Abstract
We present an analytic model of a collimated ejection with a "single pulse" Gaussian ejection velocity. This flow produces a dense "head" (the leading working surface) joined to the outflow source by a "tail" of lower velocity material. For times greater than the duration of the ejection pulse, this tail develops a linear radial velocity vs. position structure. This "head/tail plasmon" structure is interesting for modelling astrophysical "bullets" joined to their outflow sources by structures with "Hubble law" radial velocity dependencies. We study the case of a Gaussian ejection velocity law with a constant and a Gaussian ejection density history, We compare these two cases, and find that the main effect of the different ejection density histories is to change the mass and the density stratification of the plasmon tail.
