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Studies of Flow Fields in Low-Pressure Spraying Plasmas Using Laser Diagnostics

Published online by Cambridge University Press:  22 February 2011

R. Hidaka
Affiliation:
Plant and Machinery Division, Nippon Steel Corporation, Tobata Fukuoka 804, Japan
T. Ohki
Affiliation:
Plant and Machinery Division, Nippon Steel Corporation, Tobata Fukuoka 804, Japan
J. Takeda
Affiliation:
R&D Laboratories I, Nippon Steel Corporation, Kawasaki Kanagawa 211, Japan
K. Kondo
Affiliation:
Department of Energy Conversion, Kyushu University, Kasuga Fukuoka 816, Japan
H. Kanda
Affiliation:
Department of Energy Conversion, Kyushu University, Kasuga Fukuoka 816, Japan
K. Muraoka
Affiliation:
Department of Energy Conversion, Kyushu University, Kasuga Fukuoka 816, Japan
M. Akazaki
Affiliation:
Department of Energy Conversion, Kyushu University, Kasuga Fukuoka 816, Japan
M. Maeda
Affiliation:
Department of Electrical Engineering, Kyushu University, Higashi Fukuoka 812, Japan
K. Teshima
Affiliation:
Kyoto University of Education, Fushimi Kyoto 612, Japan
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Abstract

In order to make desirable surface layers by low pressure plasma spraying (LPPS), optimum operating conditions and plasma torch gun designs must be decided upon for understanding LPPS plasma and powder behavior. As the first step of this approach, LPPS plasmas without powders were measured by the Thomson scattering, the Michelson interferometry and a Pitot tube. These diagnostics revealed that LPPS plasma jets may be treated as supersonic neutral gas flows as the first approximation. In addition, the neutral particle temperature Tn and ion temperature Ti were found to be the same as the electron temperature Te, which is 1 eV at an oblique shock wave heating point and 0.2 eV at the sugsequent cooling point. LPPS plasmas and flows were modeled by a computer Simulation of a supersonic nozzle flow, 2nd yielded reasonable understanding of the thermodynamic and fluid-mechanical conditions.

Type
Research Article
Copyright
Copyright © Materials Research Society 1988

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