Spectral Band Absorptance of Radiation Traversing Two or More Cells in Series

Abstract

Theoretical equations are derived for the spectral band absorptance of radiation which traverses two or more cells in series. The amount of absorbing gas, pressure, and temperature of each cell may be chosen independently. Limiting expressions are obtained when the absorptance of all of the cells can be represented by either the weak line or the strong line approximation as well as when some of the cells can be represented by the weak line approximation while the remainder can be represented by the strong line approximation. Some of the results apply to any spectral band, while other results apply only to particular band models or to nonoverlapping spectral lines. The dependence of the absorptance on the various parameters is illustrated by numerous examples. The conditions for the validity of the usual interpolation procedure for obtaining the equivalent parameters for a homogeneous path are derived.