  This paper is a simulation based investigation of the effect of elastic
collisions and effectively elastic-like excitation collisions between electrons
and background neutrals on the dynamics of a cylindrically trapped electron
cloud that also has an ion contaminant mixed in it. Effects of the collisions
on the instability are evident from alteration in the growth rate and
energetics of the ion resonance instability caused by the presence of
background neutrals as compared to a vacuum background. Further in order to
understand if the non-ionizing collisions can independently be a cause of
destabilization of an electron cloud, a second set of numerical experiments
were performed with pure electron plasmas making non-ionizing collisions with
different densities of background neutrals. These experiments reveal that the
nature of potential energy extraction from the electron cloud by the
non-ionizing collisions is not similar to the potential energy extraction of
other destabilizing processes \textit{e.g.} a resistive wall instability. This
difference in the energy extraction process renders these non-ionizing
collisions incapable of independently triggering an instability of the cloud.

Plasma Physics