  The paper presents the results of a study of the possibility of using the WKB
approach to describe Inhomogeneous Travelling-Wave Accelerating Sections
(ITWAS). This possibility not only simplifies the calculation, but also allows
the use of simpler physical models of transient processes. Using the traveling
wave concept simplifies the understanding of pulsed-excited ITWAS transients
and the development of methods to mitigate their effect on beam parameters.
