because of the negligible Fire and Apollo 4 backshell radiometer measurements and negligible radiative heating resulting from the assumed upper-limit Boltzmann assumption of atomic electronic levels. These assumptions are shown to be erroneous in the recombining expanding flow characteristic of the wake, where the slow finite-rate recombination of electrons and ions leads to the Saha-Boltzmann distribution being larger than the Boltzmann distribution.

aftbody radiation↗