DEVIATION FROM LOCAL THERMODYNAMIC-EQUILIBRIUM STATE IN THERMAL PLASMA

Citation
T. Kitamura et al., DEVIATION FROM LOCAL THERMODYNAMIC-EQUILIBRIUM STATE IN THERMAL PLASMA, ISIJ international, 38(11), 1998, pp. 1165-1169
Citations number
16
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Metallurgy & Metallurigical Engineering
Journal title
ISSN journal
0915-1559
Volume
38
Issue
11
Year of publication
1998
Pages
1165 - 1169
Database
ISI
SICI code
0915-1559(1998)38:11<1165:DFLTSI>2.0.ZU;2-1
Abstract
Spectroscopic analysis of Ar-H-2 and Ar-N-2 plasmas revealed that the population density of the excited states of each species (Ar, H and N) followed a Boltzmann distribution, but each species had its own respe ctive excitation temperature. The temperature of the argon was lower t han that of the hydrogen in the plasma of Ar-H-2 mixture. The temperat ure of the nitrogen was close to that of the argon in the plasma of Ar -N-2 mixture under one atmospheric pressure. The estimation of the tem peratures defined by the velocity distribution functions from the expe rimental conditions indicate that there are the possibilities to have higher temperatures for the hydrogen than that for the argon in the pl asma. These results suggest that there is a deviation from local therm odynamic equilibrium (LTE) in these plasmas under one atmospheric pres sure. The deviations from LTE in these plasmas are explained by the di fferences in the energy flow in the plasmas. The energy flows of these plasmas are considered as follows from the estimated relaxation limes of energy distributions for each species. As for the Ar-H2 plasma, th e electric energy is transferred to the electrons and then the energy of electrons is transferred to the hydrogen atoms. The argon atoms are mainly heated by collisions with the hydrogen atoms. In the case of t he Ar-N-2 plasma, both the argon atoms and the nitrogen atoms are heat ed by collisions with the electrons which obtain the electric energy. As a result, the temperature state of T-e approximately equal to T-H > T-Ar and T-e > T-Ar approximately equal to T-N could exist in the pla sma.