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Title: Shock velocity in weakly ionized nitrogen, air, and argon

Abstract

The goal of this research was to determine the principal mechanism(s) for the shock velocity increase in weakly ionized gases. This paper reports experimental data on the propagation of spark-generated shock waves (1<Mach<3) into weakly ionized nitrogen, air, and argon glow discharges (1 <p<20 Torr). In order to distinguish between effects due solely to the presence of electrons and effects due to heating of the background gas via elastic collisions with electrons, the weakly ionized discharge was pulsed on/off. Laser deflection methods determined the shock velocity, and the electron number density was collected using a microwave hairpin resonator. In the afterglow of nitrogen, air, and argon discharges, the shock velocity first decreased, not at the characteristic time for electrons to diffuse to the walls, but rather at the characteristic time for the centerline gas temperature to equilibrate with the wall temperature. These data support the conclusion that the principal mechanism for the increase in shock velocity in weakly ionized gases is thermal heating of the neutral gas species via elastic collisions with electrons.

Authors:
 [1]
  1. Air Force Research Laboratory, Wright Patterson, Ohio 45433 (United States)
Publication Date:
OSTI Identifier:
20991245
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Fluids (1994); Journal Volume: 19; Journal Issue: 3; Other Information: DOI: 10.1063/1.2716803; (c) 2007 U.S. Government; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; AFTERGLOW; AIR; ARGON; ELECTRON DENSITY; GLOW DISCHARGES; NITROGEN; PRESSURE RANGE KILO PA; PRESSURE RANGE PA; RESONATORS; SHOCK WAVES; VELOCITY; WAVE PROPAGATION

Citation Formats

Siefert, Nicholas S. Shock velocity in weakly ionized nitrogen, air, and argon. United States: N. p., 2007. Web. doi:10.1063/1.2716803.
Siefert, Nicholas S. Shock velocity in weakly ionized nitrogen, air, and argon. United States. doi:10.1063/1.2716803.
Siefert, Nicholas S. Thu . "Shock velocity in weakly ionized nitrogen, air, and argon". United States. doi:10.1063/1.2716803.
@article{osti_20991245,
title = {Shock velocity in weakly ionized nitrogen, air, and argon},
author = {Siefert, Nicholas S.},
abstractNote = {The goal of this research was to determine the principal mechanism(s) for the shock velocity increase in weakly ionized gases. This paper reports experimental data on the propagation of spark-generated shock waves (1<Mach<3) into weakly ionized nitrogen, air, and argon glow discharges (1 <p<20 Torr). In order to distinguish between effects due solely to the presence of electrons and effects due to heating of the background gas via elastic collisions with electrons, the weakly ionized discharge was pulsed on/off. Laser deflection methods determined the shock velocity, and the electron number density was collected using a microwave hairpin resonator. In the afterglow of nitrogen, air, and argon discharges, the shock velocity first decreased, not at the characteristic time for electrons to diffuse to the walls, but rather at the characteristic time for the centerline gas temperature to equilibrate with the wall temperature. These data support the conclusion that the principal mechanism for the increase in shock velocity in weakly ionized gases is thermal heating of the neutral gas species via elastic collisions with electrons.},
doi = {10.1063/1.2716803},
journal = {Physics of Fluids (1994)},
number = 3,
volume = 19,
place = {United States},
year = {Thu Mar 15 00:00:00 EDT 2007},
month = {Thu Mar 15 00:00:00 EDT 2007}
}