Landau damping, free from the influence of other forms of damping, has been
experimentally detected in ion acoustic waves in traces of a dope plasma o
f a light inert gas, when it is introduced into partially ionized plasma of
a heavy inert gas. A theory has been worked out of Landau damping for long
itudinal waves in Vlasov plasma for study of this and other familiar Landau
dampings. (C) 2001 American Institute of Physics.