DEVELOPMENT OF FREE-MOLECULAR LANGMUIR PROBES FOR MEASUREMENT OF ELECTRON TEMPERATURE AND NUMBER DENSITY IN SHOCK-TUNNEL FLOWS

Thin-wire Langmuir probes were used to measure the electron temperature and electron density of the inviscid nozzle flow of a short-duration reflected-shock tunnel at conditions for which the flow was free molecular with respect to the probe diameter. Experiments were conducted at equilibrium reserv...

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Bibliographic Details
Main Authors: Dunn,Michael G, Lordi,John A
Format: Report
Language:English
Subjects:
AIR
ARGON
ELECTRON DENSITY
FREE MOLECULE FLOW
INVISCID FLOW
LANGMUIR PROBES
NOZZLE GAS FLOW
Plasma Physics and Magnetohydrodynamics
PRESSURE
RAREFIED GAS DYNAMICS
SHOCK TUBES
TEMPERATURE
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Summary:Thin-wire Langmuir probes were used to measure the electron temperature and electron density of the inviscid nozzle flow of a short-duration reflected-shock tunnel at conditions for which the flow was free molecular with respect to the probe diameter. Experiments were conducted at equilibrium reservoir conditions of 6850K and 22 atm pressure in air and at 8000K and 9.35 atm pressure and at 6090K and 10.4 atm pressure in argon. The electron densities were simultaneously measured using microwave interferometers and found to be in good agreement with the values obtained from the Langmuir probe. The experiments have confirmed the validity of Laframboise' theoretical predictions for ion collection, including that in the orbital-motion-limited region. The electron temperatures measured in both the air and argon plasmas were found to be significantly greater than the calculated heavy-particle translational temperature, although in all cases the Langmuir probe results indicated that the electron velocity distribution was Maxwellian. (Author)