  Ultracold plasmas (UCPs) are created under conditions of near but not perfect
neutrality. In the limit of zero electron temperature, electron screening
results in non-neutrality manifesting itself as an interior region of the UCP
with both electrons and ions and an exterior region composed primarily of ions.
The interior region is the region of the most scientific interest for
2-component ultracold plasma physics. This work presents a theoretical model
through which the time evolution of non-neutral UCPs is calculated. Despite
Debye screening lengths much smaller than the characteristic plasma spatial
size, model calculations predict that the expansion rate and the electron
temperature of the UCP interior is sensitive to the neutrality of the UCP. The
predicted UCP dependence on neutrality has implications for the correct
measurement of several UCP properties, such as electron temperature, and a
proper understanding of evaporative cooling of the electrons in the UCP.
