Based on the resolution of the partial differential equation describin
g the external excitation of the Bohm-Gross longitudinal wave, analyti
cal expressions for causal responses of a dissipative macroscopic plas
ma are derived. Both impulsive and harmonic solutions representing the
spatial Green's functions of the radiation problem are given. These e
xact responses of the plasma, expressed in terms of two-variable Lomme
l functions, are then used to gain some better understanding of the ex
citation and dynamics of the well-known thermal wave. Special attentio
n is paid to the resonant excitation case. Intrinsic characteristics o
f the secular behavior of the radiated signal are illustrated and anal
yzed. It is shown that the proffered algebraic solutions constitute a
generalization of previous results inferred from an asymptotic represe
ntation of the Green's functions, or from the familiar steady state ha
rmonic approach. (C) 1997 American Institute of Physics.