An analysis is made of the parametric frequency shift of an electromagnetic
wave traveling in a plasma (isotropic collisionless, isotropic collisional
, and magnetized collisionless) with time-varying parameters (Mikhel'son ef
fect). Different situations corresponding to the growth of plasma concentra
tion, a change of collision frequency, and a change of magnetic field are c
onsidered. (C) 2000 MAIK "Nauka/Interperiodica".