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Electron Temperature Relaxation in Afterglow Plasmas: Diffusion Cooling
Author(s) -
Trunec D.,
Španěl P.,
Smith D.
Publication year - 1994
Publication title -
contributions to plasma physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.531
H-Index - 47
eISSN - 1521-3986
pISSN - 0863-1042
DOI - 10.1002/ctpp.2150340109
Subject(s) - afterglow , ambipolar diffusion , atomic physics , metastability , electron , electron temperature , plasma , diffusion , materials science , relaxation (psychology) , ion , physics , thermodynamics , nuclear physics , psychology , social psychology , gamma ray burst , quantum mechanics , astronomy
We have carried out a thorough theoretical analysis of the cooling and heating processes of the electron gas in Ne, Ar and Kr afterglow plasmas. Thus the rate of relaxation of the electron temperature, T e , is seen to be in good agreement with the experimental measurements when spatial gradients of T e in the early afterglow and heating of the electron gas by superelastic collisions between the electrons and metastable atoms are accounted for. At low pressures of the rare gases, p g , the phenomenon of diffusion cooling occurs in which T e relaxes to an equilibrium temperature, T ee , which is less than the gas temperature, T g . This reduction in T ee below T g is mirrored in a reduction in the ambipolar diffusion coefficient, D a , for the rare gas atomic ions and electrons. Thus the D a can be calculated as a function of p g using the values of T ee , and when this is done, properly accounting for the heating by metastable atoms, the calculated and experimental values of D a in all three rare gas afterglows are seen to be in agreement.