The propagation of one and two electron beams in a plasma is considered
in the case
when the source is time-dependent. When the electron-plasmon interaction
time
is assumed to be much less than the electron flying-off time, the main
gasdynamic
equations are obtained on the basis of the quasilinear theory of weak turbulence.
The solution for a monoenergetic beam is a beam–plasma structure
moving with
constant velocity. In general, two beams propagate as two beam–plasma
structures
with constant velocities. However, the second electron beam influences the
flying-off
dynamics of both beams. This peculiar interaction modifies the shapes of
the
structures.