The influence of a highly energetic electron beam on the electron
distribution function (e.d.f.) in a hot dense plasma is investigated by solving the
Boltzmann equation analytically. A plateau is obtained in the tail of the e.d.f. over
an energy range between the excitation threshold and an energy value half that
of the monoenergetic electrons. The importance of this plateau is discussed for a
dense He-like argon plasma.