In a drift-tube analysis, an asymptotic solution for the transport of
inter-reacting multiple ion swarms approaching to dynamic equilibrium.
is proposed. The solution describes a set of similar Gaussian profile
s with two common ''equilibrium'' transport coefficients. Although all
the profiles apparently aggregate to the same location, there exists
a slight peak difference between arbitrary two spectra. The difference
holds even in the equilibrium. A generalized equilibrium constant is
defined by the quotient of two reaction-frequency determinants. Those
four kinetic constants are uniquely determined from the kinetic coeffi
cients of all ion species without any influence of the initial conditi
ons. The discrepancy between the thermal equilibrium and dynamic equil
ibrium is briefly discussed.