This work is concerned with the theoretical description of thermal fluctuain classical plasmas that are homogeneous or have background temperature gradients. Attention is focussed on the particularly important mode, the ion acoustic wave. Experimentalists utilize Thomson scattering from ion acoustic fluctuations to extract information such as drift velocities and temperatures. Collisionless theories are reasonably successful in describing Thomson scattering experiments and are usually adopted for simplicity. Including the effects of collisions into the theory will extend the usefulness of Thomson scattering as a diagnostic tool.

Our understanding of collisional effects (e-e), (e-i) and (i-i) on ion acoustic waves has been advanced by an analytical treatment of the electron kinetic equation. The results of this theory have led to a complete description of ion acoustic dispersion and damping over the full range of particle collisionality. The non local electron heat conductivity associated with these waves has also been investigated and the possibility of observing such non local transport effects from Thomson scattering measurements has been examined.